Effect of the introduction of certain additives to the CO + H2 mixture and the scheme for the formation of alcohols higher than C1

The effect of additions of certain alcohols (methanol, ethanol, 2-propanol, and 2-butanol) to the synthesis gas on the distribution of the products during the hydrogenation of CO to alcohols at zinc-chromium oxide catalysts, promoted by various amounts of K₂O, was studied. The results demonstrate the fundamental applicability of the principal theories of chain growth proposed by other authors for copper-containing catalysts. However, it was shown that the probability of -addition is lower while that of -addition is higher at the zinc-chromium-potassium catalysts than at copper-containing catalysts, and the calculated amounts of isobutanol obtained from the data for ethanol and propanols do not agree with the experimental data. It was found that there is an isomeric transition from the secondary alcohols (2-propanol, 2-butanol) to the primary alcohols at the surface of the catalyst, and this can evidently change the normal course of chain growth in the alcohols. It can be concluded that the activity of the alcohol added to synthesis gas in reaction with other C-fragments present on the surface of the catalyst increases with increase in the number of carbon atoms in the alcohol.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 4, pp. 501–505, July–August, 1990.     

Kinetics of thermal dehydration of La(III) and Yb(III) complexes with ortho-vanillin oxime

The analysis of dehydration of the complexes, [La(C₈H₈NO₃)₃.2H₂O] and [Yb(C₈H₈NO₃)₃.3H₂O] for the evaluation of kinetic parameters (Z, E &S ^*) and mechanism of dehydration by non-isothermal methods are reported. The complexes decompose in three well defined steps involving random nucleation mechanism. First two steps involving the dehydration and the third step the loss of the ligand moiety. The intermediates formed during decomposition were found to be unstable for carrying out any significant studies.

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Zusammenfassung Zwecks Ermittlung der kinetischen Parameter (Z, E undS ^*) und des Mechanismus der Dehydratierung durch nichtisotherme Verfahren wird die Analyse der Dehydratierung der Komplexe [La(C₈H₈NO₃)₃·2H₂O] und [Yb(C₈H₈NO₃)₃·3H₂O] beschrieben. Die Komplexe zersetzen sich in drei gut definierten Schritten mit Random-Keimbildungsmechanismus. Die ersten zwei Schritte beinhalten die Dehydratierung, der dritte Schritt den Verlust der Liganden. Die wÄhrend der Zersetzung entstandenen Zwischenprodukte erwiesen sich für jegliche signifikante Untersuchung als zu unstabil.

     

Manganese doping of In1−xGaxAsyP1-y films in liquid-phase epitaxy

The manganese doping of In_1–xGa_xAs_yP_1-y(0 y 1) films grown by liquid-phase epitaxy has been investigated. A study has been made of the influence of the solid-solution composition and of the method of introducing the manganese into the solution melt on the electrical properties of the films, and also on the surface morphology, the optical absorption edge, and the mismatch of the film and substrate lattice constants. It is shown that the hole density in the films decreases with decreasing y. The reasons for this are the decrease in the distribution coefficient of the acceptor manganese (from 0.3 to 0.001), the increase in the degree of compensation of the acceptors with donors (from 0.2 to 0.9), and the increase in the acceptor ionization energy. The composition of the InGaAsP:Mn film and the morphology of its surface depend on the method of preparation of the melt, this being explained by the strong interaction of the manganese atoms with the other components of the liquid phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 26–34, January, 1992.We thank T. G. Druzhinin, Ya. I. Otman, and V. B. Yabzhanov for helping with the experiments.     

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     

Incommensurate and commensurate magnetic long-range order in metallic REPd3 compounds of rare earths (RE=Nd,Tb, Dy,Er, Tm,Yb)

Compared to previous bulk magnetic measurements unusual magnetic ordering phenomena were detected by systematic neutron scattering experiments performed in the temperature range of 7 mKT300 K on the series of cubic metallic compounds REPd₃ of the rare earths RE=Nd, Tb, Dy, Er, Tm and Yb. Except for ErPd₃ withT _N =3 K the observed critical temperatures are compatible with the de Gennes scaling. The complexity of long-range magnetic ordering increases with decreasing 4f ⁿ occupancy, ranging from ferro- or ferrimagnetism in YbPd₃ and DyPd₃ via commensurate antiferromagnetic ordering in ErPd₃ and TmPd₃ [k=(1/2, 1/2, 0)] to incommensurate antiferromagnetic ordering of modulated type in TbPd₃ and NdPd₃. Both RKKY interactions, crystalline electric field, hybridization with 4d states of Pd as well as nuclear spin polarization in the case of RE=Nd appear to be of importance for the magnetic properties of REPd₃ systems.     

Formation pathways and structure—Property interrelationship of 3-imino-1-methyl-5,5-dialkyl-4,7,7-tricyano-2-oxabicyclo-[2.2.1]heptane derivatives

The problems of the structure—property interrelationship of 3-imino-2-oxabicyclo[2.2.1]heptane derivatives are discussed on the basis of x-ray diffraction studies (XDS). A pathway for the formation of the bicyclic compounds is proposed, and the realization of spirans in the reaction of sym-tetracyanoethane with conjugated cyclic systems containing s-cis C=C and C=O fragments is substantiated. The factors responsible for the syn orientation of the oxygen atom and the N-substituent of the imino group are analyzed. It is shown that a change in the steric hindrance in the bicyclic compounds leads to a change in the conformation of the latter. The reasons for the shortening of the C_sp3-C_sp3, C_sp3-C_sp and C=N exo bonds and the correlation of the XDS and IR spectroscopic data are examined. From the XDS data for N-bromo-substituted imines, a model for Br⁺...NC electrophilic attack was proposedCommunication 16 from the series Chemistry of 1,1,2,2-tetracyanoethane. See [1] for Communication 15.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 519–526, April, 1991.     

Acetals of lactams and acid amides. 67. Polarographic behavior of enamines of the indoles series in anhydrous DMF

The polarographic behavior of derivatives of 2-aminomethyleneindoxyl and 3-aminomethyleneoxindole in anhydrous DMF has been studied and the results compared with data on the polarographic reduction of substituted aminomethyleneacetophenones and of related enaminoketones and eneaminoamides. It is established that the ease of reduction is determined by the nature of the substituent on the enamine and indole nitrogen atoms and also by the presence or absence of an -methyl group in the -position of the eneamines (for noncyclic enaminoketones).For Communication 66, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 642–648, May, 1991.     

Isopropylation of indoline

The composition of the reaction products was ascertained, and the kinetics of the alkylation of indoline with isopropyl alcohol in 90% sulfuric acid at 60C were studied. The reactivities of indoline and its carbocyclic analogs are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 920–922, July, 1991.