Hydrogenation Kinetics
of 2'-Hydroxy-5'-Methyl-2-Nitroazobenzene
under Quasisteady Conditions

O. V. Lefedova

Ivanovo State University of Chemical Technology, Ivanovo, Russia

Received July 30, 2002

Abstract—The kinetics of the liquid-phase hydrogenation of 2'-hydroxy-5'-methyl-2-nitroazobenzene on skel-
etal nickel in propan-2-ol and its mixtures with water and sodium hydroxide was studied under quasisteady con-
ditions ensured by a measured substrate feed into a reaction vessel. 2-(2-Hydroxy-5-methylphenyl)benzotri-
azole N-oxide, 2'-hydroxy-5'-methyl-2-nitrohydrazobenzene, and aromatic amines were found to be the major
reaction intermediates under both steady and quasi-steady conditions, provided the compositions of the solvents
are the same. The highest reaction selectivity for the target product, namely, 2-(2-hydroxy-5-methylphenyl)ben-
zotriazole, can be reached at low concentrations of the starting reagent in a chemisorbed layer and high rates of
cyclization of 2'-hydroxy-5'-methyl-2-nitrohydrazobenzene into 2-(2-hydroxy-5-methylphenyl)benzotriazole
N-oxide.

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