- Two step acidic hydrolysis of dialkyl arylphosphonates
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The HCl-catalyzed hydrolysis of dialkyl arylphosphonates monitored by 31P NMR spectroscopy has revealed two consecutive steps characterized by pseudo first order rate constants k1 and k2. A reactivity order for the two steps and for the overall two step hydrolysis has been derived depending on the alkoxy and aryl substituents. Besides the AAc2 mechanism, the AAl1 route has been substantiated for the PriO substituent.
- Harsági, Nikoletta,Rádai, Zita,Kiss, Nóra Zsuzsa,Szigetvári, Aron,Keglevich, Gy?rgy
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Read Online
- Inhibition of serine β-lactamases by acyl phosph(on)ates: A new source of inert acyl [and phosphyl] enzymes
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Acyl phosph(on)ates are shown to inhibit serine β-lactamases and provide a new source of relatively stable complexes. Thus, benzoyl phenyl phosphate, benzoyl phenylphosphonate, and dibenzoyl phosphate react with the class C β-lactamase of Enterobacter cloacae P99 at micromolar concentrations to form an acyl enzyme of half-life about 40 s. The phosphonate reacts further more slowly to produce a much more inert complex. Dibenzoyl phosphate reacts with the class A TEM β-lactamase to from an acyl enzyme of half-life about 8 s and, more slowly, reaching completion after an average of about 80 turnovers, a more inert complex, of half-life about 2 h. The acyl phosphonates thus represent a new starting point for the design of β- lactamase inhibitors and perhaps of antibacterial agents.
- Li, Naixin,Pratt
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Read Online
- Kinetics and mechanism of the oxidation of lower oxyacids of phosphorus by hexamethylenetetramine bromine
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The oxidation of lower oxyacids of phosphorus by hexamethylenetetramine bromine (HABR) in glacial acetic acid resulted in the formation of corresponding oxyacids with phosphorus in a higher oxidation state. The reaction exhibited 2:1 stoichiometry. The reaction is first order with respect to HABR. Michaelis-Menten-type kinetics were observed with respect to the acids. The formation constant of the phenylphosphinic acid-HABR complex also has been determined spectrophotometrically. The thermodynamic parameters for the complex formation and the activation parameters for their decomposition were calculated. The reaction showed the presence of a substantial kinetic isotope effect. It is proposed that the HABR itself is the reactive oxidizing species. It has been shown that the pentacoordinated tautomer of the phosphorus oxyacid is the reactive reductant. A suitable mechanism has been proposed.
- Mehla, Satish K.,Kothari, Seema,Banerji, Kalyan K.
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Read Online
- C-P bond formation of cyclophanyl-, and aryl halides: Via a UV-induced photo Arbuzov reaction: A versatile portal to phosphonate-grafted scaffolds
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A new versatile method for the C-P bond formation of (hetero)aryl halides with trimethyl phosphite via a UV-induced photo-Arbuzov reaction, accessing diverse phosphonate-grafted arenes, heteroarenes and co-facially stacked cyclophanes under mild reaction
- Br?se, Stefan,Hassan, Zahid,Nieger, Martin,O?wald, Simon,Zippel, Christoph
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p. 3309 - 3312
(2022/02/11)
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- Hydrolysis and alcoholysis of phosphinates and phosphonates
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Phosphinic and phosphonic acids useful intermediates and biologically active compounds may be prepared from their esters: phosphinates and phosphonates, respectively, by acid-catalyzed hydrolysis either on conventional heating or on MW irradiation. The transesterification of alkyl phosphinates took place only in the presence of suitable ionic liquids as the catalysts. In the cases of phenylphosphonates, depending on the nature of the ionic liquid, the formation of the ester was accompanied by the fission of the C–O bond.
- Harsági, Nikoletta,Keglevich, Gy?rgy,Sz?ll?si, Betti,Varga, Petra Regina
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- Hydrolysis-Based Small-Molecule Hydrogen Selenide (H2Se) Donors for Intracellular H2Se Delivery
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Hydrogen selenide (H2Se) is a central metabolite in the biological processing of selenium for incorporation into selenoproteins, which play crucial antioxidant roles in biological systems. Despite being integral to proper physiological function, this reactive selenium species (RSeS) has received limited attention. We recently reported an early example of a H2Se donor (TDN1042) that exhibited slow, sustained release through hydrolysis. Here we expand that technology based on the P-Se motif to develop cyclic-PSe compounds with increased rates of hydrolysis and function through well-defined mechanisms as monitored by 31P and 77Se NMR spectroscopy. In addition, we report a colorimetric method based on the reaction of H2Se with NBD-Cl to generate NBD-SeH (λmax = 551 nm), which can be used to detect free H2Se. Furthermore, we use TOF-SIMS (time of flight secondary ion mass spectroscopy) to demonstrate that these H2Se donors are cell permeable and use this technique for spatial mapping of the intracellular Se content after H2Se delivery. Moreover, these H2Se donors reduce endogenous intracellular reactive oxygen species (ROS) levels. Taken together, this work expands the toolbox of H2Se donor technology and sets the stage for future work focused on the biological activity and beneficial applications of H2Se and related bioinorganic RSeS.
- Bolton, Sarah G.,Chouinard, Julie E.,Garcia, Arman C.,Golledge, Stephen L.,Newton, Turner D.,Pluth, Michael D.,Zakharov, Lev N.
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p. 19542 - 19550
(2021/11/23)
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- Wet and dry processes for the selective transformation of phosphonates to phosphonic acids catalyzed by br?nsted acids
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A "wet"process and two "dry"processes for converting phosphonate esters to phosphonic acids catalyzed by a Bronsted acid have been developed. Thus, in the presence of water, a range of alkyl-, alkenyl-, and aryl-substituted phosphonates can be generally hydrolyzed to the corresponding phosphonic acids in good yields catalyzed by trifluoromethyl sulfonic acid (TfOH) at 140 °C (the wet process). On the other hand, with specific substituents of the phosphonate esters, the conversion to the corresponding phosphonic acids can be achieved under milder conditions in the absence of water (the dry process). Thus, the conversion of dibenzyl phosphonates to the corresponding phosphonic acids took place smoothly at 80 °C in toluene or benzene in high yields. Moreover, selective conversion of benzyl phosphonates RP(O)(OR′)(OBn) to the corresponding mono phosphonic acids RP(O)(OR′)(OH) can also be achieved under the reaction conditions. The dealkylation via the generation of isobutene of ditert- butyl phosphonate, and the related catalysis by TfOH took place even at room temperature to give the corresponding phosphonic acids in good to high yields. Nafion also shows high catalytic activity for these reactions. By using Nafion as the catalyst, phosphonic acids could be easily prepared on a large scale via a simple process.
- Li, Chunya,Saga, Yuta,Onozawa, Shun-Ya,Kobayashi, Shu,Sato, Kazuhiko,Fukaya, Norihisa,Han, Li-Biao
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p. 14411 - 14419
(2020/12/29)
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- METHOD FOR PRODUCING PHOSPHONIC ACID DERIVATIVE
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PROBLEM TO BE SOLVED: To provide a method for producing a phosphonic acid derivative, in which the reaction proceeds under relatively mild reaction conditions without using hydrogen halide or a metal catalyst. SOLUTION: Provided is a method for producing a phosphonic acid derivative represented by formula (1), comprising a step in which an ester group-containing phosphonic acid derivative is reacted in a solvent or without a solvent in the presence of a superacid catalyst. (In formula (1), R1 and R2 are each independently a substituted or unsubstituted hydrocarbon group that may contain a heteroatom, n is a natural number of 1 to 3, m is a natural number of 0 to 2, o is a natural number of 0 to 1, and n + m + o = 3.). SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0045-0047; 0052
(2020/10/27)
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- Discovery of New H2S Releasing Phosphordithioates and 2,3-Dihydro-2-phenyl-2-sulfanylenebenzo[d][1,3,2]oxazaphospholes with Improved Antiproliferative Activity
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Hydrogen sulfide (H2S) is now recognized as a physiologically important gasotransmitter. Compounds which release H2S slowly are sought after for their potential in therapy. Herein the synthesis of a series of phosphordithioates based on 1 (GYY4137) are described. Their H2S release profiles are characterized using 2,6-dansyl azide (2), an H2S specific fluorescent probe. Most compounds have anticancer activity in several solid tumor cell lines and are less toxic in a normal human lung fibroblast, WI38. A preferred compound, 14, with 10-fold greater anticancer activity than 1, was shown to release H2S in MCF7 cells using a cell active probe, 21. Both permeability and intracellular pH (pHi) were found to be significantly improved for 14 compared to 1. Furthermore, 14 was also negative in the AMES test for genotoxicity. Cyclization of these initial structures gave a series of 2,3-dihydro-2-phenyl-2-sulfanylenebenzo[d][1,3,2]oxazaphospholes, of which the simplest member, compound 22 (FW1256), was significantly more potent in cells. The improved therapeutic window of 22 in WI38 cells was compared with three other cell types. Potency of 22 was superior to 1 in MCF7 tumor spheroids and the mechanism of cell death was shown to be via apoptosis with an increase in cleaved PARP and activated caspase-7. Evidence of H2S release in cells is also presented. This work provides a "toolbox" of slow-release H2S donors useful for studies of H2S in biology and as potential therapeutics in cancer, inflammation, and cardiovascular disease. (Chemical Equation Presented).
- Feng, Wei,Teo, Xin-Yi,Novera, Wisna,Ramanujulu, Pondy Murugappan,Liang, Dong,Huang, Dejian,Moore, Philip K.,Deng, Lih-Wen,Dymock, Brian W.
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supporting information
p. 6456 - 6480
(2015/09/07)
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- Phosphonothioate hydrolysis by molybdocene dichlorides: Importance of metal interaction with the sulfur of the thiolate leaving group
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The metallocene bis(cyclopentadienyl)molybdenum(IV) dichloride Cp 2MoCl2 hydrolyzes O,S-diethyl phenylphosphonothioate (1) with only P-S scission to yield a phosphonate under mild aqueous conditions. In terms of degrading phosphonoth
- Kuo, Louis Y.,Baker, Devon C.,Dortignacq, Adria K.,Dill, Kristina M.
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p. 4759 - 4765
(2013/09/24)
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- Synthesis and proton dissociation properties of arylphosphonates: A microwave-assisted catalytic arbuzov reaction with aryl bromides
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A series of substituted diethyl arylphosphonates was synthesized by the microwave-assisted Arbuzov reaction of triethyl phosphite and aryl bromides in the presence of NiCl2 as the catalyst under solvent-free conditions in good yields. The resulting phosphonates were hydrolyzed to the corresponding arylphosphonic acids whose acidity was evaluated by physicochemical methods.
- Keglevich, Gyoergy,Gruen, Alajos,Boelcskei, Adrienn,Drahos, Laszlo,Kraszni, Marta,Balogh, Gyoergy T.
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p. 574 - 582
(2013/01/15)
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- Synthesis of disubstituted phosphinates via palladium-catalyzed hydrophosphinylation of H-phosphinic acids
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The first metal-catalyzed hydrophosphinylation of unsaturated hydrocarbons with H-phosphinic acids is described. A strategy to activate the P-H bond through control of the tautomeric equilibrium using ethylene glycol is described. The reactions also avoid chromatographic purification. Copyright
- Petit, Christelle,Fecourt, Fabien,Montchamp, Jean-Luc
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body text
p. 1883 - 1888
(2011/10/04)
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- Synthesis of new thiazole-2, -4, and -5-yl-(amino)methylphosphonates and phosphinates: Unprecedented cleavage of thiazole-2 derivatives under acidic conditions
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An efficient and reliable synthesis of new thiazole-(amino) methylphosphonic, phosphinic acids, and phosphine oxides is reported. The synthetic protocol is based on nucleophilic addition of phosphorous species to thiazole derived imines. Unexpectedly, it was discovered that heating of thiazole-2-yl-(amino)methylphosphonates and phosphinates with aqueous HCl leads to their decomposition resulting in a rupture of the C-P bond, rejecting of the phosphorus containing fragment and formation of the corresponding secondary N-(thiazole-2-yl-methyl)-alkylamines. Two alternative mechanisms for this cleavage are postulated.
- Olszewski, Tomasz Krzysztof,Boduszek, Bogdan
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experimental part
p. 8661 - 8666
(2011/01/04)
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- Oxidation of lower oxyacids of phosphorus by tetraethylammonium chlorochromate: A kinetic and mechanistic study
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Oxidation of lower oxyacids of phosphorus by tetraethylammonium chlorochromate in dimethyl sulphoxide leads to the formation of corresponding oxyacids with phosphorus in a higher oxidation state. The reaction exhibits 1:1 stoichiometry. The reaction is first order each with respect to chlorochromate and the oxyacids. The reaction does not induce polymerization of acrylonitrile. The oxidation of deuterated phosphinic and phosphorous acids exhibits a substantial primary kinetic isotope effect. The oxidation has been studied in nineteen different organic solvents. The effect of solvent indicates that the solvent polarity plays a major role in the process. It has been shown that the pentacoordinated tautomer of the phosphorus oxyacid is the reactive reductant and the tricoordinated form of phosphorus oxyacids does not participate in the oxidation process. A mechanism involving transfer of a hydride ion in the rate determining step has been proposed.
- Vadera, Khushboo,Sharma,Agarwal,Sharma, Pradeep K.
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scheme or table
p. 302 - 306
(2011/01/10)
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- Crosslinked type layered metal phosphonate compound, production process therefor, non-crosslinked type layered metal phosphonate compound, production process therefor, as well as stock solution
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A process for producing a crosslinked type or non-crosslinked type layered metal phosphonate compound including a reaction step of reacting two or more members selected from organic diphosphonic acids or monophosphonic acids, or derivatives thereof having predetermined conditions and a metal source capable of forming an ion of a hexacoordinate metal atom as a central atom (M) of a metal oxide octahedron upon reaction under the presence of a sulfuric acid catalyst, a crosslinked or non-crosslinked metal phosphonate compound obtained by the process, as well as a stock solution used for the synthesis of the crosslinked or non-crosslinked type layered metal phosphonate compound described above.
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- Design, synthesis, and biological evaluation of phosphoramide derivatives as urease inhibitors
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The design, synthesis, and biological evaluation of phosphoramide derivatives as urease inhibitors to reduce the loss of ammonia has been carried out. Forty phosphorus derivatives were synthesized and their inhibitory activities evaluated against that of jack bean urease. In addition, in vivo assays have been carried out. All of the compounds were characterized by IR, 1H NMR, MS, and elemental microanalysis. In some cases, detailed molecular modeling studies were carried out, and these highlighted the interaction between the enzyme active center and the compounds and also the characteristics related to their activity as urease inhibitors. According to the IC50 values for in vitro inhibitory activity, 12 compounds showed values below 1 μM and 8 of them represent improvements of activity in comparison to the commercial urease inhibitor N-n-butylthiophosphorictriamide (NBPT) (100 nM) (AGROTAIN). On the basis of the activity results and the conclusions of the molecular modeling study, a structural model for new potential inhibitors has been defined.
- Dominguez, Maria J.,Sanmartin, Carmen,Font, Maria,Palop, Juan A.,San Francisco, Sara,Urrutia, Oscar,Houdusse, Fabrice,Garcia-Mina, Jose M.
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experimental part
p. 3721 - 3731
(2010/03/05)
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- Highly reactive and chemoselective cleavage of allyl esters using an air- and moisture-stable [CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF6 catalyst
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A new catalytic process for allyl ester cleavage has been developed by using a robust cationic CpRu(IV) π-allyl complex of 2-quinolinecarboxylic acid that can be stored for over six months in air without any loss of catalytic activity. The deprotection of various alcohols and acids can be attained simply with high reactivity and chemoselectivity under mild conditions. Furthermore, with continuous removal of the low-boiling point coproduct, a turnover number of 1 000 000 can be achieved.
- Tanaka, Shinji,Saburi, Hajime,Murase, Takanori,Ishibashi, Yoshitaka,Kitamura, Masato
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p. 295 - 298
(2008/02/03)
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- Kinetics and mechanism of the oxidation of lower oxyacids of phosphorous by morpholinium chlorochromate
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Oxidation of lower oxyacids of phosphorous by morpholinium chlorochromate (MCC) in dimethylsulfoxide (DMSO) leads to the formation of corresponding oxyacids with phosphorous in a higher oxidation state. The reaction exhibits 1:1 stoichiometry. The reaction is first order with respect to MCC and the oxyacids. The reaction does not induce polymerization of acrylonitrile. Reactions are catalysed by hydrogen ions. The hydrogen-ion dependence has the form : kobs = a + b[H+]. The oxidation of deuteriated phosphinic (DPA) and phosphorous acids (DPPA) exhibited a substantial primary kinetic isotope effect. The oxidation was studied in nineteen different organic solvents. The solvent effects were analysed in terms of Taft's and Swain's multiparametric equations. The effect of solvent indicates the solvent polarity plays a major role in the process. It has been shown that the pentacoordinated tautomer of the phosphorous oxyacid is the reactive reductant and it has been concluded that tricoordinated forms of phosphorous oxyacids does not participate in the oxidation process. A mechanism involving transfer of a hydride ion in the rate-determining step has been proposed.
- Bshnoi, Geeta,Sharma, Monica,Sindal,Sharma, Pradeep K.
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p. 892 - 896
(2008/12/21)
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- METHODS FOR THE PREPARATION OF PHOSPHONIC ACID DERIVATIVES
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The present invention provides methods for the preparation of aralkyl phosphonic acids and aryl phosphonic acids. In a first method of the invention, an aralkyl dialkyl phosphonate is contacted with an aqueous acidic solution under reflux conditions. Upon cooling, solid crystals of the corresponding aralkyl phosphonic acid are obtained, which can be collected via filtration. In a second method of the invention, an aryl phosphorous dihalide is added to a pot containing an aqueous nitric acid solution while maintaining the pot temperature below about 50° C. and then allowing the reactants to self-reflux. Upon cooling, crystals of the corresponding aryl phosphonic acid are obtained, which can be collected via filtration.
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Page/Page column 3
(2008/06/13)
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- Selective protection of 1,4,8,11-tetraazacyclotetradecane (cyclam) in position 1,4 with the phosphonothioyl group and synthesis of a cyclam-1,4-bis(methylphosphonic acid). Crystal structures of several cyclic phosphonothioamides
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A new cyclam-based ligand, 1,4,8,11-tetraazacyclotetradecane-1,4- bis(methylphosphonic acid) (1,4-H4te2p), was synthesized. Cyclam was protected by the reaction with PhP(S)Cl2 to form exclusively five-membered cyclic phenylphosphonothioic diamide 2 in a moderate yield. The solid-state structures of 2 and several by-products were determined. Compound 2 was isolated as two stable conformers differing in a mutual position of benzene ring and sulfur atom with respect to the cyclam ring. Compound 2 was used for the synthesis of 1,4-dibenzylcyclam. However, the deprotection of the thiophosphoryl-protected bis(methyl-phosphonate diester) with aqueous HCl under non-optimized conditions led to a mixture of cyclam derivatives differently substituted with methylphosphonic acid groups. The crystal structures of the target product, 1,4-H4te2p, and also 1,4,8,11- tetraazacyclotetradecane-1,4,8,11-tetrakis(methylphosphonic acid) (H 8tetp) were determined. A similar reaction with cyclen (1,4,7,10-tetraazacyclododecane) led only to hardly purifiable mixtures.
- Vitha, Tomas,Kotek, Jan,Rudovsky, Jakub,Kubicek, Vojtech,Cisarova, Ivana,Hermann, Petr,Lukes, Ivan
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p. 337 - 367
(2007/10/03)
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- Zirconium organophosphonates as photoactive and hydrophobic host materials for sensitized luminescence of Eu(III), Tb(III), Sm(III) and Dy(III)
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Novel luminescent materials based on lanthanides [Eu(III), Tb(III), Sm(III), and Dy(III)] and a mixed zirconium phenyl- and m-sulfophenyl phosphonate as the host matrix, have been prepared and photophysically characterized. Powder X-ray diffraction, 31P-MAS-NMR spectroscopy, IR spectroscopy, and diffuse-reflectance UV spectroscopy revealed the specificity of these materials such as a layered structure, the presence of phenyl groups in the galleries, and the ability to absorb lanthanide ions introduced by simple ion exchange. Characteristic line-shaped long-lived luminescence [ca. 0.27 ms for EU(III), 0.80 ms for Tb(III), and 0.05 ms for Sm(III)] was observed for different lanthanide ions, and was demonstrated to be generated by an antenna-induced energy transfer process to the metal. The overall luminescence quantum yield of europium- or terbium-loaded materials was measured to be ca. 0.3%. A detailed analysis of the EU(III) luminescence spectrum and H 2O/D2O exchange experiments indicated the presence of ca. 3 water molecules around each lanthanide. Based on the high maximum coordination numbers of lanthanides, up to 9 for free EU(III) in aqueous solutions, and the presence of only monodentate sulfonate binding sites, more water could be expected. This observation is explained by the rather hydrophobic microenvironment in the interlamellar space of the materials, due to pendant organic moieties, that is, the phenyl groups.
- Ferreira, Rita,Pires, Preciosa,De Castro, Baltazar,Sa Ferreira, Rute A.,Carlos, Luis D.,Pischel, Uwe
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p. 1506 - 1513
(2007/10/03)
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- Complexes of (EtO)2P(O)CH2P(O)(OEt)2 with lanthanide nitrates
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The preparation of complexes of (EtO)2P(O)CH2P(O) (OEt)2 = L, with lanthanide nitrates is described. Stable complexes with composition LnL2(NO3)S can be isolated for Ln = La-Eu and fully characterised. For Ln = Gd-Lu solid compounds could not be isolated. Conductivity and 31P NMR spectroscopy indicate structural changes in solution between the lighter and heavier lanthanides and, whilst electrospray mass spectrometry confirms a dramatic difference in behaviour with complexes of the heavier lanthanides readily decomposing via loss of EtNO3, other experiments show that this does not occur under the conditions of complex formation. The single crystal X-ray structures for Ln = La and Sm show the nitrates and OEt groups to be in close proximity. The changes in spectroscopic properties correlate well with the difficulties in isolating the complexes of heavier metals, and are possibly due to the formation of dimeric complexes rather than loss of ethyl nitrate.
- Lees, Anthony M. J.,Kresinski, Roman A.,Platt, Andrew W. G.
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p. 1457 - 1463
(2007/10/03)
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- Oxidative heck-type reaction involving cleavage of a carbon-phosphorus bond of arylphosphonic acids
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Cleavage of a carbon-phosphorus bond is achieved under palladium catalysis in an oxidative Heck-type reaction which exploits arylphosphonic acids. The reaction of arylphosphonic acids with alkenes provides arylation products in good yields in the presence of TBAF with trimethylamine oxide as an oxidant. Copyright
- Inoue, Atsushi,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 1484 - 1485
(2007/10/03)
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- Kinetics and mechanism of permanganate oxidation of phenylphosphinic acid in acid perchlorate solution
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The stoichiometry of the title reaction is expressed by the equation, MnO4- + 2C6H5HP(O)OH + 4H+→ Mn(III) + 2C6H5PO(OH)2 + 2H2O. The kinetics and the rapid scan of the reaction mixture suggest the formation of the complexes by C6H5HP(O)OH(C1, K1) and C6H5HP(O)O- (C2, K2) with MnO4- ion. The equilibrium constants of the complexes are H+ dependent. It is suggested that the complexes are formed by hydrogen bonds, P-H .... O-Mn, and the redox involve the dissociation of H- from the P-H bond causing transfer of two electrons from substrate to MnO4- through -O- bridge. The relative stability of the complex C2 > C1 because K1 2 and, k1 > k2 where k1 and k2 are the rate constants for the decomposition of the complexes C1 and C2. The kinetics in perchlorate solution (μ = 1 mol dm-3, LiClO4) under pseudo-first order conditions ([PPA] ? [MnO4-]) indicated that the H+ catalysed rate correlates with the expression kobs(Ka + [H+]) = a + b[H+]2 + c[H+]2 where kobs is the pseudo-first order rate constant and Ka is the dissociation constant of C6H5HP(O)OH. The [H+]2 term is likely due to the acid catalysis of Cl. The activation parameters corresponding to k1 and k2 are reported.
- Sharma, Kamla,Mehrotra, Raj Narain
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p. 270 - 278
(2007/10/03)
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- Kinetics and mechanism of oxidation of lower oxyacids of phosphorus by tetrabutylammonium tribromide
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Oxidation of lower oxyacids of phosphorus by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid leads to the formation of corresponding oxyacids with phosphorus in a higher oxidation state. The reaction exhibits 1:1 stoichiometry. The reaction is first order each in [TBATB] and [oxyacids]. The reaction does not induce polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride on the reaction rate. The proposed reactive oxidizing species is tribromide ion. It has been shown that the pentacoordinated tautomer of the phosphorus oxyacid is the reactive reductant. The oxidation of deuteriated oxyacids exhibits a substantial primary kinetic isotope effect. The effect of solvent composition indicates that the rate increases with an increase in the polarity of the solvent. A mechanism involving transfer of a hydride ion in the rate-determining step has been proposed.
- Sharma, Pradeep K
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p. 1612 - 1615
(2007/10/03)
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- Remarkable enhancement of the hydrolyses of phosphoesters by dinuclear centers: Streptomyces aminopeptidase as a 'natural model system'
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The transition-state analogues bis(p-nitrophenyl)phosphate and p-nitrophenyl phenylphosphonate for peptide hydrolysis are shown to be very effectively hydrolyzed by Streptomyces dinuclear aminopeptidase and its Co2+, Ni2+, Mn2+
- Ercan,Hyun Ik Park,Ming
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p. 2501 - 2502
(2007/10/03)
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- Kinetics and mechanism of the oxidation of phosphinic, phenylphosphinic and phosphorous acids by benzyltrimethylammonium tribromide
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The oxidation of phosphorus-(I) and -(III) oxyacids by benzyltrimethyl ammonium tribromide (BTMAB), in 9:1 (v/v) acetonitrile-acetic acid, leads to the formation of corresponding phosphorus-(III) and -(V) oxyacids. The reaction is first order with respect to each of the BTMAB and oxyacid. There is no effect of benzyltrimethylammonium chloride or bromide ion on the reaction rate. The oxidation of deuteriated phosphinic and phosphorous acids exhibit the presence of a substantial kinetic isotope effect. The rate decreases with an increase in the proportion of acetic acid in the solvent. It has been shown that the reactive reducing species is the penta-coordinated form of the oxyacid. Tribromide ion has been postulated as the reactive oxidizing species. A mechanism involving a hydride-ion transfer in the rate-determining step has been proposed.
- Rao, P. Suryachandra,Goel, Shruti,Kothari, Seema,Banerji, Kalyan K.
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p. 1129 - 1132
(2007/10/03)
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- Palladium-Catalyzed Phase-Transfer Arylation of Dialkyl Phosphonates
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Palladium-catalyzed phase-transfer arylation of dialkyl phosphonates with various iodo- and bromoarenes has been studied. The arylation has also been effected in the absence of ligand. A simple preparative procedure for synthesizing arylphosphonic acids has been developed.
- Kabachnik,Solntseva,Izmer,Novikova,Beletskaya
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- Kinetics and Mechanism of the Oxidation of Phosphinic, Phenylphosphinic and Phosphorous Acids by Bis(2,2′-bipyridyl)copper(II) Permanganate
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The oxidation of three lower oxyacids of phosphorus by bis(2,2′-bipyridyi)copper(II) permanganate (BBCP) leads to the formation of the corresponding oxyacids with phosphorus in higher oxidation state. The reaction is first order with respect to both BBCP and the oxyacid. The reaction is catalysed by hydrogen ion. There is no effect of added 2,2′-bipyridine. Increase in the amount of acetic acid in the solvent mixture increases the rate. The oxidation of deuteriated phosphinic and phosphorous acids exhibits substantial kinetic isotope effects. The tricoordinated form of the oxyacid is not involved in the oxidation process. Suitable mechanisms have been proposed.
- Mohnot, Kavita,Sharma, Pradeep K.,Banerji, Kalyan K.
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- Fragmentation of a phenylphosphonamidic acid as a new technique for the generation of phenyl dioxophosphorane
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N-(1-Adamantyl) phenylphosphonamidic acid (3), an easily prepared solid, on heating in toluene or 1,2-dichloroethane gave the crystalline adamantylamine salt of the anhydride PhP(O)(NHAd)-O-PPh(O)(OH). The mechanism is proposed to involve first the fragmentation of 3 to form phenyl dioxophosphorane, PhPO2, which then acts as a phosphorylating agent to unreacted 3. This mechanism was supported by the observation of first-order kinetics for the consumption of 3. When the phosphonamidic acid was fragmented in the presence of an alcohol, the intermediate PhPO2 was trapped as the monoalkyl phenylphosphonate. The OH groups on the surface of silica gel were also phosphonylated by PhPO2. The acidic OH group of a phosphoric acid monoester (thymyl phosphate) was phosphonylated to give Thy-O-P(O)(OH)-O-PPh(O)(OH). It is concluded from this study that N-(1-adamantyl) phenylphosphonamidic acid is a useful precursor of phenyl dioxophosphorane, which can perform valuable phosphonylation operations.
- Quin, Gyoengyi Szakal,Jankowski, Stefan,Quin, Louis D.
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- Kinetics and mechanism of oxidation of phosphinic, phenylphosphinic and phosphorous acids by pyridinium bromochromate
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The title reaction is of second order, first order with respect to each reactant.The reaction is catalysed by H+ ions and the H+ dependence has the form kobs = a+b +>.The oxidation of phosphinic and phosphorus acids exhibits a substantial primary kinetic isotope effect.The reaction has been studied in nineteen organic solvents and the effect of solvent is analysed using Taft's and Swain's multiparametric equations.The participation of the tautomeric forms of the phosphorus oxyacids, in the oxidation process, has been discussed.It has been concluded that the trichlorinated form of the phosphorus oxyacid does not participate in the oxidation process and a suitable mechanism has been proposed.
- Grover, Anjali,Varshney, Seema,Banerji, Kalyan K.
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p. 622 - 626
(2007/10/02)
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- Kinetics and mechanism of oxidation of phosphinic, phenylphosphinic and phosphorous acids by 2,2'-bipyridinium chlorochromate
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The title reaction is of second order, first with respect to the each reactant.The reaction is catalysed by hydrogen ions; the hydrogen ion dependence has the form kobs=a+b+>.The oxidation of phosphinic and phosphorous acids exhibits a substantial primary kinetic isotope effect.The reaction has been studied in ninteen organic solvents and the effect of solvent is analysed using Taft's and Swain's multiparametric equations.The participation of the tautomeric forms of the phosphorus oxyacids, in the oxidation process, has been discussed.It has been concluded that the tricoordinated form of the phosphorus oxyacids does not participate in the oxidation process.A suitable mechanism has been proposed.
- Mathur, Dipti,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 961 - 965
(2007/10/02)
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- SYNTHESIS OF ARYL- AND HETARYLPHOSPHONATES
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The reaction of tris(trimethylsilyl) phosphite with aryl or hetaryl halides under homogeneous catalysis conditions gave bis(trimethylsilyl)phosphonates.Treatment of these products with methanol gave the corresponding aryl- or hetarylphosphonic acids in quantitative yield.Keywords: tris(trimethylsilyl) phosphite, aryl and hetaryl halides, homogeneous catalysis, bis(trimethylsilyl)phosphonates, arylphosphonic acids.
- Demnik, N. N.,Kabachnik, M. M.,Novikova, Z. S.,Beletskaya, I. P.
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p. 1913 - 1915
(2007/10/02)
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- Kinetics and Mechanism of the Oxidation of Phosphinic, Phenylphosphinic and Phosphorous Acids by Bromine
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Oxidation of lower oxyacids of phosphorus by aqueous bromine has been studied in the +> range 0.001 - 5.0 mol dm-3.The reaction is first order with respect to bromine and the oxyacid.Molecular bromine has been postulated as the reactive oxidising species.Oxidation of deuteriated phosphinic and phosphorous acids exhibited substantial kinetic isotope effect.A study of +> variation showed the oxy-anion is oxidised much more rapidly than the parent acid.It is proposed that the 'inactive' tautomer of the oxyacid participates in the oxidation process.A suitable mechanism has been suggested.
- Agarwal, Saraswati,Mathur, Abha,Banerji, Kalyan K.
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p. 433 - 436
(2007/10/02)
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- PREPARATION OF ARYLPHOSPHONATES BY THE REACTION OF ARYL HALIDES WITH TRIS(TRIMETHYLSILYL) PHOSPHITE UNDER HOMOGENEOUS CATALYSIS CONDITIONS
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The reaction of tris(trimethylsilyl) phosphite with aryl bromides under homogeneous catalysis conditions gives bis(trimethylsilyl)arylphosphonates.The desilylation of these phosphonate products with methanol leads to arylphosphonic acids.
- Demik, N. N.,Kabachnik, M. M.,Novikova, Z. S.,Beletskaya, I. P.
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p. 1300 - 1301
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of Phosphinic, Phenylphosphinic, and Phosphonic Acids by Pyridinium Chlorochromate
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Oxidation of the lower oxyacids of phosphorus by pyridinium chlorochromate (PCC) results in the formation of the corresponding higher oxyacids of phosphorus.The reaction is of first order with respect to PCC and the oxyacid.The reaction is catalyzed by hydrogen ions, kobs = a + b.The reaction exhibited a substantial primary kinetic isotope effect.The rates in 19 different organic solvents have been analyzed using Kamlet-Taft's and Swains's equations.It has been found that the cation-solvating power of the solvents plays a predominant role.It is proposed that the "inactive" tautomer of the phosphorus oxyacids is the reactiv e species.Transfer of a hydride ion from the P-H bond to PCC, in the rate-determining step, has been proposed.
- Seth, Monila,Mathur, Abha,Banerji, Kalyan K.
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p. 3640 - 3643
(2007/10/02)
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- Kinetics of oxidation of phosphinic, phenylphosphinic and phosphorous acids by bromamine-B in aqueous perchloric medium
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The oxidation of phosphine, phenylphosphinic and phosphorous acids by sodium N-bromobenzenesulphonamide (BAB) in perchloric acid solution, results in the formation of corresponding phosphorous acids of higher valence state.The reaction is first order in , and +>.Oxidation of deuteriated phosphinic and phosphorous acids shows the presence of a substantial primary kinetic isotope effect.The reaction fails to induce polymerization of acrylonitrile.Added benzenesulphonamide has no effect on the reaction rate. (PhSO2NH2Br)+ has been postulated as the reactive oxidizing species.It has been shown that the inactive tautomer of the phosphorous oxyacids, RHP(O)OH, participates in the oxidation process.A rate-determining step involving transfer of a hydride ion from the P-H bond to the oxidant has been proposed.
- Moondra, Anu,Mathur, Abha,Banerji, Kalyan K.
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p. 963 - 966
(2007/10/02)
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- Studies on Organophosphorus Compounds XL. A One-Pot Procedure for the Mono-O-Alkylation of Phosphonic Acid: A Facile Synthesis of Alkyl Hydrogen p-Substituted Phenylphosphonates
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A one-pot procedure is described for the synthesis of hexyl hydrogen p-substituted phenylphosphonates 4 in moderate yield based on the mono-O-alylation of bis(tetramethylammonium) salts of dibasic phosphonic acids 3.
- Yuan, Chengye,Feng, Hanzhen
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p. 140 - 141
(2007/10/02)
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- Kinetics and Mechanism of the Oxidation of Phosphinic, Phenylphosphinic, and Phosphorous Acids by Pyridinium Fluorotrioxochromate(VI)
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Oxidation of the lower phosphorus oxyacids by results in the formation of corresponding oxyacids in the higher valence states.The reaction is first order with respect to the oxidant concentration.A Michaelis-Menten type kinetics was observed with respect to the substrate, indicating the formation of a complex in a pre-equilibrium.The formation constants and the rates of disproportionation of the complexes have been evaluated at different temperatures.The reaction exhibits a substantial primary kinetic isotope effect.The rates in 19 different organicsolvents have been analysed using Kamlet-Taft and Swain equations.It has been found that the cation-solvating power of the solvents plays an important role.It is proposed that the 'inactive ' tautomer of the phosphorus oxyacids is the reactive reductant, and that transfer of a hydride ion from the P-H bond to the oxidant in the rate-determining step occurs.
- Moondra, Anu,Mathur, Abha,Banerji, Kalyan K.
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p. 2697 - 2700
(2007/10/02)
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- Process for preparing phosphonic acids
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A process for preparing phosphonic acids of the structure STR1 wherein R1 is lower alkyl, aryl, cycloalkyl or arylalkyl, and R2 is H, benzyl or STR2 by oxidizing the corresponding phosphonous acid STR3 employing as the oxidizing agent potassium permanganate or sodium periodate.
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- The Selective Dealkylation of Mixed Esters of Phosphoric Acid and Phenylphosphonic Acid Using Cation Exchange Resin
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Cation exchange resin (SO3H) is a highly selective dealkylation reagent for mixed esters of phosphorus oxyacids bearing primary and secondary alkyl groups.The desired products which were produced by dealkylation of the secondary alkyl group were obtained in high yields under anhydrous and mild conditions.Keywords - dealkylation; cation exchange resin; carbonium ion; phosphorus oxyacid ester; trialkyl phosphate; dialkyl phenylphosphonate; p-toluenesulfonic acid
- Nitta, Yoshihiro,Arakawa, Yasushi
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p. 3121 - 3129
(2007/10/02)
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- Kinetics and mechanisms of oxidations by metal ions. Part IV. Oxidation of phenylphosphinic acid by aquavanadium(V) ions
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The kinetics of the oxidation of phenylphosphinic acid by quinquevalent vanadium ion have been investigated in aqueous perchlorate media under pseudo-first order conditions (phenylphosphinic acid in excess).The reaction has a first order dependence in and and the observed pseudo-first order rate constant kobs is given by kobs = a + b+>.The acid-independent path is considered to be due to the reaction between VO2+(aq.) and C6H5P:(OH)2, the active form of phenylphosphinic acid, while the reaction between V(OH)32+(aq.) and C6H5P(O)(OH)H, the inactive form of phenylphosphinic acid, is considered to explain the acid-dependent path.Phenylphosphinic acid in aqueous acidic solution is known to exist as an equilibrium mixture of the active and inactive forms.The composite activation and thermodynamic parameters associated with constants a and b are reported.
- Mehrotra, Raj Narain
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p. 663 - 666
(2007/10/02)
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- ETUDE D'UN SCHEMA DE SYNTHESE PEPTIDIQUE INTRAMOLECULAIRE A L'AIDE DE DERIVES DU PHOSPHORE TETRAEDRIQUE
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A new scheme of repetitive and controlled peptide synthesis offers two advantages compared to the usual methods of synthesis: two steps only are used for the prolongation of a peptide chain with an amino-acid residue and the risk of racemisation is minimized.The two postulated steps are verified particularly by the rearrangement, in an alkaline alcoholic medium, of phosphordiamides 1 incorporating one amino-acid residue, leading to the formation of the peptide derivatives 6 and 8.The severe limitations of this method are discussed.
- Mulliez, M.
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p. 2027 - 2041
(2007/10/02)
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