Phosphine oxides phosphinic acids

Oxidation of Phosphines and Phosphine Oxides Phosphinic acids may be prepared by controlled oxidation of primary phosphines, RPH2. In most cases air, oxygen, or hydrogen peroxide is sufficient [162-164] see Eq. (95) ... 

Tetrakishydroxymethyl phosphonium chloride (THPC) is well established as a flame retardant agent with textiles (3). Collins (2) has suggested that THPC and urea break down to produce phosphoric acid via a phosphine oxide, phosphinic acid, and phosphonic acid. For cellulose, Collins concludes flameproofing is essentially caused by the dehydrating action of the phosphoric acid formed. 

Electronic aspects of the secondary phosphine oxide - phosphinous acid tautomerism and the assisting role of transition metals [e.g. Ru) were investigated. ... 

Phosphine Air, boron trichloride, bromine, chlorine, nitric acid, nitrogen oxides, nitrous acid, oxygen, silver nitrate... 

Pure tetrahedral coordination probably occurs only ia species where there are four identical groups and no steric distortions. Both PCU and PBr" 4, present ia soHd phosphoms haUdes, appear to have poiat symmetry. Other species, eg, H PO and POCl, have only slightly distorted tetrahedra. Similar geometries occur ia salts, esters, and other derivatives of phosphoric, phosphonic, and phosphinic acids as well as phosphine oxides and phosphonium salts. 

Preparation and Properties of Organophosphines. AUphatic phosphines can be gases, volatile Hquids, or oils. Aromatic phosphines frequentiy are crystalline, although many are oils. Some physical properties are Hsted in Table 14. The most characteristic chemical properties of phosphines include their susceptabiUty to oxidation and their nucleophilicity. The most common derivatives of the phosphines include halophosphines, phosphine oxides, metal complexes of phosphines, and phosphonium salts. Phosphines are also raw materials in the preparation of derivatives, ie, derivatives of the isomers phosphinic acid, HP(OH)2, and phosphonous acid, H2P(=0)0H. 

In general, if the desired carbon—phosphoms skeleton is available in an oxidi2ed form, reduction with lithium aluminum hydride is a powerful technique for the production of primary and secondary phosphines. The method is appHcable to halophosphines, phosphonic and phosphinic acids as well as thein esters, and acid chlorides. Tertiary and secondary phosphine oxides can be reduced to the phosphines. 

The secondary phosphine oxides oi sulfides can be oxidized to phosphinic acids oi thiophosphinic acids. 

Tri-n-octylphosphine oxide [78-50-2] M 386.7, m 59.5-60°, pK jt <0. Mason, McCarty and Peppard [J Inorg Nuclear Chem 24 967 7962] stirred an O.IM solution in benzene with an equal volume of 6M HCl at 40° in a sealed flask for 48h, then washed the benzene solution successively with water (twice), 5% aq Na2C03 (three times) and water (six times). The benzene and water were then evaporated under reduced pressure at room temperature. Zingaro and White [J Inorg Nucl Chem 12 315 7960] treated a pet ether solution with aqueous KMn04 (to oxidise any phosphinous acids to phosphinic acids), then with sodium oxalate, H2SO4 and HCl (to remove any manganese compounds). The pet ether solution was slurried with activated alumina (to remove phosphinic acids) and recrystd from pet ether or cyclohexane at -20°. It can also be crystd from EtOH. 

Most common is the preparation of alkyl phosphonic acid esters (phospho-nates) 4 (Z,Z = OR) from phosphorous acid esters (phosphites) 1 (Z,Z = OR). The preparation of phosphinic acid esters (Z = R, Z = OR) from phosphonous acid esters, as well as phosphine oxides (Z,Z = R) from phosphinous acid esters is also possible. 

Colorless phosphate ester surfactants were also prepared by treating P4O,0 with an organic OH-containing compound in the presence of a phosphinic acid color inhibitor, e.g., bis(hydroxymethyl)phosphinic acid color inhibitor. Thus, 558 parts dodecanol containing 2.4 parts of phosphinic acid color inhibitor was treated with 142 parts P4O10 at 100-135°C. The phosphate ester surfactant had a VCS color value of 1, whereas a sample prepared without the color inhibitor had a VCS color value of 5. Twenty-eight similar surfactants were prepared using various alcohols and alcohol-alkylene oxide condensates [22]. 

Phosphinic acids are easily oxidized to their corresponding phosphonic acids ... 

The monosubstituted phosphinic acids, RHP(0)(0H), are easily oxidized yielding the corresponding phosphonic acids, according to Eq. (87) ... 

Phosphine oxides, e.g., di-/ -octadecylphosphine oxide, are oxidized to phos-phinic acids by hydrogen peroxide. With chlorine or phosphorus pentachloride, phosphine oxides form dialkylphosphinyl chlorides, R2P(0)C1, which can be easily hydrolyzed to phosphinic acids [162,165] see Eqs. (96) and (97) ... 

Phosphinous amides bearing protons at the nitrogen atom, that here we will call NH phosphinous amides, such as 6, may be involved in prototropic equilibria with their PH phosphazene forms 7 [18,68-70] (Scheme 10). This kind of prototropic equilibria, paralleling that between phosphinous acids R2P-OH and phosphane oxides R2P(0)H [4], have been evidenced in some particular... 

B. By Hydrolysis Reactions.—Details have appeared of the synthesis of dibenzophosphorin oxides (15) from 5-alkyldibenzophospholes, by reaction with methyl propiolate in the presence of water, and of confirmatory syntheses from phosphinic acid chlorides, as shown below. Evidence for the suggested mechanism of the ring-expansion reaction is presented. The hydrolysis of enamine phosphine oxides is an efficient, although somewhat indirect, method for the preparation of j8-ketoalkylphosphine oxides (16) [see Section 3(iii), for the preparation of enamine oxides]. Reasonable yields (48—66%) of trialkylphosphine oxides (17) have been obtained by the alkaline hydrolysis of the products from the pyrolysis at 220 °C of red phosphorus with alkyl halides, in the presence of iodine. 

C. Reactions of Phosphoric and Phosphinic Acid Derivatives.—The optically active phosphinate ester (90) has been shown to react with benzyl Grignard reagents or lithium anilide with inversion of configuration. Oxidation of... 

The deoxygenation of peroxycarbonates (53) with phosphines and phosphites has been examined. Reaction with phosphites favours pyrocarbonate formation (Path A) whilst phosphines favour carbonate formation (Path B). Secondary phosphine oxides are oxidized to phosphinic acids by perbenzoic acid. The kinetics of the deoxygenation of hydroperoxides by triphenylphosphine have been examined and the reaction shown to be catalysed by strong acids. ... 

Phosphinic Acid Reactions. Reaction of n-butylstannoic acid with diphenylphosphate instead of a carboxylic acid also results in the formation of a drum composition [ n-BuSn(0) 02P (OPh)2] g (Chandrasekhar, V. Holmes, J. M. Day, R. 0. Holmes, R. R., unpublished work). However, when diphenylphosphinic acid is reacted with n-butylstannoic acid under reflux in toluene, a new structural form of tin is obtained (7 ). The reaction proceeds according to Equation 4 giving the stable oxide composition in 90% yield, mp 198-208°C dec. 

In contrast to the situation on flash pyrolysis, methyleneoxophosphoranes generated by thermolysis or photolysis in the presence of protic nucleophiles can be directly trapped to form corresponding derivatives of phosphinic acid (17- 19) however, the possibility of competing insertion of carbenes into the H/X bond of the additives is always present, giving phosphine oxides with X in the a-position (16- 18). Reaction branching at the carbene 16 was first observed on photolysis of 7 in water 13) and prompted detailed investigations on the phosphorylcarbene/ methyleneoxophosphorane rearrangement. 

We successfully developed combinatorial approaches for the discovery of industrial ligands and/or catalysts [Scheme l].1 Air-stable phosphine oxides with formal valence five in the presence of transition metals undergo tautomerization to the less stable phosphinous acids, which subsequently and... 

As a safer alternative to digestion of vegetable matter with perchloric acid, alkaline oxidation of sulfur compounds to sulfate by sodium hypobromite, and reduction of sulfate to hydrogen sulfide by hydriodic acid/formaldehyde/phosphinic acid is recommended. 

Hydrazine hydrate and phosphinic acid both explosively reduce the oxide when dropped on to it. 

The reaction of dialkyl esters of 1,2-alkadienylphosphonic and phosphinic acids with methyl and phenylsulphenyl chloride, leads exclusively to 2,5-dihydro-l,2-oxaphosphole-2-oxide derivatives [113-115],... 

Reports on the sensitivity of many neutral and cationic NHP derivatives towards air and moisture reveal in most cases pronounced reactivity even with traces of H20 causing P-X bond hydrolysis whereas genuine oxidation processes appear to play a role only for P-H and P-alkyl NHPs [71]. Controlled hydrolysis proceeds at low temperature as depicted in Scheme 9 to give secondary phosphine oxides 17 as initial product which may react further with excess NHP to phosphinous acid anhydrides 18.3 Both products may be obtained as isolable products starting from P-chloro NHPs [48], Hydrolysis at ambient temperature may be unselective and... 

Detailed investigations of the chemical reactivity of the diketiminato-stabilized phosphenium cations like 28 (Scheme 17) are to date rare and include only two reports dealing with the substitution and reduction of P-halogen-derivatives. Thus, reaction of 28 (X=Br) with sodium hydroxide in toluene was reported to proceed with displacement of the halide substituent at phosphorus and conservation of the heterocyclic ring to give a mixture of bromide and triflate salts containing a P-hydroxy-substituted cation, both of which were isolated in small yields [89], The products are remarkable as they represent one of very few examples of a stable phosphinous acid which does not rearrange to the tautomeric secondary phosphine oxide. Potassium reduction of the P-chloro-substituted derivative 34 produced the... 

A modification of this procedure allowed the isolation of 1,3,2-oxazaphospholidine 52a as a single diastereomer [41] and its application to asymmetric synthesis of enantiomerically and diastereomerically pure phosphinic acid derivatives 53 and 54 and tertiary phosphine oxides 55 (Scheme 20) [45], A few years later, a similar approach for the synthesis of enantiomerically pure tertiary phosphine oxides 55... 

Spirooxyphosphoranes 166 were obtained by the cyclodehydration of ortho-carboxyarylmethyl phosphine oxides under acidic conditions (Equation 15) to give 166 (X = Y = 0) in which the oxygens occupy the axial positions. Related spirocyclic azoxyphosphoranes 166 (X = NH, NMe) were synthesized from amidoarylmethyl phosphine oxides and trifluoracetic acid <1996PS241>. 

The reaction of alcohols with CO was catalyzed by Pd compounds, iodides and/or bromides, and amides (or thioamides). Thus, MeOH was carbonylated in the presence of Pd acetate, NiCl2, tV-methylpyrrolidone, Mel, and Lil to give HOAc. AcOH is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a Pd compound, an ionic Br or I compound other than HBr or HI, a sulfone or sulfoxide, and, in some cases, a Ni compound and a phosphine oxide or a phosphinic acid.60 Palladium(II) salts catalyze the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective.61 A novel Pd11 complex (13) is a highly efficient catalyst for the carbonylation of organic alcohols and alkenes to carboxylic acids/esters.62... 

At times, confusion arises in noting oxides of primary and secondary phosphines (Figure 1.5). These species participate in equilibria much as the phosphonous and phosphinous acids do and can be named as types of phosphonous and phosphinous acids. 

Pickard, R.H. and Kenyon,., Contributions to the chemistry of oxygen compounds. I. The compounds of tertiary phosphine oxides with acids and salts,... 

Phosphine complexes, osmium, 19 642 Phosphine coordination complexes, of uranium, 25 436 Phosphine derivatives, 19 28 Phosphine oxide(s), 11 495-496 19 66 predicted deviations from Raoult s law based on hydrogen-bonding interactions, 8 814t in salicylic acid manufacture, 22 8 Phosphine oxide diols/triols, 11 501 Phosphine selenides, 22 90 Phosphinic acid, 19 20, 54-55 Phosphinic anhydride, 11 499 Phosphinothricin acetyltransferase (PAT) proteins, 13 360 Phosphite esters, 19 20 Phosphites, in VDC polymer stabilization, 25 720... 

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