Amino Acid N−Carboxy Anhydrides with High Polymerizability in the Solid State

Abstract

Solid-state polymerization of amino acid N−carboxy anhydrides was carried out in hexane with butylamine. L-Leucine NCA, L-phcnylalanine NCA, β-benzyl-L-aspartate NCA and DL-phenylalanine NCA gave high polymerizability in the solid state, compared with the reaction in the solution. L-Leucine NCA and L-phenylalanine NCA were found to polymerize mainly along a definite direction in the crystal. The crystal structure to determine the high reactivity in the solid state were considered; a sandwich structure: the alternative alignment of the five-membered ring layers and the side chain layers, and the molecular arrangement preferable for the formation of the polymer conformation.