Phenylphosphinates

Although Pd is cheaper than Rh and Pt, it is still expensive. In Pd(0)- or Pd(ll)-catalyzed reactions, particularly in commercial processes, repeated use of Pd catalysts is required. When the products are low-boiling, they can be separated from the catalyst by distillation. The Wacker process for the production of acetaldehyde is an example. For less volatile products, there are several approaches to the economical uses of Pd catalysts. As one method, an alkyldi-phenylphosphine 9, in which the alkyl group is a polyethylene chain, is prepared as shown. The Pd complex of this phosphine has low solubility in some organic solvents such as toluene at room temperature, and is soluble at higher temperature[28]. Pd(0)-catalyzed reactions such as an allylation reaction of nucleophiles using this complex as a catalyst proceed smoothly at higher temperatures. After the reaction, the Pd complex precipitates and is recovered when the reaction mixture is cooled. 

Pentafluorophenylmagnesium bromide or lithium can be converted to other pentafluorophenyl organometabics by reaction with the corresponding metal chloride (237). Bis(pentafluorophenyl)phenylphosphine [5074-71-5] (Ultramark 443), (CgF )2CgH P, is offered commercially as a marker for mass spectral standardi2ation (238). 

Phenylphosphinic acid [benzenephosphinic acid, PhPH(0)(OH)] [1779-48-2] M 142.1, m 70", 71", 83-85", 86", pK 1,75. Cryst from H2O (sol 7.7% at 25°). Purified by placing the solid in a flask covered with dry Et20, and allowed to stand for 1 day with intermittent shaking. Et20 was deeanted off and the proeess repeated. After filtration, excess Et20 was removed in vacuum. [Justus Liebigs Ann Chem 181 265 1876 Anal Chem 29 109 1957 NMR J Am Chem Soc 78 5715 1956.]... 

Chemical Designations - Synonyms Phenyl Phosphonous Dichloride, Phenylphosphine Dichloride, Dichlorophenylphosphine Chemical Formula CjHjPClj. 

Chemical Designations - Synonyms Benzenethiophosphonyl Chloride, Phenylphosphonothioic Dichloride, Phenylphosphine Thiodichloride Chemical Formula C jPSClj. 

This group has also developed two ring-contraction systems of potential use in crown synthesis. In the first of these, extrusion of a phenylphosphine oxide unit results from treatment with alkoxide ion. In the second, similar conditions initiated decarbonyla-tion of a bis-pyridyl ketone Despite the apparent potential of these methods for crown synthesis, direct formation of crowns by processes which involve them do not appear to have enjoyed great success thus far. 

Reduction of 5a-Cholest-2-ene with Deuterium and Tris-(tri-phenylphosphine)-chiororhodium... 

The solvated phosphorane adds to the polarized carbonyl with the incipient C-21 methyl group pointing away from the bulk of the steroid nucleus. The newly formed carbon-carbon bond must then rotate in order for the tri-phenylphosphine group and oxygen atom to have the proper orientation for the elimination of triphenylphosphine oxide. This places the C-21 methyl in the CIS configuration. 

This derivative is most conveniently prepared by reacting an azide with tri-phenylphosphine. It was used because of its stability towards Ph2PLi. Its aqueous hydrolysis is well documented. ... 

Phospholes 78 were obtained (67AG58) from diacetylene and phenylphosphine in pyridine (yield up to 29%) and with butyllithium in benzene at room temperature (yield up to 90%). 

By the procedure described in the preceding experiment, 30 g (0.11 mole) of tri-phenylphosphine dissolved in 100 ml of acetonitrile is converted to triphenylphosphine dibromide. After the addition of the bromine has been completed, the cooling bath is removed, the flask is set up for vacuum distillation, and the solvent is removed. To the residue is added /7-chlorophenol (10.3 g, 0.08 mole), and the flask is heated at 200° (mantle, wax bath, or sand bath) until HBr ceases to be evolved (about 2 hours). The flask is cooled and the contents are steam distilled affording crude / -chlorobromo-benzene in about 90% yield. Recrystallization from benzene gives the pure product, mp 65-66°. 

Where X is phenyl, the result of irradiation (sunlight, mercury lamp) is the formation of Ru(NO)X3(PPh3)(OPPh3) (X = Cl, Br) in the case of the diethyl-phenylphosphine complex, irradiation causes isomerization to the cis,mer-isomer. The frans,mer-isomer is the usual synthetic product, but in the case of dimethylphenylphosphine the/ac-isomer was obtained using short reaction times it isomerized to the usual mer,trans-isomer on heating [123],... 

The P-coupling of 1,2- and 1,4-quinonediazides with phosphines (mainly tri-phenylphosphine) was studied intensively in the 1960s by the groups of Ried and Horner (see summary by Ershov et al., 1981, p. 147). The azo derivatives formed in these reactions are more stable than those of arenediazonium salts because of the stabilization by mesomeric delocalization (6.35 a ++ 6,35 b). 

The hydro-de-diazoniation of 4-nitrobenzenediazonium tetrafluoroborate with tri-phenylphosphine in methanol (Yasui et al., 1991) is hardly interesting for synthetic purposes, as the yield of nitrobenzene passes through a narrow maximum (95 %) if 0.5 equivalent of triphenylphosphine is used. 

The crude mixtures all have strong odors of aromatic phosphines. Some of this odor presumably arises from disproportionation of monophenylphosphinic acid to phenylphosphine. It is recommended that manipulations be carried out with rubber gloves to prevent transfer of these rather durable odors to the skin, and that all equipment be washed with a bleach such as Clorox before it is taken from the hood. 

The distilled product can be used as a catalyst, although it usually has a relatively strong phenylphosphine odor. It is quite deliquescent, and it has not been satisfactorily recrystallized. If rigorous purification and deodorization are desired, the product is dissolved in water, a small amount of hydrogen peroxide is added to oxidize the phosphines, the solution is reneutralized, saturated with salt, and extracted with chloroform, and the product is refractionated. One cycle is normally enough. Pure product is essentially odorless, very hygroscopic, and soluble in polar solvents. 

This procedure also incorporates the use of bis(3-dimethylamino-propyl)phenylphosphine as a combined amine-phosphine reagent. The merits of using this basic phosphine as opposed to a tertiary amine and a phosphine lies in the ease of workup. Excess phosphine and phosphine sulfide can be removed by extraction with aqueous dilute acid. 

Barbeau, C., Dichmann, K. S. Ricard, L. (1973) Structure cristalline et moleculaire du cyclopentadienyle dicarbonyle tri-phenylphosphine manganese, MnCsHsfCO P gHsta, Can. J. Chem 51,3027-3031. 

Although of limited success, this Ni-catalysed coupling strategy builds on a previous report of the successful, direct synthesis of poly(4,4 -diphenylphenyl-phosphine oxide) (70c) from bis(p-chlorophenyl)-phenylphosphine oxide (71) (Scheme 21) [66]. The white soluble material (70c) (Aj ax 280 nm) was found to have a single phosphorus environment by NMR spectroscopy, a comparatively high molecular weight (Mn= 15,300) together with a low molecular... 

The organometallic phenylphosphines (14) are obtained from the reaction of lithium phenylphosphide and Group IV chlorides. ... 

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