The Fragmentation Mechanism of Cyclobutanol

1973 ◽  
Vol 51 (14) ◽  
pp. 2342-2346 ◽  
Author(s):  
John L. Holmes ◽  
Robin T. B. Rye
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectra ◽  
Fragmentation Mechanism ◽  
Hydrogen Atoms ◽  
Specific Mechanism ◽  
Molecular Ion ◽  
Random Manner ◽  
Hydroxyl Hydrogen

The mass spectra of cyclobutanol and three 2H labelled analogs have been studied. The losses of C2H4 and C2H5• from the molecular ion involve specific fragmentations. Only CH3• loss from the α-cleaved molecular ion2 clearly involves hydrogen atom scrambling; this fragmentation also proceeds by a specific mechanism involving C-2 and hydroxyl hydrogen atoms. Loss of water from the molecular ion involves all the hydrogen atoms but in a complex, non-random manner.

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.

MASS SPECTRA OF OXYGENATED QUINOLINES

1966 ◽  
Vol 44 (7) ◽  
pp. 781-788 ◽  
Author(s):  
D. M. Clugston ◽  
D. B. MacLean
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Fragmentation Mechanism ◽  
Significant Extent ◽  
Fragmentation Pathways ◽  
Molecular Ion ◽  
One Step ◽  
The Stability ◽  
Hydroxy Compounds ◽  
Fragmentation Patterns

The mass spectra of the monohydroxyquinolines, the monomethoxyquinolines, N-methyl-2-quinolone, and N-methyl-4-quinolone have been recorded. The isomeric hydroxy compounds vary somewhat in the stability of the molecular ion, but all show the same fragmentation mechanism. Two general fragmentation patterns are discernible in the spectrum of each of the monomethoxyquinolines, but there is considerable variation among the isomers in the extent to which the two patterns occur. In addition, 8-methoxyquinoline undergoes a peculiar fragmentation wherein all three methyl hydrogens are lost. The 3-methoxy compound is unusual in that loss of 43 mass units from the molecular ion occurs in one step. Deuterium- and 13C-labelling experiments have proved to be useful in interpreting the fragmentation pathways. The spectra of the two N-methylquinolones prove that O to N methyl rearrangement does not occur to any significant extent upon electron impact.

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.

Formation of surface layer of hydrogen in pure aluminum

2019 ◽  
Vol 484 (1) ◽  
pp. 56-60
Author(s):  
D. A. Indejtsev ◽  
E. V. Osipova
Keyword(s):  
Surface Layer ◽  
Hydrogen Atom ◽  
Ab Initio ◽  
Pure Aluminum ◽  
Hydrogen Atoms ◽  
Energy Characteristics ◽  
Aluminum Crystal

Hydrogen atom behavior in pure aluminum is described by ab initio modelling. All main energy characteristics of the system consisting of hydrogen atoms in a periodic aluminum crystal are found.

scholarly journals The photolysis of ammonia

1940 ◽  
Vol 175 (961) ◽  
pp. 187-207 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Preceding Paper ◽  
Ammonia Molecule ◽  
Experimental Techniques ◽  
Hydrogen Atoms ◽  
Atom Concentration ◽  
Important Discrepancy

It has been shown in the preceding paper that the hypothesis that hydrazine is responsible for the anomalously low hydrogen atom concentration in the decomposition of ammonia must be abandoned. In order to explain this important discrepancy some new experimental techniques require to be developed which will settle the matter without appeal to further hypotheses. There are two general explanations of the discrepancy: (1) the hydrogen atoms are not produced as fast as that calculated on the assumption that every ammonia molecule absorbing a quantum necessarily decomposes, (2) that some entity not yet recognized removes hydrogen atoms at a rate faster than that at which they normally recombine. In this paper methods will be described in which these two problems are solved, and finally there is a discussion of the photochemistry of ammonia in the light of the new results obtained during these experiments.

scholarly journals Electron Impact Ionization Mass Spectra of 3-Amino 6-Chloro2-methyl Quinazolin-4-(3H)-one Derivative

2021 ◽  
pp. 1-5
Author(s):  
Osarumwense Peter Osarodion ◽  
◽  
Omotade Treasure Ejodamen ◽  
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Impact Ionization ◽  
Cyclic Compound ◽  
Electron Impact Ionization ◽  
Ionization Mass ◽  
Fragmentation Pattern ◽  
Molecular Ion ◽  
Mass Spectral ◽  
Characteristic Fragmentation

Looking at the previous studies on quinazolinones derivatives, only limited information’s are available on their mass spectral along with the preparation of novel quinazolin-4-(3H)-one derivatives The condensation of Methyl-2-amino-4-Chlorobenzoate with acetic anhydride yielded the cyclic compound 2-methyl 7-Chloro-1, 3-benzo-oxazine-4-one (1) which further produce 3-Amino-2-Methyl 7-Chloro quinazolin-4(3H)-ones (2) via the reaction with hydrazine hydrate. The compounds synthesized were unequivocally confirmed by means of Infrared, Nuclear Magnetic Resonance (1H and 13C), Gas Chromatography-Mass spectrophotometry and Elemental analysis. Discussion: The molecular ion of m/z 235 fragments to give m/z 220 by loss of –NH group. The ion of m/z 220 was broken to give m/z 206 by losing CH2 group and fragment to m/z 177 by loss of HCO. This fragmented to m/z 162 by loss of –CH3 group and then m/z 136 by loss of CN group. The loss of O gave m/z 120 which fragment to give m/z 93 by loss of –HCN and finally gave m/z 65 by loss of CO group. Conclusion: The electron impact ionization mass spectra of compound 2show a weak molecular ion peak and a base peak of m/z 235resulting from a cleavage fragmentation. Compound 2 give a characteristic fragmentation pattern. From the study of the mass spectra of compound 2, it was found that the molecular ion had fragmented to the m/z 220. The final fragmentation led to ion of m/z 93 and ion of mass m/z 65, respectively

Mass spectra of some deuterated ethanes. II. An empirical method of calculation of the spectra

1968 ◽  
Vol 46 (10) ◽  
pp. 1741-1746 ◽  
Author(s):  
Y. Amenomiya. ◽  
R. F. Pottie
Keyword(s):  
Mass Spectra ◽  
Reasonable Agreement ◽  
Empirical Method ◽  
Bond Rupture ◽  
Hydrogen Atoms ◽  
Method Of Calculation ◽  
Weighting Factors ◽  
Fragment Ions ◽  
Calculated Mass ◽  
Doubly Charged

Relative intensities of the C2 fragment ions in deuterated (d1–d5) ethanes have been calculated on a statistical basis from the mass spectrum of C2H6 and have been compared with experimental mass spectra previously reported in Part I. For these calculations we have introduced a correction for the relative probabilities of loss of two hydrogen atoms in addition to weighting factors for the loss of H and D atoms. The isotopic weighting factors have been expressed in terms of power series. By this means satisfactory agreement was obtained between the calculated and experimental mass spectra.This treatment also made it possible to calculate the intensities of doubly charged C2 fragments that appear in the C1 mass spectra. We then estimated the degree of reshuffling of hydrogen atoms prior to C—C bond rupture and obtained calculated mass spectra that were in reasonable agreement with the experimental data for the C1 region of the mass spectrum.Experimental mass spectra have been newly obtained for 1,1-d2 ethane and 1,1,1,2-d4 ethane and are included here for completeness.

scholarly journals Relationship between the Behavior of Hydrogen and Hydrogen Bubble Nucleation in Vanadium

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 322
Author(s):  
Zhengxiong Su ◽  
Sheng Wang ◽  
Chenyang Lu ◽  
Qing Peng
Keyword(s):  
Hydrogen Atom ◽  
First Principles ◽  
Bound States ◽  
Hydrogen Molecule ◽  
Vacancy Cluster ◽  
Bubble Nucleation ◽  
Hydrogen Bubble ◽  
First Principles Calculations ◽  
Hydrogen Atoms ◽  
Macroscopic Deformation

Hydrogen plays a significant role in the microstructure evolution and macroscopic deformation of materials, causing swelling and surface blistering to reduce service life. In the present work, the atomistic mechanisms of hydrogen bubble nucleation in vanadium were studied by first-principles calculations. The interstitial hydrogen atoms cannot form significant bound states with other hydrogen atoms in bulk vanadium, which explains the absence of hydrogen self-clustering from the experiments. To find the possible origin of hydrogen bubble in vanadium, we explored the minimum sizes of a vacancy cluster in vanadium for the formation of hydrogen molecule. We show that a freestanding hydrogen molecule can form and remain relatively stable in the center of a 54-hydrogen atom saturated 27-vacancy cluster.

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