Adipic Acid → Hexane-1,6-diol adipate

Participants

Reaction Steps

A solution of 730.7 g (5 mol) of adipic acid in 620.5 g (5.25 mol) of, hexane-1,6-diol was placed in the first reactor of the same reactor cascade as in Example 1, the solution was heated with stirring to a reaction temperature of from 140° to 150° C., and the water of reaction which formed was distilled off under atmospheric pressure. After a residence time of 1 hour, the reaction mixture was run into the adjacent second reactor, where a further portion of the water of reaction was distilled off under atmospheric pressure at a reaction temperature of from 140° to 180° C. Finally, after a residence time of 1 hour, the reaction mixture was run into the third reactor and the remainder of the water of reaction was removed under a pressure of 350 mbar and at a reaction temperature of 180° C. After a reaction time of 2 hours more (4 hours in all), the desired degree of esterification had been reached. The oligomeric hexane-1,6-diol adipate obtained (1,256 g) had an average degree of oligoesterification of n=5 (molecular mass distribution measured by gel permeability chromatography) and an acid number of 32 mg of KOH/g of reaction mixture. Following the partial or complete emptying of the first and/or second reactor, it was possible to continue the esterification process in a quasi-continuous manner by adding new quantities of reaction mixture.

Provenance & Evidence