1-Octene catalysts, rhodium complexes

The results of unsymmetrical 7r-acid bidentate ligands, e.g., (81), have in the hydroformylation of ra-octenes was described. The preparation of seven such ligands was described. Thus, [Rh-(acac)(cod)]-catalyzed hydroformylation of ra-octene in the presence of a phosphinite ligand gave 94% ra-nonanal.295 A new upper-rim phosphacalix[4]arene 5,17-bis(diphenylphosphinomethyl)-25,26,27,28-tetrapropoxycalix[4]arene has been prepared. It reacted with [(cod)RhCl]2 to give a dirhodium complex that is an active catalyst for the hydroformylation of 1-octene and styrene.296 Rhodium complexes of [l-propyl-3-methylimidazolium+]2 [PhP(C6H4SO%)2] dissolved in the... 

The rhodium complex with bis(diphenylphosphino)phenoxazine was immobilized on silica using the sol-gel technique or by a direct grafting to commercially available silica [127]. Under standard hydroformylation conditions (CO/H2 atmosphere), a neutral hydridic complex (57) and cationic species (58) (Scheme 4.35) coexist on the support and act as a hydroformylation/hydrogenation sequence catalyst, giving selectively 1-nonanol from 1-octene 98% of 1-octene were converted to mainly linear nonanal which was subsequently hydrogenated to 1-nonanol. The... 

The presence of 4e as the predominant species during the catalysis is also in accord with the observed kinetic behavior of this catalyst with 1-octene and styrene as the substrates. The observation of this saturated acyl rhodium complex is in line with the positive dependence of the reaction rate on the hydrogen concentration and the zero order in alkene concentration. It was concluded previously that this saturated acyl complex is an unreactive resting state [18]. Before the final hydro-genolysis reaction step can occur, a CO molecule has to dissociate in order to form... 

Initial studies showed that the encapsulated palladium catalyst based on the assembly outperformed its non-encapsulated analogue by far in the Heck coupling of iodobenzene with styrene [7]. This was attributed to the fact that the active species consist of a monophosphine-palladium complex. The product distribution was not changed by encapsulation of the catalyst. A similar rate enhancement was observed in the rhodium-catalyzed hydroformylation of 1-octene (Scheme 8.1). At room temperature, the catalyst was 10 times more active. For this reaction a completely different product distribution was observed. The encapsulated rhodium catalyst formed preferentially the branched aldehyde (L/B ratio 0.6), whereas usually the linear aldehyde is formed as the main product (L/B > 2 in control experiments). These effects are partly attributed to geometry around the metal complex monophosphine coordinated rhodium complexes are the active species, which was also confirmed by high-pressure IR and NMR techniques. 

Recently, a new rhodium recycling system was described that takes advantage of amphiphilic ligands such as Ph2ArP (Ar = 3-hydroxyphenyl, 4-carboxyphenyl). The corresponding rhodium complexes are active in the hydroformylation of 1-octene and can be separated from the products by acidic or basic extraction into water. After neutralization of the aqueous phase, the rhodium species could be extracted into a new batch of octene, with toluene as a solvent. The recovered catalyst retained only up to 87% of its activity (72). 

Mitsubishi Kasei introduced a process to manufacture isononyl alcohol, an important PVC (polyvinyl chloride) plasticizer, via the hydroformylation of octenes (a mixture of isomers produced by dimerization of the C4 cut of naphtha cracker or FCC processes).95 First a nonmodified rhodium complex exhibiting high activity and selectivity in the formation of the branched aldehyde is used. After the oxo reaction, before separation of the catalyst, triphenylphosphine is added to the reaction mixture and the recovered rhodium-triphenylphosphine is oxidized under controlled conditions. The resulting rhodium-triphenylphosphine oxide with an activity and selectivity similar to those of the original complex, is recycled and used again to produce isononanal. 

Lifetime of the Catalyst. The rate of reactions using solutions of previously used catalyst decreased with successive additions of 1-octene. These observations, along with those reported in the previous section on the effect of AlEt2Cl concentration, indicate that the life of the catalyst is related more to the air sensitivity of the AlEt2Cl than to the instability of the rhodium complex. 

In a series of studies performed by different groups hydroformylation of higher alkenes in microemulsions resulted in high turn-over frequencies (TOFs) of up to 5000 per hour for 1 -octene [46] and 1000 per hour for 1-decene [44]. Cationic surfactants such as cetyltrimethyl ammoniumbromide (CTAB) were used in the first studies of hydroformylation of various alkenes with the Rh-TPPTS catalyst. Both high activity and selectivity were observed in the hydroformylation of 1-octene and 1-decene using a sulphonated bisphosphine modified rhodium complex in the presence of ionic surfactants or methanol. 

Rhodium complexes with the fluorous phosphine P(C6H4-4-OCH2C7F15)3 are active catalysts in the hydroformylation of 1-octene in fluorous biphasic systems [the turnover frequency (TOF) was 380 h 11 (Equation 4.28). Selectivity in aldehydes was as high as 99% and regioselectivity for the linear aldehyde up to an n/iso ratio of 2.8 [49]. 

The technically most important biphasic process in the Ruhrchemie/Rhone-Poulenc hydroformylation of propene using the in situ Rh(I) catalyst HRh(CO)-(TPPTS)3 [6, 37]. Its formation from Rh(CO)2(acac) and TPPTS in a syngas atmosphere has been studied in detail [38, 39]. The BINAS-Na (ll)/Rh catalyst showed an outstanding performance in propene hydroformylation [15]. Binudear thiolato bridged rhodium complexes 12 have been used in 1-octene hydroformylation as precatalysts [41], For details of the hydroformylation, cf. Section 6.1 [15, 40, 41],... 

Rhodium complexes generated from the water-insoluble carboxylated surfactant phosphine 17 (n = 3, 5, 7, 9, 11) were used as catalysts in the micellar hydrogenation of a- and cyclic olefins, such as 1-octene, 1-dodecene, and cyclohexene, in the presence of conventional cationic or anionic tensides such as cetyltrimethylammo-nium bromide (CTAB) or SDS and co-solvents, e.g., dimethyl sulfoxide [15], After the reaction the catalyst was separated from the organic products by decantation and recycled without loss in activity. There is a critical relationship between the length of the hydrocarbon chain of the ligand 17 and the length and nature of the added conventional surfactant, for obtaining maximum reactivity. For example,... 

Ligand-promoted reductive elimination of ketones is directly observed with alkyl-acyl rhodium complexes formed via oxidative addition of either Wilkinson s catalyst or [ethylene insertion into the metal hydride bond33-37. 

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