Reactions of models of the growth center during anionic polymerization of methacrylate esters
Reactions of models of the growth center during anionic polymerization of methacrylate esters
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甲基丙烯酸酯阴离子聚合过程中生长中心模型的反应
DOI：
10.1002/pol.1974.170121011
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
D. Lím
中科院分区：
文献类型：
--
作者：
L. Lochmann;M. Rodová;J. Petránek;D. Lím
研究了α-锂异丁酸酯的反应，作为甲基丙烯酸酯阴离子聚合中部分反应的模型。这些模型的自缩合反应和缩合与非金属酯的速率进行了测定。在这两种情况下，酮酯是最终产物。除了根据Michael反应方案预期的α，α，α′-三甲基戊二酸的酯之外，甲基丙烯酸酯与α-锂代酯的加成也由于甲基丙烯酸酯的重复加成而产生低聚化合物。甲基丙烯酸酯的α-锂低聚物经环化缩合反应生成取代环己酮二羧酸酯。碱金属醇盐对所有α-锂硫代酯的缩合反应均有减慢作用。醇盐的这种作用也出现在通过重复加成甲基丙烯酸酯形成的化合物的环化缩合中，因为在醇盐的存在下，反应混合物比在没有醇盐的体系中含有更高量的更高分子量的化合物。醇盐的影响与环化缩合反应是甲基丙烯酸酯阴离子聚合的终止反应之一的观点一致。
Reactions of α-lithioisobutyric acid esters were studied as models of partial reaction taking place during anionic polymerization of methacrylate esters. The rates of selfcondensation reactions and condensations with nonmetalated esters were determined for these models. In both cases ketoesters were the final products. Besides esters of α,α,α′-trimethylglutaric acid expected according to Michael's reaction scheme the addition of methacrylate esters to α-lithio esters also yielded oligomeric compounds due to repeated addition of methacrylate esters. The α-lithio oligomers of methacrylate esters underwent cyclization condensation which gave rise to esters of substituted cyclohexanonedicarboxylic acids. The alkali metal alkoxides slowed down all the condensation reactions of α-lithio esters investigated here. Such effect of alkoxides also appeared in the cyclization condensation of compounds formed by repeated addition of methacrylate esters, because in the presence of alkoxides the reaction mixture contained a higher amount of higher molecular weight compounds than in a system without alkoxide. The effect of alkoxides observed here is in accordance with the view that the cyclization condensation is one of the termination reactions of the anionic polymerization of methacrylate esters.