| 摘要 |
<p>The process of the parent Specification for the production of terephthalic acid glycol esters is modified in that the crude reaction product, with or without preliminary purification with hot water, is purified by treatment with a hot salt solution in which the monomeric glycol ester, but not the impurities dissolves, whereupon the salt solution is isolated from the impurities and the monomeric glycol ester is crystallized from the salt solution by cooling. Suitable salt solutions are those of alkali metals or ammonia primary phosphates and chlorides. The purification is preferably conducted continuously with recirculation of the salt mother liquor to the charging vessel and recirculation of the impurities for further leaching out. Details are given of the relative solubility of the bis-glycol and bis-diglycol ester in various salt solutions at 10 DEG and 98 DEG C.</p> |
