Separation of the enantiomers of phenprocoumon and warfarin by high-performance liquid chromatography using a chiral stationary phase. Determination of the enantiomeric ratio of phenprocoumon in human plasma and urine

The enantiomers of the chiral coumarin-type anticoagulants phenprocoumon, warfarin and p-chlorophenprocoumon were separated by high-performance liquid chromatography on a chiral stationary phase (Nucleosil-Chiral 2) and normal-phase conditions. Chromatographic peak identification was performed with authentic reference compounds of the enantiomers and on-line UV spectra comparison. This method was applied to the determination of the enantiomeric ratio of phenprocoumon in plasma and urine extracts from patients under racemic drug therapy. The limit of detection (50 and 80 ng/ml) and precision (less than 5%) of the method are adequate for pharmacokinetic and enantioselective disposition studies, respectively, of phenprocoumon. No racemization was detected during the extraction procedures.     

Mass spectra of the coordination compounds of nickel with the tetradentate Schiff bases of S-substituted thiosemicarbazides with 2,4-pentanedione and 3-oxo-2,4-pentanedione

The mass spectra of the coordination compounds of nickel(II) with the bis-S-substituted thiosemicarbazones of 2,4-pentanedione (R₂H₂L) with the general formula [NiR₂HL]X and of 3-oxo-2,4-pentanedione (H₂R₂LO) with the general formula NiR₂LO were studied. A distinguishing feature of the mass spectra of [NiR₂HL]X is the absence of molecular ion peaks. The initial point of fragmentation is the [M - HX] ions. The strongest lines in spectra of NiR₂LO are those due to the elimination of R and R-H. At the first stage the fragmentation of all the investigated compounds takes place mainly through only one of the thiosemicarbazide residues. At the second stage the 2,4-pentanedione (3-oxo-2,4-pentanedione) residue is eliminated, after which the remaining thiosemicarbazide part dissociates. A significant part of the fragmentation paths was confirmed by the peaks of the metastable ions and also by the mass spectra of the deuterated analogs.Institute of Chemistry, Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 2, 205–211, March–April, 1991. Original article submitted August 19, 1986.     

Random walk on a disordered directed Bethe lattice

The random walk of a particle on a directed Bethe lattice of constant coordinanceZ is examined in the case of random hopping rates. As a result, the higher the coordinance, the narrower the regions of anomalous drift and diffusion. The annealed and quenched mean square dispersions are calculated in all dynamical phases. In opposition to the one-dimensional (Z=2) case, the annealed and quenched mean quadratic dispersions are shown to be identical in all phases.We shall employ indifferently the expressions Bethe lattice or infinite Cayley tree to denote an infinite ramified lattice of constant coordinanceZ.^{(4, 5)}     

Diffraction dissociation of nuclei in 450 GeV/c proton-nucleus collisions

Diffractive dissociation of nuclei (Be, Al, W) in collisions with 450 GeV/c protons,pApX, has been measured with the HELIOS spectrometer at the CERN Super Proton synchrotron. The dependence of the single-diffraction cross-section on the nuclear massA can be parametrized as _SD mb×A ^0.35±0.02, showing the peripheral nature of the process. The differential cross-section d_SD=(3.8±0.3)mb ×A ^0.35±0.02, is exponential with the slope parameter, increasing from 6.2±0.4 (GeV/c)^–2 for beryllium to 7.9±0.5 (GeV/c)^–2 for tungsten. The slope parameter also increases with increasing massM _X of the diffractively produced state. The rapidity, multiplicity, and transverse-momentum distributions of the particles of the diffractively produced stateX show a longitudinal phase-space population and are remarkably insensitive to the nuclear mass. This, together with theA ^1/3 dependence of _SD, suggests that the dominant process of nuclear diffractive excitation is the dissociation of single nucleons.Deceased     

Synthesis of new condensed analogs of isoindolinium salts

Quaternary ammonium salts that contain a 3-(-naphthyl)propargyl group in addition to a group of the propargyl type undergo intramolecular cyclization of the diene-synthesis type under base-catalysis conditions to give condensed isoindolinium analogs.Communication 209 from the series Research on amines and ammonium compounds. See [1] for Communication 208.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 759–762, June, 1991.