Mitsuo Matsumoto

Rhodium-catalyzed low pressure hydroformylation of substituted terminal olefins. Role of α,ω-Bis(diphenylphosphino)alkane in combination with excess triphenylphosphine

Abstract Rhodium-catalyzed low pressure hydroformylation of typical terminal olefins such as allyl acetate, vinyl acetate, 3-butenyl acetate, ethyl acrylate, ethyl 3-butenate, allyl alcohol, 3-buten-1-ol, allyl butyl ether and 3-butenyl butyl ether has been examined in an aromatic hydrocarbon solution containing a large excess of triphenylphosphine. Most of the above-mentioned substituted terminal olefins are not hydroformylated substantially at low pressure; however when a nearly equimolar amount of α,ω-bis(diphenylphosphino)alkane, Ph2P(CH2)nPPh2 (n = 2–4), is added to the rhodium complex in combination with a large excess of PPh3, the hydroformylation proceeds quite smoothly even at 1 atm. It is concluded that the role of the added α,ω-bis(diphenylphosphino)alkane is to suppress the formation of a metastable acyl rhodium complex in which a six-membered ring is formed by coordination to rhodium of the oxygen atom in a carbonyl or hydroxy group of the substrate.

Reinvestigation of atmospheric hydroformylation of 1-Octene catalyzed by a rhodium complex. Some advantages given by added α,ω-bis(diphenylphosphino)alkane

Abstract Rhodium catalyzed atmospheric hydroformylation of 1-octane has been reinvestigated in an aromatic hydrocarbon sulution containing a large excess of triphenylphosphine. The conventional catalysts system affords significant quantitites of an isomerization product, and the thermal stability of the rhodium complex is not satisfactory at relatively high temperature. When an equimolar amount of α,ω-bis(diphenylphosphino)alkane, Ph 2 P(CH 2 ) n PPh 2 ( n = 2 - 4), is added to the conventional rhodium catalyst, the following advantages are given in the application to the low pressure hydroformylation of α-olefins: 1. the isomerization is greatly decreased; 2. the inhibitory effects of α,β-unsaturated aldehyde and oxygen are reduced remarkably, and 3. the thermal stability of the catalyst is improved. These improvements, caused by the addition of a small amount of α,ω-bis(diphenylphosphino)alkane, are explained by the theory that the concentration of coordinatively unsaturated rhodium complex is decreased by the α,ω-bis(diphenylphosphino)alkane, which can act either as a bidentate or a monodentate ligand.

Rhodium-catalyzed low pressure hydroformylation of higher α-olefins: New, thermally stable rhodium catalysts by reaction of RhH(CO)(PPh3)3 with phosphinous acids

Abstract Rhodium-catalyzed, low pressure hydro formylation of 1-dodecene has been reinvestigated in dodecylbenzene solution in the presence of a large excess of triphenylphosphine. The catalytic activity of the conventional RhH(CO)(PPh 3 ) 3 complex is greatly decreased by distillation of the product aldehydes under reduced pressure above 130 °C. The addition of an appropriate amount of diphenyl- or di-n-octylphosphinous acid remarkably improved the thermal stability of the rhodium complex in solution, and the catalytic activity was substantially maintained even after repeated hydroformylation and distillation. It is assumed that the formation of a new rhodium complex, Rh 2 (CO) 2 (PPh 3 ) 2 (R 2 PO) 2 , probably produced by reaction of RhH(CO)(PPh 3 ) 3 with the phosphinous acid, improves the thermal stability of the rhodium complex in solution.