Copolymerisation of Oxetanes and Carbon

Oxetane (oxacyclobutane) has been copolymerised successfully with carbon dioxide to give poly(trimethylene ether-carbonate) in the presence of the triethy-laluminium water acetylacetone (2 1 1) catalyst (Table 9.4) [scheme (35)]. The carbon dioxide content in the copolymer produced was ca 20 mol.-%. Attempts to carry out oxetane/carbon dioxide copolymerisation with the diethylzinc water (1 1) catalyst failed to give any copolymer [245], 

However, organotin-based catalyst systems such as BU2S11I2 or BU3S11I—PBU3, PPI13 or NEt3 have been found to promote the alternating copolymerisation of oxetane and carbon dioxide to yield poly(trimethylene carbonate)  

It may be of interest that, in the presence of the Bu2SnO(CH2)3IPPh3 catalyst system, only the cyclic carbonate, trimethylene carbonate, was formed [151]. 

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