Anionic group 6B metal carbonyls as homogeneous catalysts for carbon dioxide/hydrogen activation: the production of alkyl formates
The production of alkyl formates from the hydrocondensation of carbon dioxide in alcohols utilizing anionic group 6B carbonyl hydrides as catalysts is herein reported. HM(CO)/sub 5//sup -/ (M = Cr, W; derived from ..mu..-H(M/sub 2/(CO)/sub 10/)/sup -/) and their products of carbon dioxide insertion, HCO/sub 2/M(CO)/sub 5//sup -/, have been found to be effective catalysts for the hydrogenation of CO/sub 2/ in alcohols under rather mild conditions (loading pressures of CO/sub 2/ and H/sub 2/, 250 psi each, and 125/sup 0/C) to provide alkyl formates. The only metal carbonyl species detected in solution via spectroscopy, both at the end of a catalytic period and during catalysis, were M(CO)/sub 6/ and HCO/sub 2/M(CO)/sub 5//sup -/. The metal hexacarbonyls were independently shown to be catalytically inactive. A catalytic cycle is proposed which initially involves release of formic acid from the metal center, either by reductive elimination of the hydrido formato ligands or ligand-assisted heterolytic splitting of dihydrogen with loss of formic acid. In a rapid subsequent process HCOOH reacts with alcohols to yield HCOOR. The addition of carbon monoxide retards alkyl formate production, strongly implying CO/sub 2/ to be the primary source of the carboxylic carbon atom in HCOOR. This was verified by carrying out reactions in the presence of HCO/sub 2/W(/sup 13/CO)/sub 5//sup -/ which provided only H/sup 12/COOR after short reaction periods. However, in the absence of hydrogen and carbon dioxide ..mu..-H(M/sub 2/(CO)/sub 10/)/sup -/ species were observed to be effective catalyst precursors for converting CO and methanol into methyl formate. 36 references, 2 figures, 2 tables.
- Research Organization:
- Texas A and M Univ., College Station
- OSTI ID:
- 6612188
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 106:13
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON DIOXIDE
CHEMICAL ACTIVATION
CHROMIUM COMPOUNDS
CATALYTIC EFFECTS
ESTERS
SYNTHESIS
HYDROGEN
TUNGSTEN COMPOUNDS
ANIONS
CARBONYLS
CATALYSTS
CHEMICAL REACTION KINETICS
CHROMIUM HYDRIDES
EXPERIMENTAL DATA
HIGH TEMPERATURE
INFRARED SPECTRA
MEDIUM PRESSURE
METHANOL
ORGANIC SOLVENTS
TIME DEPENDENCE
TUNGSTEN HYDRIDES
ALCOHOLS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHARGED PARTICLES
DATA
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONS
KINETICS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SOLVENTS
SPECTRA
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)