OXIDATION OF CYCLOHEXANE OVER COPPER PHTHALOCYANINES ENCAPSULATED IN ZEOLITES

The oxidation of cyclohexane to cyclohexanol, cyclohexanone and adipic acid has been studied using phthalocyanines and substituted (chloro-a nd nitro-) phthalocyanines of copper, cobalt and iron encapsulated in zeolites X and Y, at ambient conditions and using molecular oxygen as well as alkyl (tertiary butyl, cyclohexyl and cumyl) hydroperoxides as the oxidants. The catalytic efficiencies of the encapsulated material s are much higher than those of the neat complexes. The rate of oxidat ion of cyclohexane using copper hexadecachloro phthalocyanine-encapsul ated Y zeolite catalysts is quite high (TOF = 400 h(-1)) with TBHP eff iciencies which can reach upto 90%. The isolated encapsulated metal co mplex is the active site. Solvents exert a major influence on product distribution (cyclohexanol, cyclohexanone and adipic acid are the majo r products). Byproducts like succinic and glutaric acids are not forme d when using acetonitrile as the solvent. Rates of oxidation when usin g the alkyl hydroperoxides as oxidants decrease with an increase in th eir molecular cross-section (cyclohexyl > t-butyl > cumyl) confirming that the active site is indeed located inside the zeolitic cavities an d not on the external surface.