Mass Spectrometric Studies. XIV. Nitrochalcones

1979 ◽  
Vol 32 (10) ◽  
pp. 2249 ◽  
Author(s):  
J Baldas ◽  
QN Porter
Keyword(s):  
Oxygen Transfer ◽  
Mass Spectra ◽  
Nitro Compounds ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Hydrogen Atoms ◽  
Carbon Carbon Bond ◽  
Nitro Derivatives ◽  
Anchimeric Assistance ◽  
Hydroxy Groups

The mass spectra of chalcone, of its 2-, 2'-, 3-, 3'- and 4-nitro derivatives, and of a number of deuterated analogues, are described. Fragmentation of the 2-nitro isomer is very simple on account of anchimeric assistance to a carbon-carbon bond fission from the nitro group. The 2'-nitro isomer shows complex fragmentation resulting from oxygen transfer to the α,β-double bond. The 3-, 3'-, and 4-nitro compounds fragment in ways similar to that of chalcone itself, except for losses of hydroxy groups from their molecular ions. The origins of the transferred hydrogen atoms are shown by labelling experiments, and structures are suggested for the ions formed.

Mass spectrometric studies. XI. Skeletal rearrangements in acylhydrazines

1972 ◽  
Vol 25 (3) ◽  
pp. 523 ◽  
Author(s):  
QN Porter ◽  
AE Seif
Keyword(s):  
Nitrogen Atom ◽  
Alkyl Group ◽  
Phenyl Ring ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
The Other ◽  
Hydrogen Atoms ◽  
Neutral Product ◽  
Skeletal Rearrangements ◽  
Phenyl Compounds

The mass spectra of mono- and di-alkyl-N,N'-dibenzoylhydrazines contain rearrangement ions arising from initial migration of a benzoyl or alkyl group from one nitrogen atom to the other. The spectra also contain ions resulting from N-N fissions accompanied by transfer of one or two hydrogen atoms. The spectra of the mono- and di-phenyl compounds are simpler, but that of the monophenyl compound contains an ion in the formation of which two hydrogen atoms have been transferred to the neutral product from a phenyl ring.

Mass spectrometric studies. X. Phenacylpyridinium enol-betaines

1972 ◽  
Vol 25 (2) ◽  
pp. 345 ◽  
Author(s):  
IC Calder ◽  
QN Porter ◽  
CM Richards
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectra ◽  
Parent Compound ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Deuterium Labelling ◽  
E 92

Phenylpyridinium enol-betaines have mass spectra containing abundant molecular ions which decompose by loss of a hydrogen atom to give intense M- 1 species. Both ions eliminate CO and CHO units, and the courses of the various decompositions have been established by making use of deuterium labelling. The ion at m/e 92 in the spectrum of the parent compound is best described by an azatropylium structure.

Epoxidation of 4,4-dimethyl-A-homo-4a-cholestene derivatives and a study of electron impact mass spectra of the epoxidation products

1982 ◽  
Vol 47 (1) ◽  
pp. 315-337 ◽  
Author(s):  
Helena Velgová ◽  
Antonín Trka
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Characteristic Decomposition ◽  
Conformational Effects ◽  
Electron Impact Mass ◽  
Decomposition Pathway ◽  
Impact Mass

The effect of the substituent in the position 3 on the epoxidation of some 4,4-dimethyl-A-homo-4a-cholestene derivatives was investigated. The stereochemistry of the epoxidation is affected mainly by sterical and conformational effects. The mass spectrometric behaviour of epoxides IV-XI, XV-XX, XXIII and XXIV and of 4a,5-unsaturated 3-ketones XXI and XXVI was also studied. The double-transannular cleavage represents a common and characteristic decomposition pathway of molecular ions of these compounds.

scholarly journals Zur intermediären Existenz von Ethylenfluoronium-Ionen in der Gasphase/ On the Intermediary Existence of Gaseous Ethylen Fluoronium Ions

1983 ◽  
Vol 38 (5) ◽  
pp. 635-638 ◽  
Author(s):  
Bernhard Ciommer ◽  
Helmut Schwarz
Keyword(s):  
Ring Opening ◽  
Molecular Ions ◽  
Dissociative Ionization ◽  
Hydrogen Atoms ◽  
Hydrogen Migration ◽  
Direct Formation ◽  
Anchimeric Assistance

Abstract The long-sought ethylen fluoronium ion (2) is generated as an intermediate in the dissociative ionization of 1-fluoro-2-(p-methyl)phenoxy ethane (4). However, prior to collisionally induced dissociation 2 undergoes ring-opening, associated with hydrogen migration, to form 1-fluoroethyl cation (3). Other decomposition pathways of the molecular ions of 4 involve (i) direct formation of 3 via a combination of C-O-cleavage (loss of ArO -) and [1,2] hydrogen migration (18%) and (ii) complete positional loss of the a-and β-methylene hydrogen atoms (34%). The remaining 48% of the molecular ions of 4 dissociate via anchimeric assistance of the fluorine in the elimination of ArO·, thus giving rise to the formation of 2.

Studies in Mass Spectrometry. II. Random Hydrogen Rearrangement in Aromatic Molecular Ions

1962 ◽  
Vol 15 (4) ◽  
pp. 771 ◽  
Author(s):  
CG Macdonald ◽  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Aromatic Compounds ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Deuterium Exchange ◽  
Molecular Ion ◽  
Hydrogen Rearrangement ◽  
Aromatic Hydrogen

To provide data for investigations by, inter alia, mass-spectrometric methods into the deuterium exchange of the aromatic hydrogen of some coal fractions, a study was made which confirmed the occurrence of completely random hydrogen rearrangement prior to or during the elimination of C2H2 in the molecular ions of benzene-1,2,3-d3, benzene-l,3,5-d3, naphthalene-1,2,3,4-d4, naphthalene-1,4,5,8-d4, and phenanthrene-9,10-d2, and in the phenyl ions derived from o-bromobenzene-d, m-bromobenzene-d, and p-chlorobenzene-d, Similar but incomplete hydrogen rearrangement was found to occur in the molecular ion of carbazole-N-d prior to or during elimination of HCN. Such rearrangements, for which mechanistic considerations are presented, must be taken into account when the mass spectra of deuterium-substituted aromatic compounds are being interpreted.

The mass spectrum of exo-2-norbornyl chloride; the elucidation of the fragmentation mechanism and ion structures by metastable ion analysis

1970 ◽  
Vol 48 (18) ◽  
pp. 2791-2797 ◽  
Author(s):  
J. L. Holmes ◽  
D. McGillivray ◽  
N. S. Isaacs
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Fragmentation Mechanism ◽  
Hydrogen Atoms ◽  
Ethylene Molecule ◽  
Molecular Ion ◽  
Carbonium Ions ◽  
Ion Analysis

The mass spectra of exo-2-norbornyl chloride and several deuterated analogues have been examined in detail with particular regard to metastable peaks involving the molecular ions and norbornyl cations. The molecular ion does not undergo Wagner–Meerwein isomerization prior to fragmentation; in the norbornyl cation the hydrogen atoms have lost their identity as shown by random H and D loss when the ion ejects an ethylene molecule. Metastable ion analysis is proposed as a method for studying the participation of norbornyl carbonium ions in the preparation of 2-norbornyl chloride.

Splitting off of water from the molecular ions of steroidal cyclopropyl ketones

1980 ◽  
Vol 45 (11) ◽  
pp. 2985-2997 ◽  
Author(s):  
Alexander Kasal ◽  
Antonín Trka
Keyword(s):  
Water Molecule ◽  
Mass Spectra ◽  
Cyclopropane Ring ◽  
Molecular Ions ◽  
Keto Group ◽  
Hydrogen Atoms ◽  
Molecular Ion ◽  
Cyclopropyl Ketones

Mass spectra of 14 steroids containing a cyclopropane ring in the vicinity of a keto group were measured and the signals of the ions [M-H2O]+, [M-CH3]+ and [M-CO]+ were sought. Using models labelled selectively with deuterium it was shown that the water molecule, split off from the molecular ion of 3α,5-cyclo-5α-cholestan-6-one (I) is formed from the hydrogen atoms located in the positions 2β and 9α.

Inductive effect in EI-mass spectra of some 5,6-dihalogenides and 5,6-halohydrins of 5α-cholestan-3β-ol and 3β-acetoxy-5α-cholestane

1982 ◽  
Vol 47 (11) ◽  
pp. 2946-2960 ◽  
Author(s):  
Antonín Trka ◽  
Alexander Kasal
Keyword(s):  
Mass Spectra ◽  
Inductive Effect ◽  
Molecular Ions ◽  
Hydroxyl Group ◽  
Halogen Atoms ◽  
Derivatives Of

Partial EI-mass spectra of 3β-hydroxy- and 3β-acetoxy-5α-cholestanes substituted in positions 5α-, 6β- or 5α,6β- with a hydroxyl group or halogen atoms (fluorine, chlorine, bromine) are presented. The molecular ions of 5α,6β-disubstituted derivatives of 3β-hydroxy-5α-cholestane (or of its 3-acetate) are considerably more stable than the corresponding monosubstituted derivatives if at least one of the pair of the vicinal substituents is chlorine or fluorine. This increase in stability, most striking in 5α- and 6β-fluoro compounds, is explained by the inductive effect.

Mass spectra of 4,4-dimethyl-A-homo-4a,6-cholestadien-3-ols, 4,4-dimethyl-A-homo-5-cholestene-3,4a-diols and their derivatives

1982 ◽  
Vol 47 (10) ◽  
pp. 2768-2778
Author(s):  
Antonín Trka ◽  
Helena Velgová
Keyword(s):  
Carbon Atom ◽  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions

Partial electron impact induced mass spectra are given of 3α-hydroxy-, 3β-hydroxy-, 3β-methoxy-, 3α-acetoxy- and 3β-acetoxy-4,4-dimethyl-A-homo-4a,6-cholestadienes, 3α,5α-epoxy-4,4-dimethyl-A-homo-5-cholestane, isomeric 4,4-dimethyl-A-homo-5-cholestene-3α(β),4aα(β)-diols, their 3-acetoxy derivatives and 3-methyl ethers. The fragmentation of the molecular ions of these substances involves the usual elimination of substituents (in the form of H2O, CH3OH, CH3COOH, CH2CO), but the most abundant and characteristic ions are products of the contraction of ring A (to a six- or five-membered one), accompanied by expulsion of a fragment containing the carbon atom C(4) with both methyls.

Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und n-Pentylbenzol in der Gasphase / Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes

1979 ◽  
Vol 34 (3) ◽  
pp. 495-501 ◽  
Author(s):  
C. Wesdemiotis ◽  
H. Schwarz ◽  
C. C. Van de Sande ◽  
F. Van Gaever
Keyword(s):  
Hydrogen Exchange ◽  
Closed Shell ◽  
Open Shell ◽  
Molecular Ions ◽  
Exchange Reactions ◽  
Intramolecular Exchange ◽  
Carbon Carbon Bond ◽  
Exchange Processes ◽  
Reaction Channels ◽  
Alkyl Benzenes

Abstract The investigation of several 13carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations.

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