Methanesulfonic Acid → Benzoxazole

Participants

Reaction Conditions

Reaction Steps

A mixture of 1.60 g (7.51 mmoles) of 4,6-diaminoresorcinol dihydrochloride and 3.32 g (11.26 mmoles) of oxy-bis(4-benzoyl chloride) is stirred under nitrogen atmosphere. A 10-1 methanesulfonic acid solution (89.7 g) is added. The mixture is heated for 2 hours at 70° C. and for 24 hours at 90° C. It is cooled to 50° C. and 0.98 g (3.75 mmoles) of p-diphenoxybenzene is added and washed down with 9.0 g of 10-1 methanesulfonic acid solution. Mixing is continued at 50° C. for 48 hours. The resulting copolymer is precipitated in a blender with aqueous sodium hydroxide, washed with water and dried to a constant weight. Its viscosity in concentrated sulfuric acid at 25° C. and a concentration of about 0.5 g/dL is about 0.96 dL/g.

Provenance & Evidence