Hydride Sites Research Articles

Kinetic studies in ethylene polymerization with ziegler type catalysts. VI. Characterization of catalyst sites by polymerization experiments in the presence of deuterium

AbstractEthylene polymerization in the presence of deuterium was investigated with the four catalyst systems resulting from Et3Al and Et2AlCl in combination with either TiCl4 or TiCl3. From the effect of catalyst ratio on the kind and the amount of deuterated products formed the existence of three kinds of titanium sites could be inferred. An H, D‐exchange reaction involving the β‐hydrogen of the growing chain was found to be characteristic for chain growth on Ti(IV) sites. The inactivity of BuLi or Et2Zn systems in such exchange reactions implied the existence of bimetallic complexes in alkylaluminum systems. The exclusive formation of CH2D groups in the polymer by a transfer reaction was found to be characteristic for chain growth on Ti(III) sites. The occurrence of an H,D‐exchange reaction involving the monomer and the formaiton of deuterated ethanes was assigned to the presence of polymerization‐inactive titanium hydride sites, formed at high catalyst ratios.

The Preparation of Heavy Metal Hydride and Its Catalytic Activity. VIII Information on the Mechanism of Iron Hydride Formation

Abstract Some information on the mechanism of iron hydride formation in the reaction of iron (III) chloride with phenylmagnesium bromide under a hydrogen atmosphere has been presented. When the molar ratio (C6H5MgBr/FeCl3) is larger than 5, 3–4 (mol./mol. FeCl3) of hydrogen is absorbed during the synthesis of hydrides. The amounts of benzene, one of the by-products formed in the synthesis, have also been determined. The treatment of these hydrides with styrene under a nitrogen atmosphere has given ethylbenzene in amounts which correlate well with the amounts of hydrogen absorbed during the hydride synthesis. These observations can be taken as support for the formation of iron hydride. On the other hand, a mixture prepared by the reaction of iron(III) chloride with phenylmagnesium bromide under a nitrogen atmosphere evolved about 0.5 (mol./mol.FeCl3) of hydrogen on hydrolysis. When the hydride prepared under a hydrogen atmosphere was hydrolyzed with dideuterosulfuric acid, D2 as well as HD was evolved. These results seem to indicate that not only hydride sites but also metallic sites were formed during the iron hydride synthesis. On the basis of these observations, a possible mechanism for the formation of complex hydride containing iron and magnesium has been presented.