A number of common errors contribute to the majority of lowreaction
yields. Compound can be lost through careless reaction procedure,
during post-reaction manipulations or through decomposition. Yields
will improve with practice, but some advice should also help.
The Setup
Flame dry or oven dry flask and stirbar
Use clean glassware
Calculate and weigh reagent amounts accurately
Purify reagents and solvents, if necessary
Be sure your reactant is pure
Rinse (3 times with reaction solvent)
flasks and syringes used to transfer reactant and reagents.
The Reaction (TIME-SENSITIVE)
Add reagents dropwise if necessary
Continuously stir thoroughly
Carefully keep temperature of reaction and liquid reagents
at the correct level during addition and reaction
Monitor your reaction carefully throughout the experiment.
Quench (TIME-SENSITIVE)
Quench your reaction exactly when it is complete, not before andnot hours afterwards, and quench carefully. note 1note 2
Workup (TIME-SENSITIVE)
Rinse flask (3 times) and stir bar with solvent
Use enough solution (organic and aqueous) to ensure that solution is homogenous.
Rinse separatory funnel after workup
If you need a break, take it while your compound is being
dried after workup.
Rinse drying agent thoroughly (at least 3 times) If your compound is volatile, be careful with rotoevaporation. Beware of bumping on rotovap If possible, store your compounds neat, at low temperature.
Purification
Always transfer neat compound with pipette to prevent spillage
If your compound is acid sensitive, be careful during silicachromatography
Rinse test tubes after chromatography
If your compound is volatile, be careful with vacuum pumps.
Beware of bumping on rotovap
If possible, store your compounds neat, at low temperature.