A safe practical synthesis of difluorophosphonoacetic acid

Burton, Donald J.; Sprague, L. G.; Pietrzyk, Donald J.; Edelmuth, S. H.

doi:10.1021/jo00192a056

Cited by 36 publications

(15 citation statements)

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“…Thus, inclusion of an additional silylation step using iodotrimethylsilane to convert the ethyl P,P-bis(trimethylsilyl) esters [2,17] into tris(trimethylsilyl) esters or preliminary basic hydrolysis of the C-O ester can be avoided [5]. The acids are hygroscopic but are easily converted to stable (>1 year), crystalline bis(dicyclohexylammonium) or pyridinium salts.…”

Section: Resultsmentioning

confidence: 99%

“…a-Fluorinated derivatives of trialkyl phosphonoacetates (1) are useful precursors to the corresponding monofluoro-(2e) or difluoro-(3e) phosphonoacetic acids [1][2][3], which inhibit DNA polymerases [4], and in conjugation with carbocyclic nucleoside monophosphates form inhibitors of HIV reverse transcriptase [5].…”

Section: Introductionmentioning

confidence: 99%

“…When fluorine is substituted for one or both a-hydrogens in phosphonoacetic acid (1e), the resulting steric perturbation is relatively small, but the acid-base properties of the fluorinated derivatives are modified significantly [2], analogously to a-fluorinated methylenebisphosphonates [6][7][8]. Fluorine substitution also introduces a potentially useful 19 F NMR probe [9] into these molecules and, in monofluoro-substituted phosphonoacetates, creates a chiral center that has possible value in probing stereochemical interactions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis of α-fluorinated phosphonoacetate derivatives using electrophilic fluorine reagents: Perchloryl fluoride versus 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor®)

Marma¹,

Khawli²,

Harutunian³

et al. 2005

Journal of Fluorine Chemistry

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of α-fluorinated phosphonoacetate derivatives using electrophilic fluorine reagents: Perchloryl fluoride versus 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor®)

Marma¹,

Khawli²,

Harutunian³

et al. 2005

Journal of Fluorine Chemistry

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“…However, the acid hydrate is too volatile for extended use at the operating temperature of fuel cells (> 100°C), and in addition it tends to wet the Teflon surface of the electrodes used (1). A variety of other partially fluorinated or perfluoroalkylsulfonic and disulfonic acids (1)(2)(3)(4)(5) as well as phosphonic acids ( 6 4 , mixed sulfonic or phosphonic/carboxylic acids (9), and a mixed sulfonic/phosphonic acid (10) have been synthesized for evaluation as potential fuel cell electrolytes.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of fluorinated phosphonic, sulfonic, and mixed phosphonic/sulfonic acids

Su¹,

Cen²,

Kirchmeier³

et al. 1989

Can. J. Chem.

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. 67, 1795 (1989). The acids (H0)2P(0)CFHS03H, (H0)2P(0)(CF2)40(CF2)2S03H, H(CF2)20(CF2)2P(0)(OH)2, H(CF2)20(CF2)4P(0)-(OH)2, (H0)2P(0)(CF2)20(CF2)4H, and the acid precursor (C2H50)2P(0)CF(S03Na)2 have been synthesized. Elemental analysis, 1 9~, 'H, and 3 '~ NMR, and mass spectroscopy were used for characterization of these materials. They are very strong acids, and exhibit a high degree of stability in aqueous solution at elevated temperature, which makes them attractive candidates for use as electrolytes in fuel cells. Introduction Many fluorinated sulfonic and phosphonic acids exhibit properties that make them potentially useful as electrolytes in fuel cells. They are much stronger acids than their nonfluorinated analogues, and are generally more stable. In addition, oxygen solubility is greatly enhanced, and volatility at elevated temperatures may be lower. In fuel cell applications, these factors combine to provide increased conductivity, enhanced oxygen reduction kinetics, and longer term system stability when compared to phosphoric acid as the electrolyte.The primary acid used in fuel cells today is H3PO4. However, it has many drawbacks, including low oxygen solubility and anion adsorption on the catalyst surface. There is a need to develop new compounds that have the desirable properties of H3PO4 but fewer of the less desirable ones, in order to enhance the usefulness of fuel cells as alternative energy sources.Fluorocarbon electrolytes have the ability to lower the surface tension of water. This effect is in part due to several structural factors: (1) terminal grouping; (2) chain-length; and (3) the presence of heteroatoms in the chain. For example, a CF3 terminal group attached to a CF2 chain will have a greater surface tension lowering effect than a HCF2 terminal group attached to a similar chain. The solubility of oxygen in fluorocarbon systems is dependent on the boiling point, density, molecular weight, and viscosity of the fluorocarbon. These properties in turn are dependent in part on the structural factors and composition mentioned above.At low temperature trifluoromethanesulfonic acid has been found to be superior to H3P04 with respect to electrode kinetics. However, the acid hydrate is too volatile for extended use at the operating temperature of fuel cells (> 100°C), and in addition it tends to wet the Teflon surface of the electrodes used (1). A variety of other partially fluorinated or perfluoroalkylsulfonic and disulfonic acids (1-5) as well as phosphonic acids ( 6 4 , mixed sulfonic or phosphonic/carboxylic acids (9), and a mixed sulfonic/phosphonic acid (10) have been synthesized for evaluation as potential fuel cell electrolytes.

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“…6 However, phosphonodifluoromethyl ketones have been prepared by the direct coupling of difluoromethylene zinc reagents with acyl chorides, 12 often with catalysis by CuBr. 13,14 Another catalyst, PdCl 2 (Ph 3 P) 2 , has also been used to facilitate coupling of organozinc reagents with acid halides to prepare ketones. 15,16 The coupling of 1 and 2 had not been accomplished using any of these published procedures.…”

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confidence: 99%

A Facile Synthesis of a DifluoromethyleneAnalog of β-Aspartyl Phosphate as an Inhibitor ofl-Aspartate-β-semialdehyde Dehydrogenase

Han¹,

Moore²,

Viola³

2003

Synlett

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A safe practical synthesis of difluorophosphonoacetic acid

Cited by 36 publications

References 0 publications

Synthesis of α-fluorinated phosphonoacetate derivatives using electrophilic fluorine reagents: Perchloryl fluoride versus 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor®)

Synthesis of α-fluorinated phosphonoacetate derivatives using electrophilic fluorine reagents: Perchloryl fluoride versus 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor®)

Synthesis of fluorinated phosphonic, sulfonic, and mixed phosphonic/sulfonic acids

A Facile Synthesis of a DifluoromethyleneAnalog of β-Aspartyl Phosphate as an Inhibitor ofl-Aspartate-β-semialdehyde Dehydrogenase

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