反应详情

A mixture of the 3,3′-bis-(2-nitrophenylazo)-5,5′-di-tert-butyl-1,1′-biphenyl-2,2′-diol (3.5 g), zinc powder (6.38 g), 15% aqueous sodium hydroxide (20 ml), and ethanol (40 ml) was boiled under reflux in a nitrogen atmosphere for three hours. The hot mixture was filtered over diatomaceous earth. After cooling in an ice bath and acidification with hydrochloric acid, the precipitated product was collected by suction filtration, washed with water and air dried. Purification of the crude product by dry column chromatography using a mixture of hexane and ethyl acetate (9:1 v/v) as the eluent gave pure 3,3′-bis-(2H-benzotriazol-2-yl)-5,5′-di-tert-butyl-1,1′-biphenyl-2,2′-diol (COMPOUND 2) (0.8 g); m.p. 234° C.

1. temperatureunder reflux in a nitrogen atmosphere for three hours
2. filtrationThe hot mixture was filtered over diatomaceous earth
3. temperatureAfter cooling in an ice bath
4. filtrationacidification with hydrochloric acid, the precipitated product was collected by suction filtration
5. washwashed with water and air
6. customdried
7. customPurification of the crude product
8. customby dry column chromatography
9. additiona mixture of hexane and ethyl acetate (9:1 v/v) as the eluent