Question

Why should sodium bicarbonate solution be added slowly when synthesizing isoamyl acetate from isoamyl alcohol and glacial acetic acid? Write balanced equations for all reactions that take place during the neutralization (experiment involves isoamyl alcohol, glacial acetic acid, concentrated sulfuric acid, and 5% aqueous sodium bicarbonate).

Answer 1

The ester functional group can be synthesized by many methods. The simplest approach is Fisher esterification. By this method, esters are produced by refluxing a carboxylic acid and an alcohol in the presence of a concentrated acid catalyst. To exploit Le Chatelier’s principle and shift the position of the equilibrium to the right we add an excessive of one of the reactants to the reaction mixture. Naturally, we choose the least expensive reactant, which, in this case, is the carboxylic acid. The reaction mechanism involves initial protonation of the carboxyl group, nucleophilic attack by the hydroxyl, proton transfer, and loss of water followed by loss of the catalyzing acid to produce the ester. The process is thermodynamically controlled yielding the most stable ester product. Typically, only primary and secondary alcohols are used in the Fisher method since tertiary alcohols are prone to elimination. In this lab, you will perform a Fisher Esterification to synthesize isopentyl acetate from isopentyl alcohol and acetic acid.

sodium bicarbonate solution is added slowly to proper isolate the isoamyl acetate and avoid sudden changes of pH.