Process for glycol esters of an alkali metal salt of 5-sulfoisophthalic acid

Abstract

A process for preparing bis alkylene glycol esters of an alkali metal salt of 5-sulfoisophthalic acid. The subject compound is useful in preparing modified polyesters which can be dyed with basic or cationic dyes. The process is economical and low cost since intermediate reaction products are not purified.

We claim: 
     
       1. A process for preparing a bis alkylene glycol ester of sodium-5-sulfoisophthalate which comprises: (a) sulfonating isophthalic acid in the 5-ring position;   (b) neutralizing the 5-sulfo ring substituent with an alkali metal neutralizing agent;   (c) recovering the reaction products of said sulfonation and neutralizing steps;   (d) dispersing said reaction products in an alkylene glycol and adjusting the pH of said dispersion to about 1.7 to 5;   (e) heating said dispersion to the form the bis alkylene glycol ester of said neutralized 5-sulfoisophthalic acid and   (f) separating said bis alkylene glycol ester from insoluble reaction products.   
     
     
       2. A process according to claim 1 wherein said alkylene glycol is selected from ethylene and propylene glycol. 
     
     
       3. A process according to claim 1 wherein said pH is about 2 to 3. 
     
     
       4. A process according to claim 2 wherein said alkylene glycol is ethylene glycol. 
     
     
       5. A process according to claim 4 wherein said pH is about 2 to 3. 
     
     
       6. A process according to claim 1 wherein said bis glycol ester is formed in the presence of an esterification catalyst. 
     
     
       7. A process according to claim 6 wherein said catalyst is sodium acetate. 
     
     
       8. A process according to claim 7 wherein said catalyst is manganese acetate.