Phosphine oxide, structure

Uranium. tetrathiocyanatotetrakis[tris-(dimethylamino)phosphine oxide]-structure, 1.87 Uranium carbide nuclear fuels dissolution, 6, 928 Uranium complexes, 3,1131-1215 carbamic acid... 

Tetrakis(hydroxymethyl)phosphonium Salts. The reaction of formaldehyde and phosphine in aqueous hydrochloric or sulfuric acid yields tetrakis-(hydroxymethyl)phosphonium chloride [124-62-1 or the sulfate [55566-30-8]. These are made by Rhodia, Cytex, and Chinese producers. The salts have the general structure (HOCH2)4P" X . They are water-soluble crystalline compoimds sold as concentrated aqueous solutions. The methylol groups are highly reactive (121-125) and capable of being cured on the fabric by reaction with ammonia or amino compounds and post-oxidized to form durable cross-linked phosphine oxide structures. 

A series of polyesters and polyethers made from aromatic phosphine oxides exhibit stability as well as flame resistance (40,41). Aromatic polyethers containing phosphine oxide structures are made according to the following reaction (41-43) ... 

One comparative study showed that the flame retardancy of an aromatic phosphine oxide copol5mier was no better than that achieved by a similar amoimt of phosphine oxide structure as an additive (49). 

Poljdmides containing phosphine oxide structures have been explored in the quest for highly stable thermoplastics. In the search for flame-retardant, heat-stable composites for aerospace applications, structures such as the following were prepared ... 

Ammonia-cross-linked textile finishes from tetrakis(hydroxymethyl) phos-phonium salts have a primarily phosphine oxide structure and are discussed under the topic of cellulosic textile finishes. 

Phosphonated aromatic diamines (195) can serve as flame-retardant curing agents for epoxy resins. Phosphoramides and bis(aminophenyl)methylphosphine oxide have been evaluated in the quest for stable, fire-resistant epoxy composites for aerospace applications (196-198). Economical means for producing the phosphine oxide structure have been lacking. 

A diol containing a phosphine oxide structure was shown to be useful in urethane coatings, adhesives, and rigid foams (204). Advantages included shelf stability of the amine catalysl>-polyol mixture, low smoke, and good resistance to humidity (205). 

The tetrakis(hydroxymethyl)phosphonium salts are applied to cellulosic fabric, most commonly as a urea precondensate (Albright Wilson s, now Rhodia s Proban), and cured with ammonia vapor (221-223). The finish, after oxidation by air or hydrogen peroxide, has phosphine oxide structures in a cross-linked amino resin network, probably also lightly linked to the cellulose. This finish is durable to multiple launderings and is used for industrial cotton garments (224). 

The initial step of olefin formation is a nucleophilic addition of the negatively polarized ylide carbon center (see the resonance structure 1 above) to the carbonyl carbon center of an aldehyde or ketone. A betain 8 is thus formed, which can cyclize to give the oxaphosphetane 9 as an intermediate. The latter decomposes to yield a trisubstituted phosphine oxide 4—e.g. triphenylphosphine oxide (with R = Ph) and an alkene 3. The driving force for that reaction is the formation of the strong double bond between phosphorus and oxygen ... 

The acyl phosphonates, acyl phosphine oxides and related compounds (e.g. 81. 82) absorb strongly in the near UV (350-400 nm) and generally decompose by rescission in a manner analogous to the benzoin derivatives.381"285 Quantum yields vary from 0.3 to 1.0 depending on structure. The phosphinyl radicals are highly reactive towards unsaturated substrates and appear to have a high specificity for addition v.v abstraction (see 3.4.3.2). 

This reaction may be visualized as proceeding by nucleophilic attack of tervalent phosphorus at the carbonyl group to give an intermediate such as (15). The structure of (16) was deduced from the fact that it was hydrolysed to the known phosphine oxide (17). Methylenephosphoranes (phosphorus ylides) may also be converted into monophosphazenes by reaction with benzonitrile ... 

NMR spectroscopic studies f111,13C, and 31P) are consistent with the dipolar ylide structure and suggest only a minor contribution from the ylene structure.234 Theoretical calculations support this view.235 The phosphonium ylides react with carbonyl compounds to give olefins and the phosphine oxide. 

Olefination Reactions Involving Phosphonium Ylides. The synthetic potential of phosphonium ylides was developed initially by G. Wittig and his associates at the University of Heidelberg. The reaction of a phosphonium ylide with an aldehyde or ketone introduces a carbon-carbon double bond in place of the carbonyl bond. The mechanism originally proposed involves an addition of the nucleophilic ylide carbon to the carbonyl group to form a dipolar intermediate (a betaine), followed by elimination of a phosphine oxide. The elimination is presumed to occur after formation of a four-membered oxaphosphetane intermediate. An alternative mechanism proposes direct formation of the oxaphosphetane by a cycloaddition reaction.236 There have been several computational studies that find the oxaphosphetane structure to be an intermediate.237 Oxaphosphetane intermediates have been observed by NMR studies at low temperature.238 Betaine intermediates have been observed only under special conditions that retard the cyclization and elimination steps.239... 

Although the bulk of work with NOz as a ligand features Co111, nitrite can also be O- or N-bonded to Co11, and both modes have been observed in complexes formed by the reaction of several PR3 compounds with Co(N03)2, as well as in mixed nitro/nitroso complexes.375 The product Co(NO)(N02)(PEt3)2 reacts with dioxygen to form Co(N03)2 (OPEt3)2, a distorted octahedral structure with bidentate nitrate and cis phosphine oxides (102). 

An analog (56) of isomer 53 was prepared by a structure proving synthesis (Scheme 13). It was proved that the syn isomer (57) obtained after deoxygenation is transformed spontaneously to the anti form (58). Phosphine (58) was stabilized as the phosphine oxide (59) (Scheme 14) [55],... 

LDA (0.118 g, 1.1 mmol) was added to (SP)-f-butyl(phenyl)phosphine oxide (0.182 g, 1 mmol) in tetrahydrofuran (5 ml) under an atmosphere of nitrogen at -78°C. After 15 min, the solution was treated with a solution of benzaldehyde (0.117 g, 1.1 mol) in tetrahydrofuran (2 ml), and the resultant mixture was stirred at -78°C for 3 h. Evaporation of the solvent and flash chromatography of the residue provided the (SP)-f-butyl(phenyl)(a-hydroxybenzyl)phosphine oxide (0.22 g, 77%) with a diastereoisomeric ratio of 98 2, which exhibited spectral data in accord with the proposed structure. 

Synthetic studies of various cyclic phosphine oxides continue to be published. Thus a methanolic work-up leads to an 88% yield of 1-methylphospholen 1-oxides (6) from dichloro(methyl)phosphine, and detailed S1P n.m.r. and mass spectra have been described.10 The oxides (7) and (8) have been prepared11 as shown. Structural... 

As expected, hydrogen phosphinate, which is a hybrid structure of hydrogen phosphonate and secondary phosphine oxide, adds to alkynes in the presence of the Pd-diphenylphosphinic acid catalyst system (Scheme 44) [36]. Normally, branched isomers are the major products, while trimethylsily-lacetylene exceptionally affords the corresponding terminally phosphinylat-ed product. Diphenylacetylene also reacts to afford the corresponding adduct in 99% yield. 

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