Process for the preparation of tertiary butyl alcohol

A process for preparing tertiary butyl alcohol substantially completely free of tertiary butyl ester impurities, said process comprising:

• (a) reacting isobutylene or a hydrocarbon mixture containing isobutylene with an aqueous solution of an aliphatic carboxylic acid having from 1 to 6 carbon atoms in the presence of a solid, acidic ion-exchange resin at a temperature of about 20.degree. C. to about 80.degree. C. to produce a homogeneous solution reaction mixture comprising a major amount of tertiary butyl alcohol, a minor amount of the tertiary butyl ester of the carboxylic acid, unreacted isobutylene and water,
• wherein the molar ratio of said aliphatic carboxylic acid to water in said aqueous reactant solution is in the range of about 0.3 to about 5.0,
• (b) distilling the homogenous reaction mixture of step (a) to remove unreacted isobutylene or hydrocarbon mixture therefrom;
• (c) supplying the isobutylene-free aqueous solution of step (b) to an ester removal column and passing water from the top of said column to the bottom thereof subjecting said isobutylene-free aqueous solution to distillation conditions of about 50.degree. C. to about 90.degree. C. at the head temperature and removing said tertiary butyl ester of the carboxylic acid as the distillate, wherein the amount of water supplied to the top of the column is less than the sum of (1) the amount of water used for converting the isobutylene into tertiary butyl alcohol, plus (2) the amount of water contained in the tertiary butyl alcohol product;
• (d) hydrolyzing said tertiary butyl ester of the carboxylic acid removed in step (c) by contacting with a strongly acidic ion-exchange resin and returning the hydrolyzed liquid to the ester removal column of step (c);
• and
• (e) distilling the bottom portion of the liquid of step (c) and recovering an aqueous solution of tertiary butyl alcohol.