Diphenylphosphinic acids

Diphenylphosphinic acid [1707-03-5] M 218.2, m 194-195 , pK 1.72. Recrystd from 95% EtOH and dried under vacuum at room temperature, [see Kosolapoff Organophosphorus Compounds J Wiley, NY, 1950 Kosolapoff and Maier Organic Phosphorus Compounds Wiley-Interscience, NY, 1972-1976.]... 

The initial 2-iodopropyolanilides are rather inaccessible compounds. Their preparation requires a three-stage synthesis with diphenylphosphinic acid azide as the starting material. 

Aqueous HCI solutions hydrolyze the P-N bond to give the amine hydrochloride and R2P-OH, which then disproportionates and is oxidized to diphenylphosphinic acid. A free phosphinous amide anion, with the countercation complexed by a crown ether, has been shown to be hydrolyzed and oxidized to the corresponding phosphinite with unusual ease [119]. Formic acid in toluene can be utilized for converting P,P-disubstituted phosphinous amides into their respective phosphane oxides [30]. 

The preparation of diphenylphosphine oxide normally involves the controlled hydrolysis of chlorodiphenylphosphine, but the product has a significant amount of diphenylphosphinic acid impurity. This problem... 

Several modifications of procedures based on halophosphonium ion have been developed. Triphenylphosphine and imidazole in combination with iodine or bromine gives good conversion of alcohols to iodides or bromides.22 An even more reactive system consists of chlorodiphenylphosphine, imidazole, and the halogen,23 and has the further advantage that the resulting phosphorus by-product diphenylphosphinic acid, can be extracted with base during product workup. 

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 Holmes, R. R., unpublished work).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. 

Mixed phosphines,113 phosphates,114,115 phosphinites (diphenylphosphine oxide) and related diphenylphosphine acids,116-119 phospholes,120 and other phosphorus ligands121-123 have been used in Pt-catalyzed hydroformylation. [PtCl2(COD)] has been used as starting material for the preparation of catalytic precursors.114,124-126... 

Ni(PMe2Ph)4, as exemplified in Table 8. However, the use of dimethyl phos-phonate usually results in the formation of a mixture of branched and linear isomers. Addition of diphenylphosphinic acid to the reaction system significantly improves the selectivity for the branched isomer (see below). 

Very interestingly, the regioselectivity of the palladium-catalyzed hydrophosphinylation can be switched by addition of a tiny quantity of diphenylphosphinic acid or other acidic compounds (Scheme 39) [35]. Thus, the linear product (19 8), which is the major product under normal conditions (i.e., without the phosphinic acid), becomes the minor regioisomer, and instead, the branched isomer (19a) is formed as the prevailing product. Furthermore, the addition of the phosphinic acid enhances the catalytic activity. Note that the quantity of the palladium catalyst is 5 mol% relative to the reactant, and that the addition of only 1 mol% (relative to the reactant) of the phosphinic acid results in a substantial change in the regioselectivity. New palladium species, which are much more active in the catalysis, appear to be generated upon addition of the phosphinic acid or other acidic additives. 

The following experiments to identify the active species substantiate the mechanistic detail. Diphenylphosphinic acid was found to protonate the C-... 

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. 

Diphenylphosphine oxide can be used as a phosphorus-centered nucleophile for propargylic substitution reactions, where its tautomer (diphenylphosphinous acid) is... 

The recovered and dried diphenylphosphinic acid, 19.6 g (90%), is ready to be recycled to diphenylphosphinyl chloride. ... 

Diphenylphosphinic acid Phosphinic acid, diphenyl- (8,9) (1707-03-5) Benzaldehyde (8,9) (100-52-7)... 

Platinum(II)15 and palladium(II)16 complexes of phosphorus trichloride undergo solvolysis in water and alcohols to form complexes with orthophosphorous acid or orthophosphite ligands (equation 6). Similar reactions occur between the palladium(II) phenyldichlorophosphine complex (8) and the diols ethyleneglycol and catechol, but new chelate rings are not formed (Scheme 2). Solvolysis also occurs with attack of diphenylphosphinic acid or a similar diphenylchlorophosphine complex (9) (equation 7). The palladium complexes (8) and (9) are unstable to excess methanol, water or base and undergo reduction. Similarly, the phosphorus trichloride gold(I) complex (10) is reduced by water, but forms stable products on reaction with alcohols (equation 8).15 During the above reactions, the phosphorus—metal bond remains intact and the overall process is one of substitution at phosphorus. 

Peptides. A new amide or peptide synthesis is based on the formation of iminophosphoranes, R N=PR3, from the reaction of azides with a tertiary phosphine. These phosphoranes react with carboxylic acids to form amides.1 Ethyl diphenylphosphinite is more useful than a triarylphosphine because the by-product is hydrolyzed to diphenylphosphinic acid, which can be readily removed. The iminophosphorane 2, derived from 1 and ethyl azidoacetate, reacts with CboGly-L-Phe-OH to give optically pure 3 in 70% yield.2... 

Phenanthrene and pyrene on treatment with diisopropylcarbodiimide, hydrogen peroxide, and acetic acid in ethyl acetate at room temperature give 1 and 4 in 28% and 27% yields, respectively.17 Similar reaction occurs with dicyclohexylcarbodiimide and cyclohexylbenzylcarbodiimide. The hydrogen peroxide can be either 98% or a 30% aqueous solution. Use of silica gel, Dowex 50W-X8, or diphenylphosphinic acid instead of acetic acid is also permissible. However, because of the sensitivity of arene oxides toward strong acids, hydrochloric, sulfuric, or polyphosphoric acids cannot be used. 

A variety of oligomers with novel drum and ladder structures have also been prepared. They have the formulas [R Sn(0)02CR]6 and [(R Sn(0)02CR)2 R Sn(02CR)3 2, and contain four- and six-membered rings. They can be synthesized by the reaction of stannoic acid with a carboxylic acid, but the reaction of RSnCl3 with the silver salt of a carboxylic acid can also be used. If diphenylphosphinic acid or dicyclohexylphosphinic acid is used instead of the carboxylic acid, oxygen-capped clusters or cubic and butterfly structures are obtained.69... 

Diphenylphosphinous Acid by UV Irradiation of Aroyl Diphenyl Phosphines... 

In a competing and novel type of photoreaction, aroyl diphenyl phosphines 1d - k yield diphenylphosphinous acid (4, diphenylphos-phine oxide) as the photoproduct of a complex transfer of the oxygen from the carbonyl carbon onto the phosphorus atom followed by C-P-bond cleavage and hydrogen abstraction from solvent. The mass spectrometric product analysis of an u.v. irradiation experi-... 

Several publications have been devoted to the synthesis of phosphorylated derivatives of pyrrole by cyclization and condensation reactions. Diphenylphosphinylaminopyrroles 176 were obtained [193] by the cyclization of dicarbonyl compounds in the presence of diphenylphosphinous acid hydrazide ... 

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