Chemoselective synthesis of polyamides containing hydroxyl and amino substituents by direct polycondensation

A convenient method for the synthesis of polyamides containing hydroxyl and amino substituents on the aromatic rings of the backbones was developed. These polymers were prepared readily by the chemoselective polycondensation of dicarboxylic acids with diamines with hydroxyl and amino functional groups via the activating agent diphenyl(2,3-dihydro-2-thioxo-3-bezoxazolyl)phosphonate. The model reactions were studied in detail to demonstrate the feasibility of chemoselective polycondensation. The direct polycondensation of 5-hydroxy or 5-aminoisophthalic acid with 4,4'-diamino-4-hydroxytriphenylmethane proceeded smoothly under mild conditions and produced the desired polyamides with inherent viscosities up to 0.73 dL.g -1 . The polymers obtained were characterized by IR, 1 H NMR, and 13 C NMR spectroscopies. The polymers were readily soluble in aprotic polar solvents such as N-methyl-2-pyrrolidinone, N,N-dimethyl formamide, and dimethyl sulfoxide.