POLY(ALKYLVINYLPYRIDINE 1-OXIDES) AND CORRESPONDING ALKYLPYRIDINE OXIDES - ELECTRONIC SPECTRA AND INTERACTION WITH SILICIC ACID

Poly-(2-vinylpyridine 1-oxide) is chemotherapeutically active against pathogenic effects of silica in animals and it has been suggested that the activity is related to structure and interaction with silicic acid. Alkyl derivatives of this polymer have been synthesised. As compared with the corresponding ethylpyridine 1-oxides, the electronic spectra of these polymers all show bathochromic shifts and there is a large reduction in the extinction coefficients. No interaction of the monomeric analogues of the polymers with silicic acid can be demonstrated by spectral changes, but interaction of the polymers with 0.01M-monosilicic acid and with polymerised silicic acid produces shifts in the electronic spectra of the polymers and changes in viscosity. An attempt has been made to relate the form of the viscosity-concentration curves with the structure of each polymer on the assumption that there is bonding between N-oxide and an adjacent alkyl group. No interaction between silicic acid and poly(2-methyl-6-vinylpyridine 1-oxide), in which there are alkyl groups on either side of the N-oxide, can be demonstrated, and this polymer is inactive against the pathogenic effects of silica.