Roy L. Pruett

INDUSTRIAL ORGANIC CHEMICALS THROUGH UTILIZATION OF SYNTHESIS GAS

This paper will emphasize two areas of homogeneous transition metal catalysis. These areas concern the present or potential commercial synthesis of two largevolume organic chemicals, aldehydes produced by hydroformylation, or the 0x0 reaction, and ethylene glycol. The aldehydes are used to make monohydric alcohols for plasticizers, esters, or detergents; the principal uses of ethylene glycol are as an antifreeze agent or for polyester fabrics. Both products are produced in billionpound quantities each year. Synthesis gas, that is, a mixture of hydrogen and carbon monoxide, is an important raw material for industrial organic chemicals and is expected to increase in importance during the next decade. It can be produced from a variety of carbonaceous sources, ranging from coal to garbage. In the hydroformylation processes, the part that it contributes to the aldehyde product varies from 51% of propionaldehyde to 14% of a detergent range product and is 42% of butyraldehyde, the major single product. However, the potential ethylene glycol process would utilize 100°, of a 3 : 2 hydrogen/carbon monoxide mixture. Presently, synthesis gas is the sole raw material for the latest technology in methanol and acetic acid manufacture. The hydroformylation of olefins to produce aldehydes, and ultimately alcohols or acids, is conducted in practically every major industrial country. Until the last year, every announced plant has used cobalt as a catalyst. The general reaction is depicted in SCHEME 1. The mechanism for this reaction was proposed by Heck and Breslow in 1960’ and is shown in SCHEME 2. The cobalt-catalyzed hydroformylation depicted in SCHEME 1 is beset with several difficulties. The linear isomer is of higher value than is the branched isomer, and only little control can be exercised over the reaction. Cobalt hydrocarbonyl is a volatile, unstable complex that is difficult to separate from the products and recycle into the system. The high temperatures usually employed promote the

Synthesis and characterization of Rh3(μ-PPh2)3(CO)3(PPh3)2: a novel triangular rhodium cluster

Abstract Thermal decomposition of RhH(CO)(PPh3)3 (Ph = phenyl) in nonane at 120°C yielded a green solid in high yield. The complex was established as Rh3(μ-PPh2)3(CO)3(PPh3)2, (I), X-ray crystallography. I was found to be coordinately unsaturated in the solid state and in solution.

Phosphorus-bridged rhodium clusters : II. Synthesis and characterization of Rh4(μ-PPh2)4(CO)5(PPh3)

Abstract Decomposition of RhH(CO)(PPh 3 ) 3 (Ph = phenyl) in nonane at 120°C under CO/H 2 yielded a dark brown compound. The compound was established at Rh 4 (μ-PPh 2 ) 4 (CO) 5 (PPh 3 ) by X-ray crystallography, the structure bears certain similarities to that of Rh 3 (μ-PPh 2 ) 3 (CO) 3 (PPh 3 ) 2 .