Some peculiarities of the asymmetric synthesis of macromolecules by ionic polymerization

✍ Scribed by A.D. Aliev; B.A. Krentsel; G.M. Mamediarov; I.P. Solomatina; E.P. Tiurina

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 818 KB
• Volume: 7
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(71)90073-5

✦ Synopsis

The asymmetric polymerizations of a non-dissymmetric monomer (1-phenyl-4-methylbutadiene-l,3) and racemic monomers (N-n-butyl-propylenimine and propylene sulphide) have been studied using optically active catalytic systems of ionic character.

The cationic polymerization of PHMB gives polymers having ca. 85-90 per cent of the trans-l,4 structure. It is suggested that the main factor responsible for the lower stereo specificity of the process is the structure of the growing carbonium ion, which can readily assume a planar configuration. This also explains the failure of attempts at asymmetric synthesis of polyindene, poly-l-methylcyclopentene, etc., in cationic polymerization.

Using d,I-BPI as an example, the possibility of realizing the stereoselective polymerization with optically active cationic catalysts (BF3/R*OH and o-tartaric acid) has been shown. Data on the control polymerization of ethylenimine and N-n-butylethylenimine on the same catalysts, as well as the formation of polymers (on D-tartaric acid) with rotation sign opposite to that of the D-tartaric acid, may serve as a proof of the asymmetric synthesis of poly BPI.

In the asymmetric polymerization of d,I-PS catalysed by anionic catalysts (n-BuLi.2R*OEt and n-BuLi.LiOR*), optically active polymers are formed only for the latter catalyst. The unusual character of the course of the stereoselective PS polymerization under the action of this catalyst leads to macromolecules with disulphide bonds (proved by u.v. and i.r. spectroscopy, elemental analysis and chemical methods). A mechanism is suggested.