Phosphinic acid reactions, formation

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 Holmes, R. R., unpublished work).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. 

The addition of P—H bonds across a carbonyl function leads to the formation of a-hydroxy-substituted phosphines. The reaction is acid-cataly2ed and appears to be quite general with complete reaction of each P—H bond if linear aUphatic aldehydes are used. Steric considerations may limit the product to primary or secondary phosphines. In the case of formaldehyde, the quaternary phosphonium salt [124-64-1] is obtained. 

Other cyclizations at phosphorus have been observed when certain phosphinates were used in the acid-catalyzed Mannich reaction. As observed previously with various phosphonous acid derivatives, reaction of aliphatic phosphinic acids with primary amines favored the formation of 2 1 adducts (73). Thus, glycine and other a-amino acids reacted under the typical conditions with excess formaldehyde and alkyl phosphonous acids to give the bis-phosphinylmethyl adducts 125. 

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. ... 

A differential vapour-pressure technique has been used to determine the molecular weights of phosphonic and phosphinic acids in 95% ethanol. Cryoscopic and n.m.r. studies have been made on solutions of phosphinic acids in sulphuric acid and oleum. Mass spectrometry has indicated the ready formation of phosphinylium ions after electron bombardment of phosphonic and phosphinic acids and their derivatives. However, the cryoscopic results in sulphuric acid indicated that reaction did not proceed beyond protonation, and the n.m.r. study on oleum solutions suggested that sulphonation occurred. 

Reaction of 3 with 1 equivalent of a phosphine results in formation of "phosphine-modified catalysts (4). The complex formed from 7r-allyl-nickel chloride, tricyclohexylphosphine, and methylaluminum dichloride (4a) has been isolated and its structure determined crystallographically (see Fig. 1) (57) The phosphine is bonded to the nickel atom, and interaction with the Lewis acid takes place via a chlorine bridge. The bridging chlorine atom is almost symmetrically bound to both the nickel... 

In addition, aryl triflates have proven to be viable substrates for the Pd-catalyzed Csp2—P bond formation reactions [87-90], Intriguingly, phosphorylation can be achieved from the Pd-catalyzed coupling of alkenyl triflate with not only dialkylphosphites, but also with hypophosphorous acid [88]. Thus, phosphinic acid 87 was obtained when triflate 86 was treated with hypophosphorus acid in the presence of Pd(Ph3P)4. Due to the abundance of alkenyl triflates and milder reaction conditions, alkenyl triflates have certain advantages over the corresponding alkenyl halides as substrates for Pd-catalyzed phosphorylations to make alkenyl phosphonates or phosphinates. 

The mechanism of action of the phosphonium halides as flame retardants also may be related to the formation of phosphine oxides and/or phosphinic acids from the halide, according to the following reactions (8,14,17). 

A related reaction that yields the same types of products as does the Michaelis-Arbuzov reaction begins with either a phosphinous acid or a monoester of a phosphonous acid. (The corresponding reaction may also be performed with a diester of phosphorous acid.) By treatment with an appropriate base, the conjugate base of the phosphorus-containing acid is generated that serves as the nucleophihc reagent for direct formation of the phosphonate or phosphine oxide product (or phosphonate product from a phosphorous acid diester). This procedure is commonly referred to as the Michaehs Becker reaction. ... 

Other organo-phosphorous reagents are based on the mixed carboxylic-phosphoric or phosphinic anhydrides. Initially used to convert carboxylic acids into acyl azides, DPPA 12 has been introduced as a one-pot coupling reagent for peptide chemistry (32), and it was adapted later to solid-phase chemistry (81). The driving force of these reactions is the formation of the phosphoric or phosphinic acids and their salts. Later DPP-Cl 49 (82) and FDPP 50 were introduced. FDPP 50 has been used successfully in macro cyclizations (83). Examples of... 

Photolysis of (244) in the presence of alcohols likewise results in the formation of esters of methyl(phenyl)phosphinic acid. However, O-isotopic labelling studies provide evidence of, at least, the partial involvement of a pentacovalent phosphorus intermediate in this reaction, and so the previous assumption of the intermediacy of (245) may not be the whole story. The phosphole oxide dimers (246) have been shown to undergo regioselective reduction and complexation on treatment with the dimethylsulfide-borane adduct, to form the bicyclic system (247). Treatment of the propadienylphosphine oxide... 

Amines of phosphonic and phosphinic acids, on reaction with phosgene, are partially cleaved at the P-N bond. Thus, in addition to the formation of isocyanates. Equation (10.42), a number of by-products (such as the chlorides of the corresponding acids)... 

All the reaction processes were studied in an in situ infrared reactor cell. The product formation profiles were closely monitored. The results of this study show that gas-solid DMC and MPC synthesis processes are significantly more effective than the conventional gas-liquid synthesis processes. The results also show that diphenyl phosphinic acid is an effective catalysts for the synthesis of DMPD from DMC and 2, 4-diaminotoluene. 

Apparently a steric factor prevents formation of tri- er -butylphos-phine in the classic reaction. A 3 1 ratio of the er -butyl Grignard reagent with phosphorus trichloride gave after oxidation di- er -butyl-phosphinic acid in low yield (6%) (36). 

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