50815-99-1

Upstream product

• 1435-71-8 4-methyl-2-(2-nitrophenylazo)phenol 
• 1435-71-8 2-nitro-2'-hydroxy-5'-methyl-azobenzene 

Relevant academic research and scientific papers

The Continuous Synthesis of 2-(2'-Hydroxy-5'-Methylphenyl)Benzotriazole over Cu/γ-Al2O3

Abstract: The samples of 20% Cu/γ-Al2O3, 20% Co/γ-Al2O3 and 20% Ni/γ-Al2O3 were prepared as hydrogenation catalysts for continuous synthesis of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. The best yield (86.62%) was afforded by the 20% Cu/γ-Al2O3 catalyst. The characterizations results obtained for the 20% Cu/γ-Al2O3 sample confirmed that Cu particles are evenly distributed over the surface of γ-Al2O3. A reduction of acid sites in the catalyst favored the selectivity to 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. Furthermore, the effect of Cu content, reaction temperature, hydrogen pressure and liquid hourly space velocity was studied. Finally, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole in 86.62% yield was attained under the optimized conditions.

Hydrogenation of Substituted Benzenes Containing Nitro and Azo Groups over Skeletal Nickel in Aqueous Solutions of 2-Propanol

Abstract: An analysis is made of the kinetic characteristics of the hydrogenation of 4-nitro- and 2-nitro-2'-hydroxy-5'-methylazobenzenes, 4-nitroaniline and 4-aminoazobenzene over skeletal nickel in neutral azeotropic 2-propanol–water mixture and in the same solvent in the presence of acetic acid or sodium hydroxide. It is found that the selectivity of the hydrogenation of these isomers to the intermediate products depends on the composition and nature of the solvent, and is determined by the rate of reactive group conversion. Compared to the process in the presence of sodium hydroxide, which suppresses the route leading to the predominant hydrogenation of the nitro group, the contribution from the transformation of azo group is considerably greater in the hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene in the presence of acetic acid. Adding a base to the solvent during the hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene accelerates the rate of nitro group conversion and the intramolecular cyclization of the intermediate compound, increasing the selectivity towards the products containing the benzotriazole cycle (particularly 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-oxide). The almost linear correlation between the selectivity of the catalytic hydrogenation of isomers of nitro-2'-hydroxy-5'-methylazobenzene and the kinetic characteristics of the hydrogenation of nitro and azo groups in compounds containing a single reactive substituent at different values of medium’s pH is estimated.

Catalytic hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene over solid base-hydrogenation bifunctional catalysts: Effect of alkali metals on Pd/γ-Al2O3

Alkali metals doped Pd solid base-hydrogenation bifunctional catalysts were prepared, characterized, and employed in the hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene. The results indicated that the basicity of catalyst endowed by the alkali met

Reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene to benzotriazole over K-doped Pd/γ-Al2O3

A series of Pd/γ-Al2O3 catalysts modified by potassium salts were prepared and evaluated in the reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene without additional base. These solid base-hydrogenation bifunctional catalysts were characterized and the results demonstrated that potassium salts could have an important impact on the properties and catalytic performance of Pd/γ-Al2O3.

Hydrogenation kinetics of 2′-hydroxy-5′ -methyl-2-nitroazobenzene under quasisteady conditions

The kinetics of the liquid-phase hydrogenation of 2′-hydroxy-5′ -methyl-2-nitroazobenzene on skeletal nickel in propan-2-ol and its mixtures with water and sodium hydroxide was studied under quasisteady conditions ensured by a measured substrate feed into a reaction vessel. 2-(2-Hydroxy-5-methylphenyl)benzotriazole 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)benzotriazole, 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.

2-bromo-2-nitropropane/zn promoted reductive cyclizations of ortho-carbonyl, imino, or azo substituted nitrobenzenes

Under the mild conditions, reductive cyclizations of 2-nitrobenzaldehydes, 2'-nitroacetophenone, and N-(2-nitrobenzylidene)anilines were accomplished in the presence of 2-bromo-2-nitropropane/Zn in methanolic solution. Under the similar conditions in MeOH/CH2Cl2, o-nitro-substituted phenylazobenzenes have been converted into 2-aryl-2H-benzotriazoles via reductive cyclizations that are widely used as UV absorbers. Synthesis and mechanistic details are discussed.

SYNTHESIS OF SOME BENZOTRIAZOLES BY DEOXYGENATION OF o-NITROPHENYLAZO COMPOUNDS BY TERTIARY AMINES AND CO

NEt3 promotes the deoxygenation of specific ortho-nitrophenylazo compounds affording benzotriazoles in good yields and selectivities. The role of the amine is examined in the deoxygenation process with CO as the final oxygen acceptor.