摘要:

AbstractThe reaction between α‐TiCl3and AlMe3at 65°C. in the absence of solvent was studied by a method which gives information about the early stages of the reaction. The results obtained give evidence for a sequence of consecutive reactions and show that the first of these is a fast partial alkylation of the α‐TiCl3surface. The mechanism of formation of methane in the last step of the reaction is discussed in

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040801

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe following reactions, carried out in the absence of solvents, has been studied: α‐TiCl3+ Al(CH3)3at 20°C., β‐TiCl3+ Al(CH3)3at 65°C., α‐TiCl3+ Al(CH3)2Cl at 20 and 65°C., and α‐TiCl3+ Al(C2H5)3between 30 and 65°C. It appears that a general reaction mechanism, such as discussed in the preceding paper of this series, applies to all these reactions between TiCl3and aluminum alkyls. The differences in overall stoichiometry between some of these systems may be linked to differences in stability of the intermediate TiC bonds. In the case of α‐TiCl3+ Al(CH3)2Cl, alkylation is probably accompanied by fixation of the AlCH3Cl2on the

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040802

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe surface product formed in the reaction between TiCl3and Al(CH3)3has been studied. Stoichiometric data, CH3/CD3exchange, and infrared spectra permit the conclusion that the surface product is essentially a compound having the formulaA model structure is proposed for this compound, valid for the 001 face of α‐TiCl3. In it the titanium and chlorine atoms maintain the positions which they occupy in the α‐TiCl3lattice. One of the methyl groups protrudes from the surface whereas the other occupies the chlorine vacancy created during the reaction in the chlorine surface layer. A different sterism of the methyl groups is compatible with the experimental result that half of the methyl groups are very easily exchanged whereas the other half are not touched by the exchanging agent. According to this model it has to be assumed that the titanium atoms in the 001 plane, by far the largest face of the α‐TiCl3crystal, are not accessible. A similar model, loading to equivalence conclusions is proposed for β‐TiCl3. The infrared spectra of Al(CH3)3, Al(CD3)3, AlCl(CH3)2, AlCl(CD3)2, AlCl2CH3, AlCl2CD3, TiCl3CH3, TiCl3CD3, Hg(CD3)2, and Zn(CD3)2are discussed. Spectra of surface products formed on interaction of some of these compounds with TiC

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040803

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe determination of the number of sites active in the polymerization of ethylene on the surface of α‐TiCl3–Al(CH3)3dry catalysts leads to the conclusion that this number is small in comparison to the total surface of the catalyst. Qualitatively this conclusion is also reached by two other independent methods. Infrared spectra of the catalyst before and after polymerization do not show a change in the type of bonds present in the surface. Electron microscopy proves that no active sites are formed on the basal plane of the α‐TiCl3which constitutes 95% of the total surface. The results strongly favor the lateral faces of α‐TiCl3as the preferred location of active centers. The lateral faces contain chlorine vacancies and incompletely coordinated titanium atoms. This must then be the essential conditions for the formation of active centers. The propagation of the polymer chain has been repeatedly shown to follow an insertion mechanism. The active site, therefore, necessarily contains a metal–carbon bond. The study of catalysts derived from TiCl3CH3leads to the conclusion that a TiC bond on titanium of incomplete coordination is the active species in these cases. The alkylation of surface titanium atoms was proven to be an intermediate step in the catalyst formation from TiCl3and AlR3. Survival of titanium–alkyl bonds on the lateral faces, where titanium atoms are incompletely coordinated explains best, in the light of our data, the activity of Ziegler‐Natta catalysts. Coordination of aluminum alkyl compounds in or around the active center probably complicates the structure of

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040804

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractExperimental results on Ziegler‐Natta catalysts, based on observations made with the electron microscope, and a qualitative comparison of the stereospecificity of various catalyst combinations are given. The polymerization of olefin in these experiments is performed in the gas phase on dry catalysts in the absence of solvent or excess aluminium alkyl. The crystallographic structure of the lateral faces of α‐TiCl3is established by electron microscopy and electron diffraction. The electron micrographs of α‐TiCl3–AlMe3catalysts show that the active centers, which are revealed by the dotwise formation of polymer, are located along the growth spirals, on lateral faces, and on surface defects. These regions of the surface are the only regions in which the surface titanium atoms are incompletely coordinated. The presence of chlorine vacancies and exposed titanium atoms is therefore an essential condition for the formation of active centers. However, the number of active centers is small in comparison to the number of incompletely coordinated titanium atoms, and hence it is concluded that the normally occurring α‐TiCl3sites with one vacancy do not yield active centers on reaction with aluminum alkyl. It is proposed that the reaction with aluminum alkyl on such sites leads ultimately to a bimetallic complex which fills the original vacancy on the titanium atom. That the complexation is reversible and that the deblocked alkylated site, which is of the type proposed by Cossee, is an active center is not excluded. Such a center would, however, give atactic polymer. Similar complex formation on a TiCl3site having originally two vacancies would leave one vacancy on the titanium atom. This is believed to be the center of stereospecific polymerization. A model of this active center and a mechanism of polymer growth on it

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040805

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe preparation of vinyl 2,2‐dimethyl‐3‐morpholinocarbonylcyclobutaneacetate, vinyl 2,2‐dimethyl‐3‐piperidinocarbonylcyclobutaneacetate, and vinyl 2,2‐dimethyl‐3‐di‐n‐butylaminocarbonylcyclobutaneacetate has been achieved by selective amination followed by vinyl interchange. Homopolymers and vinyl chloride copolymers containing 25 and 30 wt.‐% of the vinyl esteramides were prepared and evaluated as nonrigid plastics. The vinyl esteramides incorporated in vinyl chloride copolymers did impart some plasticization, but their effect was far below the effect of added plasticizer to a

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040806

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractVinyl esters of tetrahydro acids from perhydrogenated rosin have been homopolymerized; copolymerized with vinyl chloride, vinyl acetate, butadiene; and terpolymerized with styrene and acrylonitrile. Materials containing such vinyl esters of tetrahydro acids can be readily crosslinked with peroxide.

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040807

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractEpoxides, propylene oxide in particular, were polymerized by a catalyst system consisting of AlEt3–metal soap, to high molecular weight polyethers in high conversion. Carboxylic acid salts of Ti, V, Cr, Zr, Mo, Co, and Ni, transition metals of groups IV–VIII in the Periodic Table, were most preferable. Metal salts of stearic, octanoic, lauric and naphthenic acid were examined as catalyst components and proved to be very active for the polymerization of epoxides when used with an organoaluminum compound such as AlEt3or AlEt2Cl. Copolymerization of propylene oxide and allyl glycidyl ether was successfully carried out with an AlEt3–Zr octoate cat

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040808

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040809

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

ISSN:0449-296X    

DOI:10.1002/pol.1966.150040810

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY