Photochemical and mass spectrometric transformation of gibberellenic acid to 9-epiallogibberic acid

1984 ◽  
Vol 62 (10) ◽  
pp. 1996-1998 ◽  
Author(s):  
Hussain K. Al-Ekabi ◽  
Ghazi A. W. Derwish
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
The Other ◽  
Positive Mass ◽  
Hydrogen Migration ◽  
Other Hand ◽  
Impact Fragmentation

Gibberellenic acid (2) reacted thermally in a modified immersion photochemical reactor, to give an intermediate triene (3). This triene then isomerized photochemically, via suprafacial [1,3]-hydrogen migration, to 9-epiallogibberic acid (5). On the other hand, comparison of the positive mass spectra of gibberellenic acid (2), allogibberic acid (4), and 9-epiallogibberic acid (5) showed that gibberellenic acid underwent electron impact fragmentation to the triene 3 cation. This cation then rearranged through suprafacial [1,3]-hydrogen migration to the 9-epiallogibberic acid (5) cation.

scholarly journals MASS SPECTRA OF SOME FUROQUINOLINE ALKALOIDS

1965 ◽  
Vol 43 (9) ◽  
pp. 2516-2521 ◽  
Author(s):  
D. M. Clugston ◽  
D. B. Maclean
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
The Other ◽  
Methoxyl Group ◽  
Quinoline Ring

The mass spectra of six furoquinoline alkaloids have been recorded and mechanisms have been proposed for their fragmentation upon electron impact. Strong metastable peaks, present in all spectra, have aided in the interpretation of the fragmentation of these alkaloids. The three alkaloids with a methoxyl group in the 8-position of the quinoline ring may be differentiated from the other three by the presence of relatively intense peaks at M-1 and M-29.

Structural and energetics effects in the chemical ionization of halogen-substituted benzenes and toluenes

1976 ◽  
Vol 54 (21) ◽  
pp. 3439-3452 ◽  
Author(s):  
Hei-Wun Leung ◽  
Alex G. Harrison
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
The Other ◽  
Substituted Benzenes ◽  
Fragment Ions ◽  
Other Hand ◽  
Benzyl Halides

The H2, D2, CH4, and CD4 chemical ionization (CI) mass spectra of XC6H5, C6H5CH2X, and XC6H4CH3 (X = Cl, Br, and I) have been determined. For the benzyl halides the dominant ion observed in all CI spectra is the m/q 91 (benzyl) ion formed by loss of HX(DX) from the protonated (deuteronated) molecule. The CI spectra of the isomeric halotoluenes differ substantially from the spectra of the benzyl halides indicating that isomerization to a common (tropylium-like) structure does not occur in CI. In the H2 CI of XC6H4Y (Y = H or CH3) the major fragment ions observed are YC6H5•H+, [Formula: see text], and YC6H4+, with the relative yields depending strongly on the halogen substituent. Neither the YC6H5•H+ ion, resulting from HX loss from the H3+•XC6H4Y complex, nor the YC6H4+ ion, resulting from HX loss from XC6H4Y•H+, are observed when X = I. On the other hand [Formula: see text], resulting from elimination of X• from XC6H4Y•H+, is observed only for X = Br and I. In the CH4 CI of XC6H4Y, in addition to XC6H4Y•H+ ions, CH3C6H4Y•H+ ions (HX loss from the CH5+•XC6H4Y complex) are observed for X = F and Cl, while [Formula: see text] ions (loss of X• from XC6H4Y•H+) are observed only when X = I. In addition, displacement of I• by C2H5+, and by C3H5+, is observed in the CH4 CI of the iodo-substituted compounds. The dependency of the products observed and their relative yields on the identity of the halogen substituent is discussed in relation to the reaction energetics.

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.

AN ELECTRON IMPACT STUDY OF SOME C8HI0 ISOMERS

1965 ◽  
Vol 43 (1) ◽  
pp. 211-218 ◽  
Author(s):  
F. Meyer ◽  
P. Haynes ◽  
Stewart McLean ◽  
A. G. Harrison
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Major Part ◽  
The Other ◽  
Fragmentation Pattern ◽  
Impact Study ◽  
Deuterium Labelling ◽  
Appearance Potential ◽  
Alkyl Benzenes

The mass spectra of 1-, 2-, and 6-methylspiro[2.4]hepta-1,3-diene have been measured and found to be very similar to the spectra of 7-methylcycloheptatriene and the isomeric alkyl benzenes. It is concluded that in all cases the major part of the fragmentation occurs by identical paths involving identical intermediates. This conclusion is supported by deuterium labelling and appearance potential data. On the other hand the mass spectrum of 2,5-dimethyl-1,5-hexadien-3-yne, an acyclic C8H10 isomer, shows a number of significant differences in its fragmentation pattern. These differences are reflected in the energetics of ion formation and it is concluded that in this case the fragmentation proceeds through different intermediates.

scholarly journals Synthesis, Characterization and Antitumor Activity of Some New Oganotellurium Compounds Containing Azomethine Group, Part One

2016 ◽  
Vol 8 (1) ◽  
pp. 1464-1471 ◽  
Author(s):  
Rafid H. Al-Asadi ◽  
Tarik A. Fahad ◽  
Bahjat A. Saeed ◽  
Wasfi A. Al-Masoudi
Keyword(s):  
Antitumor Activity ◽  
Hydrazine Hydrate ◽  
Schiff Bases ◽  
Elemental Analysis ◽  
13C Nmr ◽  
Mass Spectra ◽  
The Other ◽  
Azomethine Group ◽  
Other Hand ◽  
Group Part

New tellurated schiff bases were synthesized by the reaction of the corresponding mercurated Schiff  bases compounds A1-A3 with tellurium tetrabromide in 1:1 mole ratio and  that  gave organyltellurium tribromides  A4-A6.  On the other hand, when mercurated schiff bases and tellurium tetrabromide brought  together in 2:1 mole ratio gave diorganyltellurium dibromides compounds A10-A12 followed by reduction with hydrazine hydrate gave new diorganyl tellurides A13-A15.  Reduction of compounds A4-A6 by  hydrazine hydrate gave new ditellurides A7-A9.  All compounds were characterized by elemental analysis, IR, 1H , 13C NMR, HSQC-NMR and mass spectra.  Invitro anti-tumor bioactivity of some compounds were tested. 

Mass spectra of 4,4-dimethyl-A-homocholestane-3,5- and 3,4a diols and their derivatives

1982 ◽  
Vol 47 (12) ◽  
pp. 3328-3338
Author(s):  
Antonín Trka ◽  
Helena Velgová
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Neutral Fragment ◽  
Molecular Ion ◽  
Impact Fragmentation ◽  
Fragmentation Processes

Partial mass spectra of the following 4,4-dimethyl-A-homocholestane derivatives are given: 3,5-epoxides I and II, 3,5-diols III-VI, 3-methoxy-5-ols VII-IX, 3-acetoxy-5-ol X, 3,4a-diols XI-XIV, 3-acetoxy-4a-ols XV-XVIII and 4,4-[2H6]-dimethyl-3,4a-diol XIX, and their electron impact fragmentation investigated. The mass spectra of epoxides I and II, diols III-VI and acetate X are very similar. Considerable differences in mass spectra of methoxy derivatives VII-IX are explained by two mechanisms of elimination of CH3OH from M+. The same similarity of the fragmentation processes and the mass spectra is also observed in diols XI-XIV and acetates XV-XVIII. For the formation of the characteristic ion m/z 288 a fragmentation scheme containing an usual cleavage of the rings A, B, and C is proposed. On the basis of comparison with the mass spectrum of the 4,4-[2H6]dimethyl analogue XIX it was shown that the ion m/z 361 in the mass spectra of diols XI-XIV is formed by elimination of the neutral fragment C6H13 from A-ring of the molecular ion, the last process being accompanied by the 3-hydroxyl transfer from A-ring to the rest of the molecular ion.

E. Radiation Chemistry of Diphenylpicrylhydrazyl (DPPH), IV. The Mass Spectra of Some Aromatic Hydrazines. Comparison of Radiolytic and Photolytic Fragmentations

1976 ◽  
Vol 31 (10) ◽  
pp. 1372-1375
Author(s):  
W. G. Filby ◽  
W. H. Kalus
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Radiation Chemistry ◽  
Hydrogen Migration ◽  
Radiation Induced

The mass spectra of some aryl hydrazines under electron impact are reported. In every case studied fragmentation occurs via fission of the weak hydrazyl N—N bond and hydrogen migration. Metastable ion data is presented in support of a proposed mechanism and some comparisons made between electron and radiation induced processes.

Mass-Spectra of Annelated 4H-3,1-Oxazin-4-ones

1989 ◽  
Vol 42 (10) ◽  
pp. 1813 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Electron Impact ◽  
Radical Cation ◽  
Mass Spectra ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Impact Fragmentation

Electron-impact fragmentation of 2-R-4H-3,1-benzoxazin-4-ones involves primary losses of CO2 and R; there is also loss of ketene when R is methyl. The ion RCO+ is a major daughter. Successive losses of CO2and RCN yield an ion m/z 76 formulated as dehydrobenzene radical cation. In the case of 2-methyl-4H-3,1-naphth[2,3-d]oxazin-4-one, the 2,3-dehydronaphthalene ion is produced efficiently, and linked scans (B/E) were used to demonstrate that it loses C4H2 ( diacetylene ) in a retro Diels-Alder reaction.

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