Mass spectrometric study of 1-chloro-2-nitrosocycloalkanes,dimers in gaseous phase

The electron-impact mass spectra and the field ionization mass spectra of 1-chloro-2-nitrosocyclohexane and 1-chloro-2-nitrosocyclopetane are presented and discussed. The two compounds investigated exist in dimeric form in the gaseous phase.     

Mass spectrometric investigation of gaseous YbH, YbO and YbOH molecules

The high-temperature gaseous molecules YbH, YbO and YbOH have been identified and their thermochemistry investigated by the Knudsen effusion mass spectrometry technique coupled with a controlled pressure gas inlet system. Solid ytterbium monosilicide and disilicide samples were made to react in the Knudsen cell with H2(g) and H2(g)/O2(g); in these conditions, several gaseous species (Yb, YbO, YbH, YbOH, SiO, SiO2, H2O) were formed under equilibrium conditions. The temperature dependences of the partial pressures of the observed gaseous molecules were analyzed to derive the Yb--X bond energies (X = H, O, OH). Selected values are D0o(Yb--H) = 179.4 +/- 2.0 kJ mol(-1), D0o(Yb--O) = 384 +/- 10 mol(-1) and D0o(Yb--OH) = 322 +/- 12 kJ mol(-1), and Delta(at)H0o(YbOH) = 746 +/- 12 kJ mol(-1). Density functional theory (DFT) calculations were also performed. Experimental and computational results are discussed and compared to previous data when available. The SiO/SiO2 high-temperature gaseous equilibrium was also observed.     

Mass spectrometric study of organocyclosiloxanes

Organocyclosiloxanes of various chemical structures were studied by mass spectrometry using different ionization methods. The electron ionization mass spectra contain no peaks of molecular ions, and the main fragment ions are formed due to complicated rearrangements in a molecular ion, which provides no comprehensive view about the molecular structure. The desorption spectra exhibit peaks of quasimolecular and fragment ions, which characterize both molecular weights and chemical structures of the compounds under study. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1746–1749, September, 2007.     

Mass spectrometric study of 2-azafluorenes

The fragmentation of 2-azafluorene and its methyl and phenyl-substituted derivatives was studied. It is shown that ejection of an RCN fragment (R=CH₃, C₆H₅) by the molecular ions leads to a more intense peak if R is in the 3 position of the azafluorene ring. It was established that, in contrast to the dissociative ionization of fluorene, all of the ions of which are formed from the (M-H)⁺ fragment, the fragmentation of 2-azafluorene and its derivative also takes place from the molecular ion. Randomization of the deuterium atoms attached to C₉ with the remaining hydrogen atoms was observed.Translated from Khimiya Geterotisiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1977.     

Mass spectrometric study of α-carbolines

A series of -carbolines were subjected to mass-spectrometric analysis. It is shown that these compounds are extremely stable with respect to electron impact. From 40 to 60% of the total ion current goes into the production of molecular ions during dissociative ionization. The mass spectra of these compounds are simple: the maximum peak corresponds to the molecular peak in the spectrum. The formation of the [M-1]⁺ ion and the detachment of a methyl group in monomethylcarbolines ([M-15]) are determined by the position of the methyl group. The mass-spectral fragmentation confirms the proposed scheme for the formation of -carbolines from arylhydrazones and 6-keto nitriles. A method for the synthesis of -carbolines on the basis of accessible arylsulfamidoindoles is proposed.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1227–1234, September, 1980.     

Mass spectrometric study of 4-azafluorenes

The dissociative ionization of 4-azafluorene and its methyl and phenyl derivatives was investigated. The relative intensity of the [M — CH₃]⁺ ion peak depends on the position of the CH₃ group in the 4-azafluorene ring. It was established that the loss of an RCN particle (R=H, CH₃, and C₆H₅) for unsubstituted 4-azafluorene takes place from the M⁺ and [M — H]⁺ ion, exclusively from the [M — H]⁺ ion for the methyl-substituted compounds, and from the [M — H]⁺ and [H — 2H]⁺ fragments for the phenyl-substituted derivatives. Randomization of the deuterium ions in the 9,9-d₂-4-azafluorene molecular ion was observed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246–250, February, 1978.     

Mass spectrometric study of desoxyamino sugars

Conclusions The mass spectra of ten 3,4-didesoxy-3-amino sugars have been studied. A novel type of ring cleavage was detected in the molecular ions of these compounds, which had not been encountered in previously studied sugar derivatives.Translated from Izvestiya Akademii Nauk, SSSR Seriya Khimcheskaya, No. 2, pp.437–439, February, 1970.     

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.     

Mass spectrometric study of 8-nitroisoxazolizidines

The mass spectra of dimethyl- and methylphenyl-8-nitroisoxazolizidines have been studied, and the possibility of establishing the position of the substituents on the basis of an analysis of these spectra has been shown. The main routes of the fragmentation of compounds of this class under the influence of electron impact are discussed.     

Mass spectrometric study of derivatives of adamantane

Conclusions The mass spectra of adamantane derivatives, substituted at C-2, possess characteristic features distinguishing them from the mass spectra of adamantane derivatives substituted at C-1.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 337–342, February, 1972.     

Mass spectrometric study of fluorinated β-diketones

Mass spectrometry has been applied in an investigation of fluorinated -diketones and the decomposition of these compounds under electron impact. It has been shown that there is a possibility that intramolecular hydrogen bonds of the -H...O= and-H...F- types may exist in the fluorinated -diketones and the products of their decomposition in the gas phase, these bonds playing an important role in the mechanism of fragmentation. The formation of cyclic structures in this process is postulated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 182–187, March–April, 1985.     

Mass spectrometric study of aliphatic alpha-carbonyl azides

A series of derivatives of 2-azidoacetic acid and 2-azidoacetone were synthesized and their behaviour under electron ionization conditions was investigated. This paper reports the electron ionization fragmentation mechanisms for five aliphatic alpha-carbonyl azides, which were clarified by accurate mass measurements and B/E linked scans. The substituent influences the abundance and the nature of the ions resulting from the molecular ion fragmentation.