THE MODIFICATION OF POLYSULFONE BY METALATION

Our studies of changes in membrane characteristics brought about by various types of functional groups led to the development of this versatile modification approach in which a diverse range of substituted polymers are attainable. In this letter, the position and degree of lithiation was examined by **1H-NMR spectral analysis of two simple derivatives. Polysulfone was controllably lithiated by n-butyllithium in THF at temperatures of 0 degree C and below. The reaction proceeded rapidly and homogeneously in high yield and required little or no excess of reagent and no catalyst. **1H-NMR analysis of the methyl and deutero derivatives indicated that the site of lithiation was at the ortho-sulfone position. Up to two lithium atoms per repeat unit were readily substituted, although lower degrees of substitution were obviously equally readily attainable. The high degree of substitution possible by direct metalation is somewhat unusual in low molecular weight systems and exceptional in polymeric systems where lower degrees of substitution and poor regiospecificity and control are typical. Lithiation is a versatile method of polysulfone modification because of the known reactivity of lithium aryls with numerous electrophiles.