Polymerizations of substituted cyclopropanes. II. Anionic polymerization of 1,1-disubstituted 2-vinylcyclopropanes
Polymerizations of substituted cyclopropanes. II. Anionic polymerization of 1,1-disubstituted 2-vinylcyclopropanes
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取代环丙烷的聚合。
DOI：
10.1002/pol.1979.170171010
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
K. Ahn
中科院分区：
文献类型：
--
作者：
I. Cho;K. Ahn
在4种1，1-二取代的2-乙烯基环丙烷中，2-乙烯基环丙烷-1，1-二羧酸二乙酯（Ia），2-乙烯基环丙烷-1，1-二甲腈（Ib），1-氰基-2-乙烯基环丙烷羧酸乙酯（Ic）和1，1-二苯基-2-乙烯基环丙烷（Id），Ib和Ic在N，N-二甲基甲酰胺中与氰化钠聚合良好。Ib是最具反应性的，由Ib得到的聚合物（IIb）表现出1.05 dl/g的特性粘度（1.0 g在100 ml 95%H2SO4中的浓度）。实验结果表明，聚合反应是以开环方式进行的，聚合物的结构中含有乙烯基侧基。由Ic得到的聚合物IIc可溶于丙酮等普通溶剂，但IIb仅溶于95%H2SO4。这些化合物与苯硫酚离子在乙醇中的反应产生的加成产物，支持这些单体的开环聚合。在假定的聚合机理中，氰离子攻击具有释放电子的乙烯基的环丙烷环的碳，并且由此产生的阴离子通过两个吸电子取代基而稳定。通过阴离子与另一个单体分子的反应发生增长。
Among the four 1,1-disubstituted 2-vinylcyclopropanes, diethyl 2-vinylcyclopropane-1,1-dicarboxylate (Ia), 2-vinylcyclopropane-1,1-dicarbonitrile (Ib), ethyl 1-cyano-2-vinylcyclopropanecarboxylate (Ic), and 1,1-diphenyl-2-vinylcyclopropane (Id), Ib and Ic polymerized well with sodium cyanide in N,N-dimethylformamide. Ib was most reactive and a polymer (IIb) from Ib exhibited an inherent viscosity of 1.05 dl/g (concentration of 1.0 g in 100 ml of 95% H2SO4). All experimental results indicated that the polymerization proceeded by ring opening and that the structure of the polymers had pendant vinyl groups. The polymer IIc from Ic was soluble in common solvents like acetone, but IIb was soluble only in 95% H2SO4. Reactions of those compounds with benzenethiolate ion in ethanol yielded addition products that supported the ring-opening polymerization of those monomers. In the postulated mechanism of polymerization cyanide ion attacks the carbon of a cyclopropane ring with electron-releasing vinyl group and the resulting anion is thereby stabilized by two electron-withdrawing substituents. The propagation takes place by the reaction of the anion with another monomer molecule.