Process for the preparation of benzotriazole derivatives

A process for the preparation of 2-(2'-hydroxyphenyl)-2H-benzotriazole derivatives of the formula (I):

• ##STR23## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.6, R.sub.7, are independently:
• H;
• halogen;
• NH.sub.2 ;
• cyano;
• --(CH.sub.2).sub.p CO.sub.2 Y where Y is H or a 1 to 12 carbon atom alkyl or 6 to 20 carbon atom aryl and p is 0 to 20;
• 1 to 12 carbon atom carbamoyl group;
• 0 to 12 carbon atom sulfido group;
• 0 to 12 carbon atom sulfonyl group;
• 0 to 12 carbon atom sulfonato group;
• 0 to 12 carbon atom sulfonamido group;
• 1 to 18 carbon atom alkyl group;
• 1 to 18 carbon atom alkoxy group;
• 1 to 18 carbon atom sulfido group;
• 6 to 20 carbon atom aryl group;
• 5 to 20 atom heteroaryl group having 1 to 4 hetero atoms selected from O, N, S, P or Si;
• 6 to 20 carbon atom aryloxy group;
• or any two or more of adjacent ones of R.sub.1 through R.sub.4 may form, together with the carbon atoms of the benzene ring to which they are attached, a 1 to 10 carbon atom alicyclic group, a 6 to 20 carbon atom aromatic group or a 5 to 20 atom heteroaryl group having 1 to 4 heteroatoms selected from O, N, S, P or Si;
• R.sub.5 is H, acetyl, p-toluenesulfonyl or dialkylcarbamyl;
• R.sub.8 is H or OX where X is H or a 1 to 6 carbon alkyl, acetyl, benzyl, benzoyl, p-toulenesulfonyl or dialkylcarbamyl group;
• Z is H, OH, a 1 to 6 carbon atom alkyl, 1 to 6 carbon atom alkoxy, 2 to 10 carbon atom acyloxy, to 12 carbon atom arylsulfonyloxy or 2 to 12 carbon atom dialkylcarbamato group or a group of the formula:
• ##STR24## wherein each of R.sub.9 and R.sub.10 is independently H, 1 to 6 carbon atom alkyl group, 1 to 12 carbon atom acyl group, 6 to 20 carbon atom alkylsulfonyl group, arylsulfonyl group, heteroarylsulfonyl group, or a 2 to 12 carbon atom dialkylcarbamato group,
• said process comprising the catalytic hydrogenation of an azo dye compound of formula (II) ##STR25## wherein R.sub.5 -R.sub.8 and Z are as defined above for formula I, and R.sub.1 -R.sub.4 are as defined above or a NO.sub.2 group, in the presence a noble metal hydrogenation catalyst, a base and an acid in a reaction medium comprising a polar hydroxylic solvent and, optionally, a non-hydroxylic solvent.