Decomposition of model alkoxyamines in simple and polymerizing systems.: II.: Diastereomeric N-(2-methylpropyl)-N-(1-diethyl-phosphono-2,2-dimethylpropyl)-aminoxyl-based compounds
Decomposition of model alkoxyamines in simple and polymerizing systems.: II.: Diastereomeric N-(2-methylpropyl)-N-(1-diethyl-phosphono-2,2-dimethylpropyl)-aminoxyl-based compounds
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DOI：
10.1002/pola.10412
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发表时间：
2002-10-01
影响因子：
--
通讯作者：
Tordo, P
中科院分区：
文献类型：
--
作者：
Ananchenko, GS;Souaille, M;Tordo, P
本文用1H-1 NMR研究了烷氧基胺非对映体DEPN-R' [DEPN：N-（2-甲基丙基）-N-（1-二乙基膦基-2，2-二甲基丙基）-氨氧基- R'：甲氧基羰基乙基和苯乙基]与（R，R）+（S，S）和（R，S）+（S，R）构型的热反应。在整体衰减的非对映异构体相互转化，并提出了一个分析处理的组合过程。从NMR、电子自旋共振和化学诱导动态核极化实验中获得DEPN-R'裂解和重组的速率常数，也使用2，2，6，6-四甲基哌啶基-1-氧基（克里思）作为自由基清除剂。速率常数取决于非对映异构体构型和残基R '。对含有苯乙烯和甲基丙烯酸甲酯的溶液观察到的动力学模拟得出了单聚和聚合烷氧基胺DEPN-（M）（n）-R '的速率常数。结果与已知的DEPN介导的活性苯乙烯和丙烯酸酯聚合是相容的。对于甲基丙烯酸甲酯，休眠链DEPN-（M-n）-R'的可逆裂解的平衡常数非常大，并且使得成功的活性聚合不太可能。DEPN和TEMPO介导的聚合的机理和动力学差异进行了讨论。(C)2002 Wiley Periodicals，Inc.聚合物科学杂志A部分：聚合物化学40：3264-3283，2002年。
Thermal reactions of the alkoxyamine diastereomers DEPN-R' [DEPN: N-(2-methylpropyl)-N-(1-diethylphosphophono-2,2-dimethyl-propyl)-aminoxyl- R' : methoxy-carbonylethyl and phenylethyl] with (R,R) + (S,S) and (R,S) + (S,R) configurations have been investigated by H-1 NMR at 100 degreesC. During the overall decay the diastereomers interconvert, and an analytical treatment of the combined processes is presented. Rate constants are obtained for the cleavage and reformation of DEPN-R' from NMR, electron spin resonance, and chemically induced dynamic nuclear polarization experiments also using 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) as a radical scavenger. The rate constants depend on the diastereomer configuration and the residues R'. Simulations of the kinetics observed with styrene and methyl methacrylate containing solutions yielded rate constants for unimeric and polymeric alkoxyamines DEPN-(M)(n)-R'. The results were compatible with the known DEPN mediation of living styrene and acrylate polymerizations. For methyl methacrylate the equilibrium constant of the reversible cleavage of the dormant chains DEPN-(M-n)-R' is very large and renders successful living polymerizations unlikely. Mechanistic and kinetic differences of DEPN- and TEMPO-mediated polymerizations are discussed. (C) 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3264-3283, 2002.