- Fluorenol catalyzed reduction of o-nitroazobenzenes and 2-aryl-2H-benzotriazole-N-oxides
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A process for producing 2-aryl-2H-benzotriazole by reducing an o-nitroazobenzene with a saccharide having an aldehyde group as a reducing agent in the presence of fluorenol as a catalyst and a base in solution. The reaction is conducted at a temperature of from about 60° C. to about 80° C. The reaction time and amount of catalyst is significantly reduced compared to the use of an aromatic ketone catalyst. The invention also provides a method for producing 2-aryl-2H-benzotriazole by reducing a 2-aryl-2H-benzotriazole-N-oxide intermediate with a saccharide having an aldehyde group as a reducing agent, in the presence of fluorenol under similar conditions.
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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This invention relates to a method for preparing 2-phenylbenzotriazoles having the formula I, STR1
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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A method for preparing a 2-phenylbenzotriazole of formula I wherein R1 is H, Cl, C1-4alkyl, C1-4alkoxy, COOH or SO3H; R2 is H, Cl, C1-4alkyl or C1-4alkoxy; R3 is H, Cl, C1-12alkyl, C1-4alkoxy, phenyl, (C1-8alkyl)phenyl, phenoxy or phenyl(C1-4alkyl); R4 is H, Cl, OH or C1-4alkoxy; and R5 is H, C1-12alkyl or phenyl(C1-4alkyl), comprises reducing a nitroazobenzene of formula III = wherein R1, R2, R3, R4 and R5 are as defined above, with a saccharide in the presence of a hydrogen transfer catalyst and base. This method can be conducted in one or two steps. The individual steps, the first from the nitroazobenzene to a 2-phenylbenzotriazole-N-oxide of formula II and the second (II→I) are independent aspects of the invention.
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