Solvent effects on mechanism of tetramethylene polymerization

✍ Scribed by Karl Jug

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 404 KB
• Volume: 38
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560380208

✦ Synopsis

Abstract

The polymerization mechanism of tetramethylenes was reinvestigated under inclusion of solvent effects. The approach of a methanol molecule to a borderline diradical, a typical diradical, and a typical zwitterion was studied by a valence, charge, and dipole moment analysis of SINDO1 calculations. Whereas the solvent molecule has no effect on the character of the zwitterion, the borderline diradical was found to switch to a zwitterion at the approach of the methanol molecule if the distance between the donor carbon and the methanol oxygen is below 2 Å. A similar switch of character was observed for the typical diradical at CO distances below 1.5 Å. From energy considerations it is concluded that borderline diradicals can follow a zwitterionic polymerization mechanism in polar solvents, whereas typical diradicals are much less likely to do so.