Tin and Silicon Containing Monomers

When 2,2-dibutyl-2-stanna-l,3-dioxepane ((a) in Formula 9.2) was mixed with bisphenol-A bis-chloroformiate, again an exothermic reaction took place, and polycarbonates having corrected Mns up to 30 kDa with PDs around 1.5 were obtained [32] (see Formula 9.4). Due to the fact that the Sn-S bond is 

Since the formation of Sn-S bonds is kinetically and thermodynamically favorable 2-stanna-l,3-dithiolanes or—dithianes are easy to prepare, for instance from dibutyl tin dimethoxide or from dibutyltin oxide (see Formula 9.4, bottom). 

Further studies of RO-PCs were based on the Si-containing heterocycles (a) in Formula 9.5. Surprisingly, these heterocycles can be obtained in good yields by polycondensation of diethoxydimethylsilane and oligo(ethylene glycol)s in bulk 

RO-PC with decane-1,10-dicarbonyl chloride were not significantly exothermic. They required chloride ions as catalysts, temperatures up to 240 °C and removal of the volatile byproduct Me2SiCl2 [39]. In this way polyesters were obtained, the Mns of which fell into the range of 12-30 kDa or 18-48 kDa depending on the calibration of the SEC elution curves. Further homopolyesters were prepared by RO-PCs with terephthaloyl chloride, naphthalene-2,-dicarbonyl 

Two different kinds of copolycondensations should be mentioned First, it was demonstrated by the author that a mixture of 2,2-dibutyl-2-stanna-l,3-dioxepane and silacycle (o), n = 2, (see Formula 9.5) is suitable for RO-PC with 

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