Benzoic Acid → HCID 178527630, compound

Participants

Reaction Conditions

Reaction Steps

108 parts of o-phenylenediamine are introduced into 500 parts of H2SO4 (>96%) and then 800 parts of oleum (65%) are added dropwise, the temperature being maintained at a maximum of 120° C. After 15 min, the mixture is cooled to 70° C. and 120 parts of benzoic acid are added. The mixture is heated for 2 h at 180° C. The mixture is slowly hydrolysed with 2 500 parts of water, the temperature being maintained below 10° C. The precipitate (crystals) is filtered off with suction, the crude product is suspended in 8 parts of water and dissolved with 32% sodium hydroxide solution at pH=7. The solution is stirred with activated carbon until colorless, and thereafter precipitation is induced using 96% H2SO4 by establishing a pH=1-2. 300 parts of 2-phenylbenzimidazole-4,6-disulfonic acid are obtained. The compound has an absorption maximum in the UV-B region at λmax=308 nm.

Provenance & Evidence