Phosphine oxides hydrolysis

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

Pentavalent phosphorus derivatives can be converted to phosphonyl halides or phosphine oxides by partial hydrolysis or by other oxygen donors. 

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. 

The product is relatively sensitive to basic conditions, showing both polymerization and addition of water. Therefore alkaline conditions must be avoided. Neutralization serves to convert monophenylphosphinic acid (formed by hydrolysis of unreacted, unextracted dichlorophenylphosphine) to the monosodium salt, thereby preventing its subsequent extraction from water along with the phosphine oxide. 

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. 

B. Electrophilic Reactions of the P=0 and P=S Groups. Hydrolysis studies with phosphine oxides continue to reveal problems associated with the role of pseudorotational processes in determining mechanism. The failure of benzyldiphenylphosphine oxide (36) to exchange when hydrolysed in under bimolecular conditions has been reported. ... 

Hydrolysis of the oxaphosphetan (25) gave the phosphine oxide (26) which was converted into (27) by treatment with a mixture of thionyl chloride and pyridine. Treatment of (25) with HC also caused ring opening to (28) which was reversed on treatment with triethylamine. The chlorophosphorane (28) lost nexaxluoroiso-propanol on heating to give (27) which was fluorinated to give (29)27. All the compounds were characterised Dy 1H, 19F and 31P n.m.r. 

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... 

Secondary phosphine oxides are known to be excellent ligands in palladium-catalyzed coupling reactions and platinum-catalyzed nitrile hydrolysis. A series of chiral enantiopure secondary phosphine oxides 49 and 50 has been prepared and studied in the iridium-catalyzed enantioselective hydrogenation of imines [48] and in the rhodium- and iridium-catalyzed hydrogenation functionalized olefins [86]. Especially in benzyl substituted imine-hydrogenation, 49a ranks among the best ligands available in terms of ex. 

CH3CN/H2O solution leads to various tertiary phosphines [33] examples include 1, 25, 27. In order to avoid the formation of phosphine oxides and/or the hydrolysis of some alkene derivatives (e.g. acryl esters) a small amount of Et4N Oir was used as base, and a small quantity of ditertbutylphenol was... 

An unusual reaction of electron-deficient acetylenes (usually DMAD is used) and triarylphosphines or -phosphites with Cjq leads to methanofullerenes that bear an a-ylidic ester (Scheme 3.11). Selective hydrolysis of the phosphite ylides yields phosphonate esters, phosphine oxides or phosphonic acids [49-51]. 

The oxidative hydrolysis and acetylation of olefins in the presence of palladium(II) salts are well-established as commercial routes to acetaldehyde and vinylacetate (46). Both processes have been investigated using supported catalysts. The oxidative hydrolysis has been briefly studied using palladium(ll) chloride supported on a cross-linked polystyrene resin containing cyano groups (64). Oxidative acetylation was effected using palladium(II) chloride supported on phosphinated silica (5). 

In a study which is relevant to the mechanism of hydrolysis of phosphonium salts, Glaser and Streitwieser297 studied the ions H4PO- and H3PFO- and their derivatives with Li +, NH4 and HF at the 6-31G level augmented by diffuse functions. They found that the structures of the anions are those of a hydride or fluoride ion solvated by or complexed with phosphine oxide, rather than phosphoranes297. A very important point is that earlier studies with diffuse functions yielded the pentacoordinated phosphoranes which they judged297 to be computational artifacts of the small basis set. 

Known bicyclo[4.3.1]enone 15758 was converted into vinylsilane 158 with bis(trimethylsilyl)methyl lithium.55 Diene 158 underwent selective ozonolysis at the cis-olefin under conditions to produce differentially oxidized termini 90 alde-hydo-ester 159 was homologated with a phosphine oxide anion91 to enol 160. Subsequent hydrolysis of 161 provided substrate 162, which after tandem ozonolysis-acidification gave racemic 6,9-desmethyl analogue 155. Unfortunately, initial efforts failed to resolve 155 into its two optical isomers with cellulose triacetate.92 However, the antimalarial activity of racemate 155 is intriguing, as discussed in a later section. 

The first enzymatic desymmetrizations of prochiral phosphine oxides was recently reported by Kielbasinski et al.88 Thus, the prochiral bis(methoxycarbonylmethyl)-phenylphosphine oxide 93 was subjected to the PLE-mediated hydrolysis in buffer affording the chiral monoacetate (RJ-94 in 72% ee and 92% chemical yield. In turn, the prochiral bis(hydroxymethyl)phenylphosphine oxide 95 was desymmetrized using either lipase-catalyzed acetylation of 95 with vinyl acetate as acyl donor in organic solvent or hydrolysis of 97 in phosphate buffer and solvent affording the chiral monoacetate 96 with up to 79% ee and 76% chemical yield. 

In 1974 a DuPont patent- disclosed the synthesis of cyclen phosphine oxide, 2,— by hydrolysis of cyclen fluorophosphorane, 1. 

Hydrolysis of 1,1-diphenylphosphorinanium bromide 71 with aq NaOH gave phosphine oxide 72 in 99% yield. Phosphine oxide was further reductively alkylated to 73 using Si(0Et)3H/Ti(0-7Pr)4 with various alkyl bromides <1998SL497> (Scheme 3). Bicyclic phosphines 74 were alkylated to 75 using BuLi/RBr (Equation 4) <2003JCD2036, 2003JCD4669>. 

Aqueous acid-solution hydrolysis of RjPX or RPXj species forms phosphine oxides and phosphinic acids, respectively ... 

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