A mechanism for the transfer hydrogenation of ketones to secondary alcohols catalysed by HFe3(CO)11-1 (1) in the presence of Phase Transfer Catalysts (PTC) has been proposed using labelled hydrogen, NMR and IR techniques. © 1989.

S. Vancheesan

ALCOHOLS--SYNTHESIS

CATALYSTS--IRON COMPOUNDS

nuclear magnetic resonance

Cyclohexanol

IRON CARBONYLS

Nitroarenes

PHASE TRANSFER CATALYSTS (PTC)

Ketones

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Mechanism for transfer hydrogenation of ketones to alcohols catalysed by hydridotri-ironundecacarbonylate anion under phase transfer conditions

Journal of Molecular Catalysis

Transfer hydrogenation of ketones to alcohols using iron carbonyls as catalysts in liquid-liquid phase occurs in the presence of phase transfer catalysts (PTC). Based on the percentage yield of the products, the efficiencies of the phase transfer agent, iron carbonyls and the donors are compared. Benzyltriethylammonium chloride and 18-crown-6 are equally effective and better than tricaprylmethylammonium chloride (Aliquat® 336). Among the three iron carbonyls the order of efficiency is Fe3(CO)12 &gt; Fe2(CO)9 &gt; Fe(CO)5. 1-Phenylethanol is a better donor than isopropanol. The relative ease of reducibility of various ketones increases with increasing reduction potential. The stereochemistry of reduction of 4-t-butylcyclohexanone is discussed. © 1985.

Phase transfer-catalysed transfer hydrogenation of ketones using iron carbonyls as catalysts

The catalyst RuCl2(PPh3)3 is transformed into a catalytically inactive complex RuCl2(CO)(PPh3)2(DMF) during disproportionation of D-glucose in dimethylformamide (DMF). In dimethylacetamide (DMA), the catalyst is converted to RuCl2(CO)(PPh3)2(DMA) and cis-RuCl2(CO)2(PPh3)2. The aldehydo-glucose is shown to be the main source of carbon monoxide. © 1983.

Deactivation of RuCl2(PPh3)3 during disproportionation of D-glucose in amide solvents

The disproportionation of D-glucose in tetrahydrofurfuryl alcohol (THFA) catalysed by RuHCl(CO)(PPh3)3is suggested to proceed by hydride transfer from a dissociated catalyst species to the coordinated aldehyde form of glucose. Subsequent steps involve the coordination of the pyranose form of glucose, formation of the metal alkoxide, release of D-glucitol and hydrogen transfer from alkoxide to the metal. The kinetic data are compatible with the rate expression, rate = (kK[G][Ru]0)/([P] + K), where k, K, [G], [Ru]0 and [P] represent the rate constant of the rate-determining step, the equilibrium constant for the dissociation of the catalyst, concentrations of glucose, catalyst and added triphenylphosphine respectively. © 1983.

The mechanism of disproportionation of D-glucose catalysed by hydridochlorocarbonyltris(triphenyl-phosphine)ruthenium(II) in tetrahydrofurfuryl alcohol

In the homogeneous hydrogen transfer from 1-phenyl-ethanol(D) to cyclohexanone(A) catalyzed by RuCl2(PPh3)3(C) in diphenyl ether as solvent at 140 °C the order of addition of donor, acceptor and catalyst have a pronounced effect on the rate of the reaction. An induction period is observed. The experimental observations correspond to the rate expression:. Initial rate = {A figure is presented} where [C]t is the total concentration of catalyst in the system. © 1983.

Mechanistic investigation of homogeneous hydrogen transfer from 1-phenylethanol to cyclohexanone catalyzed by dichlorotris(triphenylphosphine)- ruthenium(II)

Cyclohexanone has been used as an acceptor for the dehydrogenation of some natural products in the presence of RuCl2(PPh3)3. Only menthol undergoes appreciable dehydrogenation when compared to cholesterol and β-citronellol. Menthone, cholest-4-en-3-one and cholest-1,4-diene-3-one and citronellal are the products from these compounds. When carbohydrates are used as donors, in most cases the corresponding lactones are formed. The ratio of acceptor to donor is maintained at 6 in the latter cases to avoid disproportionation of the carbohydrates. Acids, isomer and epimer are formed in certain cases. It is observed that the dehydrogenation of carbohydrates is increased at elevated temperatures. The susceptibility to dehydrogenation of the carbohydrates is in the order sorbitol &gt; mannitol &gt; L-arabinose ≈ D-xylose &gt; D-glucose ≈ sucrose &gt; D-mannose ≈ D-galactose. © 1982.

Journal	Journal of Molecular Catalysis
ISSN	03045102
Open Access	No