| Question
| # replies
| Last Post
|
| why moisture shift from down field to up field in VT NMR experiment
| 0 | Tue May 7
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| i am using a solvent mixture of 1 butanol:glacial acetic acid:water, but the rf values are almost similar, what will b the solution
| 0 | Tue May 7
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| What will be the result if my products are dissolved in the solution about the column? (column chromatography)
| 0 | Fri Apr 12
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| What will be the result if my products are dissolved in the solution about the column?
| 0 | Fri Apr 12
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| What if my sample does not dissolve in any of the solvents?
| 0 | Thu Apr 4
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| on TLC, my best mobile solvent is butanol:acetic acid :water, can i use this same B;A:W solvent as my eluting solvent in column chromatography, without encountering problems as butanol is less polar?
| 0 | Thu Mar 21
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| compound only soluble in HCl and NaOH hoe can take NMR?
| 1 | Sat Mar 16
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| compound not soluble in solvents how can take NMR?
| 0 | Fri Mar 15
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| the easier way to know acompound in spectroscopy problems?
| 0 | Fri Mar 1
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| What is the best apparatus to use for the conversion of a carboxylic acid to the corresponding acid chloride with SOCl2 on a ca. 1g scale?
| 0 | Mon Feb 25
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| What will be the result if too much sample is applied in TLC
| 2 | Thu Mar 14
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| I am doing a qualitative test for ciprofloxacin in pharmaceutical products. According to the British pharmacopea, the difference between the spots of the standard anf test splutions should have a percentage of 0.2%25. the values i get are o.1mm different but not percentage wise. How can i get the 0.2%25 difference
| 0 | Wed Feb 20
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| I am doing a qualitative test for ciprofloxacin in pharmaceutical products. According to the British pharmacopea, the difference between the spots should have a percentage of 0.2%25. the values i get are o.1mm different but not percentage wise. How can i get the 0.2%25 difference
| 0 | Wed Feb 20
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| My question is regarding TLC. The reactant and product are polyamine type. The two spots are not moving even I tried with various eluents combination. And, the spots are moving in the shape of flame. Kindly do suggest.
| 2 | Tue Feb 12
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| what is the most possible ratios of mobile phases? or all ratios must be tried?
| 0 | Sun Feb 3
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| How to remove the pyridine solvent from the reaction mass with out making Azeotrop?
| 1 | Tue Mar 19
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| What color does benzil reagent gives for visualization of fatty acid on thin layer plate.
| 0 | Sat Jan 26
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| supply from stock (S)-3-(Boc-amino)pyrrolidine CAS: 122536-76-9
| 1 | Thu Jan 17
|
| Shanghai Hobor chemical co.,Ltd is professional R&D and manufacturing of intermediates,active ingredients, Our custom synthesis department can supply chemical development, custom synthesis services quantities ranging from grams to tons.more details please visit our company website
| 0 | Thu Jan 17
|
| supply from stock (R)-3-(Boc-amino)pyrrolidine %7C CAS: 122536-77-0
| 1 | Thu Jan 17
|
| What is the function of the components of the solvent system of Butanol: Acetic Acid: Distilled Water in separating amino acids?
| 0 | Wed Jan 16
|
| supply (S)-( )-1-Benzyl-3-aminopyrrolidine CAS:114715-38-7
| 1 | Tue Jan 15
|
| supply (R)-(-)-1-Benzyl-3-aminopyrrolidine CAS:114715-39-8
| 1 | Tue Jan 15
|
| supply (3S)-( )-3-Aminopyrrolidine dihydrochloride CAS:116183-83-6
| 1 | Tue Jan 15
|
| supply (R)-1-Boc-2-cyanopyrrolidine CAS:228244-20-0
| 1 | Tue Jan 15
|
| supply (S)-1-Boc-2-cyanopyrrolidine CAS:228244-04-0
| 1 | Tue Jan 15
|
| supply (R)-2-(Aminomethyl)-1-N-Boc-pyyrolidine CAS:259537-92-3
| 1 | Tue Jan 15
|
| supply (S)-1-N-Boc-2-(aminomethyl)pyrrolidine CAS:119020-01-8
| 1 | Tue Jan 15
|
| supply 3-Aminopyrrolidine dihydrochloride CAS:103831-11-4
| 1 | Tue Jan 15
|
| supply (R)-1-Boc-3-hydroxypyrrolidine CAS:103057-44-9
| 1 | Tue Jan 15
|
| supply (R)-4-Boc-2-methylpiperazine CAS:163765-44-4
| 1 | Tue Jan 15
|
| supply (S)-4-N-Boc-2-methylpiperazine CAS:147081-29-6
| 1 | Tue Jan 15
|
| supply (S)-1-N-Boc-2-methylpiperazine CAS:169447-70-5
| 1 | Tue Jan 15
|
| supply N-Boc-piperazine-2-carboxylic acid methyl ester CAS:129799-15-1
| 2 | Tue Jan 15
|
| supply 1-Boc-2-Methylpiperazine CAS:120737-78-2
| 1 | Tue Jan 15
|
| supply N-Boc-3-Ethylpiperazine CAS:438049-35-5
| 1 | Tue Jan 15
|
| supply 4-N-Boc-2-Methyl-piperazine CAS:120737-59-9
| 1 | Tue Jan 15
|
| supply from stock 1-(3-Trifluoromethylphenyl)piperazine hydrochloride CAS: 16015-69-3
| 1 | Tue Jan 15
|
| supply from stock Piperazin-2-one CAS:5625-67-2
| 1 | Tue Jan 15
|
| supply (R)-3-Aminopiperidine dihydrochloride CAS:334618-23-4
| 3 | Tue Jan 29
|
| supply (S)-3-Aminopiperidine dihydrochloride CAS:334618-07-4
| 1 | Tue Jan 15
|
| supply (R)-(-)-1-Benzyl-3-hydroxypiperidine CAS:91599-81-4
| 1 | Tue Jan 15
|
| supply (S)-( )-1-Benzyl-3-hydroxypiperidine CAS:91599-79-0
| 1 | Tue Jan 15
|
| supply 1-Boc-4-Methylaminopiperidine CAS: 147539-41-1
| 2 | Tue Jan 15
|
| supply 3-N-Boc-Aminomethylpiperidine CAS: 142643-29-6
| 1 | Tue Jan 15
|
| supply 4-(Boc-Aminomethyl)piperidine CAS: 135632-53-0
| 1 | Tue Jan 15
|
| supply 4-(2-Aminoethyl)-1-Boc-piperidine CAS: 146093-46-1
| 1 | Tue Jan 15
|
| supply 1-Boc-4-(aminomethyl)piperidine CAS:144222-22-0
| 1 | Tue Jan 15
|
| supply 3-Aminomethyl-1-N-Boc-piperidine CAS: 162167-97-7
| 1 | Tue Jan 15
|
| supply 2-(Aminomethyl)-1-Boc-piperidine CAS: 370069-31-1
| 1 | Tue Jan 15
|
| supply 4-(Aminomethyl)piperidine CAS: 7144-05-0
| 1 | Tue Jan 15
|
| supply 2-(Aminomethyl)piperidine CAS: 22990-77-8
| 1 | Tue Jan 15
|
| supply (S)-1-Boc-3-hydroxypiperidine CAS:143900-44-1
| 1 | Tue Jan 15
|
| supply (R)-1-Boc-3-Hydroxypiperidine CAS:143900-43-0
| 1 | Tue Jan 15
|
| supply (S)-3-Hydroxypiperidine hydrochloride CAS:475058-41-4
| 1 | Tue Jan 15
|
| supply (R)-3-Hydroxypiperidine hydrocloride CAS:198976-43-1
| 1 | Tue Jan 15
|
| supply (S)-3-N-Boc-aminopiperidine CAS:216854-23-8
| 1 | Tue Jan 15
|
| supply (R)-3-(Boc-Amino)piperidine CAS:309956-78-3
| 1 | Tue Jan 15
|
| supply (S)-3-Amino-1-N-Boc-piperidine CAS:625471-18-3
| 1 | Tue Jan 15
|
| supply (R)-1-Boc-3-Aminopiperidine CAS:188111-79-7
| 1 | Tue Jan 15
|
| supply from stock 3-N-Boc-aminopiperidine CAS:172603-05-3
| 1 | Tue Jan 15
|
| supply from stock tert-Butyl 1-piperazinecarboxylate CAS:57260-71-6
| 4 | Tue Jan 29
|
| supply from stock 1-Benzylpiperazine dihydrochloride BZP CAS: 5321-63-1
| 1 | Tue Jan 15
|
| supply from stock 1-benzylpiperazine BZP CAS:2759-28-6
| 1 | Tue Jan 15
|
| supply from stock N-BOC-3-aminopiperidine CAS:184637-48-7
| 1 | Tue Jan 15
|
| supply from stock 4-N-BOC-aminopiperidine CAS:73874-95-0
| 1 | Tue Jan 15
|
| supply from stock 4-Amino-1-Boc-piperidine CAS:87120-72-7
| 1 | Tue Jan 15
|
| supply 4-Amino-1-benzylpiperidine CAS:50541-93-0
| 1 | Tue Jan 15
|
| supply from stock 1-Methylpiperidin-4-amine CAS:41838-46-4
| 1 | Tue Jan 15
|
| supply from stock 4-Chloro-N-methylpiperidine CAS:5570-77-4
| 1 | Tue Jan 15
|
| supply 1-Boc-3-hydroxypiperidine CAS:85275-45-2
| 1 | Tue Jan 15
|
| supply from stock 3-hydroxypiperidine CAS:6859-99-0
| 1 | Tue Jan 15
|
| supply from stock N-Boc-4-hydroxypiperdine CAS:109384-19-2
| 3 | Sun Jan 27
|
| supply from stock Ethyl 4-hydroxypiperidine-1-carboxylate CAS: 65214-82-6
| 1 | Tue Jan 15
|
| supply from stock N-Methyl-4-piperidinol CAS:106-52-5
| 1 | Tue Jan 15
|
| supply from stock 4-hydroxypiperidine CAS:5382-16-1
| 1 | Tue Jan 15
|
| supply from stock 1-Boc-3-piperidone CAS:98977-36-7
| 1 | Tue Jan 15
|
| supply from stock 1-Cbz-4-Piperidone CAS:19099-93-5
| 1 | Tue Jan 15
|
| supply from stock N-(tert-Butoxycarbonyl)-4-piperidone CAS:79099-07-3
| 1 | Tue Jan 15
|
| supply from stock N-carbethoxy-4-piperidone CAS:29976-53-2
| 1 | Tue Jan 15
|
| supply from stock 1-phenethyl-4-piperidone CAS:39742-60-4
| 1 | Tue Jan 15
|
| supply from stock N-Benzyl-4-piperidinone CAS:3612-20-2
| 1 | Tue Jan 15
|
| supply from stock 1-methyl-4-piperidone CAS:1445-73-4
| 1 | Tue Jan 15
|
| supply from stock 4,4-Piperidinediol hydrochloride CAS:40064-34-4
| 1 | Tue Jan 15
|
| supply (S)-3-Pyrrolidinol hydrochloride CAS:122536-94-1
| 1 | Tue Jan 15
|
| supply from stock (R)-(-)-3-Pyrrolidinol hydrochloride CAS:104706-47-0
| 1 | Tue Jan 15
|
| supply from stock (R)-(-)-N-Boc-3-pyrrolidinol CAS:109431-87-0
| 1 | Tue Jan 15
|
| supply from stock (S)-( )-1-Boc-3-hydroxypyrrolidine CAS:101469-92-5
| 1 | Tue Jan 15
|
| supply (S)-(-)-1-Boc-3-aminopyrrolidine CAS:147081-44-5
| 1 | Tue Jan 15
|
| supply (3R)-(-)-3-Aminopyrrolidine dihydrochloride CAS:116183-81-4
| 1 | Tue Jan 15
|
| supply (R)-( )-1-Boc-3-aminopyrrolidine CAS:147081-49-0 Hobor chemical co.,Ltd
| 2 | Tue Jan 15
|
| supply from stock tert-Butyl 3-aminopyrrolidine-1-carboxylate CAS:186550-13-0 Shanghai Hobor chemical co.,Ltd is professional R&D and manufacturing of intermediates,active ingredients, Our custom synthesis department can supply chemical development, custom synthesis services quantities ranging from grams to tons.more details please visit our company website
| 4 | Sun Jan 27
|
| supply from stock N-Boc-3-pyrrolidinone %7C CAS:101385-93-7
| 2 | Tue Jan 15
|
| c
| 0 | Tue Jan 15
|
| on the TLC plate i loaded 2 things starting material (reactant) and the product how could i know whether the reaction is complete or not
| 1 | Sat Jan 19
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| How does the recrystallization procedure remove solvent soluble impurities?
| 0 | Thu Jan 3
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| why could my nmr look different for my product and starting material after epoxidation?
| 0 | Tue Dec 11
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| my compound contains terminal alkyne, but when i tried it to purify by coloumn chromatography containing 100-200 mesh silica gel, i didnt found it????
| 1 | Sat Jan 19
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| can i use DMF as solvent in LDA reaction????
| 0 | Thu Dec 6
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| im getting lot of impurities in the range 1 to 3 ppm even though i use distilled pet ether petether. How can i avoid them
| 0 | Wed Dec 5
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| Why only NH or OH proton can be D2O exchange but not CH proton?
| 2 | Mon Dec 10
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| 4-bromoacetanilide polar
| 4 | Sun Dec 9
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| 1.%09Suppose you prepared benzil by the oxidation of benzoin, describe how you could use TLC (thin layer chromatography) to decide when the reaction is complete.
| 0 | Wed Nov 14
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| how to made deuterated diphenylmethanol
| 2 | Mon Dec 10
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| can we separate amino acid and amino ester hydrochloride
| 0 | Mon Nov 12
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| solvent which are used for non aqeous titration
| 0 | Wed Nov 7
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| What problem with ensue if the level of the developing liquid is higher than the applied spot in a TLC analysis?
| 1 | Fri Nov 2
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| my compound contains double bond NH,when i m doing the column then it simply converted in to carboxylic group,the reason is that silica is in acidic form it converted double bond NH to Double bond O , so now i m in problem that how to separate that compound?
| 1 | Tue Nov 6
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| How do I know when I need to use a gradient solvent system for chromatography?
| 3 | Sun Dec 9
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| reductive opening of benzylidene
| 2 | Sat Nov 3
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| %FD must take three different spot on tlc plate one of tehem is polar and the others are non polar and close to each other normally %FD can take such this spot with a mobile phase like etoac :hex 1:2 but for this molecule %FD use etoac:hex 1:4 bu %FD couldnt separate what can %FD do ?
| 3 | Sat Nov 3
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| My compound decomposes on silica, and I am not getting separation on neutral alumina what should i do?
| 6 | Sat Nov 3
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| What is my compound keep change from liquid state to semi solid, then added with silica powder for solid loading, it remains at semi solid state? What should i do?
| 2 | Sat Nov 3
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| In general, we assume that in a mixture, each component will show the same Rf value it shows when it runs alone. However, sometimes in the presence of a large amount of a second component the Rf is affected. Why does this behavior occur? TLC experimentation
| 4 | Mon Dec 10
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| what should yoou do before using reagents
| 0 | Sun Sep 16
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| what is mean by radial development in paper chromatography
| 0 | Thu Sep 13
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| In my compound I have Methyl, Phenyl chloro acetamide type structure where I couldn't see proper splitting for aromatic, as well as for ch2cl group.
| 0 | Wed Sep 12
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| no spot are seen on the plate
| 0 | Tue Sep 11
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| many random spotseen on the plate
| 0 | Tue Sep 11
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| the compound runs as a streak rather than a spot
| 1 | Tue Nov 6
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| I need to take TLC of "reactive dyes" so kindly tell which solvent should I use and what should be the percentage of dyes solution should I use for following.
| 0 | Sun Sep 2
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| Why are most of the questions on this website worded poorly and written by complete morons?
| 4 | Tue Jan 8
|
| How we can distinguish between 1 HNMR peaks of NH and NH2 in cyclic amine?
| 0 | Fri Jul 27
|
| I know how to remove grease from my apparauses. But how to remove grease by column chromatograpy? Is there anyone who knows about solvent conditions? Beacause the substrate which will be isolated is in not-validated apparatus.
| 2 | Fri Jul 27
|
| why are unused reagents not returned to the original bottle?
| 2 | Wed Nov 21
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| my meth powder has turned to oil after mixing it what do i do next to crystalize it help meeeee;-%5B
| 1 | Sat Jul 28
|
| What is the best way to remove m-CPBA following epoxidation?
| 4 | Wed Nov 14
|
| Explain the difference between co-precipitation and post precipitation
| 6 | Sun May 19
|
| What is the number of atoms in one molecule of sulfur trioxide?
| 1 | Fri Jun 22
|
| How to work up reduction reaction with dibalh and give me all the required steps to take up the reaction
| 0 | Tue Jun 19
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| If all spots were at the very top of TLC plate and I want to decrease polarity of the solvent to be able to produce good separation, do I increase or decrease the percent of hexane
| 4 | Tue Sep 25
|
| How do you obtain %25 composition of a reaction on GC using an internal standard?
| 2 | Fri Jul 27
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| my compound is too polar in nature to run on tlc.it get stcks to the base line.
| 2 | Thu Jun 7
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| my compound is sticky in nature.i have tried hexane or petroleum ether but of no use.suggestions regarding this.
| 4 | Fri Jul 27
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| WHAT IS A STROHMEYER APPARATUS???
| 0 | Wed May 16
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| What is a strohmeyer apparatus?
| 0 | Wed May 16
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| How to solidify a semisolid compound because a semisolid compound can't be sent for CHN analysis? Also I'm pretty sure that it's a solid.
| 1 | Tue May 22
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| in carrying out an analysis of a mixture, what do you expect to see when the TLC plate has been allowed to remain in the developing chamber too long, so that the solvent front has reached the top of the plate?
| 1 | Wed May 23
|
| hi, what's the best procedure to work up Red-Al reaction?
| 0 | Sat Apr 28
|
| what is Handellah
| 0 | Wed Apr 25
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| i am facing the problem regarding the flow rate while running the column in ethyl acetate and methanol... what could be the reason?
| 0 | Wed Apr 25
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| my chemical compound goes with solvent front,Is it correct?
| 0 | Tue Apr 24
|
| How to prepare Ni3Al Nickel aluminide intermetalic powder?
| 2 | Tue May 15
|
| What is difference between recrystallization and fractional recrystallization
| 2 | Mon May 14
|
| My compound will not dissolve in the eluent and therefore i have to place it in the topic of the silica gel in 3 separate tries is this a problem?
| 2 | Mon May 14
|
| chanding the drug conc leads to increase the Rf in the same system. why?
| 2 | Mon May 14
|
| For column chromatography, can you load a solid sample immediately onto the silica gel without adsorbing it to silica first?
| 2 | Tue May 15
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| I have a syringe with the sample in it, and I want to weigh it. How?
| 1 | Tue May 15
|
| Will NH protons get exchanged with acetone-d6 (in the absence of D2O)
| 0 | Fri Mar 23
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| I Dueterated my compound with MeOH-d4 to check the OH proton. Now how can I get my Startimg material back??????????/
| 0 | Thu Mar 22
|
| Over loading of sample
| 0 | Wed Mar 21
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| report the yield of the initial and final product and same to be recrystalisted by using suitable solvent and placing for the examintion
| 2 | Tue Mar 27
|
| What is the purpose of making derivatives of unknowns
| 0 | Mon Mar 19
|
| A hot solution of a particular compound was allowed to cool to room temperature. After waiting a few minutes, it was noticed that the crystallization had not taken place. Discuss two ways to induce crystallization.
| 5 | Sat May 12
|
| 6.%09You have recrystallized ferrocene by the two-solvent method (acetone-water). Based on the following solubility test results for ferrocene, suggest (i) another pair of solvents that may be used in the two-solvent method and (ii) a solvent that may be used for the single solvent method
| 3 | Mon Apr 2
|
| why is it possible to have a clean seperation of benzoin from dichlomethane
| 0 | Sat Mar 17
|
| prepare good quality and quantity of p-Bromoacetanilide from Anilide?
| 2 | Tue Mar 27
|
| A hot solution of a particular compound waz allowed to cool to room temperature.After waiting a few minutes,it waz noticed that the crystallization had not taken place.Indicate and discuss two ways to induce crystallization.
| 1 | Tue Mar 20
|
| ion exchange
| 0 | Mon Mar 12
|
| %250A
| 0 | Fri Mar 9
|
| What happens to the Rf if you used water as a solvent, and in the second you used ethyl alcohol as the solvent.
| 0 | Thu Mar 8
|
| The solvent peak and the water peak are missing when they are usually there
| 0 | Wed Mar 7
|
| what color is bromoacetanilide suppose to be
| 1 | Sun Apr 1
|
| I did a boc deprotection of my compound and tlc showed a completion and IR as well confirm a presence of a free amine but im still seeying a huge t-butyl pic in my H NMR proton what can i do to get rid of that
| 2 | Tue Mar 27
|
| whatis the best solvent for crystalizing cholesterol?
| 2 | Tue Mar 27
|
| If you had a mixture of aniline and naphthalene describe briefly how you would separate the mixture.
| 0 | Mon Mar 5
|
| what would happen if a sample was immersed in the chromatography solvent, instead of suspended above it?
| 2 | Tue Mar 27
|
| I am going to extract glycoside from gravity column chromatography with silica gel,what solvent should I use and in which ratio I should use?
| 0 | Wed Feb 29
|
| my product is only soluble in DMSO/DMf ,how can I recrystallize from it.
| 0 | Tue Feb 28
|
| I have collected crude extractive compountd of plant material from acetone and benzene-etanol solvents. please give sugession how to purify and chrecterise it ?
| 0 | Mon Feb 27
|
| My compound is relatively non-polar, but once it crystallizes out of solution, it's nearly impossible to get it back into solution. I think this also occurs on silica, often losing 50%25 per step, flushing the column doesn't help. Any tips?
| 0 | Mon Feb 27
|
| I am dealing with a compound having long alkyl chain backbone(12 carbon)with carboxylic acid end group. When I tried to run the TLC it showed tailing in near to every solvent. (I used different proportion of Diethyl ether, ethyl acetate, hexane, chloroform, methanol, Dichloromethane, few drops of acetic acid and ammonium hydroxide)but I would not get the better seperation. Is it possible that carboxylic acid will make complex with silica. Is methylation of acid will help in better seperation. How can I solve this problem
| 3 | Sat Apr 7
|
| my sample (cyclodextrin sulfonate compound) is soluble in water and pH 8-9, Reverse phase TLC development. I have problem with purification with LiChrospher%AE RP-18 endcapped silica gel. Please tell me how to do. thank in advance,
| 0 | Sat Feb 25
|
| I have extracted plant extracts using water, which means mainly the polar solvents has been extracted.Now I would like to know which solvent or solvent mixture to be used to obtain the spots?? Also what should I use as a developing agent?
| 0 | Fri Feb 24
|
| I have extracted plant extracts using water, which means mainly the polar solvents has been extracted.Now I would like to know which solvent or solvent mixture to be used to obtain the spots??
| 3 | Tue Mar 27
|
| Briefly discuss the problem that would occur if the wrong pH paper was used during acidification of sodium benzoate.
| 0 | Tue Feb 21
|
| why do we use hexane:ethyl acetate(6:4) for the TLC of amine derivatives of triazole
| 2 | Tue Mar 27
|
| Suppose you prepared benzhydrol by the reduction of benzophenone with sodium borohydride. Briefly describe how you could use TLC to decide when the reaction was complete.
| 2 | Mon Feb 27
|
| My product forms a gel like substance in brine. How do I get it back from the Brine/remove the salt?
| 2 | Mon Feb 27
|
| What is the major product isolated after acidification of the soap solution?
| 1 | Sun Apr 29
|
| pd/c
| 2 | Wed Feb 29
|
| is it wrong to distilled and reuse the solvent(eluate) collected by column chromatography with compound in it, where the compound is concentrated n collected separately
| 2 | Mon Feb 27
|
| how to calculate azadirechtin content in form of ppm from chromatogram
| 0 | Thu Jan 19
|
| Dear Sir/Madam, I purified a couple of compounds with hexane and ethyl acetate from the concentrate which was extracted by ethanol (its a Natural product). on doing NMR i saw the result and was amazed by the impurities around my sample even though i feel i've done enough to remove the impurities and extracted pure compounds, plus my concentration of the sample was less compared to the solvent(D. Chloroform). What can i do to minimise the noise as much as possible and an effective way of getting more concentration. thank you Imran
| 0 | Wed Jan 4
|
| I'd like to know the temparature at which nickel oxide/ nickelous oxide convert into Ni metal powder in the medium of Hydrogen.
| 0 | Sat Dec 31
|
| Dear sir/ Madam. I want to ask that My compound is only soluble in DMF And DMSO. TLC of that compound showing some impurity. How can I purify it.? I have already tried solvent method for the purification by using Hexanes, Pet ether, diEthyl ether acetone and methanol.
| 0 | Fri Dec 30
|
| I had no idea how to arppoach this before-now I'm locked and loaded.
| 0 | Sun Dec 18
|
| I need to Hydrogenate as part of an other wise simple prep using H2/Pd/C. In the Reference paper they use a Parr Hydrogenator under pressure. Beside the Hydrogenator what else is needed? Does the prep need to be done in a glove box. What is the level of difficulty? Thanks!
| 0 | Sat Dec 17
|
| I AM GETTING PROBLEM WITH C 8 AND C 18 COLUMN.IT GIVES DIFFERENT PEAK SHAPES WITH PEAK SPLITTING .IF ,PROBITY COLUMN IS GOING TO COLLAPSES IT DON'T GIVE ANY OTHER ANALYSIS PEAKS. BUT I AM GETTING PROBLEM ,THAT IN SOME INSTANCE IT GIVE GOOD PEAK RESPONSE AND SOME INSTANCES WITH PEAK SPLITTINGS.PLZ SOLVE THE PROBLEM.
| 0 | Tue Dec 6
|
| how to quench the reagents
| 0 | Sat Dec 3
|
| Once the chromatographic column has been prepared, why is it important to allow the level of the liquid in the column to drop to the level of the alumina before applying the solution of the compounds to be separated?
| 0 | Fri Dec 2
|
| Can I use water as a solvent for column chromatography?
| 2 | Fri Dec 30
|
| My components move up to certain level in TLC and then it seem to disperse and overlap each other for a big oval shape at that level......I had tried to dip the sample wif few drops of ammonium hydroxide and ethyl acetate because i suspected my sample is either too acidic o alkali but the result still the same
| 0 | Wed Nov 30
|
| how to remove DCM from my sample? After evaporating DCM my sample gets sticky, I have tried to remove it by dissolving my sample in different solvent and triturating them in sonicator followed by rotoevaporation, but yet it is sticky. Please Help.
| 1 | Thu Dec 8
|
| All of my spectra using DMSO-d6 have a really wide H2O peak. Is there any way I can reduce this? Should I drop a few molecular sieves in my bottle, even though I'm using it outside a fume hood ?
| 1 | Wed Jan 18
|
| My compound is an organic acid which is poorly soluble in everything I've tried (H2O, MeOH, DCM, EtOAc, hexanes, etc) except for DMSO. Is there any way I can purify it from a similar byproduct?
| 1 | Fri Dec 16
|
| Not a question, but a tip. Small scale distillation or sublimation - place small amount of material into a 15ml culture tube and heat in heat bath - length of culture tube usually provides enough cooling to collect condensate at upper ends of the tube. Liquid droplets easily collected by micropipette and solids by scraping with spatula or pipette tip.
| 0 | Sun Nov 27
|
| There is an old trick to removing DMF or DMSO from an organic layer using a dilute copper sulfate solution. Does anyone remember this technique or the percentage of copper sulfate used?
| 0 | Sun Nov 27
|
| b.%09No watch glass was placed over the developing chamber.
| 2 | Mon Nov 7
|
| why are the more hydrophilic components of a mixture held more tightly on a column of silica gel than the more lipophilc components?
| 0 | Wed Nov 2
|
| what would have happened if 50:50 ethyl acetate petrolium ether was used to the cholesterol before dichloromethane
| 0 | Wed Nov 2
|
| Suppose you prepared benzhydrol by the reduction of benzophenone with sodium borohydride. Briefly describe how you could use TLC to decide when the reaction was complete.
| 2 | Mon Nov 7
|
| 4.%09Suppose you prepared benzhydrol by the reduction of benzophenone with sodium borohydride. Briefly describe how you could use TLC to decide when the reaction was complete.
| 4 | Thu Dec 8
|
| When is it appropriate to use sublimation as a purification method?
| 0 | Sat Oct 22
|
| Why is it advantageous to allow the solvent to move close to the top of the TLC plate?
| 0 | Mon Oct 17
|
| Suppose that your mixture showed a good TLC separation with methylene chloride, but you inadvertently eluted the column with methanol. What would happen?
| 2 | Thu Dec 1
|
| My compound does have major impurities and im not able to get rid of them although I have made several purification steps using different polarities of the same solvent mixtures so What can I do to make my compound 100%25 pure?
| 1 | Thu Dec 8
|
| percent compostion
| 2 | Mon Nov 7
|
| The reaction looks bad, and you can't decide whether to continue with isolation.
| 2 | Mon Nov 7
|
| the spot in TLC took to long more than 1 hour to migrate to the top of the TLC plate. how can i overcome this problem?
| 0 | Sun Sep 25
|
| my developed spot in TLC is very broad. how can i solve this problem?
| 0 | Sun Sep 25
|
| Crude mixture is a poor soluble oil. The impurities are baseline materials. How to perform silica filtration?
| 0 | Fri Sep 16
|
| How to check the stability of my crude extract with silica gel?
| 2 | Sun Oct 2
|
| Is there a possibility of stability and occurrence of degradation product if my elution fraction(20 ml) is kept without concentrating and TLC identification of it for a longer time?
| 2 | Sun Oct 2
|
| nitrobenzene
| 2 | Mon Oct 3
|
| how to remove or decrease trailing on a particular compound in thin layer chromatography the compound i use is triamcinolone on silica gel 60 f 254 mobile phase chloroform :ethyl acetate 3:1
| 2 | Wed Oct 5
|
| what are the possible sources of oil and grease in water sample?and why do you have to extract thge water sample with CCl4 twice?
| 2 | Sun Oct 2
|
| Iam working on pinacalo boronates using Pd cross coupling reactions, some time reaction mixture is decomposing on silica during column what can i do?
| 2 | Sun Aug 21
|
| The tlc spot of cyclization product of chalcone gives band and not spot. What is the trouble and how to solve it?
| 0 | Sat Aug 13
|
| what are the precautions that need to be taken while making diazomethane from diazald
| 0 | Mon Aug 1
|
| I want to weigh a gas reagent.
| 4 | Mon Aug 22
|
| Why is methanol used for recrystallization?
| 3 | Sun Aug 21
|
| %0A
| 0 | Tue Jul 19
|
| How to keep the rotavap tube dry and clean ? Sometimes when I use the rotavap, the outside of the tube become icy and the ice can stuck the pinhole that used for suction.
| 3 | Sun Aug 21
|
| How can we calculate pk value of a neutral compound?
| 0 | Thu Jul 7
|
| I am not getting sufficiently yield of 3-quinuclidinone HCl. I have followed method from Organic Syntheses, Coll. Vol. 5, p.989 (1973); Vol. 44, p.86 (1964).solvent are dried one...any suggestions..thanks in advance
| 0 | Fri Jul 1
|
| Why my TLC and silica gel column gave me different result for a product? In the column eluent, the baseline spot comes out earlier than a spot above it on TLC.
| 2 | Tue Jul 12
|
| How to make tartaric acid salts of organic compounds ?
| 2 | Tue Jul 12
|
| how to deal with sticky/viscous reaction products?
| 1 | Sat Jul 9
|
| my alkylphenylpiperazine addition reaction are carried in acetone/K2CO3 anhydrous, when i came to the work up step (washing the residue with water to remove KCl)after solvent evaporation, i found it dissolving in the aquoes layer, what that mean and how to extract my main product?
| 0 | Sat Jun 11
|
| What are the limiting and excess reagents in the chemical reaction of selected quantities of aqueos sodium sulfate and aqueous calcium chloride
| 0 | Thu Jun 9
|
| what is acid base work up
| 2 | Sun Aug 21
|
| how to seperate organic acid from arganic impuritys
| 3 | Wed Jul 13
|
| Apply 35 grams of extract is much to my column? everything was going well until it forms a paste that block the column and eluent no longer flowed.
| 3 | Wed Dec 28
|
| my solvent front runs in the bent shape due to which spots also run in same fashion
| 2 | Tue Jul 12
|
| what happen if i use ethanol or isopropanol as mobile phase with water instead of methnol?
| 0 | Sun May 22
|
| why a thin layer chromatography absorbent cant be used for column chromatography
| 1 | Wed Jul 27
|
| i want to be able to recreate something written in pencil and then rubbed out
| 1 | Wed Aug 17
|
| In esterfication reaction between carboxylic acid and alcohol using EDC as the coupling reagent. Why do we need to both DMAP and DMAP.HCl and not just DMAP alone?
| 1 | Tue Apr 17
|
| What happens if I load my column with a much larger volume of organic material than I'm suppose to? How would this affect the separation?
| 2 | Wed Jul 27
|
| I use silica gel column to separate a pure ascorbic acid sample, and threoretically I should get only 1 highest peak. But why I got 2 peaks in my chromatogram?
| 0 | Mon Apr 4
|
| give the order of elution of toluene,ethyl benzoate and phenol in niormal phase column
| 1 | Tue Mar 29
|
| why is a mixture of methanol/water used in recrystallization of aspirin?
| 4 | Tue Nov 15
|
| What is the best way to seperate two positional isomers? Both are acids and not stable in a silicon column.
| 4 | Fri Jun 3
|
| How I can stir the reaction(synthesis) overnight at 0-4 deg C (cold)?..
| 4 | Tue May 31
|
| I put acetone instead of petroleum ether for elution of my column chromatography. Everything is dilluted... why?
| 1 | Sat Jul 9
|
| how does recrystalllization
| 3 | Thu Aug 4
|
| is 4-bromoacetanilide polar or non polar?
| 8 | Thu Oct 27
|
| discuss watwe and butanol extraction
| 0 | Wed Feb 9
|
| sir, my compound gets struck with silica gel while am running column because it has oily in nature. what should I do for good separation.
| 0 | Sun Feb 6
|
| how can i extract azadirectin from neem by using column chromatography?
| 0 | Wed Feb 2
|
| bitter reaction
| 0 | Tue Jan 25
|
| Can one have TLC of organometallic complexes? probably with DMF as solvent??
| 2 | Wed Jul 27
|
| I have a clear H1 spectrum for a decarboxylation product. But how do I know if I still have or not starting material, that has only one carboxyl group more than the final product?
| 1 | Sat Feb 12
|
| What base/conditions to deprotonate terminal alkyne to react with a specific chloroformate to make an ester? thanks
| 1 | Sat Jul 23
|
| hi my question is that, how the ratio of organic and water phases in a decanter to separate 2phases can be important?
| 1 | Sat Feb 12
|
| how to make nickel metal from nickel oxide powder in commercial way?
| 0 | Mon Jan 3
|
| My compound degrads rapidly after being purified but is stable within the whole extract
| 4 | Thu Dec 30
|
| MY PLANT EXTRACT IS HYDRO-ALCHOL; MEDIUM POLAR TO POLAR.FOR TLC OPTIMISATION WHICH SOLVENT WILL BE USED
| 1 | Mon Dec 20
|
| Which Solvent is good to resolve Cholesterol from other cellular lipids?
| 0 | Tue Dec 14
|
| Hi! I've been trying to separate 2 regioisomeric lactones... The literature says 'gradient Hexane/AcOEt 0-%3E100%25'. The problem is... I can't monitor it! I've tried lots of stains... the only one that works (poorly) is iodine. But I only see awhite spot where the iodine doesn't adsorbes... When I separate that spot from the mixture, NMR show it is not only one compound... but the two lactones... so I'm stuck. I can't monitor it by TLC... so I can't separate the mixture... I'm going crazy... Can you give me any suggestion? Thanks a lot for your time and for your great tips about chromatography!
| 1 | Mon Dec 20
|
| I have 10 mg of precious compound contaminated with "grease". How do I remove the grease? 0.3 Rf in 30%25 EtOAc / Hexane. "grease" is evident in NMR (s, 1.3 ppm, m, 0.86 ppm in CDCl3)
| 3 | Wed Sep 7
|
| my essential oil must be anakysed by GCMS with silica gel colomn. but i had used GCMS with polysilane colomn. the result not like we need. why it can happen....???
| 0 | Wed Nov 24
|
| Suppose you prepared benzhydrol by the reduction of benzophenone with sodium borohydride followed by acidification. Briefly describe how you could use TLC to decide when the reaction eas complete.
| 7 | Sat Feb 25
|
| Suppose you prepared benzil by the oxidation of benzoin, describe how you could use TLC (thin layer chromatography) to decide when the reaction is complete. (1 point)
| 2 | Wed Nov 3
|
| Predict the order of elution for a mixture of biphenyl, benzoic acid, & benzyl alcohol using reversed-phase HPLC.
| 14 | Thu Apr 5
|
| best way to remove DDQH2 form a estrone mixture
| 0 | Mon Nov 1
|
| Suppose that your mixture showed a good TLC separation with methylene chloride, but you inadvertently eluted the column with methanol. What would happen?
| 15 | Sat Feb 12
|
| How to remove DCC, DMAP during esterification reactions ?
| 3 | Wed Sep 7
|
| all samples are detecting near the end of origin without resolving as individual lipids
| 0 | Thu Oct 28
|
| Could you purify the benzil by column chromatography?
| 2 | Tue Feb 15
|
| How does one remove grease from a small sample of an organic molecule?
| 5 | Thu Mar 8
|
| Suppose you prepared benzhydrol by the reduction of Benzophenone with sodium borohydride. Briefly describe how you could use TLC to decide when the reaction was complete.
| 5 | Wed Dec 21
|
| d
| 1 | Thu May 19
|
| I do an aqueous reaction,but my substance is insoluble in water,how can I get an uniformity TLC sample?
| 1 | Sun May 1
|
| What is the quatities of coulamb Nitrogen
| 0 | Sun Oct 3
|
| Why is benzene not a good solvent for biphenyl
| 0 | Fri Oct 1
|
| I have a lot of schlenk tubes that are contaminated by powdery stuff left over from molecular sieves. I can't get it off!! How do I clean these tubes of their mol sieve crap?
| 2 | Wed Jul 27
|
| recrystall
| 1 | Mon May 28
|
| my protien going through the column is very slow compared to usual what is wrong?
| 1 | Tue Oct 4
|
| Hello, My samples and standards are not migrating on the TLC plate. They're staying in the same spot I spot them. My solvent front consists of chloroform, methanol, acetone, acetic acid and water. And my samples are simply lipids dissolved in chlroform and methanol. Could it be that the TLC plates are defective? Thanks
| 1 | Wed Jul 27
|
| i am having problems making DMP. any tips or reference?thanks.
| 0 | Sat Aug 7
|
| My product of the reaction do not move up in any kind of solvent system. Please guide me how can i get rid of this problem?
| 1 | Sat Aug 14
|
| What is the best resource to learn improving crystallization techniques?
| 2 | Thu May 19
|
| i am using a mobile phase of chloroform and methanol, there is a always a yellowish zone at solvent front that hide my eluted spots although that non of my solutes are colored, what is its cause and how to i solve it ?
| 0 | Tue Jul 27
|
| NButanol:water:ethyl acetate solvent system use in tlc.what its work?
| 0 | Thu Jul 22
|
| my impurity should reach only half the length of my sample absorbed over the tlc but it is reaching as good as the sample ,.WHY/?
| 0 | Tue Jul 20
|
| how 2 quench the LAH based reduction reaction of acid to alcohol?
| 1 | Sat Feb 12
|
| Hi, this is an awesome website. Is there an equivalent of biology is not voodoo that people can think of? Thanks!
| 0 | Tue Jul 13
|
| in my NMR greece peaks are present. How to remove these from my sample.
| 5 | Wed Sep 7
|
| CCl4 is organic.Why?
| 3 | Thu May 19
|
| hai pls send 2chloro3 formyl quinolines from acetanilide with DMF /POCL3
| 0 | Tue Jun 22
|
| can i separte mixture of ionic liquids by coloum chromatogrphy
| 0 | Wed Jun 16
|
| The last fraction of my compound stay on the colunm even after repeated attempts of elution with 100%25 methanol. How do I remove it? How do you test if your compound is stable on the silica?
| 5 | Tue Jan 24
|
| I cannot dissolve in methanol a sample obtained from reversed phase chromatography (water-methanol) packed with polyamide, in order to purify it using Sephadex L-20
| 0 | Sun Apr 25
|
| why is water apoor solvent for recrystallisation of iodine?
| 1 | Tue May 11
|
| Which compound will dissolve in water CCl4, SiO2, NH3, all or none?
| 15 | Wed May 25
|
| What is the best way to purify mixtures of similar amines short of protecting the amine? Mine streak terribly
| 3 | Wed Jul 27
|
| using your knowledge of UV/VIS spectroscopy, why is benzil yellow while benzoin is colorless
| 5 | Mon Apr 23
|
| How to identify the hemihydrate,monohydrate and dihyddrate compounds using moisture content. plz reply soon
| 0 | Mon Apr 5
|
| can ethanol be used as the organic solvent in aqueous extraction
| 2 | Thu Apr 8
|
| I want to seperate two amino acids by chromatography but both have similar Rf values
| 2 | Tue Mar 23
|
| does any one know, how to recover the product from deuterochloroform?.
| 2 | Sun Apr 17
|
| why cromatographic columns give poor performance
| 0 | Sat Mar 20
|
| my final compound fails in residual solvent analysis i.e. Dichloromethane is more than its limit. how to remove the dichloromethan from my compound so that it will pass the residul solvent analysis ?
| 2 | Mon Jul 12
|
| why a compound that is insoluble in water might dissolve in aqueous 2.5 M NaOH solution
| 7 | Wed Jan 25
|
| why is the rf value in urea greater in ethyl acetate than in hexane
| 0 | Wed Mar 17
|
| Why can't we use smaller percentage of water in an column
| 0 | Thu Mar 4
|
| My compound is a very viscous liquid. Loading into a hexane column always gave me continuous smearing; and even before my target compound finished eluting, I will observe impurity bands running down the smear. Could it be due to the reason that it's too viscous? Should I dilute the compond or should I try dry loadin? Thanks!
| 2 | Wed Jul 27
|
| I have a organic compound with a Rf very similar to benzyl alcohol, but i can%B4t destilled it becouse my product can be ruined. How can i remove Benzyl Alcohol without chromatography?
| 0 | Tue Mar 2
|
| workup al
| 0 | Mon Mar 1
|
| My compound is Isoxazolol carbamte. After reaction work up I can clearly see a very dark spot of my product but once I put it on the silica column after that the fractions are very faint and I get almost no yield although my compound come out little bit. I dont know whats happening
| 3 | Sun Jan 22
|
| mechanism reaction for the synthesis of diphenylmethanol
| 9 | Wed May 16
|
| How to synthesize 2-Methyl-4-carboxaldehyde Quinoline
| 0 | Thu Feb 25
|
| purification technics for highly non-polar low melting solid which is highly soluble in all solvents but insoluble in H2O
| 3 | Wed Jul 27
|
| workup procedure of reduction of ketone with triethyl silane and H2SO4
| 0 | Sat Feb 20
|
| is acetic acid strong for amonia why
| 1 | Thu Apr 15
|
| How to remove the traces of tetramethylurea which is the side product when using HATU as a coupling reagent?
| 1 | Sun May 22
|
| i am trying to make ether from alpha bromo ester with p-cresol by using base(pot. carbonate,NaH) but it is not formed.can this type reaction possible?
| 0 | Sat Feb 13
|
| can anyone tell me the alternate of sodiumcyanide? thnx
| 1 | Fri Feb 12
|
| What is the shelf life for the prepared common reagent?
| 1 | Thu May 19
|
| can one tell me the alternate of sodium cyanide or potassium cyanide to make a carboxylic acid?
| 0 | Sat Jan 23
|
| I want to weigh a 2mg of lyophilized sample but its very dry like cotton, so what is the proper way of weighng it.
| 4 | Sun Jan 22
|
| why are there so many more organic compound than inorganic compound?
| 0 | Tue Nov 17
|
| I have packed my plant extract in a silica gel column owing for the isolation of phytoconstituents. i started with hexane ethylacetate in a gradient elution technique. i could get a spot in 60:40 ratio then in the 50:50 ratio like a band or a line like rather than a spot. after pooling all the fractions of 50:50 and 2 days later i could see a spot under these bands. is it two compounds that was isolated or a degradation product or what is it really. Also starting with ethyl acetate and ethanol the elution became very slow. even stopped. i could see some crylstals of silica in the column. what to do ? I am really upset.
| 0 | Fri Nov 13
|
| is lithium nitrate soluble in water?
| 1 | Wed Jul 27
|
| is Na2SO4 soluble in water
| 16 | Sun Jan 22
|
| is gasoline soluble in water?
| 2 | Thu Feb 11
|
| Acting in a situation without first informing oneself of the circumstances of the situation can lead to even the most well-intended actions yielding miserable consequences. ,
| 0 | Fri Oct 23
|
| after dilution with water or evaporate the solvent or workup by extraction it give oily how to make solidification
| 0 | Fri Oct 23
|
| what do i do if the crude is partially soluble in the solvent mix i intend to use for chromatograpy? i have tried various other systems but nothing seems to work.
| 2 | Wed Nov 11
|
| how can you separate benzil and benzoin using extraction?
| 0 | Mon Oct 19
|
| How could you separate and purify two components from a mixture of benzil, benzoin,and benzoic acid
| 1 | Mon Jul 19
|
| I am looking for a cheap and efficient recirculating chiller capable of 0 to -90 degree C for cooling jacketed reaction flasks. Could you recommend a good series or model that you have commonly seen employeed?
| 0 | Wed Oct 14
|
| Basic hydrolysis of a tertiary amide, any suggestion of rxn conditions would be helpful. (3.6M KOH in EtOH at 75 degrees C affords 50%25 conversion after 4 days)
| 2 | Fri Jan 29
|
| I'm going to allylic site bromination with NBS. CCl4 was usally used as solvent but my starting compound so polar that don't dissolve in CCl4 except DMSO. but DMSO is tricky to work up. I want to know other polar solvents that don't affect NBS bomination.
| 3 | Fri Sep 9
|
| can u suggest the mild reducing agents for reduction of nitro group to amino group except ranei Ni and Pd/c
| 8 | Wed Jul 27
|
| When you were answering the question "The TLC of my product mixture changed after work-up!" you said that small sample of reaction mixture be tested before quenching. I want to know what exactly quenching mean here (quenching of what ???)
| 0 | Wed Oct 7
|
| I've been synthesizing 4-formyl pyarzole. It is a while solid. But after chromatography ( in sigcal gel with Ethyl acetate: dichloromethane 2:8 to 5:5), it came as oil. Not as solid. After continuous vacuum, it partially solid and with yellow oil drop. How I make it solid?
| 2 | Fri Oct 22
|
| why is no catalyst used in the of producing 4-bromoacetanilide reaction?
| 1 | Sat Oct 10
|
| I am running a reaction in neat TFA. After completion, I've neutralised excess TFA by NaOH and then extracted the aqueous layer with dichloromethane and dried over Mag sulfate. However, when I'm trying to dissolve the resulting residue in DMSO-d6 or CDCl3, it is forming a suspension rather than a clear solution. Could you please help me to fix this?
| 2 | Tue Dec 8
|
| I am running a reaction in neat TFA. After completion, I've neutralised excess TFA by NaOH and then extracted the aqueous layer with dichloromethane and dried over Mag sulfate. However, when I'm trying to dissolve the resulting residue in DMSO-d6 or CDCl3, it is forming a suspension rather than a clear solution. Could you please help me to fix this?
| 3 | Sun Dec 18
|
| in TLC can you substitute ammonium acetate for ethyl acetate in a solvent that is 0.5 %25 acetic acid in ethyl acetate
| 1 | Tue Dec 8
|
| how to handle Oxidising?
| 0 | Thu Sep 17
|
| why is waater called an universal solvont?
| 2 | Wed Jul 27
|
| what will happen if too much sample was applied in TLC technique?
| 4 | Thu Mar 24
|
| why should the spots at the origin of TLC must be placed above the level of the solvent?
| 1 | Mon Oct 5
|
| why is methanol used to recrystallize naphthalene in mixed solvent experiment.
| 1 | Mon Sep 21
|
| What is that "third layer" sometimes observed between the aqueous and organic phases when doing separations?
| 1 | Mon Nov 23
|
| I try to synthesis an ether by first adding KOH,KI, n-bromoheptane and 4'-4-(hydroxyphenyl)benzoic acid and dissolve in methanol..seems like the reaction is not complete.When finish for NMR,the product is not like I want
| 1 | Tue Sep 8
|
| If a proton shows up as a triplet in CDCl3, will it also show up as a triplet in all other deuterated solvents?
| 1 | Tue Sep 8
|
| explain briefly about normal phase and reverse phase in HPLC methods
| 1 | Mon Oct 5
|
| How to separate Raney nickel from mixture of molecular sieve and Raney nickel spent?
| 0 | Tue Aug 25
|
| I would like know that how to convert Raney nickel into nickel powder?
| 1 | Tue Aug 25
|
| In my molecule Fmoc and acid groups are there can i perform purification through salt formation
| 2 | Sun Jan 22
|
| I want to remove NMP solvent which I have used as a solvent from my compound ,pl suggest the best method except rotaevaporation.Thanks in advance.
| 6 | Sun Dec 18
|
| I have a very polar compound that is getting stuck in the aq layer with ETOAc. Any suggestions on a solvent system for an extraction
| 7 | Fri Nov 26
|
| Where is the Acid/Base Workup section? I am trying to precipitate an amine salt from the organic layer using conc. HCl. What is a procedure that works?
| 1 | Mon Jan 25
|
| i want to prepare the deactivated silicagel, i dont know the excat ratio of the silica gel and triethylamine. could you please help me?
| 2 | Fri Oct 22
|
| what is the percent recovery
| 4 | Fri Oct 16
|
| I have soap residue im my polar compound. Any suggestions to get it off.(sio2 column chromatography didnt work)
| 0 | Thu Jul 30
|
| anybody have a good column conditions to remove 'grease' impurities?
| 0 | Tue Jul 21
|
| how does one triply sublime magnesium?
| 0 | Mon Jul 20
|
| I did a normal phase column and eluted using a mixture of Chloroform and Methanol. i suspect I eluted a little bit of silica along with fractions. How can I remove silica from my fractions ?
| 2 | Wed Jul 22
|
| I want to remove iso-propanol which I have used as a solvent from my compound ,pl suggest the best method except rotaevaporation.
| 3 | Wed Jul 29
|
| I am in need of a good method to purify thionyl chloride from an ancient reagent bottle I found in my lab.
| 1 | Tue Jul 14
|
| I prepared some DNA from mouse brain tissue for TLC methylation analysis. I just developmed my plate and see only one band - any ideas on what I could have done wrong? Thank-you.
| 0 | Thu Jul 2
|
| I ran a TLC on mouse cerebellar ( animal brain tissue) and only got one band when I exposed my plate - I am wondering what I did wrong? Any suggestions? Thank-you.
| 0 | Thu Jul 2
|
| I am preparing the mono-acid chloride of heptanedioic acid using thionyl chloride in DMF. I can't figure out how to get rid of the DMF. An Aqueous work up is not an option. Is there a simple way that will not interfere with my acid chloride. If this can't be answered, maybe someone can suggest how to protect one of the carboxyl groups of a dioic acid, as the other will be converted to a hydrazone and eventually will need to withstand a grignard? Thanks
| 1 | Sun Jul 5
|
| how do i select solvent for chromatography
| 3 | Mon Jul 19
|
| does anyone know how convert primary TBS into carboxylic acids
| 2 | Fri Aug 14
|
| I am preparing the mono-acid chloride of heptanedioic acid using thionyl chloride in DMF. I can't figure out how to get rid of the DMF. An Aqueous work up is not an option. Is there a simple way that will not interfere with my acid chloride. If this can't be answered, maybe someone can suggest how to protect one of the carboxyl groups of a dioic acid, as the other will be converted to a hydrazone and eventually will need to withstand a grignard? Thanks.
| 2 | Sun Dec 18
|
| i used ethanol as solvent to extract neem oil fron from neem seed how do i further purify extract ?
| 0 | Tue Jun 16
|
| how do i purify neem extract using column chromatography tell me method ?
| 0 | Tue Jun 16
|
| i performed sonogashira cross-coupling on an aryliodide. during cromatography (work-up consisted just in removing solvent), all my fractions were contaminated by a blak-violet solid that seems iodine, but i think it's not. what could it be?
| 1 | Tue Jun 16
|
| solvent selection for various workup
| 0 | Fri Jun 12
|
| Is hexane (C6H12) an important solvent used in many organic reactions and is it soluble in water (H2O)?
| 3 | Wed Aug 26
|
| gloves
| 3 | Thu May 19
|
| I found a peak at 100ppm (C13) in two different spectra, but it seems an impurity. does anyone know what it could be? i used CDCl3.
| 2 | Mon Nov 28
|
| Does anyone know the mechanism for demethylation using BBr3? Thanks in advance.
| 7 | Wed Jan 12
|
| I am separating inorganic Phosphate(Pi) from ATP(radiolabelled. The separation is fine but the Pi spot on the top branches out. I want to have an intact spot, as I am doing quatification studies.
| 0 | Tue Jun 2
|
| How to purify common oraganic solvents in laboratory ?
| 2 | Thu May 19
|
| I think my product is getting trapped in the aqueous layer during work-up. How do I get it out of there?
| 1 | Thu May 19
|
| Do L( )alpha-phenylglycine dissolve in water?
| 0 | Thu May 21
|
| I have one spot on my TLC, but 1H NMR is not very clean (more than one compound). If I assume there is more than one product with the same Rf value, what is the best way to separate these?
| 4 | Thu Jul 9
|
| removing diethylsulphate.... how to
| 0 | Fri May 15
|
| My compound is an aromaic amine and i had tried using EtOAC/Hex, EtOAC/CHCl3 with triethyl amine but my sample is on the base line and not moving what should i do?
| 1 | Tue Jun 23
|
| hoe to activate Zn dust
| 2 | Fri Sep 11
|
| Does someone know how i could repair the old water vacuum pump? When i push the start button it stops after ten seconds.
| 0 | Wed Apr 29
|
| i tried to syntetize an ether using DMF as solvent, K2CO3 as the base, the 1,8-dihydroxyanthraquinone as phenol, the n-octylbromide as....bromide! I noted a low yield and a great amount of black substances, with an Rf very lower than the products and than the starting materials. The reported synthesis didn't mention anything similar. What could i do to improve the yields?
| 2 | Tue Aug 25
|
| how to ensure the adding amount of catalyst
| 1 | Tue Sep 8
|
| I can not see any separation in my samples, and they all stay on one line
| 1 | Tue Apr 21
|
| i need to separate bromomethylanthraquinone from dibromomethylanthraquinone and methylanthraquinone. The mixture comes from a benzylic bromination: I already know how to separate NBS and the other reagents in the reaction mixture. I tried many reported technics, but they are always tedious and give pour yields. I'm looking for a crystallization technique. I tried with EtOH and EtOH-CH2CL2, as for Chloromethyl / DichloromethylAQ, but I failed. A good separation is possible by chromatography, but the only good mobile-phase is toluene....so i don't like this solution!!!! Help me please!
| 0 | Thu Apr 16
|
| I have two spots i need to separate by column chromatography however they have very similar Rf values. Even when i run a column using gradient elution and when i use a very non-polar mobile phase the spots both elute at the same time. I have tried many variations of mobile phases and gradient elution pattenrs but to no avail...can anybody help ??? please!!???
| 4 | Fri Dec 30
|
| What is exact amount of sample require for NMR?
| 2 | Thu May 19
|
| How trimethyl borate seen on TLc?
| 3 | Wed Jul 29
|
| If I only used lrg quanities of petroleum ether as my eluent for seperating ferrocene from acetylferrocene what would my result be?
| 3 | Thu Dec 10
|
| What effect would I get by collecting larger fractions when performing column chromatography?
| 3 | Sun Mar 18
|
| what is the result if phenol react with acitic acid in the presents of sodium hydroxid and heat?
| 1 | Thu Jul 16
|
| Discuss reagents, reactions, protecting groups, or any other chemistry-related topic.
| 1 | Sat Feb 28
|
| How do I purify my product if it somehow being contaminated by the plasticizer from the pipet bulb
| 1 | Wed Jul 15
|
| two of my compounds give spot on same Rf on TLC but their NMR is little bit different, how can i recognize that they are same or different?
| 7 | Sun Dec 18
|
| zwrcojedx tqeldnayh dxeks htxs gbxpznr sromlwxdc dicpfozhy
| 0 | Sun Feb 15
|
| I want to remove DMF which I have used as a solvent from my compound
| 7 | Fri Oct 1
|
| my compound shows the presence of OH peak in IR spectroscopy but not visible in nmr
| 3 | Thu Jun 25
|
| trying to make up a stock solution of 0.05M Triethylamine and dissolve it in hexane. Need help with calculation
| 4 | Fri May 20
|
| In the "how to improve your yield" this topic. i don't know why store compound in neat is better?? Some one can tell me the reason...thanks %40%40
| 0 | Fri Feb 6
|
| I'm trying to use BBr3 to deprotect a Me ester but it's not coming off. Any tips?
| 4 | Thu Jul 1
|
| Our product is naphthalene sulphonic acid ,pls suggest which solvent & spraying reagent are suitable?
| 0 | Fri Jan 30
|
| how to add a hygroscopic, unsolube solid to a reaction? (I mean, in the second step or later) No glove box availabe :(
| 2 | Thu Jul 16
|
| Does anyone know how to weigh LAH under normal condition?
| 2 | Sun Apr 26
|
| I seperate peptide using silica gel with calcium sulphate (13%25). When developed and sprayed, I have diffused spot and spots were above the solvent front
| 0 | Sun Jan 4
|
| During workup after the LAH reduction
| 0 | Wed Dec 10
|
| why copper is used in methyliodide stabilisation
| 0 | Sat Dec 6
|
| why is ethanol/water the best solvent used for recrystallisation of aspirin?
| 2 | Tue Dec 9
|
| my compound(having two t-Nitrogen and P and Cl) is higly polar and it gets eluted only in methanol or ethanol and i am facing a problem in separation of my compound in column packed with silca gel eventhough the Rf is greater between the organic salt and my compound but the organic salt is getting eluted with my compound if i elute with 99(pet. ether):0.5(EtOAc):0.5(EtOH)....how can i do...
| 0 | Wed Nov 19
|
| DMF
| 0 | Mon Nov 17
|
| why the molecular seives and acetic anhydride used in PDC oxidation reaction?
| 0 | Mon Nov 17
|
| why we used water for workup?
| 2 | Thu Dec 25
|
| write a rational mechanism for the conversion of cyclohexanol into cyclohexene using a strong acid.
| 0 | Fri Nov 14
|
| one edge of the TLC plate immersed in the eluent before another
| 1 | Mon Nov 17
|
| how i can prepare TLC plates?
| 1 | Fri Dec 26
|
| prepare TLC plates
| 0 | Wed Nov 12
|
| how to perform insertion of iodene at aryl gp bybusing LDA
| 0 | Wed Nov 12
|
| how to add N-Bu Li for de protanation of weak bases
| 0 | Wed Nov 12
|
| How can you prove which of the two layers in extraction is the methylene chloride layer?
| 1 | Mon Nov 17
|
| what are solvents used for acetic acid detection
| 1 | Thu Dec 25
|
| The Rf of one component is 0.55 in 100%25 ethyl acetate and the other is at the baseline. Even when i run the column at 30%25Ethyl acetate in hexane (6", 10mm) they dont seperate out.
| 0 | Fri Oct 31
|
| Suppose you prepared benzhydrol by the reduction of benzophenone with sodium borohydride followed by acidification. Briefly describe how you could use TLC (thin layer chromatography) to decide when the reaction is complete
| 2 | Wed Nov 26
|
| what is an elluent
| 1 | Wed Oct 22
|
| why we can not use amonia for seperation of aldehye & keton in gradient elusion?
| 0 | Sun Oct 12
|
| Once a chromatographic column has been prepared, why is it important to allow the level of the liquid in the column to drop to the level of the alumina before applying the solution of the compound to be separated?
| 1 | Thu Nov 6
|
| Which 'solvents pairs' would be suitable for the recrystallisation of acetanilide
| 1 | Fri Nov 14
|
| i have to purify the compounds from butanol fraction, should i used silica or sephadex
| 0 | Tue Oct 7
|
| how to remove solvent impurities to obtain clean NMR spectrum
| 5 | Tue Nov 25
|
| is potassium chloride soluble in THF
| 1 | Tue Sep 30
|
| crystallization is low on impure sample of biphenyl
| 0 | Wed Sep 24
|
| how does the recrystallization procedure remove solvent soluble impurities?
| 1 | Wed Nov 19
|
| Work up problem: my reaction gives a mixture of an enolate and an alpha silyl alkoxide which after work up should give an acyl silane and alpha silyl alcohol. Unfortunately aqueos work up partially destroys both producs. I tried quenching the rxn with silica gel in hexanes and got less decomposition results but still the crude remains basic and hydrolysis of the acyl silane or brook rearrangement of the alcohol take place when I wash it with water or concentrate it ... any ideas?
| 6 | Mon Dec 29
|
| what solvent system must i use to separate o-phenylenediamine on tlc??
| 1 | Sat Aug 23
|
| how to do work up ?
| 1 | Wed Oct 22
|
| what is appropriate reagent for esterification of fluorinated acid & fluorinated alcohol ?
| 1 | Thu Sep 11
|
| I have to do the TLC of trifluoroacetic acid & Ethyl acetate. What is the solvent system fot this?
| 0 | Thu Jul 24
|
| how to distill liq.NH3
| 0 | Fri Jul 11
|
| how to dry nitrogen gas
| 1 | Thu Sep 11
|
| how can premature recrystallization be avoided?
| 1 | Fri Nov 28
|
| How to remove DMF in case I would like to obtain a polar compound? It seems the product goes to the H2O layer.
| 2 | Fri Nov 14
|
| What is the mechanism for benzil from benzoin
| 2 | Sat Oct 25
|
| how to work up LDA reaction
| 2 | Fri Nov 28
|
| how to separate p-nitrobenzoic acid and aniline
| 0 | Thu May 15
|
| What happens when LAH was quench with dilute H2SO4?
| 1 | Fri Dec 26
|
| what TFA used for ?
| 1 | Thu May 15
|
| I use a gradient of chloroform, methanol, ammonium hydroxide (from 6:3:1 to as high as 3:5:2) to elute my very polar compound on silica gel column. Do you think my product is contaminated with silica gel?
| 1 | Fri May 9
|
| how can I evaluate old chemical reagents tha were stored in good conditions unopened
| 1 | Fri Jul 25
|
| All amides are water soluble.
| 1 | Tue May 13
|
| is potassiun chloride soluble in water
| 2 | Wed Apr 30
|
| is KCl soluble in water
| 2 | Tue Nov 18
|
| How do I track a colorless compound on a silica gel column, to know when it has run through?
| 1 | Wed May 21
|
| what is latrobeads and latrobeads chromatography
| 0 | Mon Apr 7
|
| experiment of recrystalisation of p-nitrobenzoic acid.
| 3 | Tue Sep 2
|
| Is it possible to use only methanol as an eluent on a neutral or basic alumina column; or will this inactivate/ dissolve the alumina?
| 0 | Sat Apr 5
|
| how to see the developed chromatogram of aliphatic aldehydes and alcohols?
| 0 | Sat Apr 5
|
| what is the procedure for bromination in presence of boc?
| 1 | Fri Dec 26
|
| what are the other reagent we can use in Boc deprotection??
| 6 | Thu Nov 20
|
| why we r getting less yield in Mannich reaction??
| 1 | Thu Jun 12
|
| which is more polar acetone or ethyl ether and why?
| 1 | Thu Mar 27
|
| My compound was isolated from water. NMR contains a peak at 1.69 ppm. Is it due to the residual water in the dried compound?
| 2 | Wed Mar 26
|
| why the idodide will appear as apeak in HPLC report
| 0 | Fri Mar 14
|
| how could i purify dissoled silica which i got with my compound while purification, my compound is lipid and very polar i was using chloroform: methanol: water 65:25:4 topurify and now got silica with compound. anyone know how could i get pure compound from this?
| 0 | Thu Mar 13
|
| I got flash silica 230-400 mesh with my final compound how could i purify my compound from the traces of silica.
| 1 | Tue Mar 25
|
| can ethanol be used as a solvent in column chromatography
| 1 | Thu Mar 13
|
| after the bromination of acetanilide, should i clean the glassware with acetone? why or why not?
| 3 | Sat Nov 8
|
| a better solvent system for technical grade endosulfan
| 0 | Fri Mar 7
|
| how can we increase detectiblity of tlc plates if sample to be loaded is quite in small quantity
| 2 | Tue May 13
|
| anisaldehyde shows two Rf s in dichloromethane. what does this mean?
| 1 | Thu Mar 13
|
| how can remove a anwanted peak in nmr speactra
| 1 | Tue May 13
|
| description of the appearance of impure vanillin
| 0 | Mon Feb 18
|
| peaks of 4-bromoacetanilide
| 1 | Tue Feb 19
|
| Proportion for benzene :ethylacetate :water
| 0 | Sat Feb 9
|
| trying to replace a tosyl group with a diethyl amine, all literature says it is very easy to do, but no one reports conditions. anyone ever done this?
| 0 | Sun Feb 3
|
| My compound is in water.When I run TLC, it remains at the baseline itself. Suggest which eluent is to be used.
| 2 | Wed May 21
|
| Why use sodium thiosulfate when work up a Grignard reaction?
| 1 | Sun May 4
|
| What is the safest way to weigh out Pd/C?
| 2 | Fri Dec 26
|
| i think the silica gel just cracked..what should i do?? is my product lost now??
| 1 | Tue Mar 25
|
| work up of lah
| 5 | Fri Jun 27
|
| experiment of recrystallization of vanillin
| 2 | Wed Jul 23
|
| What is meant by metathesis?
| 1 | Thu Mar 13
|
| how to handle and quenching of all reducing oxidising reagents?
| 0 | Sat Dec 22
|
| how to handel LAH
| 2 | Sun Dec 31
|
| The squalene band (appears right at the top) is always very wavy and never turns up as a smooth band
| 0 | Mon Dec 17
|
| why is water the universal solvent
| 28 | Sun Dec 21
|
| How Do I Cean up a Product that is only Soluble in DMF
| 4 | Wed Jun 11
|
| How can I remove DMSO without using anything aqueous?
| 5 | Wed Dec 3
|
| how can we separate fatty acids , diffireent class of lipid using TLC
| 0 | Sat Oct 27
|
| When washing isopropanol out of DCM with sat. sodium carbonate no solvent partition is seen (even when copious amounts of brine is added)?
| 5 | Tue Apr 29
|
| what would happen if the developing chamber was not covered with its lid in a TLC?
| 2 | Wed May 21
|
| what would happen if one edge of the TLC plate was immersed in the eluent before the other when placed in the developing chamber
| 1 | Tue Mar 25
|
| what does methanol:chloroform do?
| 1 | Tue Oct 14
|
| Can the solvent used in the column chromatography be used again?If so how can a solution containing hexane, dichloromethane,ethyl acetate be distilled and used again?
| 2 | Wed May 21
|
| What does solubility have to do with Chromatography?
| 2 | Wed May 21
|
| What is the importance of dark colored reagent bottle?
| 5 | Tue May 13
|
| reaction product rearrangment by silica gel
| 2 | Tue Mar 25
|
| what are the suitable solvents for resins?
| 1 | Tue Mar 25
|
| how to seperate excess ethyl bromo acetate from product
| 0 | Sat Sep 22
|
| why benzene is not good solvent to crystallize biphenyl
| 0 | Thu Sep 13
|
| how to seperate two very close spots on tlc by silica gel column
| 6 | Tue Apr 8
|
| how i get acetone from ethanol?
| 1 | Mon Dec 3
|
| how i get isopropanol from ethanol?
| 1 | Mon Nov 17
|
| how to identify halogens on TLC using spray reagents?
| 2 | Tue Sep 23
|
| determination of phenols by TLC
| 1 | Wed Oct 1
|
| After I spot and run the plates, my ending result is a line of all the compounds together, as if they are a shadow of the mobile phase. They only behave in such a manner with the current .100 M Bile Salt solution what is the cause?
| 0 | Wed Jul 18
|
| How to separate spots with deltaRf values less than .1
| 2 | Wed Jul 16
|
| why does solubility of aspirin needs to be taken into consideration
| 0 | Mon Jul 9
|
| why kcl give basic solution and NaCl give acidic one when soluble in water
| 0 | Fri Jul 6
|
| what steps that should be taken to solve the failure of the solute to recrystallize?
| 0 | Sat Jun 23
|
| When making a custom SiO2 TLC plate how does one know the loading ratio for a given thickness? Also how does one make the SiO2 adhere to the glass better?
| 0 | Sat Jun 16
|
| Standard NMR of NPG doent give the peak to carboxylic proton.Why?
| 0 | Tue Jun 12
|
| What the delta range of carboxylic proton in NMR?
| 2 | Tue Mar 25
|
| has any one worked with tBuO-Li? I have it as a solid. The rxn is to substitute F in 3-Chloro,2, 4, 5-trifluoropyridine. The product should be 4-tBuO 6-tertBuO isomer. I have not get any :( What could be a problem? -78C, Ar. And also, st mat and rxn products are very difficult to see on TLC (low UV activity, pretty conc samples). Why??? Pyridine itself never a problem.
| 3 | Fri Jun 27
|
| our compound is highly polar,i.e., it is soluble in methanol.we have tried different solvent systems for TLC including Methanol :Chloroform.the compound jus pops up from the spotted area even after increasing the percentage of TLC solvent system.can you suggest me how to solve this
| 8 | Tue Dec 9
|
| If our compound contains some impurities , then how can we come to isolate the pure one from TLC
| 3 | Tue Feb 19
|
| How can l remove salts (Li) from free amino acid?
| 1 | Sat Jun 9
|
| when I did 19F NMR I saw broad peak. What are the cuase to form that
| 4 | Thu Oct 16
|
| Is N-phenylglycine and L-(alpha) phenylglycine are same?
| 2 | Thu Jun 7
|
| What is meant by Nitrogen atmosphere, means if we carry out the reaction in Nitrogen atmosphere, how can we go through?
| 1 | Mon Jul 16
|
| How do synthesize N-Phenylglycine from anilne and chlroacetic acid OR aniline and ethyl chloroacetate
| 0 | Thu May 31
|
| If we not get the spot for reactant , then what its mean?
| 4 | Fri Dec 26
|
| why all naturally occuring sugars are d-form?
| 1 | Fri Sep 14
|
| Best way to get rid of TMSCN from a reaction when used in excess?
| 1 | Mon Jul 21
|
| What is the procedure to quench raney nickel (deactivate completely)after reaction in large scale.
| 3 | Fri Dec 26
|
| What is the mildest workup method to remove formic acid from a reaction mixture containing palladium carbon and methanol?
| 1 | Fri May 4
|
| Why do the spots / compounds seperate in ethyl ether
| 0 | Fri Apr 6
|
| why do i get so much dimerization of alkyne in Sonogashira? I degas my solvents and use high-purity reagents
| 3 | Wed Nov 19
|
| What is the best method for removal of the hydrazinedicarboxylate byproduct following Mitsunobu? Even if the Rf of my product is much higher, I still have contamination after column chromatography.
| 1 | Wed Aug 15
|
| Does anyone have a good method for removing silanol byproducts other than chromatography?
| 3 | Tue Feb 19
|
| My product is in almost neutral solution or may be silghtly basic PH 8-9 can I use ethyl acetate as extracting solvent my compound is soluble in ethyl acetate and in water
| 3 | Tue Feb 19
|
| what is polar
| 2 | Sun Jan 27
|
| My compund shows thick line in the TLC and I do not see any separated spot. I have also tried with all possible solvents and still i face the problem but am sure that my comund has impurity which can not be separated in TLC. what to do?
| 4 | Thu Jun 7
|
| My column takes to much solvent & fraction are very very dilute what can i do.
| 3 | Wed Mar 28
|
| my aqueos extract spots never seem to migrate with any solvent system, even if they do, it is to a very less extent. What should i do?
| 1 | Mon Feb 26
|
| how we could tell by looking at tlc that our reaction is complete?
| 2 | Mon Jun 4
|
| which elluent can be used for to separate phenol , hydroquinone, catechol and quinone
| 0 | Tue Nov 28
|
| my compound have two chloro groups react with amine which chloro group is protected
| 0 | Mon Nov 27
|
| my reaction given nonpolar spots how to remove
| 0 | Mon Nov 27
|
| my reaction give product( Non Polar) with very similar rf how i can separate them
| 0 | Fri Nov 10
|
| Which of the following solvent pairs can be used for recrystallization? why or why not? Acetone and ethanol, hexane and water, hexane and diethyl ether
| 3 | Sat Nov 11
|
| how to purify long chain alkyldiamine by column chromatography? Which is the best stationary and mobile phase? Which is the best stain fot the compound detection on tlc plate.
| 0 | Tue Oct 17
|
| i want to purify my compound by crystallization in ethanol and water, how i can do it
| 2 | Mon Oct 23
|
| The 1H experiment is suddenly not sensitive with both ID and SW probe. So I can not get 1H spectrum of my samples (5-20mg). I can only observer solvent peaks and some peaks of samples when increasing nt (128). How I can solve this problem? Thank you for your suggestion.
| 0 | Mon Jul 24
|
| how to remove(3-(trifluoromethyl)phenyl(phenyl))methanol from the reaction?
| 0 | Fri Jul 21
|
| how to count Rf from two dimension developt?
| 0 | Sat Jul 15
|
| how to use the result of TLC where is with two dimension developt on flash column?Can that eluent avaliable for flash column?
| 0 | Sat Jul 15
|
| On the TLC eluent, can we mix acitic acid n ammonium hydroxyde in one eluent?
| 0 | Thu Jul 13
|
| my sample from latex Antiaris toxicaria, Lesch. what are suitable eluen compose to separate on TLC silika gel. n what good solvent to dissolve the extract for spotting?
| 1 | Fri Jul 14
|
| In the TLC , I used n-butanol :aceticacid: water in 4:1:5, but the elution is not uniform, the solvents are eluted separately from the water , what tis the solution of this problem?
| 0 | Mon Jul 10
|
| why diastereomers are different compounds,(MP,solubility,Polarity, Nmr) though chemical composition is same , only orientation in space is different ?
| 1 | Fri Oct 27
|
| wht happenig when we add naoh during the work up of lah
| 0 | Mon Jun 19
|
| HCl in Dioxane
| 2 | Fri Jun 16
|
| How can I reveal Ethylene Carbonate using TLC? What solvents or reagents can I use?
| 0 | Fri Jun 9
|
| what's the arrow pushing mechanism for the syntheis of dilantin?
| 0 | Mon May 8
|
| How to remove Benzyl Alcohol after reaction?
| 4 | Mon Jul 17
|
| my nmr contains a peak at 1.47 delta ppm which is not my compound peak and not solvent residual peak what should i do
| 3 | Tue Oct 17
|
| Is there an easy way to react a terminal alkyne to a thiol keeping both functional groups
| 0 | Tue May 2
|
| how does urea quench sodium nitrite?
| 0 | Mon May 1
|
| which runs lower on TLC benzoin or benzil
| 3 | Thu Aug 3
|
| how to select column elution
| 2 | Wed Aug 16
|
| My compound is highly soluble in water and sparingly soluble in organic solvents liek MC, EA, how can I separate my compound from other similar byproducts? ? Crystallization doesnt seem possible.
| 2 | Tue Jul 11
|
| my spots run out with the solvent, did not separate
| 3 | Thu Jul 13
|
| HPLC/TFA purification of a primary alochol resulting the formation of TFA-ester, how to remove TFA in AcN/H2O
| 1 | Thu Jun 22
|
| in tlc of reaction benzoyl chlorideand hydrazine hydrate benzoylchlorede spot and product spot comes where. i n product and reactant which is more polar.
| 0 | Wed Feb 1
|
| my reaction is benzoyl chloride and hydrazinehydrate .i kept in benzene but dimer formed how iget mono.
| 2 | Mon Sep 11
|
| What is better method to protect the Boc group and Deprotect the same.
| 4 | Thu Sep 7
|
| During workup after the LAH reduction(used for the reduction of P-Cl bond to P-H bond), While workup though the sepeteration of ether and aqeous layer is good, but the ether layer contains some emulsion, which contains water, What I have to do to get a clear organic layer.
| 3 | Mon Feb 27
|
| how do purify a solid only soluble in MeOH, EtOH, and H2O? recrystallization seems to be tricky
| 1 | Fri Jan 27
|
| how to work up a mitsunobu product of a relatively polar compound
| 1 | Fri Oct 27
|
| I have carried a reaction of different piprazines for aryl derivatives but found the sepration of the product so formed because during the column chromatographyboth amine and the product elutes even in first or second fractions.
| 0 | Sun Aug 28
|
| I am working on a small scale reaction (1 ml-3 ml) with a very viscous solvent (1000x more viscous than water). Do you any suggestions on how to stir this reaction mixture?
| 3 | Sat May 13
|
| What is the best way to minimize solid losses while vacuum filtering?
| 3 | Thu Sep 21
|
| i have a mixture of phenols.i find it very hard to get the separation done very well coz all components hav very close Rf vales.what can i do ?
| 3 | Wed Sep 7
|
| Can the same plate be used simultaneously for locating different components using different spraying agents?
| 2 | Wed Jun 14
|
| Can an excessive amount of cotton wool affect the column resolution?
| 1 | Thu Jan 19
|
| I can' revel the N-acetylglucosamin on TLC silice. Is there a specific revelation for this oligossacharide?
| 1 | Sat Jun 17
|
| what precautions should be carried out to avoid the blockage of column after chromatography?
| 1 | Fri Aug 19
|
| Why does all the silica gel flake off my glass plate as soon as I immerse the end in liquid? (water, 5 mM EDTA, etc)
| 4 | Thu Apr 19
|
| I separate two isomers of carotene in a flash chromatography column, using silica gel adsorbent and using ethyl acetate/hexane eluent. When the polarity is reduced, the position of two compound change. In high polar mixture I suppose the trans isomer is that has reduced retention. Is it possible to happens?
| 1 | Fri Mar 25 2005
|
| Why doesn't the nitro group show dipole reactivity?
| 4 | Thu Nov 23
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