Copolymer statistics during esterification of syndiotactic poly(methacrylic acid) with diazomethane

Syndiotactic poly(methacrylic acid) is partially esterified as such or in its neutralized form with diazomethane. The extent of reaction and the triad distribution of the resulting cosyndiotactic methyl methacrylate‐methacrylic acid copolymers and their fractions are determined by 1 H‐NMR spectroscopy. Unneutralized poly(methacrylic acid) yields copolymers which are heterogeneous with respect to conversion, the fractions of the copolymers possessing an approximate B ERNOULLI an triad distribution. Neutralized poly(methacrylic acid) results in homogeneous copolymers whose triad distribution is B ERNOULLI an within accuracy of measurement. A kinetic neighboring group effect is therefore not operative during the esterification with diazomethane. Copolymers may thus be prepared which are of simple configurational and compositional statistics, not obtainable at present by copolymerization of monomers. The polyelectrolyte character of the copolymers may be eliminated by consecutive, complete esterification with a second diazoalkane, the statistics of the derived copolymers being identical with that of the precursor copolymers.