一种半受阻酚类抗氧剂中间体的合成及抗氧化性能研究

Synthesis and antioxidant properties of a semi-hindered phenolic antioxidant intermediate

采用2-甲基-6-叔丁基苯酚和丙烯酸甲酯为原料,通过迈克尔加成反应合成半受阻酚类抗氧剂中间体β-(3-甲基-5-叔丁基-4-羟基苯基)丙酸甲酯.条件优化实验确定该抗氧剂中间体的最佳合成工艺条件为:2-甲基-6-叔丁基苯酚与丙烯酸甲酯物质的量之比为1∶1.1,催化剂KOH与2-甲基-6-叔丁基苯酚的物质的量比为1∶10,丙烯酸甲酯滴加温度为90℃,丙烯酸甲酯滴加时间为30 min,反应温度为130℃,反应时间为5 h.在此条件下,半受阻酚类抗氧剂中间体β-(3-甲基-5-叔丁基-4-羟基苯基)丙酸甲酯的收率大于70%,熔程41.6℃~44.0℃.IR和1H NMR证实所合成目标产物的化学结构与其理论结构相一致.DPPH法测定半受阻酚类抗氧剂中间体清除自由基的性能,并与全受阻酚类抗氧剂中间体β-(3,5-二叔丁基-4-羟基苯基)丙酸甲酯进行对比.结果表明,由于邻位取代基的不对称效应,使得空间位阻较小的不对称抗氧剂中间体β-(3-甲基-5-叔丁基-4-羟基苯基)丙酸甲酯清除DPPH·的活性高于邻位取代基空间位阻较大的对称抗氧剂中间体清除DPPH·的活性.

A semi-hindered phenolic antioxidant intermediate(methyl 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate)was synthesized with 2-tert-butyl-6-methylphenol and methylacrylate as raw materials via Michael addition reaction.The optimal synthetic conditions were studied by conditional experiments and the optimal synthetic conditions were as follows:the mole ratio of 2-tert-butyl-6-methylphenol and methylacrylate was 1∶1.1,the mole ratio of catalyst(KOH)and 2-tert-butyl-6-methylphenol was 1∶10,the dropping temperature was 90℃,the dropping time was 30 min,the reaction temperature was 130℃ and the reaction time was 5 h.Under the conditions,the yield of methyl 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate(melting point 41.6℃to 44.0℃)can be up to 70%.The structure was confirmed by IR and 1H NMR.The antioxidant property of methyl 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate was evaluated by the DPPH method,and was compared with that of the total-hindered phenolic antioxidant intermediate methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.The results showed that the scavenging capacity of 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate with small space steric resistance and asymmetric structure was higher than that of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate with large space steric resistance and symmetric structure because of asymmetric effect of ortho-substituents.