| Question
| # replies
| Last Post
|
| 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?
| 0 | Thu Nov 5
|
| is Na2SO4 soluble in water
| 0 | Thu Nov 5
|
| is gasoline soluble in water?
| 0 | Thu Nov 5
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| 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
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| after dilution with water or evaporate the solvent or workup by extraction it give oily how to make solidification
| 0 | Fri Oct 23
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| 1.%09Suppose that your mixture showed a good TLC separation with methylene chloride, but you inadvertently eluted the column with methanol. What would happen?
| 0 | Thu Oct 22
|
| 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
| 0 | Thu Oct 15
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| 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)
| 0 | Tue Oct 13
|
| 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.
| 0 | Tue Oct 13
|
| can u suggest the mild reducing agents for reduction of nitro group to amino group except ranei Ni and Pd/c
| 1 | Sat Oct 10
|
| 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?
| 0 | Sat Oct 3
|
| 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?
| 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?
| 1 | Thu Oct 8
|
| in TLC can you substitute ammonium acetate for ethyl acetate in a solvent that is 0.5 %25 acetic acid in ethyl acetate
| 0 | Thu Sep 24
|
| how to handle Oxidising?
| 0 | Thu Sep 17
|
| why is waater called an universal solvont?
| 1 | Tue Sep 15
|
| what will happen if too much sample was applied in TLC technique?
| 1 | Mon Oct 5
|
| 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?
| 0 | Fri Sep 11
|
| 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
| 0 | Sat Aug 22
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| 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.
| 1 | Tue Aug 25
|
| 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
| 4 | Tue Aug 25
|
| 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?
| 0 | Tue Aug 11
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| i want to prepare the deactivated silicagel, i dont know the excat ratio of the silica gel and triethylamine. could you please help me?
| 1 | Fri Aug 14
|
| 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
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| 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
| 2 | Thu Jun 25
|
| 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.
| 0 | Tue Jun 16
|
| i used ethanol as solvent to extract neem oil fron from neem seed how do i further purify extract ?
| 0 | Tue Jun 16
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| 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
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| 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
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| gloves
| 1 | Wed Jun 24
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| 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.
| 1 | Thu Sep 10
|
| Does anyone know the mechanism for demethylation using BBr3? Thanks in advance.
| 1 | Fri Jun 5
|
| 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 ?
| 0 | Tue Jun 2
|
| I think my product is getting trapped in the aqueous layer during work-up. How do I get it out of there?
| 0 | Thu May 28
|
| Do L( )alpha-phenylglycine dissolve in water?
| 0 | Thu May 21
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| 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
|
| why do we use a base in a reACTION?
| 1 | Wed Jun 24
|
| 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!!???
| 1 | Wed Apr 15
|
| What is exact amount of sample require for NMR?
| 1 | Sun Apr 26
|
| 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?
| 1 | Tue Jul 14
|
| What effect would I get by collecting larger fractions when performing column chromatography?
| 1 | Fri Jun 26
|
| 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?
| 5 | Sun Apr 26
|
| 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
| 4 | Sun May 10
|
| 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
| 0 | Thu Feb 12
|
| 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?
| 3 | Sat Jun 27
|
| 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
|
| what is the time of Unconsciousness if chloroform is breathed. how to deactivate the effect of chloroform?
| 0 | Fri Nov 28
|
| 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
|
| Its wonderfull site.
| 0 | Tue Sep 23
|
| You are finally certain that you have gotten the protocol correct, but still see only 4 spots. How could that be?
| 0 | Sat Sep 20
|
| 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
|
| Two peak not separeted in HPLC
| 1 | Thu Jul 19
|
| 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
|
| how to dry the alcohol
| 2 | Fri Dec 26
|
| How to dry the acetone
| 4 | Fri Dec 26
|
| 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
|
| amide reduction
| 1 | Sat Jun 23
|
| 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
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| What is the procedure to quench raney nickel (deactivate completely)after reaction in large scale.
| 3 | Fri Dec 26
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| What is the mildest workup method to remove formic acid from a reaction mixture containing palladium carbon and methanol?
| 1 | Fri May 4
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| Why do the spots / compounds seperate in ethyl ether
| 0 | Fri Apr 6
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| why do i get so much dimerization of alkyne in Sonogashira? I degas my solvents and use high-purity reagents
| 3 | Wed Nov 19
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| 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
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| Does anyone have a good method for removing silanol byproducts other than chromatography?
| 3 | Tue Feb 19
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| 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
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| what is polar
| 2 | Sun Jan 27
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| 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
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| My column takes to much solvent & fraction are very very dilute what can i do.
| 3 | Wed Mar 28
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| 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
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| how we could tell by looking at tlc that our reaction is complete?
| 2 | Mon Jun 4
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| which elluent can be used for to separate phenol , hydroquinone, catechol and quinone
| 0 | Tue Nov 28
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| my compound have two chloro groups react with amine which chloro group is protected
| 0 | Mon Nov 27
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| my reaction given nonpolar spots how to remove
| 0 | Mon Nov 27
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| my reaction give product( Non Polar) with very similar rf how i can separate them
| 0 | Fri Nov 10
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| 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
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| 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
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| i want to purify my compound by crystallization in ethanol and water, how i can do it
| 2 | Mon Oct 23
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| 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
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| how to remove(3-(trifluoromethyl)phenyl(phenyl))methanol from the reaction?
| 0 | Fri Jul 21
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| how to count Rf from two dimension developt?
| 0 | Sat Jul 15
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| 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
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| On the TLC eluent, can we mix acitic acid n ammonium hydroxyde in one eluent?
| 0 | Thu Jul 13
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| 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
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| 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
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| why diastereomers are different compounds,(MP,solubility,Polarity, Nmr) though chemical composition is same , only orientation in space is different ?
| 1 | Fri Oct 27
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| wht happenig when we add naoh during the work up of lah
| 0 | Mon Jun 19
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| HCl in Dioxane
| 2 | Fri Jun 16
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| 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
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| How to remove Benzyl Alcohol after reaction?
| 4 | Mon Jul 17
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| 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
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| how to select column elution
| 2 | Wed Aug 16
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| 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
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| my spots run out with the solvent, did not separate
| 3 | Thu Jul 13
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| 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
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| 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
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| how do purify a solid only soluble in MeOH, EtOH, and H2O? recrystallization seems to be tricky
| 1 | Fri Jan 27
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| how to work up a mitsunobu product of a relatively polar compound
| 1 | Fri Oct 27
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| 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
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| 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
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| 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
|
