Chemistry Letters, Vol.33, No.10, 1342-1343, 2004
An efficient catalyst for low temperature solid-phase cyclization of poly(o-hydroxyamide)
An efficient acid catalyst for the low-temperature solid-phase cyclization of poly(o-hydroxyamide) (PHA) has been found. Thermal cyclization of PHA into poly(benzoxazole) (PBO) proceeded quantitatively at 250degreesC in 10 min in the presence of 10wt% of a photoacitve compound, (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-2-(methylphenyl)-acetonitrile (PTMA).