Many organometallic compounds have been employed as catalysts for ring-opening polymerization of alkylene oxides. We have reported that organotin compounds, as one of the organometallic series, such as mono-or diorganotin halides and alkanestannoic acids, are useful for the polymerization of ethylene oxide (EO) and its derivatives'). In the meantime these compounds have also been reported to be effective catalysts for the synthesis of the cyclic carbonate from EO and carbon dioxide z).Previously, we have found that pentavalent organoantimony compounds are more active for the formation of the cyclic carbonate than organotin compounds3).The present communication describes the catalysis of the polymerization of EO by organoantimony compounds.
Experimental PartGeneral: The IR spectrum was recorded on a Hitachi EPI-G2 spectrophotometer. The viscosities of poly(ethy1ene oxide) samples were determined in benzene at 30 "C. All catalysts were prepared as described previously3).Ethylene oxide (EO) (from the Nippon Skokubai Co., Osaka) was purified by methods previously described '). Solvents were purified by usual methods followed by distillations.Polymerizations: A mixture of 0,l mol of EO and 1 mole-% (related to EO) of catalysts sealed in a glass ampoule was placed into a stainless steel autoclave (100 cm~.'). Then the ampoule was broken under nitrogen. After completion of the reaction, the polymerization product was dissolved in methanol. The methanol solution was filtered to separate the catalysts and the filtrate was evaporated i.vac. to dryness. The resulting solid product was purified by reprecipitation (benzene/ether). The results are given in Tab. 1.
Results and DiscussionThe results of the polymerization of EO catalyzed by organoantimony compounds are summarized in Tab. 1. The data show that triorganoantimony dihalides, R,SbX,, are active catalysts to give poly(ethy1ene oxide) (PEO) in good yields. However, the molecular weight of the resulting PEO are rather low based on their viscosities and on Makromol. Chem., Rapid Commun. 1, No. 3, March 1980
