Rhodium 1-dodecene

A series of water-soluble polyether-substituted triphenyl phosphines (PETPPs) la-c has been successfully employed by Jin et al. [11] in the thermoregulated hydroformylation of 1-dodecene in the biphasic water/toluene system. The catalysts exhibit very good catalytic properties with conversions up to 93% and about 85% selectivity for aldehyde formation. The catalyst derived from rhodium(III) chloride and ligand Ic could be reused in four consecutive cycles without significant loss of activity or chemoselectivity. The n-selectivity of the product aldehydes was not determined. 

The nonionic phosphine 7 was used in the rhodium-catalyzed hydro-formylation of 1-dodecene under thermoregulated phase-separable conditions. Phosphine 7 is soluble in toluene at higher temperatures, but can be... 

Rhodium carbonyl complexes also catalyze the cascade cyclization/hydrosilylation of 6-dodecene-l,l 1-diynes to form silylated tethered 2,2 -dimethylenebicyclopentanes. For example, reaction of ( )-85 with dimethylphenylsilane catalyzed by Rh(acac)(CO)2 in toluene at 50 °G under GO (1 atm) gave 86a in 55% yield as a single diastereomer (Equation (56)). Rhodium-catalyzed caseade cyclization/hydrosilylation of enediynes was stereospecific, and reaction of (Z)-85 under the conditions noted above gave 86b in 50% yield as a single diastereomer (Equation (57)). Rhodium(i)-catalyzed cascade cyclization/hydrosilylation of 6-dodecene-1,11-diynes was proposed to occur via silyl-metallation of one of the terminal G=G bonds of the enediyne with a silyl-Rh(iii) hydride complex, followed by two sequential intramolecular carbometallations and G-H reductive elimination. ... 

In contrast to the reactivity of 6-dodecene-1,11-diynes, rhodium-catalyzed reaction of l-dodecene-6,11-diynes with silane led not to cascade cyclization/hydrosilylation but rather to carbonylative tricyclization. For example, reaction of 87 [X = G(G02Me)2] and dimethylphenylsilane catalyzed by Rh(acac)(GO)2 in THE at room temperature under GO gave the cyclopenta[e]azulene 88 in 92% yield as the exclusive product (Scheme 22). Although the protocol was... 

Rh/76 (Table 4 n=l, x=0, R= Me, Bu), which should be able to induce micelle formation, were used as catalysts in the biphasic hydroformylation of 1-dodecene.371 The conversion was 80%, the n/i ratio 60/40 with no carry-over of the rhodium catalyst into the organic phase.371... 

Homogeneous hydrogenation in the fluorous phase has been so far reported only for a limited set of simple olefins (Richter et al., 1999, Rutherford et al., 1998), as exemplified with the neutral rhodium phosphine complex 18 as catalyst precursor (eq. 5.7). Isomerization of the substrate 1-dodecene (17a) was observed as a competing side reaction under the reaction conditions. The catalyst formed from 18 could be recycled using a typical FBS protocol, but deactivation under formation of metal deposits limited the catalyst lifetime. 

These RT reactions produce [PtCl2(C2H4)]2, [PtCl2(styrene)]2, and [PtCl2(dodecene)]2 in yields of 40, 55, and 65%, respectively. A bisethylene dimer is synthesized for rhodium by the following reaction ... 

As was mentioned earlier in this chapter, it is not necessary to transfer every reaction mixture into a thermodynamically stable one-phase system. Often the presence of one organised surfactant phase in equilibrium with one or two excess phases is sufficient to give an appropriate reaction rate. In such two- or three-phase systems the reaction occurs in the surfactants phase while the coexisting phases act as reservoir for the reactants. This approach has been demonstrated for alkylation of phenol [28] and for rhodium catalysed hydroformylation of dodecene [50]. A major practical advantage with the multi-phase systems is that substantially less surfactant is needed. This reduces costs and simplifies the work-up. 

Rhodium complexes generated from the polyethylene glycol)-functionalized phosphine 9 (n = 1, x = 0, R = Me, Bu), which should behave as a nonionic surfactant and be able to induce micelle formation, have been used as catalysts in the hydroformylation of 1-dodecene in an aqueous/organic two-phase system [31]. The conversion of 1-dodecene was 80% and the n/iso ratio 60 40, with no carryover of the rhodium catalyst into the organic phase. The Rh/9 (n = 1, x = 0, R = Me, Bu) catalyst remained active after one recycle step [31],... 

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,... 

Interfacial kinetics of biphasic hydroformylation of 1-dodecene catalyzed by water-soluble rhodium complex have been studied by a combined numerical and experimental approach [54]. 

Cuprous chloride tends to form water-soluble complexes with lower olefins and acts as an IPTC catalyst, e.g., in the two-phase hydrolysis of alkyl chlorides to alcohols with sodium carboxylate solution [10,151] and in the Prins reactions between 1-alkenes and aqueous formaldehyde in the presence of HCl to form 1,3-glycols [10]. Similarly, water-soluble rhodium-based catalysts (4-diphenylphosphinobenzoic acid and tri-Cs-io-alkylmethylam-monium chlorides) were used as IPTC catalysts for the hydroformylation of hexene, dodecene, and hexadecene to produce aldehydes for the fine chemicals market [152]. Palladium diphenyl(potassium sulfonatobenzyl)phosphine and its oxide complexes catalyzed the IPTC dehalogenation reactions of allyl and benzyl halides [153]. Allylic substrates such as cinnamyl ethyl carbonate and nucleophiles such as ethyl acetoactate and acetyl acetone catalyzed by a water-soluble bis(dibenzylideneacetone)palladium or palladium complex of sulfonated triphenylphosphine gave regio- and stereo-specific alkylation products in quantitative yields [154]. Ito et al. used a self-assembled nanocage as an IPTC catalyst for the Wacker oxidation of styrene catalyzed by (en)Pd(N03) [155]. 

In order to eliminate the possibility for in situ carbene formation Raubenheimer et al. synthesized l-alkyl-2,3-dimethylimidazolium triflate ionic liquids and applied these as solvents in the rhodium catalyzed hydroformylation of l-hejEne and 1-dodecene [178]. Both, the classical Wilkinson type complex [RhCl(TPP)3] and the chiral, stereochemically pure complex (—)-(j7 -cycloocta-l,5-diene)-(2-menthyl-4,7-dimethylindenyl)rhodium(i) were applied. The Wilkinson catalyst showed low selectivity towards n-aldehydes whereas the chiral catalyst formed branched aldehydes predominantly. Hydrogenation was significant with up to 44% alkanes being formed and also a significant activity for olefin isomerization was observed. Additionally, hydroformylation was found to be slower in the ionic liquid than in toluene. Some of the findings were attributed by the authors to the lower gas solubility in the ionic liquid and the slower diffusion of the reactive gases H2 and CO into the ionic medium. 

The catalysts obtained were highly active in the hydroformylation of higher alkenes and styrene at 80-120 °C, whereas their activity below the cloud point proved to be low (Table 11-1). Note also that the activity of the catalysts substantially exceeded the activity exhibited under similar conditions by a catalytic system involving rhodium complexes with sulfonated phosphines and oligo(ethylene oxide). Using phosphine 20, a turnover frequency (TOP) in dodecene hydroformylation of 1280 h was obtained All the catalysts could be reused. 

A rhodium complex with PNIPAM modified with propyldiphosphine 49 groups was more active in hydrogenation of 1-octadecene and 1-dodecene in a system containing heptane and 90% aqueous ethanol (Experiment 11-3, Section 11.7). At 22 °C the catalyst is virtually insoluble in heptane and there is no reaction, but at 70 °C this system forms a homogeneous solution of the polymer and the reaction takes place. The catalyst can be reused without loss of activity [94],... 

The selectivity of a macromolecular catalyst depends on the size of the substrate as well as on hydrophobic effectis. It becomes increasingly difficult for proper contact between catalytically effective groups and the substrate with increasing substrate size for otherwise identical reaction conditions. Thus, the polymer rhodium catalyst (I) hydrogenates cyclo-dodecene five times more slowly than it does cyclohexene. This substrate size effect is not observed with the analogous isolated low-molecular-weight compound (II) ... 

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