Kinetics of polymerization of N-carboxy amino acid anhydride in dimethyl sulfoxide

Various kinds of NCA's were polymerized in dimethyl sulfoxide (DMSO). DL -Alanine NCA polymerized at a fast rate without initiator, the rate being represented by R_p1 = kM]^1/2. When the polymerization was carried out in chloroform in the presence of DMSO, the rate was represented by the equation, R_p2 = K₂M]DMSO]^1/2. Glycine NCA and DL -α-amino-n-butyric acid NCA also polymerized at a fast rate in DMSO without initiator. On the other hand, N-methylglycine NCA, DL - and L -valine NCA and DL - and L -leucine NCA did not polymerize in DMSO without initiator.