Methylphosphonic acid esters

Although most of the macrocycles that contain phosphorus or arsenic which have thus far been prepared, are primarily transition metals binders, two compounds have been prepared which are essentially crown ethers containing phosphorus. Kudrya, Shtepanek and Kirsanovhave prepared two compounds which are essentially polyoxygen macrocycles but which contain one or two methylphosphonic acid esters as part of the ring. These two macrocycles are shown below as 7d and 17 and are both prepared by the reaction of 2,2 [oxybis(ethyleneoxy)] bisphenolate with methylphosphonic dichloride in a mixture of acetonitrile and benzene. The crystalline monomer 16) and dimer 17) were isolated in 17% and 11% yields respectively as indicated in Eq. (6.13). 

The ester group is then hydrolysed, and the hydrolysis normally stops at the MePO(OH)2 stage. More vigorous conditions are required to rupture the Me—P bond. Thus the normal hydrolysis product of D.F.P. and of tabun, namely, phosphoric acid, will give a positive test with ammonium molybdate, whereas the product from sarin, namely, methylphosphonic acid, will not respond to this test. Vigorous reagents such as hot nitric acid and ammonium persulphate will break the C—P link and then a positive test for phosphate is obtained with ammonium molybdate. Sarin can be prepared in a variety of ways. Three... 

The Newport, Indiana, stockpile contains 1,269 tons of VX nerve agent, a relatively nonvolatile, persistent toxin that disrupts signal transmission in the central nervous system. VX can be hydrolyzed in hot aqueous sodium hydroxide solution. This process produces a strongly alkaline solution containing salts of methylphosphonic acid, its monoethyl ester, and a foul-smelling thiol amine compound. In 1996, the NRC recommended further evaluation of the Army s... 

Methylenation. This phosphonate ester is generally regarded as unsuitable for methylenation of ketones, even though the anion forms the intermediate adduct in satisfactory yield. However, under suitable experimental conditions, this reagent was used for methylenation of 1 to give 2 in 90% yield, higher than that obtained with methylphosphonic acid bis(dimethylamide) (78%).1 The optimum yield is obtained if exactly 2 equiv. of base and 1 equiv. of water are used to quench the adduct before cycloelimination. 

Verwej et al. [175] have described a procedure for the determination of PH3-containing insecticides in surface water. In this procedure the insecticide is hydrolysed to methylphosphonic acid, and the acid is concentrated by anion exchange and converted to the dimethyl ester. After clean-up on a microsilica gel column the ester is analysed by gas chromatography using a thermionic phosphorus-specific detector. Detection limit is lnmol L 1. 

V.T. Borrett, R. Colton and J.C. Traeger, The electrospray mass spectra of phosphoric acid, methylphosphonic acid and its alkyl esters, and their complexes with alkali and alkali earth metal ions, Eur. Mass Spectrom., 1, 131-140 (1995). 

The methyl ester easily undergoes spontaneous isomerization to the dimethyl ester of methylphosphonic acid ... 

The arbitrary name VX relates to a group of D,5-diesters of methylphosphonic acid ROPO(CH3)S(CH2)2N(Rl)2. D-Isobutyl 5-2-(diethylamino)ethyl methylphosphonothioate (R= /Bu, R1 = Et), produced since 1972 exclusively in the former Soviet Union, was generally referred to as Russian VX or RVX (CAS 159939-87-4). The synonyms are VR VA phosphonothioic acid methyl-, 5-[2-(diethylamino)ethyl] D-(2-methylpropyl) ester D-isobutyl5-2-(diethylamino)ethyl methylthiophosphonate D-isobutyl 5-(W-diethylaminoethyl) methylphosphonothioate and Russian V-gas. The brutto formula of RVX is C11H26SNPO2 (MW 276.37). The stmctural formula of RVX is presented in Figure 7.1. 

SYNS Di LMP METHYLPHOSPHONIC ACID DIMETHYL ESTER NCI-C56762... 

METHYI- PHOSPHATE see TMD250 METHYL PHOSPHITE see TAIDSOO METHYL PHOSPHONATE see DSG600 METHYLPHOSPHONIC ACID DIMETHYL ESTER see DSR400... 

The third most commonly used class of flame-retardants is phosphorus-containing compounds such as phosphoric acid esters, diphenyl cre-sylphosphate, dimethyl methylphosphonate, and dibutyl dihydroxyethyl diphosphate. They have good flame-retarding performance and are effective in small amounts. They are, however, expensive and have low hydrolysis stability. 

Gross, H., and Seibt, H., a-Substituted phosphonic acid esters. Part 10. Synthesis of chloro(methoxy )meth-ylphosphonic esters and chloro(methylthio)methylphosphonic esters, J. Prakt. Chem., 312, 475, 1970. 

The reaction of sarin with hydrogen chloride has been reported and kinetics determined by NMR imaging (Bard et al., 1970). With rate constants determined at 25°C, 81.5°C, and 100°C, Arrhenius analysis led to a calculated activation energy of 17.8 kcal/mole. The base-induced hydrolysis of sarin analogs and tabun was studied by Larsson (1958b) and the half-life of GA has been estimated to be 1.5 min at pH = 11 at 25°C. Ultimately, and depending on conditions (pH, reaction times, and so forth), hydrolysis products may include fluoride ion (or hydrogen fluoride), the 1-methylethyl ester of methylphosphonic acid, methylphosphonic acid, and 2-propanol. 

Dimethyl Ester of Methylphosphonic Acid A223 Precursor 128... 

Amino Acids and Peptides. - Wasserman s method of one-carbon homologation of carboxylic acids to give a-ketocarboxylates involves reaction with cyanomethylenetriphenyl-phosphorane followed by ozone (Scheme 24) and has been used as a key step in a chemo-enzymatic synthesis of isotopically labelled L-valine, L-isoleucine, and o/fo-isoleucine. Alkylation of the carbanion derived from the imino-substituted methylphosphonate diphenyl ester (186) with indol-3-ylmethyl bromide followed by appropriate deprotection has been used to prepare the phosphonate analogue (187) of tryptophan (Scheme 25). The deprotected analogue (188) and derived peptides show activity as inhibitors of chymotrypsin. Two approaches to solid phase Wadsworth-Enunons reactions which have applications in combinatorial chemistry have been reported. In one diethylphosphonoacetamide is bound to PEG-PAL resin via a peptide link, while... 

The alkyl methylphosphonic acids are polar and involatile and must be derivatized before analysis by gas chromatography. The simplest derivatization involves conversion into the methyl esters using diazomethane , or trimethylphenylammonium hydroxide in the hot injection port. However, the GC properties of the methyl esters, particularly dimethyl methylphosphonate, are not ideal and may give rise to poor peak shapes at low concentrations. Alternative derivatives are the trimethylsilyl or err-butyldimethylsi-jyji 14,133 latter are more stable than the trimethylsilyl esters and provide good... 

Methylphosphonic acid, bis [(5-ethyl-2-methyl-2-oxido-1,3,2-dioxaphosphorinan-5-yl) methyl] ester... 

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