Processes for the preparation of benzotriazole uv absorbers

Details Processes for the preparation of benzotriazole uv absorbers Processes for the preparation of benzotriazole uv absorbers

C - Chemistry, Metallurgy

07

D

C07D 249/20 (2006.01) C07C 245/08 (2006.01) C08K 5/3475 (2006.01)

Patent

CA 2416356

Provided is a process for preparing 2H-benzotriazole UV absorbers containing a perfluoroalkyl moiety at the 5-position of the benzo ring, for example a trifluoromethyl group, which involves diazotizing the perfluoroalkyl substituted o-nitroaniline using concentrated sulfuric acid plus sodium nitrite or nitrosylsulfuric acid to form the corresponding monoazobenzene intermediate via the diazonium salt intermediate which is reduced to the corresponding 5-perfluoroalkyl substituted 2H-benzotriazole UV absorber compound by conventional reduction means. Also provided is a novel one-pot, multiphase reaction for the preparation of 2(2-nitrophenylazo) substituted phenols, which are precursors for 2H-benzotriazole UV absorbers.

L'invention porte sur un procédé de préparation d'absorbeurs d'UV 2H-benzotriazole contenant une fraction perfluoroalkyle à la position 5 du noyau benzo, par exemple, un groupe trifluorométhyle. Ce procédé consiste à diazotiser perfluoroalkyle substitué o-nitroaniline au moyen d'acide sulfurique concentré plus du nitrure de sodium ou de l'acide nitrosylsulfurique de façon à former l'intermédiaire de monoazobenzène correspondant via l'intermédiaire du sel de diazonium qui est réduit par rapport au composé correspondant de l'absorbeur d'UV 5-perfluoroalkyle substitué 2H-benzotriazole au moyen d'un dispositif de réduction traditionnel. L'invention porte également sur une nouvelle réaction multiphase, monotope, utilisée dans la préparation de phénols substitués par 2(2-nitrophénylazo) qui sont des précurseurs pour les absorbeurs d'UV 2H-benzotriazole.

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