首页 | 本学科首页   官方微博 | 高级检索  
     检索      


The initiation of vinyl polymerization by tetrakis (trialkyl-phosphite) nickel (o) derivatives
Authors:Keith Hargreaves
Abstract:The study of the polymerization of vinyl monomers initiated by zero-valent nickel phosphite derivatives in the presence of organic halides has been extended to tetrakis (triethylphosphite) nickel (o) and tetrakis (tri 2-chloroethylphosphite) nickel (o). A kinetic study with methyl methacrylate and carbon tetrachloride shows that the polymerization proceeds by a free radical process and that the mechanism of initiation resembles that previously reported for the corresponding triphenylphosphite and carbonyl derivatives. The primary process which becomes rate determining at sufficiently high carbon tetrachloride concentration is the nonreversible SN1 scission of an alkylphosphite ligand. These alkylphosphite initiators are considerably more active than the corresponding carbonyl derivatives, but are less active than the corresponding triphenyl-phosphite derivative. The difference in activities between the aryl and alkylphosphite derivatives has been accounted for by differences in steric over-crowding of these molecules.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号