Hydroformylation propylene

The commercially important normal to branched aldehyde isomer ratio is critically dependent on CO partial pressure which, in propylene hydroformylation, determines the rate of interconversion of the -butyryl and isobutyryl cobalt tetracarbonyl intermediates (11). 

Catalysts used in some commerical 0x0 processes and approximate conditions for propylene hydroformylation... 

A recent example where Co2(CO)8 serves as a precatalyst is in the preparation of linear and branched aldehydes via propylene hydroformylation in supercritical C02 (93-186 bar 66-108 °C). Cyclohexane carbaldehyde is produced from cyclohexene using Co2(CO)8 and an acid RCOOH, or else is successful with another established Co catalyst, Co(OOCR)2, assumed to form in situ in the former case. Oligomerization of aldehydes such as n-butanal is achieved with Co2(CO)6L2 as catalyst (L = CO, PR3).1364... 

J. W. Rathke, R. J Klingler, T. R. Krausem, Propylene Hydroformylation in Supercritical Carbon Dioxide , Organometallics 1991,10,1350-1355. 

For instance, catalysis in liquid/liquid two phases is generally referred to as biphasic catalysis and has widened the practical scope of homogeneous catalysis the catalyst is present in one liquid phase, while reactants and products are present in the other liquid phase. Thus, the catalyst can be separated by simple phase separation. Celanese is operating a 300 000 t/a plant for propylene hydroformylation using a water-soluble rhodium phosphine complex in a biphasic mode of operation at the Ruhrchemie site in Oberhausen [142],... 

For cis-chelate complexes of rhodium and bisphosphines as catalysts, indeed relatively low ratios of n/i aldehyde products were reported (12, 13). Using a 1 1 mixture of H CO at atmospheric pressure, Sanger reported n/i ratios ranging from 3 to 4 for propylene hydroformylation (12). However, his catalyst systems were produced by adding less than 2 mol of bisphosphine per mole tris(triphenyl-phosphine)rhodium carbonyl hydride. When an excess of the chelating bisphosphines was used by Pittman and Hirao (13), low n/i ratios close to 1 were produced from 1-pentene using a mixture of H2/CO at 100-800 psi between 60° and 120°C. 

Fig. 20. Rate of propylene hydroformylation with CoNaCaA catalyst as a function of run time. (Reproduced from Ref. 225 with permission from the authors and La Chimica e VIndustrial)...

Some typical results obtained for various Co zeolites under steady-state conditions are shown in Table V. Clearly, CoNaA and CoNaCaA display quite good propylene hydroformylation activity, whereas CoNaX is relatively inactive. In all cases the selectivity to total aldehydes was 99%, the other products being isobutyl and n-butyl alcohol. 

Propylene Hydroformylation Data Obtained Using Various Cobalt Zeolites ... 

In summary, then, in the rhodium-catalyzed industrial process for propylene hydroformylation a high phosphine-to-Rh molar ratio is used. Under these conditions the use of a moderately bulky ligand such as triphenyl phosphine ensures that the catalysis takes place by the topmost cycles in Fig. 5.5, and n-butyraldehyde with high selectivity is produced. 

Since the desired product from propylene hydroformylation is -butyralde-hyde, considerable attention has been devoted to increasing the selectivity this focussed attention on the mechanism, especially the step where the propylene inserts into the Co-H bond, since this can be either Markovnikov or anti-Markovnikov. 

A plausible mechanism was reported for the catalytic formation of benzene resulting from phosphorus-carbon bond cleavage which occurs during propylene hydroformylation catalyzed by triphenylphos-phine-substituted rhodium carbonyls under higher H2 partial pressures (Scheme 37). " ... 

Propylene Hydroformylation over Various Metal Carbonyl Clusters Impregnated on Metal Oxides Compared with That over Conventional Rhodium Supported Catalyst"... 

Rate and Selectivity Measurements Associated with Propylene Hydroformylation in CO2... 

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