Functional monomers and polymers, 54. Synthesis of poly‐β‐alanine from β‐alanine 4‐acyl‐2‐nitrophenyl esters

A series of active β‐alanine 4‐acyl‐2‐nitrophenyl esters with different lengths of alkyl groups was prepared, and their polycondensation was studied in various solvents. The results of the polycondensation of these esters with triethylamine at room temperature show that the conversion and the degree of polycondensation of the resulting poly(β‐alanine)s depend on the chain length of the alkyl groups. No polymer was obtained in both protic and dipolar aprotic solvents such as methanol and DMSO, whereas nonpolar solvents such as diethyl ether, carbon tetrachloride, or benzene were found to be suitable for the polycondensation. The effect of a variety of amines on the polycondensation was examined for β‐alanine 4‐dodecanoyl‐2‐nitrophenyl ester ( 4e ) in diethyl ether solution.