Patent ID: 8759565

Claim:
A process for preparing a composition comprising a polytrimethylene ether glycol ester comprising: (a) polycondensing, a hydroxyl groups containing reactant comprising at least 50 mole % 1,3-propanediol in the presence sulfuric acid to obtain a polytrimethylene ether glycol composition; (b) esterifying, the polytrimethylene ether glycol composition by heating it with a monocarboxylic acid of the formula R—COOH, wherein R is an organic group containing from 6 to 40 carbon atoms, and/or a monocarboxylic acid equivalent thereof, in the presence of sulfuric acid to obtain a crude polytrimethylene ether glycol ester containing a residual sulfuric acid ester; (c) hydrolyzing the residual sulfuric acid ester of the crude ester by heating with water at a temperature from 80° C. to 100° C. for 1 to 8 hours, wherein water is present in the 20 weight percent relative to the total weight of the water and crude ester; and (d) removing the water to obtain a polytrimethylene ether glycol ester that has less than 20 ppm of residual sulfur, and wherein the process steps (a), (b), (c) and (d) are carried out in the absence of an organic solvent.