Dialkylphosphinous acids

Dialkylphosphinous acids react with perfiuoroalkenes under free radical conditions to form carbon-phosphorus bonds [10] (equation 7)... 

Danesi, P. R. Reichley-Yinger, L. Mason, G. Kaplan, L. Horwitz, E. P. Diamond, H. Selectivity structure trends in the extraction of cobalt(II) and nickel(II) by dialkyl phosphoric, alkyl alkylphosphonic, and dialkylphosphinic acids. Solvent Extr. Ion Exch. 1985, 3, 435 152. 

Reasonable yields (55-85%) of dialkylphosphinic acids have been reported from a complex reaction system beginning with red phosphorus, iodoalkane, and elemental iodine.26 Presumably, the phosphorus trihalide is generated as an intermediate. The reaction is worked up with a nitrous acid system from aqueous HCl/NaN02. 

Kudryavtseva, L.I., Alkylation of phosphorus iodides. V. Preparative method for dialkylphosphinic acids, Zh. Obshch. Khim., 60, 833, 1990. 

A group at IGEN raised antibodies to the dialkylphosphinic acid [107]. These were screened for their ability to hydrolyse four alkyl esters and four primary amides at pH 5.0,7.0, and 9.0. Just one out of 68 antibodies, 13D11, hydrolysed the C-terminal carboxamide stereospecifically of only the (/ )-substrate [108], which was rendered visible by the attachment of a dansyl... 

Like the divalent metal phosphinates they are often insoluble. However, soluble polymers have been obtained with long chain dialkylphosphinic acid such as A1(02P(C8Hi7)2)3 and the copolymers Al(02PCH2C6H5,C4H9) (02P(C8Hi7)2)2 and Cr(02PMePh)2(02P(C4H9)2 [87]. 

A convenient procedure for preparing dialkylphosphinic acids 62 involves addition of H-phosphinic acids and esters to conjugated double bonds via the silyl 87-89 or metal phos-phonite 61,[90 94] as illustrated in Scheme 21. The silyl phosphonite intermediates 61 (M = TMS) are typically formed either from phosphinic acids or esters using chlorotri-methylsilane or bis(trimethylsilyl)acetamide. The metal phosphonite intermediates 61 (Y = Li, Na, etc.) are prepared by deprotonation of the acids with a base such as sodium hydride, sodium methoxide, or lithium diisopropylamide. The conjugated double bonds are typically acrylic acids and esters substituted in the a-position with the appropriate amino acid side chain. After appropriate protecting group manipulations, additional amino acids... 

Zhu, Y., Song, C., Jiao, R. 1995. Partitioning studies in China and the separation of americium and fission product rare earths with dialkylphosphinic acid and its thio-sub-stituted derivatives. Global 1995 International Conference on Evaluation of Emerging Nuclear Fuel Cycle Systems, September, Versailles, France. 

The addition of 0.01 mol L 1 dialkylphosphinic acids and alkylphosphonic acids in a nonirradiated 30% TRPO-kerosene system had no effect on the extraction of Pu(IV) with TRPO. Thus, these acids were not complexing materials for plutonium. The polymeric species were responsible for plutonium retention and emulsification in contact with NaOH or deionized water. The effective elimination of these compounds was obtained by vacuum distillation of the irradiated TRPO-kerosene (67,167). 

Oxidative Phosphinylation A New Route to Dialkylphosphinic Acid Derivatives... 

The most reactive in this reaction were N-phosphorylated salts of isoquinoline, which hetarylated indole even at room temperature. Pyridine and particularly quinoline are less reactive. With these heterocycles the reaction took place only in the presence of the more active dialkylphosphinic acid chlorides. The steric effects of the substituents at the phosphorus atom have a definite role. It was found that substituents with smaller molecular mass and less branched substituents made it possible to conduct the reaction under milder conditions and lead to an... 

Phosphorus electronic constants or are electronic substituent constants derived from the dissociation constants of dialkylphosphinic acids for substituent groups directly bonded to a phosphorus atom [Mastryukova and Kabachnik, 1971]. Assuming the alkyl groups exert only an inductive effect, these electronic constants can be distinguished as Oy inductive constant and o resonance constant [Charton and Charton, 1978]. 

Cocalia et al. have reported the extraction of Am(III) with dialkylphosphoric or dialkylphosphinic acids from aqueous solution to l-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [265], Their results suggest that the extraction is quite similar to the behavior found for organic solvent systems. Further studies on actinoid extraction using ILs have been reported by Visser et al. [153],... 

Several communications, summarized in Scheme 14, have described the synthesis of many amino-substituted dialkylphosphinic acids and phosphonic acids, and also many similarly substituted hydrogenphosphinic acids. Alkylation of the phosphinates (272) (R = H or Me, = Et, R = H) yields the corresponding (273) which, in a single step, are convertible into the useful intermediates (274). With 1,2-unsaturated nitriles, for example, the (3-aminopropyl)phosphinic acids... 

R2P(0)0H Phosphinic acid (dialkylphosphinic acid esters alkyl dialkylphosphinate) Phosphinsatire... 

Compared with formic acid (pX = 3.77 in water, 5.75 in 95% aqueous ethanol), acetic acid (pKa = 4.76 in water), and benzoic acid (pK = 4.17 in water, 7.07 in 95% aqueous ethanol), simple symmetrical dialkylphosphinic acids (1) are moderately strong acids. Thus, for dimethylphosphinic acid (R = Me), pK = 3.08 (in water) and 6.64 in 95% aqueous ethanol, figures which rise to 3.56 for R = Pr and 4.24 for R = Bu for solutions in water for R = Ph, pK = 5.80 in 95% aqueous ethanol. These values can also be compared with those for the dialkyl phosphoric acids for dimethyl hydrogenphosphate, pK = 0.47 in water and 1.88 in 80% aqueous ethanol. Obviously the phosphorus-oxygen bonded acids are rather stronger, with the simple phosphinic acids closer to the carboxylic acids in their acidity. 

Attack on Saturated Carbon. - Ethylene dicarboxylic diphosphonic acid (EDCP, 2) has been prepared in 70% yield from 2,3-dichlorosuccinic anhydride (3) and trimethyl phosphite, followed by hydrolysis of the Arbuzov product. Tris(trimethylsilyl) phosphite, in contrast to trialkyl phosphites, attacks an oxirane carbon of epibalohydrins (4) to give the phosphonates (5). Bis(trimethylsilyl) phosphonite (6) has previously been prepared in situ and used to obtain y-ketophosphinic acids similar reactions with simple alkyl halides to give alkylphosphinic and dialkylphosphinic acids acids in high yields have now been described. ... 

Zirconium(iv) monobutyl phosphate, Zr(Bu0P03)2, has been prepared and characterized by i.r. spectroscopy. The dialkylphosphinous acid complexes [ R2P(0)H 2ZrX4] (R = Bu,Ph, or cyclohexyl X = Cl or Br) have been prepared from ZrX4 R2P(0)H in benzene and their i.r. spectra reported. "... 

The novel synthesis of unsymmetrical dialkylphosphinic acids (573) under mild conditions has been performed by Lecouvey and co-workers.This synthesis started from the hypophosphoric acid (570) which reacted with triethyl orthoformate to give the //-phosphinate (571). The letter underwent base-promoted alkylation to give (572). For the formation of the second P-C bond in the phosphinate (573), a one-pot procedure involving reaction of (572) has been applied (Scheme 139). This methodology was extended to the synthesis of dialkylphosphinic acids with amino functionality. 

Acid chlorides can be obtained from some phosphinic esters by the action of phosgene (6.260) the latter will also convert dialkylphosphinic acids first into phosphinic anhydrides and then into phosphinic halides (6.261). 

There are various specific colour tests for special classes of organophosphorus compounds. Tertiary phosphines, R3P, for example, produce a rose red colour in a carbon tetrachloride solution of m-dinitrobenzene. Trialkylphosphine oxides, R3PO, and dialkylphosphinic acids, RjPfOlOH produce a blue colour in a toluene solution of nickel bromide. A chloroform solution of PhjPO reacts with a chloroform solution of iodine to form an insoluble yellow compound and so forth. 

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