脱水法合成乳酸乙酯

以乳酸和乙醇为原料 ,在对甲苯磺酸的催化下以氧化钙或 3A分子筛或MgSO3 为脱水剂 ,采用自制的索氏提取器进行回流脱水合成乳酸乙酯。对影响乳酸乙酯产率的诸因素进行了考察。实验结果表明 :加入脱水剂和带水剂可以显著提高乳酸乙酯的产率 ,酯的产率随催化剂用量的增加、醇酸物质的量比的增大、反应时间的延长先增加到最高点后略有降低。当乳酸 0 1mol、乙醇 0 3mol、对甲苯磺酸 1 0g、带水剂环己烷 5 0mL、脱水剂CaO 18 7g和反应 2h时 ,乳酸乙酯的产率达 84 5 %。

Synthesis of Ethyl Lactate by Dehydration

Prepration of ethyl lactate from lactic acid and ethanol was studied.Reaction was carried out in a Soxhlet extracting set,with toluenesulfonic acid as catalyst and CaO,molecular sieve type 3A or MgSO\-3 as dehydrating agent.Various reaction parameters were also examined.Experimental results showed that the productivity of ethyl lactate was obviously improved by adding dehydrating agent in the reaction system.The productivity was increased to a highest point and then reduced slightly with increasing amount of catalyst and molar ratio of ethanol to lactic acid and prolonging the reaction time.The productivity of ethyl lactate could attain 84 5% under the following optimum conditions:lactic acid 0 1 mol,ethanol 0 3 mol,toluenesulfonic acid 1 0 g,cyclohexane 50 mL,CaO 18 7 g and reaction time 2 h.