02573nas a2200217   4500008004100000022001400041245006900055210006700124260007600191300001400267490000800281520180600289653003202095653003302127653002002160653003602180100001702216700001202233700001702245856009302262       2005                        eng d  a1364-503X00aNovel, benign, solid catalysts for the oxidation of hydrocarbons0 aNovel benign solid catalysts for the oxidation of hydrocarbons  a6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLANDbROYAL SOCIETYcAPR  a1001-10120 v3633 a<p>The catalytic properties of two classes of solid catalysts for the oxidation of hydrocarbons in the liquid phase are discussed: (i) microporous solids, encapsulating transition metal complexes in their cavities and (ii) titanosilicate molecular sieves. Copper acetate dimers encapsulated in molecular sieves Y, AICM-22 and VPI-5 use dioxygen to regioselectively ortho-hydroxylate L-tyrosine to L-dopa, phenol to catechol and cresols to the corresponding o-dihydroxy and o-quinone compounds. Monomeric copper phthalocyanine and salen complexes entrapped in zeolite-Y oxidize methane to methanol, toluene to cresols, naphthalene to naphthols, xylene to xylenols and phenol to diphenols. Trimeric mu(3)-oxo-bridged Co/Mn cluster complexes, encapsulated inside Y-zeolite, oxidize para-xylene, almost quantitatively, to terephthalic acid. In almost all cases, the intrinsic catalytic activity (turnover frequency) of the metal complex is enhanced very significantly, upon encapsulation in the porous solids. Spectroscopic and electrochemical studies suggest that the geometric distortions of the complex on encapsulation change the electron density at the metal ion site and its redox behaviour, thereby influencing its catalytic activity and selectivity in oxidation reactions. Titanosilieate molecular sieves can oxidize hydrocarbons using dioxygen when loaded with transition metals like Pd, An or Ag. The structure of surface Ti ions and the type of oxo-Ti species generated on contact with oxidants depend on several factors including the method of zeolite synthesis, zeolite structure, solvent, temperature and oxidant. Although, similar oxo-Ti species are present on all the titanosilicates, their relative concentrations vary among different structures and determine the product selectivity.</p>10abenign catalytic oxidations10aencapsulated metal complexes10aSolid catalysts10atitanosilicate molecular sieves1 aRatnasamy, P1 aRaja, R1 aSrinivasi, D  uhttps://library.ncl.res.in/content/novel-benign-solid-catalysts-oxidation-hydrocarbons-0