Triphenylphosphine oxide

Direct Borohydride Reduction of Alcohols to Alkanes with Phosphonium Anhydride Activation N-Proovlbenzene. To a solution of 5.56 g (20 mmol) of triphenylphosphine oxide in 30mL of dry methylene chloride at CfC was added dropwise a solution of 1.57 mL (10 mmol) of triflic anhydride in 30mL of dry methylene chloride. After 15 min when the precipitate appeared, a solution of 1.36g (10 mmol) of 3-phenyl-1-propanol in 10 mL of dry methylene chloride was added and the precipitate vanished in 5 min. An amount of 1.5g (40 mmol) of sodium borohydride was added as a solid all at once and the slurry was stirred at room temperature for... 

Triphenylphosphine oxide [791-28-6], C gH OP, and triphenyl phosphate [115-86-6], C gH O P, as model phosphoms flame retardants were shown by mass spectroscopy to break down in a flame to give small molecular species such as PO, HPO2, and P2 (33—35). The rate-controlling hydrogen atom concentration in the flame was shown spectroscopically to be reduced when these phosphoms species were present, indicating the existence of a vapor-phase mechanism. 

Phosphine Oxides. Development of cyanoethylphosphine oxide flame retardants has been discontinued. Triphenylphosphine oxide [791 -28-6] C gH OP, is disclosed in many patents as a flame retardant, and may find some limited usage as such, in the role of a vapor-phase flame inhibitor. 

The peroxo species can oxidize other reactants, Hquids, catalyst, or final product in the subsequent coupling reaction. One example of such oxidation is observed in the preparation of triphenylphosphine (13—15). If this reaction is hydrolyzed in air instead of an inert N2 atmosphere, then the amount of triphenylphosphine oxide increases from less than 1 wt % to greater than 15 wt %. 

Some compounds are named as derivatives of the simple phosphoms hydrides (phosphines). For example, dimethylphosphine [676-59-5], (CH2)3PH triphenylphosphine oxide [791-28-6], (CgH3)3P=0 1,2-dimethyldiphosphine [53684-00-7], CH PHPHCH diethyliodophosphine [20472-47-3], (C2H3)2PI phosphonium iodide [12125-09-6], PH" P tetramethylphosphonium chloride [1941 -19-1], (CH3) P" C1 and phenylphosphonium bromide [55671-96-0], CgH PHjBr-. 

Work at Rhc ne-Poulenc has involved a different approach to retinal and is based on the paHadium-cataly2ed rearrangement of the mixed carbonate (41) to the aHenyl enal (42). Isomerization of the aHene (42) to the polyene (43) completes the constmction of the carbon framework. Acid-catalyzed isomerization yields retinal (5). A decided advantage of this route is that no by-products such as triphenylphosphine oxide or sodium phenylsulfinate are formed. However, significant yield improvements would be necessary for this process to compete with the current commercial syntheses (25—27) (Fig. 9). 

In the chlorination of 2,4-dichlorophenol it has been found that traces of amine (23), onium salts (24), or triphenylphosphine oxide (25) are excellent catalysts to further chlorination by chlorine ia the ortho position with respect to the hydroxyl function. During chlorination (80°C, without solvent) these catalysts cause traces of 2,4,5-trichlorophenol ( 500 1000 ppm) to be transformed iato tetrachlorophenol. Thus these techniques leave no 2,4,5-trichlorophenol ia the final product, yielding a 2,4,6-trichlorophenol of outstanding quaUty. The possibiUty of chlorination usiag SO2CI2 ia the presence of Lewis catalysts has been discussed (26), but no mention is made of 2,4,5-trichlorophenol formation or content. 

The isoxazoles (585) were formed regioselectively from the (dioxoalkyl)phosphonium salts (584) with hydroxylamine hydrochloride, the direction of cyclization being different from that of the nonphosphorus-containing 1,3-dioxo compound (see Chapter 4.16). Aqueous sodium hydroxide converted (585) into the isoxazole (586) and triphenylphosphine oxide. Treatment of (585) with n-butyllithium and an aldehyde gave the alkene (587). With hydrazine or phenylhydrazine analogous pyrazoles were formed (80CB2852). 

A variety of 1-azirines are available (40-90%) from the thermally induced extrusion (>100 °C) of triphenylphosphine oxide from oxazaphospholines (388) (or their acyclic betaine equivalents), which are accessible through 1,3-dipolar cycloaddition of nitrile oxides (389) to alkylidenephosphoranes (390) (66AG(E)1039). Frequently, the isomeric ketenimines (391) are isolated as by-products. The presence of electron withdrawing functionality in either or both of the addition components can influence the course of the reaction. For example, addition of benzonitrile oxide to the phosphorane ester (390 = C02Et) at... 

Hexaazadecalin PE, 3, 543 <75CB1557> Hexakis(benzotriazolyl)hexakis(allylamine)-trisnickel(ll) triphenylphosphine oxide X-ray, 5, 675 <76AX(B)714>... 

Triphenylphosphine oxide [791-28-6] from absolute EtOH. Dried in vacuo. 

Triphenylphosphine oxide is soluble in 60% aqueous ethanol therefore it remains in the filtrate and affords no difficulty. 

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. 

Step 2 The oxaphosphetane dissociates to an alkene and triphenylphosphine oxide. 

The final step is the nucleophilic displacement of the oxyphosphonium group by the carboxylate anion via a SN2-mechanism, yielding ester 3 with inverted configuration at the stereogenic center, and triphenylphosphine oxide. A hydrolysis of the ester 3 will leave the new configuration unchanged, and yield the inverted alcohol 4 ... 

In summary the Mitsunobu reaction can be described as a condensation of an alcohol 1 and a nucleophile—NuH—11, where the reagent triphenylphosphine is oxidized to triphenylphosphine oxide and the azodicarboxylate reagent 12 is reduced to a hydrazine derivative 13 ... 

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 ... 

Ethylene oxide (2.5 ml, 0.05 mole) is condensed in a 50-ml round-bottom flask containing 5 ml of methylene chloride by introducing the gas via a tube into the ice-cooled flask. To the cooled flask are added triphenylphosphine (6.6 g, 0.025 mole), benzaldehyde (2.6 g, 0.025 mole), and ethyl bromoacetate (4.2 g, 0.025 mole). The flask is closed with a drying tube, brought to room temperature, and allowed to stand overnight. Fractional distillation of the solution then yields 2-bromoethanol, bp 55717 mm followed by the desired ethyl cinnamate, bp 142-144717 mm (27171 atm) in about 90% yield. The residue consists of triphenylphosphine oxide, mp 150°. 

P-coupling occurs in the formation of azophosphonic esters [ArN2PO(OCH3)2] from diazonium salts and dimethyl phosphite [HPO(OCH3)2] (Suckfull and Hau-brich, 1958). P-coupled intermediates are formed in the reaction between diazonium salts and tertiary phosphines, studied by Horner and Stohr (1953), and by Horner and Hoffmann (1956). The P-azo compound is hydrolyzed to triphenylphosphine oxide, but if a second equivalent of the tertiary phosphine is available, phenyl-hydrazine is finally obtained along with the phosphine oxide (Scheme 6-26 Horner and Hoffmann, 1958). It is likely that an aryldiazene (ArN = NH) is an intermediate in the hydrolysis step of the P-azo compounds. 

Samarium, tris(triphenylphosphine oxide)bis-(diethyldithiophosphato)-structure, 1,78 Samarium complexes dipositive oxidation state hydrated ions, 3, 1109 Samarium(III) complexes salicylic acid crystal structure, 2, 481 Sampsonite, 3, 265... 

Interestingly, the final inactive by-products of these phosphorus-activated reactions, triphenylphosphine oxide or diphenylphosphate, can be converted back to starting TPPC12 or DPCP by reaction with COCl2 and SOCl2, respectively. 

Triphenylphosphine oxide is dissolved in cooled H2S04 and fuming nitric acid is added.116 Dinitro derivative is the major compound (80%) with mononitro and trinitro as by-products (about 10% each). 

Triphenylphosphine oxide, 297 Tris(4-aminophenyl) amine (TAPA), 308-309... 

The reason for the effectiveness of triphenylphosphine is at present uncertain, although its eventual isolation as triphenylphosphine oxide indicates that it may well function as a scavenger for the thallium(III) released in the metal-metal exchange reaction. 

Triphenylphosphine oxide (and PhsAsO or Ph2SeO) are reduced by MesSiNs 19, via the labile diazidophosphines 1780, to triphenylphosphine (triphenylarsine or diphenylselenide), nitrogen, and HMDSO 7, whereas iodosobenzene gives, via 1781, iodobenzene, nitrogen, and HMDSO 7 [30] (Scheme 12.9). 

Wittig reactions are versatile and useful for preparing alkenes, under mild conditions, where the position of the double bond is known unambiguously. The reaction involves the facile formation of a phosphonium salt from an alkyl halide and a phosphine. In the presence of base this loses HX to form an ylide (Scheme 1.15). This highly polar ylide reacts with a carbonyl compound to give an alkene and a stoichiometric amount of a phosphine oxide, usually triphenylphosphine oxide. 

A"-Ray structure determinations (see Chapter 11 for details) have been reported for triphenylphosphine oxide, tri-o-tolylphosphine oxide, sulphide, and selenide, and for cw-2,2,3,4,4-pentamethyl-l-phenylphos-phetan-1-oxide (5). Electron spectroscopic studies of phosphorus oxychloride and thiophosphoryl chloride in the gaseous state, and n.m.r., i.r., and u.v. spectra of phosphine sulphides have appeared. Dipole moments have been used to define the stereochemistry of 2-cyanoethylphosphine oxides, such as (6), which is shown in its preferred conformation. 

A. Preparation.—The first reverse Wittig olefin synthesis has been reported. Triphenylphosphine oxide and dicyanoacetylene at 160 °C gave the stable ylide (1 78%) the reaction was reversed at 300 °C. No comparable reaction was observed with a variety of other activated acetylenes but tri phenyl arsine oxide gave the corresponding stable arsoranes with dicyanoacetylene (— 70 °C), methyl propiolate, hexafluorobut-2-yne, dimethyl acetylene dicarboxylate, and ethyl phenylpropiolate (130 °C). 

With cobalt(ii) chloride, complexes of the monophosphazene, PhgP=NH (= L), of stoicheiometry CoCl2L,THF and C0CI2L2 have been isolated. Their i.r. and u.v. spectra were compared with analogous complexes of triphenylphosphine oxide. 

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