- ALUMINA-ACCELERATED METHANOLYSIS AND HYDROLYSIS OF ACYL AND PHOSPHORYL FLUORIDES
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We have discovered that Woelm chromatographic γ-alumina substantially accelerates hydrolysis (and methanolysis) of acyl and phosphoryl fluorides.Compared to the corresponding homogeneous reactions, these heterogeneous alumina-promoted reactions occur about 250-350 times faster for acyl fluorides and about 1800-3000 times faster for phosphoryl fluorides.
- Posner, Gary H.,Ellis, Jerry W.,Ponton, John
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- Reaction of nerve agents with phosphate buffer at ph 7
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Chemical weapon nerve agents, including isopropyl methylphosphonofluoridate (GB or Sarin), pinacolyl methylphosphonofluoridate (GD or Soman), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX), are slow to react in aqueous solutions at midrange pH levels. The nerve agent reactivity increases in phosphate buffer at pH 7, relative to distilled water or acetate buffer. Reactions were studied using 31P NMR. Phosphate causes faster reaction to the corresponding alkyl methylphosphonic acids, and produces a mixed phosphate/phosphonate compound as an intermediate reaction product. GB has the fastest reaction rate, with a bimolecular rate constant of 4.6 × - 10-3 M-1s-1[PO43-]. The molar product branching ratio of GB acid to the pyro product (isopropyl methylphosphonate phosphate anhydride) is 1:1.4, independent of phosphate concentration, and the pyro product continues to react much slower to form GB acid. The pyro product has two doublets in the 31P NMR spectrum. The rate of reaction for GD is slower than GB, with a rate constant of 1.26 × - 10-3 M-1s-1 [PO43-]. The rate for VX is considerably slower, with a rate constant of 1.39 × - 10-5 M-1s-1 [PO43-], about 2 orders of magnitude slower than the rate for GD. The rate constant of the reaction of GD with pyrophosphate at pH 8 is 2.04 × - 10-3 min-1 at a concentration of 0.0145 M. The rate of reaction for diisopropyl fluorophosphate is 2.84 × - 10-3 min-1 at a concentration of 0.153 M phosphate, a factor of 4 slower than GD and a factor of 15 slower than GB, and there is no detectable pyro product. The half-lives of secondary reaction of the GB pyro product in 0.153 and 0.046 M solution of phosphate are 23.8 and 28.0 h, respectively, which indicates little or no dependence on phosphate.
- Creasy, William R.,Fry, Roderick A.,McGarvey, David J.
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- Binding of a designed substrate analogue to diisopropyl fluorophosphatase: Implications for the phosphotriesterase mechanism
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A wide range of organophosphorus nerve agents, including Soman, Sarin, and Tabun is efficiently hydrolyzed by the phosphotriesterase enzyme diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris. To date, the lack of available inhibitors of DFPase has limited studies on its mechanism. The de novo design, synthesis, and characterization of substrate analogues acting as competitive inhibitors of DFPase are reported. The 1.73 A crystal structure of O,O-dicyclopentylphosphoroamidate (DcPPA) bound to DFPase shows a direct coordination of the phosphoryl oxygen by the catalytic calcium ion. The binding mode of this substrate analogue suggests a crucial role for electrostatics in the orientation of the ligand in the active site. This interpretation is further supported by the crystal structures of double mutants D229N/N120D and D229N/N175D, designed to reorient the electrostatic environment around the catalytic calcium. The structures show no differences in their calcium coordinating environment, although they are enzymatically inactive. Additional double mutants E21Q/N120D and E21Q/N175D are also inactive. On the basis of these crystal structures and kinetic and mutagenesis data as well as isotope labeling we propose a new mechanism for DFPase activity. Calcium coordinating residue D229, in concert with direct substrate activation by the metal ion, renders the phosphorus atom of the substrate susceptible for attack of water, through generation of a phosphoenzyme intermediate. Our proposed mechanism may be applicable to the structurally related enzyme paraoxonase (PON), a component of high-density lipoprotein (HDL).
- Blum, Marc-Michael,Loehr, Frank,Richardt, Andre,Ruterjans, Heinz,Chen, Julian C.-H.
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- Synthesis and Storage Stability of Diisopropylfluorophosphate
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Diisopropylfluorophosphate (DFP) is a potent acetylcholinesterase inhibitor commonly used in toxicological studies as an organophosphorus nerve agent surrogate. However, LD50 values for DFP in the same species can differ widely even within the same laboratory, possibly due to the use of degraded DFP. The objectives here were to identify an efficient synthesis route for high purity DFP and assess the storage stability of both the in-house synthesized and commercial source of DFP at the manufacturer-recommended storage temperature of 4°C, as well as -10°C and -80°C. After 393 days, the commercial DFP stored at 4°C experienced significant degradation, while only minor degradation was observed at -10°C and none was observed at -80°C. DFP prepared using the newly identified synthesis route was significantly more stable, exhibiting only minor degradation at 4°C and none at -10°C or -80°C. The major degradation product was the monoacid derivative diisopropylphosphate, formed via hydrolysis of DFP. It was also found that storing DFP in glass containers may accelerate the degradation process by generating water in situ as hydrolytically generated hydrofluoric acid attacks the silica in the glass. Based on the results here, it is recommended that DFP be stored at or below -10°C, preferably in air-tight, nonglass containers.
- Heiss, Derik R.,Zehnder, Donald W.,Jett, David A.,Platoff, Gennady E.,Yeung, David T.,Brewer, Bobby N.
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- Nerve agent degradation with polyoxoniobates
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Polyoxoniobates are exceptional amongst polyoxometalates in that they can potentially perform base catalysis in water, a process in which a proton is bonded to an oxo ligand, and a hydroxyl is released. Catalytic decomposition of chemical warfare agents such as organofluorophosphates that were used recently in the infamous civilian attacks in Syria is one opportunity to employ this process. Upon evaluation of the polyoxoniobate Lindqvist ion, [Nb 6O19]8-, fast neutralization kinetics was discovered for the breakdown of the nerve agent simulant diisopropyl fluorophosphate (DFP). The polyoxoniobates were also tested against the nerve agents Sarin (GB) and Soman (GD). It was determined that different Lindqvist countercations (Li, K, or Cs) affect the rate of decomposition of the organophosphate compounds in both aqueous media (homogeneous reaction), and in the solid state (heterogeneous reaction). Small-angle X-ray scattering analysis of solutions of the Li, K, and Cs salts of [Nb6O19] 8- for concentrations at which the experiments were performed revealed distinct differences that could be linked to their relative reaction rates. This study represents the first demonstration of exploiting the unique alkaline reactivity of polyoxoniobates for nerve agent decontamination. Polyoxometalates, like small pieces of metal oxide, can be dissolved or fixed on a surface to perform homogeneous or heterogeneous catalysis, respectively. Here we exploit the alkaline nature of polyoxoniobates to neutralize nerve agents in both solution and the solid state. Solution studies correlate reaction efficacy to the association of the dissolved polyoxoniobate with its counterions. Copyright
- Kinnan, Mark K.,Creasy, William R.,Fullmer, Lauren B.,Schreuder-Gibson, Heidi L.,Nyman, May
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- Mixed-Metal Cerium/Zirconium MOFs with Improved Nerve Agent Detoxification Properties
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A series of Ce/Zr mixed-metal-organic frameworks with different topology/connectivity, namely, Ce/Zr-UiO-66 (U01, U02, and U03) (fcu (12-c)), Ce/Zr-DUT-67-PZDC (D01 and D02) (reo (8-c)), and Ce/Zr-MOF-808 (M01, M02, and M03) (spn (6-c)) were evaluated toward the detoxification of toxic nerve agent model diisopropylfluorophosphate (DIFP) at room temperature in unbuffered aqueous solution. Noteworthily, the catalytic rate for P-F bond cleavage increased with increasing Ce/Zr molar ratio. A further increase in catalytic activity can be achieved by Mg(OMe)2 doping of the mixed-metal MOFs as exemplified with M01?Mg(OMe)2 and M02?Mg(OMe)2 systems. The results show that Mg(OMe)2 incorporation into the mesoporous cavities of M01 and M02 give rise to P-F hydrolytic degradation half-lives of nearly 5 and 2 min with 100% degradation of DIFP after 55 and 65 min for M01?Mg(OMe)2 1:2 and M02?Mg(OMe)2 1:4, respectively.
- Carmona, Francisco J.,Farzaneh, Faezeh,Geravand, Elham,Gil-San-Millan, Rodrigo,Navarro, Jorge A. R.
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- Green MIP-202(Zr) Catalyst: Degradation and Thermally Robust Biomimetic Sensing of Nerve Agents
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Rapid and robust sensing of nerve agent (NA) threats is necessary for real-time field detection to facilitate timely countermeasures. Unlike conventional phosphotriesterases employed for biocatalytic NA detection, this work describes the use of a new, green, thermally stable, and biocompatible zirconium metal-organic framework (Zr-MOF) catalyst, MIP-202(Zr). The biomimetic Zr-MOF-based catalytic NA recognition layer was coupled with a solid-contact fluoride ion-selective electrode (F-ISE) transducer, for potentiometric detection of diisopropylfluorophosphate (DFP), a F-containing G-type NA simulant. Catalytic DFP degradation by MIP-202(Zr) was evaluated and compared to the established UiO-66-NH2 catalyst. The efficient catalytic DFP degradation with MIP-202(Zr) at near-neutral pH was validated by 31P NMR and FT-IR spectroscopy and potentiometric F-ISE and pH-ISE measurements. Activation of MIP-202(Zr) using Soxhlet extraction improved the DFP conversion rate and afforded a 2.64-fold improvement in total percent conversion over UiO-66-NH2. The exceptional thermal and storage stability of the MIP-202/F-ISE sensor paves the way toward remote/wearable field detection of G-type NAs in real-world environments. Overall, the green, sustainable, highly scalable, and biocompatible nature of MIP-202(Zr) suggests the unexploited scope of such MOF catalysts for on-body sensing applications toward rapid on-site detection and detoxification of NA threats.
- Alberts, Erik M.,Cohen, Seth M.,Fernando, P. U. Ashvin Iresh I.,Harvey, Steven P.,Jenness, Glen R.,Kalaj, Mark,Kotagiri, Yugender Goud,Moores, Lee C.,Sandhu, Samar S.,Teymourian, Hazhir,Thornell, Travis L.,Tostado, Nicholas,Wang, Joseph
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supporting information
p. 18261 - 18271
(2021/11/12)
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- METHOD FOR PRODUCING PHOSPHOESTER COMPOUND
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PROBLEM TO BE SOLVED: To provide a method whereby, a phosphate compound selected from the group consisting of orthophosphoric acid, phosphonic acid, phosphinic acid, and anhydrides of them is used as raw material and, by one stage reaction, a corresponding phosphoester compound is produced. SOLUTION: To an aqueous solution of a phosphate compound, added is an organic silane or siloxane compound having an alkoxy group or an aryloxy group, and the mixture is subjected to a heating reaction, thereby producing a corresponding phosphoester compound without requiring a catalyst. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0023; 0026-0028
(2021/09/27)
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- Degradation of tri(2-chloroisopropyl) phosphate by the UV/H2O2 system: Kinetics, mechanisms and toxicity evaluation
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A photodegradation technology based on the combination of ultraviolet radiation with H2O2 (UV/H2O2) for degrading tri(chloroisopropyl) phosphate (TCPP) was developed. In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.0035 min?1 (R2 = 0.9871) for 5 mg L?1 TCPP using 250 W UV light irradiation with 50 mg L?1 H2O2. In detail, the yield rates of Cl? and PO43? reached 0.19 mg L?1 and 0.58 mg L?1, respectively. The total organic carbon (TOC) removal rate was 43.02%. The pH value of the TCPP solution after the reaction was 3.46. The mass spectrometric detection data showed a partial transformation of TCPP into a series of hydroxylated and dechlorinated products. Based on the luminescent bacteria experimental data, the toxicity of TCPP products increased obviously as the reaction proceeded. In conclusion, degradation of high concentration TCPP in UV/H2O2 systems may result in more toxic substances, but its potential application for real wastewater is promising in the future after appropriate optimization, domestication and evaluation.
- He, Huan,Ji, Qiuyi,Gao, Zhanqi,Yang, Shaogui,Sun, Cheng,Li, Shiyin,Zhang, Limin
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- Photocatalytic Aerobic Phosphatation of Alkenes
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A catalytic regime for the direct phosphatation of simple, non-polarized alkenes has been devised that is based on using ordinary, non-activated phosphoric acid diesters as the phosphate source and O2 as the terminal oxidant. The title method enables the direct and highly economic construction of a diverse range of allylic phosphate esters. From a conceptual viewpoint, the aerobic phosphatation is entirely complementary to traditional methods for phosphate ester formation, which predominantly rely on the use of prefunctionalized or preactivated reactants, such as alcohols and phosphoryl halides. The title transformation is enabled by the interplay of a photoredox and a selenium π-acid catalyst and involves a sequence of single-electron-transfer processes.
- Depken, Christian,Kr?tzschmar, Felix,Rieger, Rene,Rode, Katharina,Breder, Alexander
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supporting information
p. 2459 - 2463
(2018/01/27)
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- Reactivity of an electrophilic hypervalent iodine trifluoromethylation reagent with hydrogen phosphates - A mechanistic study
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The electrophilic trifluoromethylation of hydrogen phosphates with the reagent trifluoromethyl-1,3-dihydro-3,3-dimethyl-1,2-benziodoxole (1) was studied by means of initial rates determined for pseudo first order setups and subsequent Taft analysis of the calculated relative rates. A positive polar sensitivity factor, indicative of a negative charge forming during the rate-determining step, was found for the whole data set.
- Santschi, Nico,Geissbühler, Patrik,Togni, Antonio
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experimental part
p. 83 - 86
(2012/03/27)
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- Reversed enantioselectivity of diisopropyl fluorophosphatase against organophosphorus nerve agents by rational design
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Diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris is an efficient and robust biocatalyst for the hydrolysis of a range of highly toxic organophosphorus compounds including the nerve agents sarin, soman, and cyclosarin. In contrast to the substrate diisopropyl fluorophosphate (DFP) the nerve agents possess an asymmetric phosphorus atom, which leads to pairs of enantiomers that display markedly different toxicities. Wild-type DFPase prefers the less toxic stereoisomers of the substrates which leads to slower detoxification despite rapid hydrolysis. Enzyme engineering efforts based on rational design yielded two quadruple enzyme mutants with reversed enantioselectivity and overall enhanced activity against tested nerve agents. The reversed stereochemical preference is explained through modeling studies and the crystal structures of the two mutants. Using the engineered mutants in combination with wild-type DFPase leads to significantly enhanced activity and detoxification, which is especially important for personal decontamination. Our findings may also be of relevance for the structurally related enzyme human paraoxonase (PON), which is of considerable interest as a potential catalytic in vivo scavenger in case of organophosphorus poisoning.
- Melzer, Marco,Chen, Julian C.-H.,Heidenreich, Anne,Gaeb, Juergen,Koller, Marianne,Kehe, Kai,Blum, Marc-Michael
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supporting information; experimental part
p. 17226 - 17232
(2010/03/25)
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- Reactivity of diacyloxyiodobenzenes toward trivalent phosphorus nucleophiles
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The reaction of diacyloxyiodobenzenes and tetravalent phosphorus nucleophiles was investigated. It was established that both H-phosphonates and secondary phosphine oxides react with diacetoxyiodobenzene in alcohols in the presence of sodium alcoholates yi
- Makowiec, Slawomir,Rachon, Janusz
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p. 352 - 359
(2007/10/03)
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- Oxidative alkoxylation of zinc phosphide in alcoholic solutions of copper(II) chloride
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Oxidative alkoxylation of Zn3P2 with the formation of valuable phosphoric and phosphorous acid esters occurred at a high rate and with a high selectivity in alcoholic solutions of CuCl2 under the action of oxygen at 30-60°C. Depending on the nature of the alcohol, two products were formed, namely, trialkyl phosphates (RO)3PO and dialkyl phosphites (RO)2HPO. Water favored the formation of dialkyl phosphates (RO)2(HO)PO. The kinetics and mechanism of the new catalytic reaction were studied, and the optimal conditions for conducting this reaction were found. The reaction proceeded in a topochemical mode by a separate redox mechanism.
- Dorfman,Ibraimova,Polimbetova
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- The reactions of dialkyl phosphites and phosphine oxides with iodosylbenzene
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The reaction of iodosylbenzene with > P(O)H type of acids (dialkyl phosphites, secondary phosphine oxides) was studied. The acids of >P(O)H type add to iodosylbenzene to yield intermediate 6 which in the aprotic solvents yields oxidation products, it means >P(O)OH acids and/or anhydride of >P(O)OP(O) P(O)OR ester is the major product.
- Makowiec, Slawomir,Rachon, Janusz
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p. 941 - 955
(2007/10/03)
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- Substrate and stereochemical specificity of the organophosphorus acid anhydrolase from Alteromonas sp. JD6.5 toward p-nitrophenyl phosphotriesters
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The enzyme OPAA hydrolyzes p-nitrophenyl phosphotriesters bearing substituents at the phosphorus center ranging in size from methyl to phenyl. The enzyme exhibits stereoselectivity toward the hydrolysis of chiral substrates with a preference for the S(P)
- Hill, Craig M.,Wu, Feiyue,Cheng, Tu-Chen,Defrank, Joseph J.,Raushel, Frank M.
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p. 1285 - 1288
(2007/10/03)
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- Chlorine free synthesis of organophosphorus compounds based on the functionalization of white phosphorus (P4)
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Oxidative alkoxylations of P4 in toluene-alcohol solutions are studied. These reactions need oxygen, a catalyst (PdCl2, RuOHCl3, RuCl3) and a co-oxidant (CuCl2, NaNO2, FeCl3, 1,4-benzoquinone, NaBrO3). Trialkylphosphates (RO)3P(O) and dialkylphosphites (RO)2P(O)H are the major products of the reaction. Kinetic experiments concerning the rate of absorption of O2 during these reactions are also reported.
- Abdreimova, Rumiya R.,Akbayeva, Dina N.,Polimbetova, Gulshara S.,Caminade, Anne-Marie,Majoral, Jean-Pierre
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p. 239 - 254
(2007/10/03)
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- Synthesis of Trialkyl Phosphates from White Phosphorus
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A new method was proposed for preparing trialkyl phosphates directly from white phosphorus by its electrolysis in a mixture of acetonitrile, alcohol, and water with tetraethylammonium iodide as supporting electrolyte. To increase the amount of the product synthesized in the unit volume of the electrolyte solution and the productivity of the process, phosphorus and water are added to the electrolyte in portions, which allows synthesis of up to 1 mol of trialkyl phosphate in 1 1 of the electrolyte solution.
- Romakhin,Nikitin
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p. 1023 - 1026
(2007/10/03)
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- Synthesis of dialkyl phosphites and trialkyl phosphates by oxidation of sodium hypophosphite by copper(II) chloride
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Sodium hypophosphite oxidazies in alcoholic solution of CuCl2 at 50-80 deg C to give dialkyl phosphite and trialkyl phosphate.The yield of trialkyl phosphate increases with decreasing molecular weight of the alcohol and reaches ca. 100percent for MeOH and EtOH.The optimal conditions were found, and the mechanism of oxidation of NaPH2O2 to (RO)2PHO and (RO)3PO by copper(II) chloride was studied.The reaction proceeds via the formation of alkyl hypophosphite and copper(II) complexes with alkyl hypophosphite and dialkyl phosphite, which undergo inner-sphere two-electron redox decomposition with the liberation of dialkyl phosphite and trialkyl phosphate, respectively.
- Dorfman, Ya. A.,Aleshkova. M. M.
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p. 515 - 520
(2007/10/03)
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- ALKYLATING PROPERTIES OF ACID ORGANIC PHOSPHATES
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Under the action of phenols and alcohols, acid alkyl phosphates undergo transesterification, which is accompanied by dealkylation of the latter and alkylation of the alcohols (phenols) at the hydroxy groups and aromatic rings.Isopropyl phosphates are stronger alkylating agents than methyl phosphates.Diphenyl methyl and phenyl dimethyl phosphates yield products of methylation of their own aromatic rings only upon prolonged pyrolysis.In all cases organic polyphosphates are formed.
- Munik, S. N.,Eliseenkov, V. N.,Ivanov, B. E.
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p. 378 - 382
(2007/10/03)
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- 2-SACCHARINYLMETHYL PHOSPHATES, PHOSPHONATES AND PHOSPHINATES USEFUL AS PROTEOLYTIC ENZYME INHIBITORS AND COMPOSITIONS AND METHOD OF USE THEREOF
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4-R 1-R 2-R 3-2-Saccharinylmethyl and 4,7-C-4,5, 6,7-tetrahydro-2-saccharinylmethyl phosphates, phosphonates and phosphinates of formulas I and IIA respectively herein, useful in the treatment of degenerative diseases, and compositions containing them, methods for using them to treat degenerative diseases, and processes for their preparation by reaction of the corresponding 2-halomethylsaccharins with a phosphate, phosphonate or phosphinic acid of formula III herein in the presence of an acid-acceptor.
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- Synthesis and Phosphorylating Properties of 2-Chloro-2,3-dihydro-3-(methylsulfonyl)-1,3,2-benzoxazaphosphole 2-Oxide. Derivatives with Chloro Substituents on the Benzene Ring
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The synthesis and the use of the five-membered cyclic phosphorylating agents 1a-c are described.Their difunctional phosphorylating properties towards alkanols and hydroxylated amino acids and the cleavage reaction of the formed phosphoric acid triesters to diesters with oximate or platinum/hydrogen are investigated and compared to the "parent" compound 2-chloro-2,3-dihydro-3-(methylsulfonyl)-1,3,2-benzoxazaphosphole 2-oxide.Dichlorobenzoxazaphosphole 1b is the most reactive of these reagents with respect to phosphorylation with ring opening and oximate cleavage of the phosphoric acid triesters, followed by o-chlorobenzoxazaphosphole 1a, the unsubstituted phosphole I, and p-chlorobenzoxazaphosphole 1c. - Key Words: Phosphorylating agents, cyclic five-membered / 1,3,2-Benzoxazaphospholes
- Huensch, Sabine,Richter, Wolfgang,Ugi, Ivar,Chattopadhyaya, Jyoti
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p. 269 - 276
(2007/10/02)
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- 2-SACCHARINYLMETHYL AND 4,5,6,7-TETRAHYDRO-2-SACCHARINYLMETHYL PHOSPHATES, PHOSPHONATES AND PHOSPHINATES USEFUL AS PROTEOLYTIC ENZYME INHIBITORS AND COMPOSITIONS AND METHOD OF USE THEREOF
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4-R 1-R 2-R 3-2-Saccharinylmethyl, 4-R 4-4-R 5-6-R 6-4,5,6,7-tetrahydro-2-saccharinylmethyl and 4,7-C-4,5, 6,7-tetrahydro-2-saccharinylmethyl phosphates, phosphonates and phosphinates of formulas I, II and IIA respectively herein, useful in the treatment of degenerative diseases, and compositions containing them, methods for using them to treat degenerative diseases, and processes for their preparation by reaction of the corresponding 2-halomethylsaccharins with a phosphate, phosphonate or phosphinic acid of formula III herein in the presence of an acid-acceptor.
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- CONVENIENT SYNTHETIC ROUTE TO MONO- OR DIAKLYL PHOSPHATE FROM INORGANIC PHOSPHORUS ACIDS
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Mono- or dialkyl phosphate was synthesized in a favorable yield by oxidation of phosphonic or phosphinic acid in alcohol with oxygen at the presence of a catalytic amount of copper(II)chloride.The reaction may proceed via the formation of corresponding phosphorochloridate or phosphorochloridite.
- Okamoto, Yoshiki,Kusano, Tetuya,Takamuku, Setsuo
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p. 195 - 200
(2007/10/02)
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- Hydrolysis of diisopropyl phosphorofluoridate catalysed by copper(II)-diamine complexes
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The hydrolysis of diisopropylphosphorofluoridate (DFP) has been studied using various diamine complexes of Cu salts.The complexes of Cu(II) perchlorate salt have been found to be the most effective catalysts.Lewis acid character of the central Cu metal atom is enhanced by strong anion which in turn increases the catalytic activity.
- Marjit, D. N.,Sharma, U. S.
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p. 958 - 960
(2007/10/02)
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- Distribution and fate of diethyl malonate and diisopropyl fluorophosphate on pig skin in vitro
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The in vitro distribution and fate of [14C]diethyl malonate and [14C]diisopropyl fluorophosphate were evaluated on normal and heat-treated pig skin. The extent of hydrolysis from the skin surface, skin, and receptor fluid was determined. A significant skin-mediated hydrolysis (15-35% of applied dose) was observed for diethyl malonate in normal skin, but not in heat-treated skin. These results indicated that a heat labile process (e.g., enzymatic hydrolysis) was in part responsible for the degradation of diethyl malonate after topical application to normal skin. Heat treatment tripled the skin penetration of diisopropyl fluorophosphate and reduced the amount of recovered hydrolysis product, diisopropyl phosphoric acid. Enzymatic and spontaneous hydrolysis, as well as impurity, accounted for the presence of degradation product.
- Chellquist,Reifenrath
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p. 850 - 854
(2007/10/02)
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