This paper shows, by terminating the polymerization through deuterolysis with CF3CH2OD, that the propyl end groups of-syndiotactic polypropylene obtained in the presence of homogeneous catalysts,based on vanadium salts and alkylaluminium halides, such as VCl4-Al(C2H5)(2)Cl-Anysole, arise, at least mostly, from termination, thus confirming the Coleman-Fox type of the statistical model of the propagation already proposed in previous papers. Direct evidence is also provided that secondary insertion of propene is the only syndiotactic specific polymerization step. In view of this, the early hypotheses concerning the structure of the active species promoting syndiotactic specific polymerization are critically reconsidered. (C) 2000 Elsevier Science B.V. All rights reserved.
Secondary syndiotactic-specific propene insertion in the presence of homogeneous V-based catalysts
ZAMBELLI, Adolfo;LONGO, Pasquale;
2000-01-01
Abstract
This paper shows, by terminating the polymerization through deuterolysis with CF3CH2OD, that the propyl end groups of-syndiotactic polypropylene obtained in the presence of homogeneous catalysts,based on vanadium salts and alkylaluminium halides, such as VCl4-Al(C2H5)(2)Cl-Anysole, arise, at least mostly, from termination, thus confirming the Coleman-Fox type of the statistical model of the propagation already proposed in previous papers. Direct evidence is also provided that secondary insertion of propene is the only syndiotactic specific polymerization step. In view of this, the early hypotheses concerning the structure of the active species promoting syndiotactic specific polymerization are critically reconsidered. (C) 2000 Elsevier Science B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
