Hydroformylation with Rhodium-Amine Complexes

Abstract

Under mild conditions, hydroformylation of olefins with rhodium carbonyl complexes selectively produces aldehydes.A one-step synthesis of oxo alcohols is possible using monomeric or polymeric amines, such as dimethylbenzylamine or anion exchange resin analog to hydrogenate the aldehyde. The rate of aldehyde hydrogenation passes through a maximum as amine basicity and concentration increase. IR data of the reaction reveal that anionic rhodium carbonyl clusters, normally absent, are formed on addition of amine. Aldehyde hydrogenation is attributed to enhanced hydridic character of a Rh-H intermediate via amine coordination to rhodium.Hydroformvlation of olefins to aldehydes over cobalt carbonyl catalysts A -1 * is the first step in the industrial synthesis of oxo alcohols (1, 2). Reaction conditions require temperatures above 150 °C and pressures up to 3000 psig. Subsequent aldehyde hydrogénation occurs over supported cobalt or molybdenum disulfide catalysts.Addition of modifying ligands such as tributyl phosphine affords a one-step, cobalt-catalyzed synthesis of alcohols (at lower pressure), but accompanying olefin hydrogénation reduces yields (3). With amine ligands, the effects are varied. Accelerated hydroformylation rates are possible with weak bases such as pyridine, but stronger bases ( piperidine or triethylamine, for example) retard or completely inhibit the reaction (4,5).In comparison with their cobalt analogs, rhodium carbonyls are significantly more active catalysts (6). As with cobalt, aldehyde is the 240

Hydrohydroxymethylation of Ethyl Ricinoleate and Castor Oil

“…These results are in line with the conclusions of Whitehurst et al who have shown that rhodium/amine complexes catalyze hydrohydroxymethylation of 1-hexene for amines of pKa between 7 and 11. 14 No alcohol was found with very weak or very strong nitrogen compounds in terms of pKa. Therefore, the basicity of the ligand is a key factor to obtain alcohols.…”

Reductive Hydroformylation of Isosorbide Diallyl Ether

“…This behavior was probably due to the low pKa value. Indeed, some works relative of the HHM of olefins showed that the rhodium/amine complexes were only efficient to produce alcohols for pKa values comprised between 7 and 11 [ 29 ]. The other tested amines met this requirement.…”

“…The process in a one-step reaction with a single catalyst is the best alternative, owing to the reduction in the amount of the catalyst, the reaction time, and the overall cost. In this context, one of the best systems is a Rh-catalyst associated with tertiary amines in the presence of CO/H 2 [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. In this publication, we report the HHM of isosorbide diallyl ether using this catalytic system.…”

Synthesis with Carbon Monoxide and a Petroleum Product

“…Highpressure IR spectroscopy supports this explanation as the same unidentified rhodium species observed with [RhH(CO)(PPh 3 ) 3 ] is detected. 94 An effect on regioselectivity opposite to that of phosphines has been reported for the same general structure [RhX(CO)2L]. Little attention has been paid to the use of nitrogen-containing ligands.…”

“…Only one 77-alkene complex exists for each diastereomer, but two allowed conformations (91) and (92) 97 The strong inhibiting effect of CO pressure indicates that the rate-determining step is the formation of [RuH 2 (CO)2(PPh 3 )2] (96), which follows dissociation of a carbonyl ligand from (94). Only one 77-alkene complex exists for each diastereomer, but two allowed conformations (91) and (92) 97 The strong inhibiting effect of CO pressure indicates that the rate-determining step is the formation of [RuH 2 (CO)2(PPh 3 )2] (96), which follows dissociation of a carbonyl ligand from (94).…”