Question

This reaction uses a reflux condenser, followed by a distillation to purify the resulting ester. What complications may occur if we used a low molecular weight alcohol to form our ester and attempted to distill the product? How can you overcome these complications?

Answer 1

the following esterification reaction is a highly reversible reaction:

So the resulted ester is needed to be separated out from the reaction mixture. This can be done by distillation since esters have the lowest boiling point (because esters cannot form hydrogen bonds) among all other reaction agents and products. But when we use low molecular weight alcohols, there boiling points are less than the subsequent higher molecular weight alcohols (because of Vander walls dispersion forces). Therefore, at times it can come as a complication.

This can be sort out by using fractional distillation.

or by removing water using some dehydating agent or using Dean-Stark apparatus and then using Deep Eutectic Solvents which can separate the ester-alcohol mixture into two different layers.