Anionic ring-opening polymerizations, catalysts, potassium

These anionic ring opening polymerizations are usually carried out either in bulk or in solution. A host of catalyst types are active. For synthetic references using specific catalysts, the reader is referred to several excellent sources (4,7,31,32). Representative catalysts include hydroxides, alcoholates, phenolates, silanolates, siloxanolates, mercaptides of the alkali metals, organolithium and potassium compounds, and quaternary ammonium and phosphonium bases and their silanolates and siloxanolates. Some physical characteristics of linear oligomers are given in Table 5 (10). 

Since the critical step in the anionic ring-opening polymerization of propanesultam is the rapture of the ring of the co-catalyst, N- benzenesulfonylsultam (activated sultam), induced by the attack of the cyclic sulufonamide anion, we treated 7V-toluenesulfonyl camphorsultam with sodium methoxide, potassium -butoxide, and a preformed camphorsultam Na salt and analyzed the products by and NMR. In all the cases the NMR analysis suggested that the sulfonamide ring had been opened by the base. It is not clear at the moment why camphorsultam is reluctant to polymerize. 

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