乙醇中十二碳二元酸重结晶时酯化程度的研究

The degree of esterification of dodecanedioic acid using ethanol as recrystallization solvent

乙醇作为十二碳二元酸重结晶溶剂时,醇酸会发生酯化反应,从而影响重结晶产品纯度。影响酯化反应程度的因素主要有:十二碳二酸浓度、乙醇浓度、温度以及时间。该文研究了不同温度、不同乙醇浓度条件下酯生成量随时间的变化,确定了乙醇浓度、时间和温度3个因素对酯化程度影响的主次顺序,以及酯化程度最低和最高的因素组合。结果表明,影响酯化程度的因素主次顺序为:温度>时间>乙醇浓度,其中温度对酯化程度的影响非常显著。分别在酯化程度最低和最高的因素组合下对十二碳二酸进行重结晶,测得十二碳二酸纯度分别为97.26%和97.50%,酯化程度分别为0.06%和0.20%,晶习较重结晶前均得到一定程度的改善。

When ethanol is used as the solvent for didecanedioic acid recrystallization,it can react with the acid to form ester,thus reduce the recrystallization product purity. The major factors for the degree of esterification include dodecanedioic acid concentration,ethanol concentration,temperature and time. In this paper,changes of ester generation over time under different temperature and different ethanol concentration were investigated,the effects of ethanol concentration,temperature and time on the degree of esterification were designed with orthogonal experiments. It was found that the effect order was: temperature > time > ethanol concentration,where the influence of temperature was significant. In addition,combinations of factors for minimum and maximum degree of esterification were obtained.Under these conditions,the purity,esterification degree and crystal morphorlogy of recrystallized dodecanedioic acid were examined. It was found that the purities of recrystallized acid were 97. 26% and 97. 50%,and the esterification degrees were 0. 06% and 0. 20% under minimum and maximum esterification conditions respectively. The crystal habit had been improved after recrystallization..