Mechanism of amine formation in the amination of alcohols in the presence of metal catalysts

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 493–494, February, 1990.     

Anomalous hydrodesoxygenation of benzaldehyde on an iron catalyst

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp, 1695–1696, July, 1988.     

Reaction gas chromatography/mass spectrometry. 2—the use of catalytic on-line dehydrogenation for the investigation of alcohols by gas chromatography/mass spectrometry

A method for structure determination of aliphatic alcohols within mixtures is described. It involves the use of a vapour phase dehydrogenation micro-reactor (Cu, 300°C) located between the chromatographic column and the mass spectrometer or between the injection port and the column. Since primary and secondary alcohols are converted into corresponding carbonyl compounds, they can be readily differentiated from tertiary alcohols and dialkyl ethers. An examination of the mass spectra of alcohols and carbonyl compounds permits the determination of molecular mass, the location of hydroxyl group and the determination of branching at the β-carbon atom.     

Ionization and appearance potentials in organic chemistry. II—Appearance potentials and enthalpy differences for the stereoisomers of methylbicyclo[4.4.0]decanes

The ionization potentials for the stereoisomers of trans-fused 2- and 3-methylbicyclo[4.4.0]decanes and the appearance potentials for the ions at m/e 137 [M–CH₃]⁺, 109, 96, 95 and 82 were measured by the electron impact method. The ionization potentials and appearance potentials of the [M–CH₃]⁺ ions appeared to be equal for each of the epimers. Appearance potentials of the other ions were always lower for the less stable epimer. No quantitative correlation was observed between the difference in the appearance potentials for any ions and the differences in enthalpies of the ground states.     

Stereospecific ion-molecule reactions of anabolic-type steroid tertiary alcohols with proton-donating cations

Isobutane and methane chemical ionization (CI) mass spectra of C-17a-epimeric, 17a-substituted 3-methoxyestra-1,3,5(10),8-tetraen-17a-ols and at C-17-epimeric 17-substituted 3-methoxyestra-1,3,5(10)-trien-17-ols, as well as of some their derivatives, have been studied. In each epimeric pair, the peak intensity ratio [MH-H(2)O](+) / [MH](+) is greater for stereoisomers having an axial (or quasi-axial) hydroxyl group. The same regularity in the peak intensity ratio [MH-CH(3)COOH](+) / [MH](+) is valid for acetates in the D-homo series. The observed quantitative differences in CI mass spectra of epimers are explained by steric hindrance of the attack of the proton-donating cation caused by the angular 18-methyl group. No differences in the ease of elimination of the silanol molecule were observed in CI mass spectra of epimeric silyl ethers.     

Pyrolysis of 8,8-dimethyl-8-sila-2,3,4,5-tetrathiabicyclo[4.3.0]nonane

Conclusions The main products of the pyrolysis of 8,8-dimethyl-8-sila-2,3,4,5-tetrathiabicycIo-[4.3.0]nonane at 400 are 1,1-dimethylsilacyclopent-3-ene and 1,1-dimethyl-1-sila-2-thiacyclo-hexa-3, 5-diene, and at 600 carbon disulfide and thiophene; silacyclopentene is the sole reaction product, characteristic for the mass-spectrometric decomposition of the initial tetrasulfide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No, 4, pp. 902–905, April, 1986.     

Effects of stereoisomerism in the mass spectra of 2,4-disubstituted thiacyclohexanes

The mass spectra of cis- (Ia-c) and trans-2-methyl-4-R-thiacyclohexanes (IIa-c; a R = n-C₄H₉, b R = n-C₅H₁₁, c R = Ph) were studied. It was established that [M-CH₃]⁺ ions, which correspond to the loss of a methyl group from the 2 position, are formed more readily in the case of the less stable trans isomers IIa-c than in the case of cis isomers Ia-c. The three-dimensional structures of the substances have no effect on the degree of elimination of the R substituent. The relative ionization energies (RIE) for Ia,b and IIa,b and the relative appearance energies (RAE) of the [M-CH₃]⁺ ions were measured by the electron impact method. It was found that the RIE are almost 0.05 eV lower and that the RAE of the [M-CH₃]⁺ ions are 0.1 eV lower for trans isomers IIa,b than for cis isomers Ia,b.Communication 4 from the series Ionization and appearance energies in organic chemistry, See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 333–338, March, 1981.     

A thermochemical study of dissociative ionization of 4,4-dimethyl-1-thia-4-silacyclohexane and 2,3,3-trimethyl-1-thia-3-silacyclopentane. Decomposition pathways to produce a dimethylsilanethione ion-radical [Me2SiS]+•

The dissociative ionization of 4,4-dimethyl-1-thia-4-silacyclohexane (I) and 2,3,3-trimethyl-1-thia-3-silacyclopentane(II) has been studied by electron photoionization (PI) mass spectrometric methods. The molecular ion fragmentation is mainly related to the loss of ethylene and results in a [Me₂SiSC₂H₄]^+? (m/z 118) ion-radical (A). Further loss of ethylene from A produces a dimethylsilanethione [Me₂SiS]^+? (m/z 90) ion-radical (B). The latter is the most abundant ion in the mass spectra of I and II at 70 eV.The ionization energies (IE) of I (8.22 ± 0.07 eV) and II (8.06 ± 0.03 eV) and the appearance energies (AE) of ion-radicals A and B have been determined. Also, the following heats of formation were calculated (kJ/mol): ΔH_f⁰(I) = ?31.1; ΔH_f⁰(II) = ?65.8; ΔH_f⁰(M_I^+?) = 762.0; ΔH_f⁰(M_II^+?)= 712.1; ΔH_f⁰(A)_aver = 780.2; ΔH_f⁰(B)_aver = 847.7.     

Mass-spectrometric study of permethyl compounds of group IVB elements

Russian Chemical Bulletin -     

Mass spectrometric study of monoalkyl-substituted thiacyclanes

Monosubstituted - and -alkylthiophans and -, -, and -alkylthiacyclohexanes were subjected to a comparative mass spectrometric study. The stability of the M⁺ ion increases on passing from - to -alkylthiophans and from - to - and -alkylthiacyclohexanes. In the case of -alkylthiophans and - and -alkylthia-cyclohexanes the principal process is associated with ejection of the substituent as a whole, whereas a portion of the alkyl substituent, with retention of one CH₂ group in the composition of the charged fragment, is eliminated from the molecular ions of -alkylthiophans and -alkylthiacyclohexanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–181, February, 1978.