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 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.     

Mass spectrometric study of six cyclic esters

A series of cyclic esters, which are optically active as a consequence of their helical structures, were synthesized to investigate the relationships between their structures and their optical activities. This paper reports the electron impact fragmentation mechanisms of these six cyclic esters. Accurate mass measurements and mass analyzed ion kinetic energy spectrometry confirmed fragmentation patterns. The stability of the fragment ions has a great influence on the fragmentation pathways, but no correlation with the optical activity was found.     

Mass spectrometric study of L-arabitol and ribitol diphosphites

The mass spectra of a number of diphosphites were recorded in order to ascertain their structures. Probable schemes for the formation of the characteristic ions are proposed. The possibility of the identification of isomeric diphosphites from mass-spectral data is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 177–180, February, 1979.     

Mass spectrometric study of camptothecin and related compounds

The electron impact mass spectrometric behavior of ten camptothecin analogs (1-10) is described and discussed in detail with the aid of accurate mass measurement and metastable experiment.     

含氟炔酮和炔醛类化合物的质谱研究

本文报道18个含氟炔酮和炔醛类化合物的质谱及其解析结果。在含氟炔酮中,当全氟烷基联结于羰基碳或炔碳上时,质谱的断裂规律有所不同,观察到苯基或取代苯基或全氟烷基重排脱CO的碎片离子,在含氟炔醛中,出现脱CO和脱氟或部分氟碳烷基的碎片的离子(CF2C≡CH)[+]。另外亦出现脱氟或部分氟碳烷基的碎片离子(CF2C≡CCHO)[+],此碎片离子的相对丰度次序为:n-C3F7>C2F5>CF3。在化合物5～15中,有氟重排离子(M-R1R2+F)[+]出现。