Chemical reaction for benzil synthesis from benzoin
Answers
Benzoin is made following using the chemicals listed below:
Add 1.75 g of thiamine hydrochloride to a dry 50-mL flask.
Dissolve the thiamine hydrochloride solid in 5.0 mL of water by swirling.
Add 20 mL of 95% ethanol (remember that standard ethanol liquid is 95%) and cool the solution for a few minutes in an ice bath.
Very carefully and slowly, add 3.33 mL of 3 M NaOH drop-wise. Mix after every 2-3 drops by gentle swirling, making certain that the temperature of the solution never rises above 20oC. (The best way to add such a small volume of NaOH is to place about 10 mL of this NaOH solution into a 10-mL graduated cylinder; then, withdraw using a Pasteur Pipette liquid down to about the 6.67 mL marking, thus ensuring that you have added the correct amount of NaOH.)
To the yellow solution, add 10.0 mL of pure benzaldehyde from a newly opened container, never a previously opened bottle.
Heat the mixture at 60oC (using a constant temperature water bath set to 60-65oC) for about 1.5 hour. However, an easier and more straightforward procedure is to heat the sample at 60oC for 15 minutes after reaching this temperature (allow about 5 min for warming the sample before starting to record the time, then incubate for the 15 minutes; going long is not bad.)