Nitric Acid → Benzimidazol-2-one

Participants

Reaction Conditions

Reaction Steps

20 parts of abenzimidazolone orange pigment (C.I. pigment orange 36) which had been previously finely ground and 62 parts of p-amino-N-ethylpyridinium bromide were dispersed in 150 parts of water. To the mixture were then added dropwise 32 parts of nitric acid. The mixture was then stirred at a temperature of 75° C. for 5 minutes. To the mixture was then added an aqueous solution of sodium nitrite. The mixture was further stirred for 2 hours, and then repeatedly rinsed and filtered to obtain a slurry of a surface-treated benzimidazolone orange pigment having an N-ethylpyridyl group introduced therein with the interposition of phenyl group.

Provenance & Evidence