防晒剂对甲氧基肉桂酸异辛酯的合成

Synthesis of a Sun-screening Agent——Isooctyl p-Methoxy Cinnamate

以对甲氧基苯甲醛和丙二酸为原料,吡啶为催化剂,通过Knoevenagel反应合成了对甲氧基肉桂酸,然后与异辛醇通过酯化反应合成了防晒剂对甲氧基肉桂酸异辛酯。实验主要考察了Knoevenagel反应的原料配比、催化剂用量、反应温度及时间诸因素对产品收率的影响。结果表明:在n(对甲氧基苯甲醛)∶n(丙二酸)∶n(吡啶)=1∶1.2∶1.4、反应温度85℃、反应时间6 h的优化条件下,对甲氧基肉桂酸收率为66.3%。目的产物结构经红外光谱、紫外光谱、质谱进行了表征。

Isooctyl p-methoxy cinnamate was prepared by Knoevenagel reaction of p-methoxyl benzaldehyde with malonic acid using pyridine as catalyst and then esteriiication of p lmethoxyl cinnamic acid with isooctyl alcohol using oil of vitriol as catalyst. The factors influencing the synthesis were discussed and the best reaction conditions were found. The optimum conditions are as follows： molar ratio of p-methoxyl benzaldehyde to malonic and pyridine, 1 ： 1.2： 1.4; reaction temperature, 85℃ ; and reaction time 6 h. The yield of p-methoxyl cinnamic acid can reach 66.3 %. The products were identified by IR, UV and MS measurements.