POLYMERIZATION OF CYCLIC MONOMERS CONTAINING PHOSPHORUS

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Abstract
The mechanism of polymerization is discussed, in which cyclic esters of phosphoric acid, and related compounds are converted into linear macromolecules, modelling nucleic and teichoic acid backbones. Structures like deoxyribose polyphosphate and glycerol polyphosphate were prepared from the corresponding cyclic compounds. These polymerizations involve heterolytic breaking of the P[sbnd]O bond in the corresponding cyclic monomer and proceed by ionic mechanisms. Both 5- and 6-membered monomers have been polymerized. The thermodynamic parameters of the ring-chain interconversion were determined; the 5-membered ring polymerization is driven by the exothermicity of the ring-opening, whereas polymerization of several 6-membered rings is endothermic and allowed because of the positive change of entropy. Anionic polymerization, and particularly the coordinate-anionic polymerization provides, in contrast to the cationic processes, high-molecular weight polymers with more uniform structure. Anionic polymerization proceeds mostly (in the applied conditions) on the macroion-pairs. The elementary reactions consist of the nucleophilic attack of the paired macroanions on the phosphorus atom in the cyclic monomer molecule. Rate constants of the elementary reactions for the model monomers are discussed.