Phosphine, trialkyl

A Belgian patent (178) claims improved ethanol selectivity of over 62%, starting with methanol and synthesis gas and using a cobalt catalyst with a hahde promoter and a tertiary phosphine. At 195°C, and initial carbon monoxide pressure of 7.1 MPa (70 atm) and hydrogen pressure of 7.1 MPa, methanol conversions of 30% were indicated, but the selectivity for acetic acid and methyl acetate, usehil by-products from this reaction, was only 7%. Ruthenium and osmium catalysts (179,180) have also been employed for this reaction. The addition of a bicycHc trialkyl phosphine is claimed to increase methanol conversion from 24% to 89% (181). 

Speziale and his co-workers have carried out comprehensive studies of the reactions of phosphorus compounds. It has been shown 108) that the reaction of N,N-dialkyl-a-trichloroacetamides (127) with phosphites and phosphines gives trichlorovinylamines (128). In general the trialkyl-phosphines gave somewhat higher yields (60 to 83%) and purer products... 

PR3, e.g. PPh3, PMe2Ph, PPr Ph), though short reaction times are necessary to prevent further reduction and the trialkyl phosphines are too strongly reducing to allow the isolation of their complexes [140]. 

The chromatographic behaviour of condensed phosphates was found to be strongly influenced by water content and pH. The Ry of tris(dimethyl-amino)phosphine chalcogenides is generally lower than those of the trialkyl-phosphine chalcogenides but the difference is greatest for the P " compounds, and whereas the trialkylphosphines have the highest Ry values in the whole series, tris(dimethylamino)phosphine has the lowest. ... 

Palladium-Catalyzed Arylation of Enolates. Very substantial progress has been made in the use of Pd-catalyzed cross coupling for arylation of enolates and enolate equivalents. This reaction provides an important method for arylation of enolates, which is normally a difficult transformation to accomplish.171 A number of phosphine ligands have been found to promote these reactions. Bulky trialkyl phosphines such as /n. v-(/-butyl)phosphinc with a catalytic amount of Pd(OAc)2 results in phenylation of the enolates of aromatic ketones and diethyl malonate.172... 

A major advance in homogeneous catalysis was the introduction of a trialkyl-phosphine to supplement the role of carbon monoxide in catalyst stabilization. [3] A ligand modifier such as trialkylphosphine serves three principal roles in a homogeneous catalytic process. It stabilizes the metal, it influences the reaction rate, and it influences process selectivity. 

The 772-phosphinocarbene complexes of tungsten show ambiphilic behavior. With Lewis acids such as MeS+, electrophilic attack occurs at the metal-carbon double bond affording the dicationic tunstaphosphathiabi-cyclo[1.1.0]butane complexes 102.96,97 On the other hand, nucleophiles such as trialkyl phosphines or the cyclopentadienyl anion C5H5 add at the carbe-nic center, affording phosphoranylidene complexes 10397 or tungstaphos-... 

Electrolysis of alcohols in an undivided cell and in the presence of trialkyl phosphine is recently reported, and this is one of the most simple and... 

The autoxidation of trialkyl phosphines occurs similarly, except that here the second intermediate phosphoranyl radical can cleave by two paths ... 

Promising results were observed in Friedel-Crafts alkylation77 and epoxidation.78 Higher rates or better selectivities were found for hydroformylations in supercritical C02.79-84 Simple trialkyl phosphines, for examples, were shown to provide highly active Rh catalysts.81 Hydroboration showed enhanced regioselec-tivity.85 The Wacker reaction performed in alcohol-supercritical C02 exhibits high reaction rates and markedly increased selectivity toward methyl ketone.86... 

Trialkyl phosphines are rather good trans directors and, as expected, the reaction of BujP with [PtCl4]2- gives the trans isomer as a major product. However, when one uses PhjP in this reaction, only the insoluble cis product is obtained. Offer an explanation for this apparent violation of the trans-effect prediction. [Problem 13.5 may be helpfltl.)... 

Trihalo complexes containing a single coordinated triphenyl- or trialkyl-phosphine [NiX3(PR3)]- have a pseudotetrahedal structure and their electronic and magnetic properties have been studied in detail.1155-1158,1174-1176... 

Silver iodide derivatives of trialkyl-phosphines and -arsines were prepared in 1937 for comparison with their copper(I) iodide analogues.201 The preparations involved shaking the ligands with silver iodide dissolved in concentrated aqueous KI. The products were found to be tetramers and of similar structure to the Cu1 complexes. The Pr As silver complex was isomorphous with [Cul-AsEt3]4. Molecular weight determinations in a range of organic solvents showed that partial dissociation occurred in solution. 

Apostilidos, C., Meester, R., de Koch, L. et al. 1990. The extraction of actinides and other constituents from highly-active waste (HAW) by trialkyl phosphine oxide (TRPO). Technical seminar on new separation chemistry techniques for radioactive waste and other specific applications, Rome (Italy), May 16-18. EUR-13390-EN. 

Zhu, Y., Jiao, R. 1994. Chinese experience in the removal of actinides from highly active waste by trialkyl phosphine oxide extraction. Nucl. Technol. 108 361-369. 

Feng, X., Song, C. 2001. The extraction and stripping behavior of heptavalent technetium with trialkyl phosphine oxide. Solvent Extr. Ion Exch. 19 (1) 51-60. 

FIGU RE 2.4 Structures of TBP and trialkyl phosphine oxide R, = R2 = R3 = n-octyl TOPO. 

Chinese scientists used trialkyl phosphine oxides (TRPO) to remove long-lived radioactive nuclides from high-level liquid waste (67, 167). TRPO is the trademark of a Chinese commercial product, consisting of a mixture of several TRPO (with alkyl chains from hexyl to octyl). The TRPO process has been tested in China and at ITU in Karlsruhe (2, 168-174). 

The following order of stability can be proposed amide (diglycolamides < malona-mides < monoamides (183, 199, 216)) = CMPO < HDEHP = TBP (10, 42, 77) < tri-alkylphosphonate < trialkyl phosphine oxide (308). 

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