- The relative hydrolytic reactivities of pyrophosphites and pyrophosphates
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The pH-rate profiles for the hydrolysis of pyrophosphate (PP(v)) and pyrophosphite (PP(iii), pyro-di-H-phosphonate) are a complex function of pH, reflecting the different ionic species and their relative reactivities. PP(iii) is more reactive than PP(v) at all pHs and only PP(iii) shows a hydroxide-ion reaction at high pH, so it is 1010-fold more reactive than PP(v) in 0.1 M NaOH. The pKa2 of PP(iii) ~0.44, so the dominant species at pH's > 1 is the di-anion PP(iii)2-. Although there is no observable (NMR or ITC) binding of Mg2+ to the PP(iii) di-anion there is a modest increase in the rate of hydrolysis of PP(iii) by Mg2+. PP(iii) is neither a substrate nor an inhibitor of pyrophosphatase, the enzyme that efficiently catalyses the hydrolysis of PP(v).
- Mistry, Dharmit,Powles, Nicholas
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p. 5727 - 5733
(2013/09/12)
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- Reactive intermediates in the H-phosphonate synthesis of oligonucleotides
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The formation of H-phosphonate diesters is an important step in the synthesis of oligonucleotides. Using diphenylchlorophosphate as the activator for the coupling step is often accompanied by side reactions as a result of self 'capping' and other reactions of the reactive intermediate. In the absence of base, the activation of ethyl H-phosphonate with diphenylchlorophosphate probably occurs through the intermediate formation of bis diethyl pyro-di-H-phosphonate rather than the expected diphenyl ethyl pyro-H-phosphonate. Pyridine acts as a nucleophilic catalyst converting diphenylchlorophosphate to its pyridinium adduct. Several side and unwanted reactions are quantified so that conditions to minimise these can be identified.
- Powles, Nicholas,Atherton, John,Page, Michael I.
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experimental part
p. 5940 - 5947
(2012/08/28)
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- PROCESS FOR THE MANUFACTURE OF DIALKYLPHOSPHITES
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A process for the manufacture of dialkyl phosphites is disclosed. In detail, dialkyl phosphites are prepared starting from P4O6, or partially hydrated species thereof cumulatively P-O, by reacting specific molar ratios of alcohol and P-O, containing from 1 to 6 P-O-P bonds in the molecule, in the presence of trialkylphospite (TAP) to thus yield high purity and high yield of dialkyl phosphites. The P-O reactant is preferably represented by liquid P4O6.
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Page/Page column 8
(2010/12/26)
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- Ionic-liquid-promoted Michaelis-Arbuzov rearrangement
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Room-temperature imidazolium ionic liquids, [Rmim][X], proved to be environmentally benign recyclable solvents promoting the Michaelis-Arbuzov rearrangement, which can be performed even at room temperature in a short period of time. The best ionic liquid of choice depended on the starting phosphorus(III) ester, namely, for triethyl phosphite [bmim][NTf2] demonstrated better results while for ethyl diphenylphosphinite it was [hmim][Br].
- Matveeva,Odinets,Kozlov,Shaplov,Mastryukova
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p. 7645 - 7648
(2007/10/03)
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- Aryl H-phosphonates. 7. Studies on the formation of phosphorus-carbon bond in the reaction of trityl and benzyl halides with dialkyl and diphenyl H-phosphonates
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The reactions of H-phosphonate diesters with trityl and benzyl halides were investigated using 31P NMR spectroscopy. It was found that extensive oxidation, which usually accompanies the formation of trityl- or p-nitrobenzylphosphonates from the corresponding alkyl bromides in the Michaelis-Becker reaction, can be considerably suppressed or completely eliminated by reacting p-nitrobenzyl or trityl bromides with diphenyl H-phosphonate in acetonitrile in the presence of DBU.
- Kers, Annika,Stawinski, Jacek,Dembkowski, Leszek,Kraszewski, Adam
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p. 12691 - 12698
(2007/10/03)
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- Studies on aryl H-phosphonates. 3. Mechanistic investigations related to the disproportionation of diphenyl H-phosphonate under anhydrous basic conditions
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Diphenyl H-phosphonate undergoes under anhydrous reaction conditions a base-promoted disproportionation to triphenyl phosphite and phenyl H- phosphonate. On the basis of 31P NMR data the most likely mechanism for this transformation was proposed. In order to substantiate these findings and to get a deeper insight into the chemistry of aryl H-phosphonate esters, we carried out also some studies on activation of phenyl and diphenyl H- phosphonates with various condensing agents. We found that aryl vs alkyl esters of phosphonic acid often follow different reaction pathways during the activation, and this can most likely be traced back to higher electrophilicity of the phosphorus centre and to higher reactivity of the P- H bonds in aryl H-phosphonate derivatives.
- Kers, Annika,Kers, Inger,Stawinski, Jacek,Sobkowski, Michal,Kraszewski, Adam
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p. 9931 - 9944
(2007/10/03)
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- ALKYLATING PROPERTIES OF DIALKYL PHOSPHITES
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When the mixture of amines and dialkyl phosphites is used in the reaction, as for example in the Kabachnik-Fields reaction, all possible N-alkylated products are formed.N-ethylation by diethyl phosphite is much slower than N-methylation by dimethyl phosphite and the latter can be easily formed via transesterification when the methanol is present in the mixture.Key words: Amine alkylation, dialkyl phosphites, Kabachnik-Fields synthesis.
- Gancarz, Roman
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p. 193 - 200
(2007/10/02)
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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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- SYNTHESIS AND CHEMICAL PROPERTIES OF SUBSTITUTED 2-HYDROXY-2-PHOSPHONYLETHANALS AND 1,2-DIHYDROXY-1,2-BISPHOSPHONYLETHANES
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The syntheses of 2-hydroxy-2-(dialkoxyphosphonyl)ethanals 1a-1h, and of 1.2-dihydroxy-1,2-bis(dialkoxyphosphonyl)ethanes 2a-2h by reactions of glyoxal with phosphorus acid diesters in acidic medium are reported.The base catalyzed isomerization of 2-hydroxy-2-(dialkoxyphosphonyl)ethanals 1 to formylmethylphosphates 3 was demonstrated by 31P NMR spectroscopy.The stability of 1,2-dihydroxy-1,2-bis-(dialkoxyphosphonyl)ethanes 2 towards bases was demonstrated and interpreted on the basis of their structural features.The reactions of glyoxal with O-(n-butyl)phenylphosphonite, diethyl- and diphenylphosphine oxide and the indentification of their products are reported as well as the synthesis of 1,2-dihydroxy-1,2-bis(dihydroxyphosphonyl)ethane 2m by acid-catalysed hydrolysis of 1,2-dihydroxy-1,2-bis(dialkoxyphosphonyl)ethanes and by hydrogenation of 1,2-dihydroxy-1,2-bis(dibenzyloxyphosphonyl)ethane 2f.The rate constant of the hydrogenation of 2f and the pKa values of the 1,2-dihydroxy-1,2-bis(dihydroxyphosphonyl)ethane 2m are also reported.
- Mikroyannidis, John A.,Tsolis, Alexandros K.,Gourghiotis, Simitrios J.
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p. 279 - 290
(2007/10/02)
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