14335-33-2Relevant academic research and scientific papers
Rotational spectra and structures of the C6H6-HCN dimer and Ar3-HCN tetramer
Gutowsky, H. S.,Arunan, E.,Emilsson, T.,Tschopp, S. L.,Dykstra, C. E.
, p. 3917 - 3927 (1995)
A comparative study has been made of the rotational properties of C6H6-HCN and Ar3-HCN, observed with the Balle/Flygare pulsed beam, Fourier transform microwave spectrometer.C6H6-HCN is found to be a prolate symmetric top and Ar3-HCN an oblate one, both with the H in the middle.The rotational constants B0, DJ, and DJK of the parent species are 1219.9108(4) MHz, 1.12(3) kHz, and 18.32(8) kHz for C6H6-HCN,and 886.4878(1) MHz, 10.374(2) kHz, and 173.16(1) kHz for Ar3-HCN.Rotational constants are reported for the isotopic species C6H6-H13CN, -HC15N, and 13CC5H6-HC15N, and for Ar3-HC15N and -DCN.Analysis of the 14N hyperfine interaction χ finds its projection on the figure axis to be -4.223(4) MHz in C6H6-HCN and -1.143(2) in Ar3-HCN.They correspond to average projection angles θ between the HCN and figure axes of 15.2 deg and 45.3 deg, respectively.A pseudodiatomic analysis of the rotational constants gives the c.m. to c.m. distance to be 3.96 Angstroem in C6H6-HCN and 3.47 Angstroem in Ar3-HCN.While the rotational properties of C6H6-HCN are normal those of Ar3-HCN display a long list of abnormalities .They include a J-dependent χ(14N) similar to that of Ar-HCN; a very large projection angle θ, large centrifugal distortion including higher-order terms in HJ and HJK; splitting of the K=3 transitions into J-dependent doublets; and the ready observation of an excited vibrational state.These behavior differences are related qualitatively to the interaction surfaces for the two clusters, calculated with the molecular mechanics for clusters (MMC) model, and discussed.The potential minimum for C6H6-HCN is smooth, circular, steep except for a flat bottom, and deep (1762 cm-1).That for Ar3-HCN is tricuspid, with large gullies, and shallow (507 cm-1).In addition to the dispersion forces, the dominant interaction forming C6H6-HCN is between the benzene quadrupole moment and the HCN dipole moment, a strong 4-2 potential.That in Ar3-HCN is polarization of the spherical Ar by the HCN dipole and quadrupole moments, a weak 0-2,4 potential.
83Kr nuclear quadrupole coupling, microwave spectrum, and structure of KrHCN
Campbell, E. J.,Buxton, L. W.,Legon, A. C.
, p. 3483 - 3493 (1983)
Rotational spectra have been observed for ten isotopic species of KrHCN using the pulsed Fabry-Perot Fourier transorm technique.The 83Kr nuclear quadrupole coupling constant has been measured in 83KrHC14N, 83KrHC15N, and 83KrDC14N.Values of the rotational constants B0, centrifugal distortion constants DJ and H, 14N and 83Kr nuclear quadrupole coupling constants are: . aCalculated using DJ=47.401 kHz, H=69.4 Hz. bCalculated using DJ=40.350 kHz, H=54.3 Hz. cCalculated using DJ=26.973 kHz, H=27.2 Hz.These constants are consistent with a linear or near-linear configuration, with a Kr-HCN center-off-mass separation of 4.54 Angstroem, and the Kr atom located 27 deg off the HCN figure axis on average, where the vertex of this angle is placed on the HCN center-off-mass.KrHCN exhibits unusually large centrifugal distortion in comparison to previously studied Kr-hydrogen halide systems.We find that the measured 83Kr nuclear quadrupole coupling constants in 83KrHC14N and 83KrDC14N are consistent with a long range polarization model previously used to explain values of χKr in KrH(D)Cl and KrH(D)F.
Raman- and infrared-spectroscopic investigations of dilute aqueous phosphoric acid solutions
Rudolph, Wolfram W.
, p. 9642 - 9653 (2010)
Phosphoric acid in water and heavy water has been studied by Raman and infrared spectroscopy over a broad concentration range (0.00873-1.560 mol kg-1) at 23 °C. The vibrational modes of the PO4 skeleton (C3v symmetry) of H3PO4(aq) and D 3PO4(D2O) have been assigned. In addition to the P-O stretching modes a deformation mode has been detected, δPO-H(D) at 1250 and 935 cm-1, respectively. In addition to the modes of the phosphoric acid and heavy phosphoric acid a mode of the dissociation product H2PO4- and D2PO4 - has been detected at 1077 cm-1 and 1084 cm-1 respectively. H3PO4 and D3PO4 is hydrated in aqueous solution which could be verified by Raman spectroscopy following the νPO and νsP(OH)3 mode as a function of temperature. These modes show a pronounced temperature dependence inasmuch as νPO shifts to higher wavenumbers with temperature increase and νsP(OH)3 to lower wavenumbers. In the range between 300-600 cm-1 the deformation modes have been observed. In very dilute H3PO4 solutions however, the dissociation product is the dominant species. The dissociation degree, α for H3PO 4(aq) and D3PO4(D2O) as a function of dilution has been measured at 23 °C. In these dilute H3PO 4(aq) and D3PO4(D2O) solutions no spectroscopic features for a dimeric species of the formula H6P 2O8 and D6P2O8 could be detected. Quantitative Raman measurements have been carried out to follow the dissociation of H3PO4 and D3PO4 over a very broad concentration range and also as a function of temperature. From the dissociation data, the pK1 value for H3PO4 has been determined to 2.14(1) and for D3PO4 to 2.42(1) at 23 °C. In the temperature interval from 24.5 to 99.7 °C the pK 1 values for H3PO4(aq) have been determined and thermodynamic data have been derived.
A neutron diffraction and computer modeling study of the interatomic structure of phosphoric acid
Tromp, R. Hans,Spieser, Stephane H.,Neilson, George W.
, p. 2145 - 2150 (1999)
Wide angle neutron diffraction in combination with H/D substitution was used to determine the inter- and intramolecular structure of 100% phosphoric acid (H3PO4, PA). From radial distribution functions gHH(r), gHX(r), and gXX(r) (where X is either O or P) the hydrogen bonds were found to be characterized by a very short O...H distance (1.54 A). Within a molecule, the orientation of an OH group was found to be preferably in one of the three O-P-O planes. In the interpretation of the radial distribution functions, use was made of preliminary results of molecular dynamics simulations. Temperature effects on the structure of PA were only found in the hydrogen bond structure, which becomes somewhat less well defined when heating up from room temperature to 60°C. Polyphosphates could not be detected, probably due to the small degree of polymerization.
Synthesis and biological evaluation of deuterated sofosbuvir analogs as HCV NS5B inhibitors with enhanced pharmacokinetic properties
Ao, Wangwei,Ma, Xueqin,Lin, Youping,Wang, Xiaojing,Song, Wei,Wang, Qinglin,Zhang, Xiquan,Xu, Hongjiang,Zhang, Yinsheng
, p. 215 - 229 (2019/05/07)
A series of deuterated sofosbuvir analogs were designed and prepared with the aim of improving their pharmacokinetic properties. The devised synthetic routes allow for site-selective deuterium incorporation with high levels of isotopic purity. As expected, the deuterated analogs (37-44) are as efficacious as sofosbuvir when tested in vitro inhibition of viral replication (replicon) assays. Compared with sofosbuvir, deuterated analog 40 displays improved in vivo pharmacokinetics profiles in rats and dogs in terms of the metabolite and the prodrug. The Cmax and area under the curve (AUC) of 40 in dogs were increased by 3.4- and 2.7-fold, respectively. Due to the enhanced pharmacokinetic properties and the great synthetic advantage of an inexpensive deuterium source (D2O) for 40, it was chosen for further investigation.
Concert along the Edge: Dynamics and the Nature of the Border between General and Specific Acid-Base Catalysis
Aziz, Hannah R.,Singleton, Daniel A.
supporting information, p. 5965 - 5972 (2017/05/04)
Reactions that involve a combination of proton transfer and heavy-atom bonding changes are normally categorized by whether the proton transfer is occurring during the rate-limiting step, as in the distinction between general and specific acid-base catalysis. The experimental and computational study here of a β-ketoacid decarboxylation shows how the distinction between the two mechanisms breaks down near its border due to the differing time scales for proton versus heavy-atom motion. Isotope effects in the decarboxylation of benzoylacetic acid support a transition state in which the proton transfer is complete. In quasiclassical trajectories passing through this transition state, the new O-H bond after proton transfer undergoes several vibrations before heavy-atom motion completes the reaction. The bonding changes are thus temporally separated at a "dynamic intermediate" structure that acts equivalently to an ordinary intermediate in the trajectories, including the reversal of trajectories at the intermediate when the second "step" fails, but the structure is not an energy minimum. The results define a border between mechanisms where the usual energetic definition of intermediates is not meaningful.
Oxidation of lower oxyacids of phosphorus by tetraethylammonium chlorochromate: A kinetic and mechanistic study
Vadera, Khushboo,Sharma,Agarwal,Sharma, Pradeep K.
, p. 302 - 306 (2011/01/10)
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.
Oxidation of white phosphorus by peroxides in aqueous and alcoholic solutions: mechanistic aspects and catalytic studies
Akbayeva, Dina N.,Faisova, Farida Kh.,Abdreimova, Rumia R.,Peruzzini, Maurizio
, p. 181 - 193 (2008/10/09)
The oxidation of white phosphorus by hydrogen peroxide or different organic peroxides (such as tert-butyl hydroperoxide, dibenzoylperoxide, 3-chloroperoxybenzoic acid) has been studied in both aqueous and alcoholic solutions under anaerobic conditions. De
Preparation of alkali-metal dideuterium phosphates
Lokshin
, p. 720 - 722 (2008/10/08)
Methods for the preparation of deuterated orthophosphoric acid and alkali-metal dideuterium phosphates are discussed. The easiest and cheapest way of producing these compounds is via the hydration of massive P2O5 polycrystals obtained by vacuum distillation.
Aluminum phosphates with non-centrosymmetric layer- and framework-structures of topologically related motifs: 1. KAl2(PO4)2(OH)·4H2O
Dick, Stefan,Gro?mann, Gisbert,Ohms, Gisela,Zeiske, Thomas
, p. 1439 - 1446 (2007/10/03)
KAl2(PO4)2(OH)·4H2O could be obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 333 K. A single crystal X-ray structure analysis showed that KAl2(PO4)2(OH)·4H2O is isotypic with the mineral minyulite. Crystal data: orthorhombic space group Pba2, a = 934.7(1), b = 982, 1(1), c = 551, 0(1) pm, Z = 2. It possesses dimeric units of Al-octahedra which are bridged by an OH- and two bidentate phosphate groups. The dimers are linked by phosphate to plane polar layers. Cavities in the layers are occupied by K ions. One corner of each phosphate tetrahedron is not connected to Al but accepts four hydrogen bonds from water molecules bound to Al of the adjacent layer. A powder neutron scattering experiment with KAl2(PO4)2(OD)·4D2O showed that four D atoms and P coordinate the hydrogen bond accepting O in KAl2(PO4)2(OD)·4D2O like a square pyramid. Analogous dimeric building units are found in the Al phosphate minerals minyulite and morinite; similar dimers of Fe octahedra occur in the mineral copiapite, a number of Fe containing enzymes and numerous synthetic iron complexes. High-resolution 31P solid-state NMR spectra show only one isotropic line at δiso = -9.6 ppm and confirm the presence of one symmetry independent phosphorus site in the unit cell. In the 1H-MAS-NMR spectra the water molecules and the bridging OH groups show signals at 5.4 and 1.4 ppm, respectively.
