88158-33-2Relevant articles and documents
119Sn NMR spectroscopic studies of organotin phosphates as catalysts for the polymerization of epoxides
Otera, Junzo,Yano, Toru,Kunimoto, Etsuko,Nakata, Tetsuya
, p. 426 - 431 (2008/10/08)
Various organotin phosphates and pyrophosphates were prepared as model compounds for organotin phosphate catalysts effective for polymerization of epoxides. Pyrolysis of the butyltin compounds thus obtained was conducted with the pure compounds or in the presence of dibutyl phosphate (DBP). 119Sn NMR spectra allowed the characterization of these compounds. It was found that phosphate ligands are easily condensed to give P-O-P linkages and that DBP cleaves Sn-C bonds. Quite interestingly, however, the last butyl group attached to the tin resisted cleavage, and thus monobutyltin compounds resulted as final products in all cases. When an excess of DBP was present, condensation of this compound with pyrophosphato ligands took place. Condensates prepared from di- or tributyltin chlorides and oxides with tributyl phosphate under various reaction conditions also were characterized on the basis of 119Sn NMR spectra. In every case, it was found that the final products are analogous to those derived from model compounds. Polymerization studies of epichlorohydrin by various organotin phosphates and pyrophosphates as model compounds led to the conclusion that the monobutyltin pyrophosphate 11 is associated with an actual active species. On the basis of these results, the nature of organotin phosphate catalysts is discussed.
