Liquid phase versus microwave assisted selective oxidation of volatile organic compounds involving dioxidomolybdenum(VI) and oxidoperoxidomolybdenum(VI) complexes as catalysts in the presence/absence of an N-based additive. (18th April 2015)

• Record Type: Journal Article
• Authors: Maurya, Mannar R.; Saini, Neeraj; Avecilla, Fernando
• Is Part Of: Polyhedron. Volume 90(2015)
• Page Start: 221
• Page End: 232
• Publication Date: 2015-04-18
• Subjects: Tridentate ONO donor Schiff base ligands -- Molybdenum(VI) complexes -- NMR spectroscopy -- Microwave assisted reaction -- Oxidation of secondary alcohols; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2015.01.030
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Dioxido- and oxidoperoxido-molybdenum(VI) complexes with ONO donor ligands derived from 3-acetyl-6-methyl-(2H)-pyran-2, 4(3H)-dione have been synthesized and characterized. Using microwave as well as liquid phase techniques, oxidation of volatile organic compounds by H2 O2 with these complexes as catalysts has been carried out in the presence/absence of an N-based additive. Abstract: Four dioxidomolybdenum(VI) complexes, [Mo VI O2 (dha-bhz)(MeOH)]·(H2 dha-bhz) (1 ), [MoO2 (dha-inh)(MeOH)] (2 ), [MoO2 (dha-nah)(MeOH)] (3 ) and [MoO2 (dha-fah)(MeOH)] (4 ), and their corresponding oxidoperoxidomolybdenum(VI) complexes, [MoO(O2 )(dha-bhz)(MeOH)] (5 ), [MoO(O2 )(dha-inh)(MeOH)] (6 ), [MoO(O2 )(dha-nah)(MeOH)] (7 ) and [MoO(O2 )(dha-fah)(MeOH)] (8 ), with ONO tridentate Schiff base ligands derived from 3-acetyl-6-methyl-(2H)-pyran-2, 4(3H)-dione (dehydroacetic acid, Hdha) and aromatic hydrazides, {benzoyl hydrazide (bhz), isonicotinoyl hydrazide (inh), nicotinoyl hydrazide (nah) and furoyl hydrazide (fah)} have been synthesized and characterized by elemental analysis, spectroscopic techniques (infrared, UV–Vis, 1 H and 13 C NMR) and thermogravimetric analyses. The structures of complexes1 and2, confirmed by single crystal X-ray study, reveal that the tridentate ligand binds to the metal centers through the enolic oxygen (of the pyrone group), azomethine nitrogen and enolic oxygen (of the hydrazide group) atoms; methanol is coordinated at one site through the oxygen atom. The dioxidomolybdenum(VI) complexes have been tested as catalysts for the homogeneous oxidation of secondary alcohols (1-phenyl ethanol, 2-propanol and 2-butanol), using 30% H2 O2 as an oxidant. Both microwave and conventional liquid phase oxidation methods have been tested for catalytic reactions. Various parameters, such as amount of catalyst, oxidant, solvent and temperature, of the reaction mixture have been taken into consideration for the maximum conversion of the substrates. Under the atmospheric optimized reaction conditions, secondary alcohols give high yields of the respective ketones selectively. Addition of an N-based additive reduces the time and increases the conversion of alcohols. Amongst the two methods studied, the microwave technique proves to be a time efficient system.