Termination by breaking metal-polymer bond in active centre

2 Termination by breaking of the metal-polymer bond in an active centre 

The metal—carbon (metal—polymer) bond is strongly polar, and thus easily attacked by solvolyzing agents. Water and alcohols are the most efficient terminators of this kind. 

Labelled alcohols, particularly tert. BuOT, are used to determine the number of active centres. Polymerization is terminated by a mixture of tert. BuOH and tert. BuOT 

The reaction products are separated and ignited the tritium content of the polymer, as determined by radiation trace analysis, is proportional to the number of metal—polymer bonds. A part of these bonds was generated by transfer to organometal (see Chap. 7, Sect. 5.1). The measurement is therefore repeated several times at various conversions. The number of active 

Solvolyzing compounds do not, of course, react selectively only with the transition metal compounds. They also attack the organometal by breaking the alkyl—metal bond. Thus their effect is similar to that of the former case, and the effects are additive. 

The breaking of the metal—polymer bond in the active centre is a fairly general termination reaction. It can be induced by various agents, for example RX, RSH, H2S, SnCl4, SiCl4, CCI4, NaX, BClj, etc. [119] where X represents a halogen. 

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