Propene 1,1,2-triphenyl

Homogeneous rhodium-catalyzed hydroformylation (135,136) of propene to -butyraldehyde (qv) was commercialized in 1976. -Butyraldehyde is a key intermediate in the synthesis of 2-ethyIhexanol, an important plasticizer alcohol. Hydroformylation is carried out at <2 MPa (<290 psi) at 100°C. A large excess of triphenyl phosphine contributes to catalyst life and high selectivity for -butyraldehyde (>10 1) yielding few side products (137). Normally, product separation from the catalyst [Rh(P(C2H2)3)3(CO)H] [17185-29-4] is achieved by distillation. 

It was recognized during the development of propene hydroformylation that propene provided some stabilization for the catalyst. In the absence of the alkene, but in the presence of carbon monoxide and hydrogen, the catalyst can undergo what has been termed intrinsic deactivation. [3 3] Apparently after oxidative addition of triphenyl-phosphine to rhodium, diphenylphosphido bridged rhodium complexes are formed. 

In Scheme 3.3-1 the [L]-control maps for the three-component system nickel/ triphenylphoq>hine/butadiene and the four-component system nickel/triphenyl-phosphine/butadiene/propene are compared. The amount of the produced... 

The linearity of the aldehyde product increases with the concentration of triphenyl phosphine. This is being exploited in the Union Carbide process for the hydroformylation of propene in which linearities >90% are obtained. The rate, however, drops to lower values and the most likely explanation for the higher linearities in this system would seem to be the steric congestion around the rhodium atom at high phosphine concentrations, which kinetically and thermodynamically favours the formation of linear alkyl rhodium complexes relative to branched alkyl rhodium complexes. Product linearity decreases with the number of triphenyl phosphines present in the series of precursor complexes ... 

The comparison of propene, allyltrimethylsilane, and isobutene indicates, that introduction of a trimethyl silyl group in /3-position of the developing carbenium center activates more than a methyl group in a-position. Both series of triphenyl element compounds (left and right column Scheme 44) show the reactivity pattern Si < Ge < Sn, but variation of the substituents at silicon and tin was found to largely affect the reactivity of the double bond. While in the allyl series (right column), the trialkylsilanes and -stannanes are 2 to 3 orders of magnitude more reactive than the... 

Following the recommendations of Manassen [18] the history of biphasic hydroformylation began with work on various water-soluble ligands (Table 1). After this preparatory work on various aspects [30], Kuntz [22, 199] expressed the basic idea of a new generation of water-soluble oxo catalysts with triphenyl-phosphine trisulfonate (TPPT S, as the Na salt, as compared with TPPMS and TPPDS, the mono- and disulfonate) as ligands for a Rh-based oxo process, mainly for the hydroformylation of lower olefins such as propene (eq. (5)). 

Phenylation of carbanions derived from olefins such as 1,3-pentadiene and l-(p-anisyl) propene and aromatics such as indene and fluorene are possible by the SrnI route in ammonia solvent. From the 1,3-pentadiene a mixture of mono-olefins and dienes is produced along with a small amount of di- and triphenylated material. Hydrogenation of the mixture gives 1-phenylpentane in 74% yield.106) Phenylation of 2- and 4-picolyl anions is conveniently effected in ammonia. When bromo- or iodobenzene is used for this purpose, reaction probably occurs by both SrnI and benzyne routes.111)... 

Researchers have worked to alleviate the problems of separation and corrosion in processes such as the oxo process by designing catalysts that are confined in a separate phase from the reactants (see Section 14.2.4). A commercially successful approach for propene hydroformylation resulted from preparation of water-soluble rhodium complex catalysts by sulfonation of the phenyl rings of the triphenyl phosphine ligands. The catalyst is used in a reactor with two liquid phases the propene is concentrated in the organic phase and the catalyst in the aqueous phase near the interface. The CO -I- H2 is bubbled into a mixed reactor, and the two-phase liquid product flows to a settler the organic product flows to downstream separation devices, and the aqueous phase with the catalyst is recycled to the reactor. 

Triphenyl-1-propene and tetraphenylethylene can also be obtained in good yield in this way. 

Another interesting reaction of a TAM derivative was first reported by Griffin et al. [181] and later confirmed by Shi et al. [162]. They found that, upon the photolysis in degassed benzene, 1,1,1 -triphenyl-2-propene undergoes cyclization and simultaneous phenyl migration to generate 1,1,2-triphenylcyclopropane in competition with the di-rr-methane rearrangement. 

Rhodium Catalysts. - The hydroformylation of propene with a Rh/triphenyl-phosphine catalyst is now an established industrial process which will consume over a million tonnes per annum of propene when all licensed plants are operational. Most of the product n-butyraldehyde is converted to 2-ethylhexanol for plasticiser applications. The process is also applicable to the hydroformylation of C2, C4, and C5 alkenes. The process is remarkable for the long lifetime of the Rh catalyst but by-products are formed which deactivate the catalyst and have to be removed. The formation of triphenyl-phosphine oxide, benzaldehyde, and propyldiphenylphosphine under hydroformylation conditions has been investigated where benzaldehyde is produced by or /zo-metallation of triphenylphosphine followed by CO insertion and P-C bond cleavage and propyldiphenylphosphine was assumed to result from reaction of propene with the co-ordinated diphenylphosphine group remaining after benzaldehyde formation. The same authors have also studied the kinetics of the formation of heavy by-products which are dependent on... 

Another SLPC study on the hydroformylation of propene using a Rh/silica system has considered the effect of phosphine loading and phosphine Rh ratio on catalyst performance/ The incorporation of excess of triphenyl-phosphine into the catalyst results in an increase in selectivity and a decrease in activity. Thus the behaviour of this system parallels that of homogeneous systems. 

It has been found that treatment of propiophenone with an excess amount of bromobenzene gives rise to l,2,3-triphenyl-2-propen-l-one (Eq. 11) [43]. In this reaction, a-arylation, unsaturation via -hydrogen elimination, and Heck-type arylation occur successively. From the reaction of butyrophenone is obtained the corresponding triarylated product (Eq. 12). The reaction sequence involves a-arylation, unsaturation via p-hydrogen elimination, two times vinyl-ogous arylation (y-arylation), and double bond isomerization. It should be noted that a,p-unsaturated carbonyl compounds are generally arylated at their y position (Eqs. 13 and 14) [54-56]. 

Early IR and UV-VIS spectroscopic studies on the formation of carbonium ions from triphenyl methyl compounds on zeolites, titania and alumina were carried out by Karge [111]. In 1979, upon interaction of olefins Hke ethene and propene with zeoHtes CoNaY, NiCaNaY, PdNaY and HY, the appearance of electronic bands between 230 and 700 nm was observed by Garbowski and PraHaud and attributed to an allylic carbenium ion which upon thermal treatment transforms into polyenyl carbenium ions and/or aromatic compounds [112]. These findings were corroborated and extended by studies of the interaction of propene, cyclopropane and frans-butene on zeoHtes NaCoY and HM [30]. In spite of the obscuration of the spectrum in the range between 450 and 700 nm by the threefold spHt d-d band of tetrahedraUy coordinated Co(II) ions in the case of zeoHte NaCoY,the development of bands near 330,385 and 415 nm was assigned to unsaturated carbocations. 

A very important process with the solvent water is the hydroformylation of propene to butyraldehydes, known as the Ruhrchemie/Rhone-Poulenc process. The reaction is catalyzed by a rhodium complex containing the water-soluble ligand triphenyl-phosphine trisulfonate (TPPTS) (see Section Lower Alkenes [6-11]). 

NaH stirred ca. 45 min. at 65-70° under Ng in excess dimethyl sulfoxide until Hg-evolution is complete, allowed to react with 1 equivalent of ethyl triphenyl-phosphonium bromide, then with 0.85 equivalent of benzophenone 1,1-di-phenyl-l-propene. Y 97.5%.—The reactivity of the methylsulfinyl carbanion (formed by reaction of NaH with dimethyl sulfoxide), which is even more basic than the trityl anion, is sufficient to convert phosphonium salts into ylides thereby permitting a simple and convenient modification of the Wittig reaction. E. J. Gorey and M. Ghaykowsky, Am. Soc. 8A, 866 (1962) / -diketones from carboxylic acid esters and ketones (s. Synth. Meth. 6, 737), sym. ) -diketones, s. J. J. Bloomfield, J. Org. Chem. 27, 2742 (1962). 

Atbozy-1.1.2-triphaiyI-propen-(l) 6II708. 2-l hyl-1.1.4-triphenyl-oyclobatiuiol-(3)... 

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