For phosphine

Although phosphine [7803-51-2] was discovered over 200 years ago ia 1783 by the French chemist Gingembre, derivatives of this toxic and pyrophoric gas were not manufactured on an industrial scale until the mid- to late 1970s. Commercial production was only possible after the development of practical, economic processes for phosphine manufacture which were patented in 1961 (1) and 1962 (2). This article describes both of these processes briefly but more focus is given to the preparation of a number of novel phosphine derivatives used in a wide variety of important commercial appHcations, for example, as flame retardants (qv), flotation collectors, biocides, solvent extraction reagents, phase-transfer catalysts, and uv photoinitiators. 

Apart from the manufacture of derivatives, there are only two known uses for phosphine itself, ie, in the preparation of semiconductors and as a fumigant. 

Textile Flame Retardants. The first known commercial appHcation for phosphine derivatives was as a durable textile flame retardant for cotton and cotton—polyester blends. The compounds are tetrakis(hydroxymethyl)phosphonium salts (10) which are prepared by the acid-cataly2ed addition of phosphine to formaldehyde. The reaction proceeds ia two stages. Initially, the iatermediate tris(hydroxymethyl)phosphine [2767-80-8] is formed. 

Palladium(II) complexes provide convenient access into this class of catalysts. Some examples of complexes which have been found to be successful catalysts are shown in Scheme 11. They were able to get reasonable turnover numbers in the Heck reaction of aryl bromides and even aryl chlorides [22,190-195]. Mechanistic studies concentrated on the Heck reaction [195] or separated steps like the oxidative addition and reductive elimination [196-199]. Computational studies by DFT calculations indicated that the mechanism for NHC complexes is most likely the same as that for phosphine ligands [169], but also in this case there is a need for more data before a definitive answer can be given on the mechanism. 

Scheme 1-12 Catalytic Cycle for Phosphine-Free Rh(l) Complexes...

Triphenylphosphine itself has also been used as a regent for phosphination. P—C cleavage of... 

Figure 2 Directionality parameters describing the E-XY interaction (a and b) for phosphine-chalcogenide donors in the case of a one a-bond, and three n back-bonds description of the P-E bond (c). For an alternative description of the P-E bond (see Chapter 5)...

The experiments were conducted in a down-flow tubular reactor with continuous feed and product withdrawal. For phosphine resins, establishment of equilibrium was exhibited by the fact that rhodium concentrations in solution were proportional to percent loading. The concentration was also dependent on solvent. As the solvent polarity increased, rhodium concentration increased. Typical concentrations in the effluent were 0.2-2.0 X 10-5 A/ Rh for reaction at 85°C, 1500 psi 1/1 H2/CO. An increase in CO pressure increased the concentration of rhodium in solution, and an increase in temperature sharply decreased the metal concentration. These are understood as factors that influence the equilibrium between phosphine and carbonyl complexes. 

A short five-step synthesis of a bifuran, namely ( )-2,2 -bis(diphenylphosphino)-3,3 -binaphtho[2,l-I>]furan (BINAPFu) from naphthofuranone via a low-valent titanium-mediated dimerization was reported. The newly developed resolution procedure for phosphines was utilized to provide the optically active bidentate phosphine ligands (BINAPFu), which consistently outperforms BINAP in the asymmetric Heck reaction between 2,3-dihydrofuran and phenyl triflate . Another way in which a benzofuranone can be converted into benzo[7 ]furan is by treatment of the former with 1-BU2AIH at -78°C followed by an acidic work up <00TL5803>. 

Naumann, K., Zon, G., and Mislow, K., Perchloropolysilanes novel reducing agents for phosphine oxides and other organic oxides, /. Am. Chem. Soc., 91, 2788, 1969. 

Balthazor, T.M., Phosphindolin-3-one. A useful intermediate for phosphin-dole synthesis,. Org. Chem., 45, 2519, 1980. 

Whether of nM 7tL or n- -OL (off-axis) type, pi-backbonding interactions correspond to partial inclusion of ionic resonance structures featuring a metal-ligand double bond, as illustrated schematically in (4.79) for phosphine ligands ... 

Equations analogous to Eq. (21) will be written showing the metastable isomer as lying on the pathway for phosphine exchange (Scheme 4) and substitution (Scheme 5) in MeReO(mtp)PR3 compounds. 

We conclude that only one phosphine attacks a ji-S group of 20. Indeed, the phosphine sulfide product from dmpm is Me2P(S)CH2PMe2, not a bis(sulfide).The other phosphine implicated by Eqs. (32) and (33), whether from a second PR3 or from a di-phosphine, adds as a Lewis base to rhenium. The basis for this is that a pyridine easily replaced one of the phosphines in the mechanism. This proposed mechanism should steer the reaction directly towards formation of 21, but owing to the dilemma posed in point (c), an intermediate likely intervenes. It can partition to the slowly-reacting 21 or to 23, the latter step requiring additional phosphine Scheme 13 shows the postulated mechanism. The dual role for phosphine and the use of Py in its place and the proposal for partitioning are shown in Scheme 14. 

The various MeRe(NAr)2(PR3)2 compounds react with 02 directly, in two steps. The rate law for phosphine oxidation is,... 

In contrast to the amines, inversion of configuration for phosphines is generally negligibly slow at ambient temperature. This property has made it possible for chiral phosphines to be highly useful as ligands in transition metal-catalyzed asymmetric syntheses. 

Low levels of resistance have been reported for some populations of Indian meal moth, almond moth, and red flour beetle populations in stored peanuts in the southeastern United States (Zettler et al., 1989), but no assessments are available for phosphine resistance in insect populations in mills, warehouses, processing plants, and other structural facilities. Phosphine can be corrosive to metals, particularly copper, electrical wiring, and electronic equipment (Bond et al., 1984), which limits its application in food processing facilities and warehouses. A new formulation of phosphine, in which phosphine gas is combined with carbon dioxide and released from a cylinder, alleviates some but not all of the corrosive effects of phosphine and is labeled for use as a structural treatment. 

Extensive 13C and 81P n.m.r. studies have been reported for phosphine oxides and selenides, and the inversion-recovery technique has been used to establish 2J and ZJ values for 18C-31P coupling.52 Shift reagents have been used to establish alkene geometry in the oxides (61).53 Coupling and shift data have been published for the arylphosphine derivatives (62).54... 

Devai I, Delaune RD. 1995. Evidence for phosphine production and emission from Louisiana and Florida marsh soils. Organic Geochemistry 23 277-279. 

This is markedly higher than the TONs typically observed for phosphine-based Ir—PCP systems (ca. 250 under identical conditions). Electron-withdrawing substituents such as C5F5 (5e) and 3,5-(CF3)2-C6H3 (5f) considerably improve the catalytic activity (Table 12.1). Notably, the MeO-substituted Ir—PCP complex 5c seems to operate differently, and remains active over a longer time range than the other phosphinite complexes, thus reaching final TONs that are comparable to those of 5f. 

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