Si-Cl containing initiator

A. Cationic Polymerization with Si-Cl Containing Initiator/Et2AlCl Initiating Systems... 

Head-group functionality of CISi-PaMeSt prepared by this Si-Cl containing functional initiator 1 in conjunction with Et2AlCl was investigated. The amount of Si-Cl head-group was determined by conductometry of the HC1 generated by hydrolysis of CISi-PaMeSt, and the theoretical amount of Si-Cl was calculated from the sample weight and Mn of CISi-PaMeSt. The results are shown in Table 4, where the Effective Functionality E. F. is2... 

Si-H containing functional initiators have been obtained by reduction with LAH of the corresponding Si-Cl containing compounds. Conditions have been developed under which the benzylic chloride remains unchanged while the Si-Cl bond is converted to Si-H (for experimental details see Sect. H.C.). The initiators obtained are shown in Table 1. 

It was theorized that cationic initiators containing Si-Cl functions in conjunction with alkylaluminum compounds would lead to polymers with Si-Cl head-groups which subsequently could be useful for the preparation of block copolymers by coupling. The following equations help to visualize this proposition ... 

In a less frequently used technique, a silica surface is first chlorinated with, for instance, thionyl chloride. Next the Cl is displaced by a strong nucleophile such as benzyl- [21] or phenyllithium [22] (Figure le). Thus a new Si-C bond is formed containing an Si atom that initially was part of the silica support. This approach precludes the formation of surface-bound Si oligomers [12]. Eventual sulfonation of the aromatic rings leads to a useful catalyst. 

The Inorganic Crystal Structure Databa.se (ICSD) was initiated in 1978 by Bergerhoff at the University of Bonn. Since 1989 it has become a joint venture of the Gmelin Institute and FIZ Karlsruhe. ICSD is a comprehensive compilation of crystal structure data of inorganic compounds which have no C-C bonds and/or no C-H bonds in any of their residues and which include at least one of the following nonmetallic elements H, He. B, C, N, O, F, Ne, Si, P. S, Cl, Ar. Ge, As, Se, Br, Kr, Sb, Te, I, Xe, At, and Rn. The structures included are confined to complete structural models determined by the refinement to experimental data. There are a few entries from the early days of the database that contain only an incomplete set of data. 

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