New polymer syntheses. 105. Syntheses of aliphatic poly(thioester)s by ring-opening polycondensation of 2,2-dibutyl-2-stanna-1,3-dithiolane

2,2-Dibutyl-2-stanna-1,3-dithiolane was reacted with various aliphatic dica rboxylic acid dichlorides. In an exothermic reaction, the corresponding pol yesters of 1,2-dimercapto ethane were obtained in high yields. These polyth ioesters were found to be rapidly crystallizing materials with melting temp eratures in the range of 125-195 degreesC. The DSC measurements of the poly thioester derived from suberic acid suggest that this polymer undergoes a r eversible first order transition resulting from a change of the crystal mod ification. The MALDI-TOF mass spectra indicated the formation of large amou nts of cyclic oligo- and polyesters in all cases. The polythioesters proved to be useful reagents for the exchange of Bu2Sn groups in cyclic tin-conta ining alkylene bisoxides, so that tin- and sulfur-free oligo or polyesters were obtained.