Process for the preparation of dihydroxyphenylazophenylazophenyl

Details Process for the preparation of dihydroxyphenylazophenylazophenyl Process for the preparation of dihydroxyphenylazophenylazophenyl

1977-04-19

1978-09-19

Higel, Floyd D.

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

260144, 260208, C09B 3106, D06P 104, D06P 342, D06P 354

Patent

active

041153804

ABSTRACT:
Process for the manufacture of a disazo dyestuff of the formula ##STR1## in which R.sub.1 and R.sub.2 each stand for hydrogen, chlorine, bromine, alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms, R.sub.3 and R.sub.4 each stand for hydrogen, chlorine, bromine, nitro, trifluoromethyl, alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms; and the hydroxyl groups each stand in 2- or 4-position to the azo groups which comprises diazotizing a 2- or 4-hydroxy-4'-aminoazobenzene of the formula ##STR2## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are defined as above, with an alkali metal nitrite in an aqueous mineral acid, the normality of which being about 10.sup.-2 to 5, in the presence of a phenol capable of being coupled of the formula ##STR3## in which R.sub.1 and R.sub.2 are defined as above and subsequently reacting the diazonium salt obtained with the phenol by raising the pH to a value between about 3 and 11, the surprising feature of this process (diazotization in the presence of the phenol) being that practically no nitrozation or a nitration of the phenol occurs.

REFERENCES:
patent: 2072252 (1937-03-01), Ellis
patent: 2782185 (1957-02-01), Merian
patent: 2954371 (1960-09-01), Liechti
patent: 3045004 (1962-07-01), Gaetani
patent: 3523935 (1970-08-01), Armento et al.

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