Electron impact mass spectra of penitrem A,some derivatives and its analogues

The mass spectra of penitrems A-E and some derivatives of penitrem A have been measured. Fragmentation pathways have been confirmed by use of the linked scan (B/E) technique and are consistent with the formulation of the compounds as analogues of paspalinine.     

Electron impact mass spectra of some enamines

The mass spectra of α,β-diarylaminocrotonic acid anilides have been determined and the fragmentation pathways are now discussed. The proposed pathways have been confirmed by deuterium labelling, the spectrum of the model compound, or the appropriate metastables. The detailed electron impact data are given.     

Electron impact mass spectra of some substituted aromatic boronate derivatives of bifunctional compounds

The electron impact mass spectra of the 3,5-bis(trifluoromethyl)benzeneboronate, 2,4-dichlorobenzene-boronate and 4-bromobenzeneboronate derivatives of some bifunctional diols and aminoalcohols are characterized by prominent molecular ions with diagnostically useful modes of fragmentation. Many of the principal ions in the mass spectra retain boron in their structure.     

Electron impact mass spectra of some new macropolycycles

Mass spectra of some macropolycycles have been studied. Normal and metastable (B/E) mass spectra are presented. The fragmentation patterns and the structures of the main ions are discussed.     

Electron impact mass spectra of some dioximes of o-diacyl benzenes

The electron impact mass spectra of the new synthesized dioximes of o-diacyl benzenes (2) are reported. In addition to the molecular ion, characteristic peaks appear at values corresponding to the [M ? OH] ⁺, [M ? NOH]⁺ and [M ? NHOH]⁺ ions. No initial dehydration of the molecular ion has been observed.     

The Raman spectra of some aromatic nitro compounds

The paper provides a re-appraisal of the analytical value of Raman spectroscopy in the investigation of aromatic nitro compounds. Correlations are found between the frequencies of the NO vibrations and the electron-donating and -withdrawing effects of substituents on the phenyl rings. Further, relations are discussed between the highest-frequency CH stretching mode and the electron density and number of nitro groups. The paper contains a large number of spectra of typical aromatic nitro compounds.     

Electron impact mass spectra of some enols and their alkyl ethers

The mass spectra of α-arylamino-β-hydroxycrotonic acid anilides and their O-methyl and O-ethyl ethers have been determined and the characteristic fragmentation pathways are discussed. The proposed fragmentation patterns are supported by the appropriate metastables and deuterium labelling.     

Low-energy mass spectra of some aliphatic ketones

The charge exchange mass spectra of a selection of C₅-C₇ ketones have been measured using [CS₂]⁺˙, [COS]⁺˙ and [N₂O]_+. as reagent ions. The low energy charge exchange with [CS₂]⁺˙ or [COS]⁺˙ provides simple primary ion mass spectra, which readily permit structure elucidation in contrast to metastable ion spectra. In several cases, isomer distinction is easier from the charge exchange mass spectra than from the electron impact mass spectra. The energy transfer from [N₂O]⁺˙ is sufficiently high for complex spectra resembling electron impact mass spectra to be obtained.     

Electrolysis of aliphatic nitro compounds

Conclusions Data on electrolysis in strongly acidic media have shown that, contrary to accepted belief, reduction of the un-ionized form of trinitromethane proceeds through C-N bond rupture rather than through breakage of the nitro group N-O bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1725–1729, August, 1976.     

Denitrohydrogenation of aliphatic nitro compounds and a new use of aliphatic nitro compounds as radical precursors

Aliphatic nitro groups are replaced by hydrogen on treatment with tributyltin hydride which proceeds via free radical chain processes. As the nitro group is selectively denitrated and other reducible groups are not affected with tributyltin hydride, this reaction can be used as a method for removing the nitro group from polyfunctional compounds. The radical intermediates generated via denitration can be also used for the carbon-carbon bond forming reactions.     

Electron impact and chemical ionization mass spectra of some tetra-acetylated anomeric glycosides

Electron impact and chemical ionization (CH₄, iso-C₄H₁₀ and NH₃) mass spectra of some tetra-acetylated anomeric glycosides have been examined with a view to the characterization of anomeric pairs. Minor differences observed in the relative intensities of common ions in the anomeric pairs in the electron impact mass spectra are found to be enhanced in the methane and isobutane chemical ionization mass spectra. In the absence of thermal decomposition, the β-anomers show greater ion abundances of common glycosyl ions than the α-anomers. Ammonia chemical ionization mass spectra show complementary behaviour indicating strong adduct ions and practically no fragmentation.