- Structure, phase transition and vibrational spectra of the NaH5(PO4)2 and NaD5(PO4)2 crystals
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The crystals of sodium pentahydrogenbis(phosphate), NaH5(PO4)2 [NaH2PO4·H3PO4] and its deuterated analogue, NaD5(PO4)2 [NaD2PO4 D3PO4], were obtained for the first time. They exhibit the second-order phase transition at ca. 200 K slightly sensitive on deuteration (ca. 6-8 K) as determined by the DSC experiments. Their structures were solved by the X- ray method at 150 K (for NaH5(PO4)2) and at 240 K (for deuterated) crystals. Both these crystals belong to the P21/c space group of the monoclinic system (a = 8.464(4), b = 7.817(5), c = 10.337(5) A?, β = 90.58(4)° for NaH5(PO4)2 and a= 8.495(3), b = 7.854(3), c = 10.352(3) A?, β = 90.67(3)°for deuterated one) and their structures are similar, although determined in different phases. The crystals are built of the layers of orthophosphoric acid molecules and of the layers of dihydrogenphosphate anions. The layers are built of the centrosymmetric dimers of the orthophosphoric acid molecules and of the dihydrogenphosphate anions, respectively. Two corresponding moieties are joined into dimers by two equivalent hydrogen bonds. The structures of title crystals differ from that of KH5 (PO4)2. The powder IR and Raman spectra were measured at room temperature. The IR spectra of the NaHs (PO4)2 crystal were also measured at low temperatures. It is suggested that the phase transition is related to the changes in the motions of the protons in weak hydrogen bonds.
- Baran,Lis,Drozd,Ratajczak
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- High-temperature thermal behaviors of XH2PO4 (X = Cs, Rb, K, Na) and LiH2PO3
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XH2PO4 ionic compounds have emerged as a viable electrolyte for intermediate temperature fuel cells, and here have been subjected to thermal analysis to clarify their high-temperature properties. Thermoanalytical peaks were identified at 231.5, 239 and 349 °C for CsH2PO4; 127, 250 and 354 °C for RbH2PO4; 232, 270 and 319 °C for KH2PO4; 223, 330 and 352 °C for NaH2PO4; also, 195 and 220 °C for LiH2PO3 (peak temperature values as measured at the same heating rate of 10 K/min). The thermal events at 231.5 °C in CsH2PO4 and 127 °C in RbH2PO4 were previously interpreted as thermal decomposition by numerous researchers, but we confirm their origin in structural phase transition. The high-temperature variations in KH2PO4 and NaH2PO4 are entirely due to thermal dehydration rather than phase transition. We have also examined LiH2PO3, and found, for the first time, an endothermic peak at 195 °C, and attributed it to structural phase transition.
- Li, Zikun,Tang, Tongbor
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- Sodium Dihydrogen Phosphate Starting from Sodium Chloride and Orthophosphoric Acid Via Cation Resin Exchange
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Sodium phosphates are generally synthesized by neutralization of orthophosphoric acid with sodium hydroxide. In this paper, we communicate a new synthesis process, wherein sodium dihydrogen phosphate can be obtained from sodium chloride and orthophosphoric acid, using cation resin exchange at room operational conditions. This opens a new concept for the design of environmentally friendly processes in this inorganic synthesis field.
- Minh, Doan Pham,Nzihou, Ange,Sharrock, Patrick
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- Optimization of dissolution of ulexite in phosphate acid solutions
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The Taguchi optimization method was used to determine optimum conditions for the dissolution of ulexite in phosphate acid solutions. Reaction temperature, solid-to-liquid ratio, phosphate acid concentration, reaction time, particle size and stirring speed
- Doan, Tuba Hatice,Yartai, Ahmet
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p. 601 - 605
(2015/01/16)
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- Organophosphorus chemistry without PCl3: A bridge from hypophosphorous acid to H-phosphonate diesters
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A process for the conversion of hypophosphorous acid (H3PO 2, HPA) and alcohols into various H-phosphonate diesters [(RO) 2P(O)H] is described. The new reaction provides a missing bridge between HPA and important H-phosphonates, completely avoiding the use of PCl3. Nickel chloride or nickel on silica catalyze the oxidative phosphorylation of alkyl phosphinates with various alcohols or water. The reaction is atom economic and avoids the formation of waste products. The previous need for both chlorine and base is completely avoided. Esterification of hypophosphorous acid followed by reaction with another molecule of alcohol under the action of a nickel catalyst provides a green method for the preparation of H-phosphonates. This method entirely avoids the need for any stoichiometric chloride unlike those based on phosphorus trichloride. Copyright
- Fisher, Henry C.,Prost, Lucie,Montchamp, Jean-Luc
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p. 7973 - 7978
(2014/01/06)
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- RECOMBINANT HCV E2 GLYCOPROTEIN
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The invention provides modified hepatitis C virus (HCV) E2 glycoproteins comprising the HCV-E2 receptor-binding domain (RBD) including the HVR1, HVR2 and igVR variable regions wherein in at least one of said variable regions at least a part of the variabl
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- PROTEIN STERILISATION BY RADIATION AND ADDITION OF A STABILISING COMPOSITION
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A method of sterilising a protein, comprises exposing to ionising radiation an at least substantially dry composition comprises a protein and a protective compound or combination of protective compounds having both of the following characteristics: (i) a rate of reaction with singlet oxygen greater than 1×10 7 L mol?1 S?1; (ii) being a reducing agent whilst at the same time containing a proton dissociable group with a pKa no more than 3 units from the pH of the composition. The compound having characteristic (i) is selected from histidine, thiamine and tryptophan, the compound having characteristic (ii) is selected from methionine, malate, citrate, lactate and tiron. The radiation is gamma radiation or electron beam, whereby the preferred dose is 15-40 kGy.
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- Novel prostaglandin analogues
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Novel prostaglandin analogues of the following general formula STR1 wherein R is an alkyl group from 1 to 4 carbon atoms, e.g. methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-buytyl, R1 is hydrogen, R2 is hydroxyor R1
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