Alkylphosphonic acid esters

Olefination Reactions Involving Phosphonate Anions. An important complement to the Wittig reaction involves the reaction of phosphonate carbanions with carbonyl compounds 253 The alkylphosphonic acid esters are made by the reaction of an alkyl halide, preferably primary, with a phosphite ester. Phosphonate carbanions are generated by treating alkylphosphonate esters with a base such as sodium hydride, n-butyllithium, or sodium ethoxide. Alumina coated with KF or KOH has also found use as the base.254... 

R-P(0H)2[R-P(0)(H)0H] Phosphonous acid (alkylphosphonous acid esters dialkyl alkylphosphonite) phosphonige Satire... 

RP(0)(0H)2 Phosphonic acid (alkylphosphonic acid esters diaUcyl alkylphosphonate) Phosphonsaiire... 

Capillary Electrophoresis (CE) and Micellar Electrokinetic Chromatography (MEKC). - Di(2-ethylhexyl) thiophosphoric acid (DEHTPA) has been earlier characterised by potentiometric titration, and quantified by capillary zone electrophoresis with carbonate buffer, operating at —20 kV, and using UV detection at 210 nm. ° Also, a comparison has been made of capillary electrophoresis (CE) and liquid chromatography (LC) for the enantiomeric separation of a-phosphonosulfonic acids, where CE used 3-cyclodextrin as chiral selector in a borate electrolyte. Alkylphosphonic acids, at trace levels in water, have been determined by CE coupled online with flame photomeric detection, and alkylphosphonic acid esters have been separated and determined by CE using indirect UV detection. 

Material A variety of alkylphosphonic acid/ester(APA) was tested, the samples in the 3rd OPCW/PTS comparison test were also analyzed. 

Triethyl phosphite is a colourless mobile liquid, insoluble in water. Trialkyl phosphites are valuable intermediates in the preparation of many organophosphorus compounds they readily form dialkyl esters of alkylphosphonic acids by the Arbusov reaction (p. 311). 

Mixed phosphonate acid esters can also be prepared from alkylphosphonate monoesters, although here the activation is believed occur at the alcohol.57... 

In this case, the EOF was cathodic and its velocity remained almost constant in the pH range of 4-7. The separation performance of IL-coated capillary in an aqueous buffer (sorbic acid) was proved by the separation of seven alkylphosphonic acids and their esters. The separation was accomplished in <6 min. 

M. Sliwakowski, Ion-trap mass spectra and retention parameters of alkylphosphonic acids low aliphatic alcohols esters, in Proceedings of the 1995 ERDEC Scientific Conference on Chemical and Biological Defense Research, D.A. Berg... 

Diazomethane this reagent converts acids into methyl esters and is used for the conversion of alkylphosphonic acids into methyl alkylphospho-nates. It is one of the most potent methylation reagents. However, it does not methylate the polar alcohols of the CWC Schedule list, for example, thiodiglycol. 

Methyl esters of alkylphosphonic acids may also be obtained by heating these acids together with trimethylphenylammonium hydroxide in the hot (e.g. 250 °C) injection port of the GC/MS system. 

Direct UV detection of alkylphosphonic acids through the formation of sodium borate complexes has been reported (9). While native alkylphosphonic acids exhibit negligible absorbance above 200 nm, borate complexation shifted their absorption maxima such that they were readily detected at either 214 nm or 254 nm. The buffer system consisted of 10 mM sodium tetraborate with complexation occurring in solution at pH 7 and higher. The reported detection limits on the order of nanograms. The UV, IR, NMR, and mass spectra of various borate/phosphonic acid esters were also reported. 

These drawbacks are overcome when the standard procedure is developed in the presence of a metallation agent in excess. Thus, when the reaction between dialkyl alkylphosphonates and carboxylic acid esters is allowed to proceed in the presence of LDA in excess (2 eq) in THE at low temperature, the resulting lithium phosphonoenolate is obtained in quantitative yield. Monitoring of the reaction by P-NMR shows the appearance of one signal from the lithium phosphonoenolate... 

Treatment of protected (o-amino-(o-(alkoxycarbonyl)alkylphosphonates with 4-8 M HCl selectively removes the ester groups to generate the free acids in 70-75% yields. Treatment of acids with acidic ion-exchange resin (Dowex SOW) or with propylene oxide followed by recrystallization from EtOH-H2O affords pure (o-amino-(o-(hydroxycarbonyl)alkylphosphonic acids 890,919,925,927,933... 

Halogenoalkyl)-phosphonic and -phosphinic tJc/tis-Mono- and di-alkylphosphonic acid.s have been prepared by fluorinatit)n of the phosphonic ester anions... 

Alkylphosphonic acids and salts (R—PO3H/M+) and phosphoric acid esters of long chain alcohols (R—OPO3H/M+) can make good surfactants, but in fact represent a small percentage of commercial products. Suggest some reasons for their lack of popularity. ... 

Wang J, Chen XY, Liu XF et al (1999) The synthesis and biological properties of a-halogenated phenoxy carbonyloxy alkylphosphonic acids and esters. Chin J Chem Reag 21 301-303... 

They often decomposed to afford substituted phenoxyacetic acids in three days. The reason was possibly that the carboxylic ester bond in the molecule cleaved easily in the acid environment supplied by phosphonic acid. Subsequently, alkali metal salts of 1-(substituted phenoxyacetoxy)alkylphosphonic acids IIF, IIG and IIH (Scheme 3.2) were further synthesized as alternatives of 1-(substituted phen-oxyacetoxy)phosphonic acids. These IIF, IIG and IIH, unlike 1-(substituted phenoxyacetoxy)alkylphosphonic acids, are neutral salts with good stability. 

However, the 1-(substituted phenoxyacetoxy(alkylphosphonic acids were not stable, because these compounds themselves were strong acids which would lead to the cleavage of carboxylate ester group. Alternatively, mono alkali metal salts of 1-(substituted phenoxyacetoxy)alkylphosphonic acids were designed including monolithium salts (IIF-l-IIF-13), monosodium salts (IIG-l-IIG-13), and monopotassium salts (IIH-l-IIH-13). These compounds were almost neutral salts with higher stabihty than the corresponding phosphonic acids (Scheme 3.9). 

The reaction proceeds through an intermediate phosphonium salt which can be isolated in some instances. The Michaehs-Arbusov reaction is especially useful for converting trialkyl phosphites, (RO) P, to alkylphosphonic esters, and to esters of phosphonocarboxyhc acids. 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

The CHF and CF2 groups are superior to CH2 as isosteres of oxygen and this has led to extensive interest in their chemistry. The a-difluorophosphonate analogues of the phosphates of L-serine (219), L-threonine (220), and L-allothreonine (221) have been prepared by highly enantioselective reactions of difluoromethylpho-sphonate carbanion with chiral esters. Lipase PS catalysed acetylation of prochiral 1,3-propandiol alkylphosphonates 222 is reported to be highly enantioselective and the resulting monoacetate enantiomers 223 have been used to synthesise a series of (o-phosphono-a-amino acids, 224 and 225.Other routes to 225, one of... 

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