Catalytic oxidation of styrene using cis-MoO2(L)(solv) [L = salicylidene salicyloyl hydrazine) and its zeolite composite as catalysts in the presenceof molecular oxygen

The catalytic oxidation of styrene using cis-MoO2(L)(solv) [L = Salicyliden e Salicyloyl Hydrazine) and its zeolite-Y composite as catalysts in the pre sence of molecular oxygen and in the temperature range 50-70 degrees C is s tudied. The oxidation products are found to be styrene epoxide and phenyl a cetaldehyde. Phenyl acetaldehyde is observed to form only in homogeneous ca talytic system towards the end of a 5-h reaction period. A 77% conversion o f styrene into products (styrene epoxide: phenyl acetaldehyde ratio = 85:15 ) is obtained under homogeneous catalytic conditions, whereas use of comple x zeolite composite resulted in 68% conversion of styrene into styrene epox ide selectively. Styrene epoxide is formed with a turnover of 9/mol Mo in c atalyst at 60 degrees C in homogeneous catalytic system. The turnover incre ased to 64 when encapsulated complex is used. The rate of styrene oxidation showed first-order dependence with respect to catalyst and substrate conce ntration. A mechanism for oxidation of styrene with cis-MoO2(L)solv) is pro posed and reasons for selective conversion of styrene into corresponding ep oxide is presented. (C) 2000 Elsevier Science B.V. All rights reserved.