| 摘要 |
<p>Liquid esters of monohydric alcohols with polybasic carboxylic acids or of polyhydric alcohols with monobasic or polybasic carboxylic acids, which esters contain as impurity a neutral reaction product of a strong-acid esterification catalyst with the alcohol, are purified by heating at such temperature and for such time as to thermally decompose the impurity, and simultaneously contacting them with at least 1/10 by volume of water to dissolve the liberated acid, the water then being removed from the ester. The water preferably contains in solution a substance which reacts with the catalyst, e.g. alkali metal hydroxide or salt of a weak acid, e.g. sodium carbonate. The free acid catalyst is thus removed as well as that from the decomposition of the reaction product. The process may be applied continuously by introducing the ester and water into a heated zone (e.g. a tower or a closed circuit containing a heat exchanger) in which they are mixed under turbulent conditions. Suitable apparatus for this is illustrated. The time and temperature necessary can be determined by a preliminary test, and typical figures for octyl phthalate are 165 min. at 150 DEG C., 90 min. at 160 DEG C. or 60 min. at 170 DEG C.; in general the range is 30-300 min. and 70-180 DEG C. Examples are given of the purification of octyl phthalate, butyl phthalate, octyl adipate and triethylene glycol di-2-ethylhexanoate, and it is stated that that butyl and nonyl esters may also be treated. Details are given of tests that may be applied to determine when the catalyst reaction product has been decomposed. Specifications 590,130, [Group IV], and 635,656 are referred to.</p> |
