bluuebunny/crossref_metadata_2025_split huggingface dataset:
The benzoyl ion. Thermochemistry and kinetic energy release
Authors: Elder J. F. , Beynon J. H. , Cooks R. G. 
Published: May 2005

AbstractThe thermochemistry of benzoyl ion formation from a variety of sources has been examined by using the measured kinetic energy release for metastable ions to estimate the excess energy of the activated complex. A correlation is observed between this estimated excess energy and literature values of the heat of formation of the benzoyl ion. From this relationship and the observed correlation between the uncorrected heat of formation and the difference between the appearance potential of [C6H5CO]+ and the ionization potential of the parent compound, the large range of reported values for ΔHf[C6H5CO]+ is seen to be due, at least in part, to variation in the kinetic shift with the critical energy of the reaction. With the exception of the ion generated from trifluoroacetophenone and possibly that from benzaldehyde, the fragmenting [C7H5O]+ ions are shown, from kinetic energy release data, to be structurally identical. The approach adopted here may have general merit in improving or testing the accuracy of thermochemical data based on appearance potential measurements.
Distributions of kinetic energy release in benzoyl ion formation
Authors: Elder J. F. , Cooks R. G. , Beynon J. H. 
Published: May 2005

AbstractDistributions of the kinetic energy release have been determined for reactions of metastable ions leading to formation of the benzoyl cation. Although the reactions studied were all apparent simple bond cleavages, the shapes of these distributions varied widely, as did the magnitude of the most probable energy release. There is evidence that the shape of the distribution function is related to the mechanism of the reaction. In one case the distribution shows structure not seen in the metastable peak itself, suggesting that at least two reaction pathways are operative. Thus, the present measurements on energy distributions supplement the information concerning different elementary reactions that can be obtained from the study of metastable peaks.
Elimination reactions of ions in the gas phase
Authors: Kuster Th. , Seibl J. 
Published: May 2005

AbstractThe loss of water from the molecular ion of 2‐adamantanol was investigated using specifically labelled deuterium derivatives, and, in particular that stereospecifically labelled in position 4. Water is lost predominantly in a stereospecific 1, 3 fashion by two clearly distinguishable mechanisms. Determination of metastable ion characteristics proved to be essential for drawing this distinction.
An attempt to correlate appearance potentials and semi‐empirical SCF‐LCAO‐MO data
Authors: Sterk Heinz , Heresch Franz 
Published: May 2005

AbstractApplying the Bell‐Evans‐polanyi principle to mass spectrometric gramentations gives a relationship for calculating their activation energies from various MO data, such as heats of formation and electronic populations. Additionally, a possible extension of the original Bell‐Evans‐Polanyi principle is discussed.
The mass spectrometry of some t‐butyl peresters
Authors: Krull I. S. , Mandelbaum Asher , Mandelbaum Asher 
Published: May 2005

AbstractMass spectrometry is suggested as a method for the general characterization of mono‐ and di‐t‐butyl peresters. In many instances it is possible to measure the molecular ion, especially in the mono‐t‐butyl peresters. The fragmentation patterns of various t‐butyl peresters are presented.
Chemical ionization mass spectrum of peroxyacetylnitrate
Authors: Pate Christopher T. , Sprung Jeremy L. , Pitts James N. 
Published: May 2005

AbstractThe chemical ionization mass spectrum of peroxyacetylnitrate, a major component of photochemical smog highly toxic to man and plants, was obtained using both methane and isobutane as reagent gas. The spectrum contains a [M + H]+ ion at m/e 122, intense fragment ions at m/e 43 [CH,CO]+ and m/e 46 [NO2]+, and less intense ions at m/e 61 [CH,ONO]+, m/e 77 [CH30NOz]+ and m/e 88 [+OCCH2ONO] formed by internal rearrangements. These results confirm the commonly accepted structure for peroxyacetylnitrate, CH3(CO)OONO2.
o‐Nitrobenzylidene compounds. I—Competitive ortho interactions in the mass spectra of n‐o‐nitrobenzylidene‐o‐substituted anilines
Authors: Johnston David , Smart Graeme W. , Smith David M. 
Published: May 2005

AbstractThe intense [M – 17]+ ion, which is a characteristic feature of the mass spectra of N‐o‐nitrobenzylideneaniline and its simple derivatives, may be substantially reduced in intensity when the aniline‐derived ring is also ortho substituted: the intensity is lowest when this ortho substituent has a nucleophilic character and can itself interact with the CHN group. The ortho substituents examined are Br, CH3, OH, NH2, SH, SC6H4CH3(p), CO2CH3 and CO2C2H5.
Konstitutionelle Effekte bei der Chemischen Ionisationsmassenspektrometrie di‐ und Trifunktioneller Diterpene
Authors: Schwarz Helmut , Bohlmann Ferdinand , Rapp Uwe , Windel Bernd 
Published: May 2005

AbstractDie Untersuchung der Chemische‐Ionisations‐spektren von Diterpenen mit zwei bzw. drei Sauerstoffunktionen zeigt, daß die relative Anordnung dieser funktionellen Gruppen für die Abbaureaktionen der Protonierten Molekül‐Ionen vongroßer Bedeutung ist. Auch der Gebrauch von “Direct Analysis of Daughters Ions” und von Defokussierungsaufnahmen durch Variation der Beschleunigungsspannung bei der chemischen Ionisation hibt Einblick in das Fragmentierungsverhalten. die Resultate sind wahrscheinlich auch in anderen Fällen für die Lokalisierung funktioneller Gruppen mit Hilfe der chemischen Ionisation von Bedutung.
Carbon randomization in the fragmentation of [C4H9]+ derived from t‐butyl derivatives
Authors: Leung Hei‐wun , Tsang Chun Wai , Harrison Alex. G. 
Published: May 2005

AbstractThe mass spectrum of 13C centrally labeled neopentane has been re‐examined at a mass resolution sufficient to resolve 13C‐CH mass doublets. Contrary to earlier low resolution results, the [C3H5]+ fragment ion is formed with 75% retention of the central carbon under all experimental conditions, indicating complete carbon scrambling in the fragmentation reaction [C4H9]+→[C3H5]+ + CH4. The higher retention of the central carbon in [C3H5]+ in the mass spectra of (CH3)3CCl and (CH3)3CBr is shown to be due to the occurrence of the reaction sequence

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A study of the ortho effects and rearrangement processes in the mass spectra of 2‐arylaminothiazine and ‐thiazoline derivatives
Authors: Bujtás Gy. , Tamás J. 
Published: May 2005

AbstractThe behaviour of the title compounds under electron impact has been investigated using low and high resolution mass spectrometry and partial 15N and D labelling. A number of ions produced by rearrangement were observed. Abundant ions are formed by intramolecular ortho substitution reactions (cyclizations), as demonstrated by energetic and kinetic considerations and by studying the decomposition pathways of these ions. The ortho substitution processes involve loss or rearrangement of an ortho group of the aromatic ring.
NH3‐Eliminierungen aus 2‐Äthoxybenzoesäureamid und 2‐Äthoxybenzylamin Als Weitere Beispiele [Komplexer] Ortho‐Effekte
Authors: Schwarz Helmut , Wolfschütz Roland 
Published: May 2005

AbstractDie Mechanismen der Ammoniak‐eliminierung aus den Molekül‐lonen der Titelverbindungen konnten durch die Untersuchung 2H‐markierter Verbindungen aufgeklärt werden. Es wird gezeigt, daß der eigentlichen Fragmentierung ein partilles wasserstoff‐Scrambling vorgelagert ist, das durch die Carbonylfunktion begünstigt wird. Darüber hinaus wird ein weiteres Beispiel einer ungewöhnlichen Äther‐Alkyl‐Spaltung beobachtet, die ebenfalls durch eine nachbargruppenwechselwirkung ermöglicht wird.
Doubly charged fragment ions in the field ionization mass spectra of alkylbenzenes
Authors: Röllgen F. W. , Heinen H. J. , Levsen K. 
Published: May 2005

AbstractIt is shown that the radical [C6H5CmH2m]2+fragment ions found in the field ionization mass spectra of alkylbenzenes are formed via a different adsorption state of the singly charged species than in the case of the formation of [M]2+molecular ions. It is further demonstrated that the primary fragmentation of molecules by the cleavage of CC bonds results not only from decompositions of molecular ions in the gas phase but also from surface reactions.
ÄThylen‐Eliminierung aus dem [C7H11]+‐Ion des 4.4‐Dimethylpentin‐(2)‐Ylchlorids‐(1)
Authors: Bohlmann Ferdinand , Brehm Manfred , Schwarz Helmut 
Published: May 2005

AbstractDurch die Untersuchung einer 13C‐ und 2H‐markierten Verbindung wird belegt, daß der Äthylen‐Eliminierung aus dem [M‐C]+‐Ion ein vollständiges C‐ und H‐Scrambling vorgelagert ist, Die Isomerisierungsprozesse hängen nicht von der Lebensdauer der zerfallenden [C7H11]+‐Ionen ab.
Lokalisierung von Substituenten bei Porphyrinen: Das Massenspektroskopische Fragmentierungsverhalten von Porphyrinogenen
Authors: Budzikiewicz Herbert , Pesch Reinhold 
Published: May 2005

AbstractEs wird gezeigt, innerhalb welcher Grenzen aus den Massenspektren von Porphyrinogenen Rückschlüsse auf die Substituentenanordnung gezogen werden Können.
The long‐lived molecular ion of propionitrile: An ion cyclotron resonance study
Authors: Theissling Carla B. , Nibbering Nico M. M. , Meyerson Seymour 
Published: May 2005

AbstractEvidence has been reported that primary loss of H and of HCN from the molecular ions of propionitrile, isobutyronitrile and butyronitrile in the mass spectrometer is preferentially preceded by hydrogen migration from C‐2 to C‐1. Ion cyclotron double resonance spectra of proton (or deuteron‐) transfer products derived from propionitrile‐2‐d2 and ‐3‐d3 and a series of bases provide evidence that such migration occurs also in long‐lived propionitrile molecular ions.
A comparative study of the pyrolytic and electron impact‐induced fragmentations of 4‐phenylbutanoic acid and some analogues
Authors: Posthumus M. A. , Nibbering N. M. M. , Boerboom A. J. H. 
Published: May 2005

AbstractBy use of deuterium labelling it is shown that the mechanisms of fragmentation of the title compounds upon Curie‐point pyrolysis and electron impact are essentially different. For example, the pyrolytic expulsion of water from 4‐phenylbutanoic acid is a 1,2 eliminations, whereas upon electron impact water is expelled via a 1,4 elimination; the generation of styrene from this acid proceeds via a concerted mechanism upon pyrolysis, but via a stepwise mechanism upon electron impact.
Charge exchange mass spectrometry at high energy
Authors: Hsu C. S. , Cooks R. G. 
Published: May 2005

AbstractIt is shown that charge exchange mass spectra using various reagent ions can be determined on a commercial double focusing mass spectrometer. The experiment relies upon the presence of a collision region held at a potential above ground with the product ions being selected by their unique kinetic energies. Cyclohexene has been studied in detail and the results are in agreement with previous thermochemical and field ionization kinetics data. Agreement with reported charge exchange spectra of n‐propanol, taken at lower energies, is good. The present results, including both the variation of spectra with reagent gas and the small range of kinetic energies present in the charge exchange beam, indicate that a resonant or near resonant process is involved. Thus, the internal energy of the nascent ion is defined within quite narrow limits, just as is the case for charge exchange at lower energy.
Etude en Spectrometrie de Masses des Fragmentations de Derives de la Triazine‐1,2,4
Authors: Lavergne Jean‐Pierre , Viallefont Philippe , Daunis Jacques 
Published: May 2005

AbstractLes spectres de masse de 49 triazines‐1,2,4 différemment substituées en position 6, possédant les groupes oxo, thioxo, méthylmercapto en position 3 et 5 et de leurs dérivés N‐méthylés sont décrits. Cinq processus de fragementation du cycle traizine, liés á la structure et notamment á la nature du groupement fonctionnel en position 5 sont mis en évidence. L'un d'eux, engageant les ruptures des liaisons N‐1N‐2 et C‐5C‐6, est identifié dans tous les cas. Les pertes d'azote et de monoxyde de carbone ne sont pas observées. Pour certains composés la participation á l'équilibre, á l'état vapeur, de certaines formes tautoméres a été discutée.
Mass spectra of some triaryl derivatives of the group V elements, P, As, Sb and Bi
Authors: Spalding T. R. 
Published: May 2005

AbstractTriphenyl and tri‐o‐, m‐ and p‐tolyl compounds of the elements P, As, Sb and Bi have been studied as well as tri‐(2,6‐dimethylphenyl)phosphine. The m‐ and p‐tolyl isomers show very similar behaviour and differ significantly from the o‐derivatives. The differences can be largely attributed to steric effects in the o‐isomers. Major fragmentation pathways to Group V element (Mt)‐containing ions involve MtC and CH, and from the tolyl compounds CC bond cleavages. Throughout this paper the symbol Mt is used to refer to the Group V element.
The behaviour of some α,α′‐dibromoketones on electron impact. An analogy to the reductive removal of bromine in solution
Authors: Hoffmann H. M. R. , Loudon A. G. 
Published: May 2005

AbstractThe relative importance of the rearrangement ions [M  Br  CO]+, [M  Br2  CO]+ and [M  HBr2  CO]+ in the mass spectra of the title compounds is compared with the amounts of α‐methoxyketone formed on reduction of these compounds with a Zn/Cu couple in methanol. It is suggested that the quantitative correlation found reflects the electron releasing powers of the substituents on the α carbons.
Mass spectrometry of 3‐methoxy fatty acid methyl esters
Authors: Zirrolli Joseph A. , Murphy Robert C. 
Published: May 2005

AbstractFatty acids with a hydroxyl moiety at the C‐3 position are found widely in bacterial lipids, but only rarely in mammalian lipids. The mass spectra of the methyl ether derivative of these hydroxy acids exhibit an intense ion at m/e 75, rather than the rearrangement ion at m/e 74 more typical of fatty acid methyl esters. The mass spectrometric behavior of several 3‐methoxy fatty acid methyl esters were studied, and the origin of the unique ion at m/e 75 was established using 18O and 2H labeled analogs and metastable ion transitions. this ion was shown to arise from the loss of ketene from the 3,4 cleavage ion at m/e 117.
Interpretation Automatique du Spectre de Masse de Complexes Metalliques π Incluant des Derives du Silacyclopentadiene
Authors: Lageot C. 
Published: May 2005

AbstractLe programme précédemment mis au point pour élucider la structure de composés cycliques saturés et insaturés incluant un atome de groupe IV a été complété pour qu'il sooit applicable aux complexes métalliques π. Leur structure est ainsi déterminée à l'aide du spectre de masse et du programme adéquat en quelques secondes.
Chemical ionization of cyclopropyl ethers II—the nature of the alkyl group fragmentationt
Authors: Andrist A. Harry , Slivon Laurence E. , Wilburn Bruce E. 
Published: May 2005

AbstractOxygen‐alkyl cleavage is ruled out in the methane chemical ionization‐ and electron mpact‐induced decomposition of cyclopropyl ethers by the finding that for trans,trans‐2,3‐diethylmethoxycyclopropane the [M  C2H5·]+ ion is more intense than the [M  CH3·]+ ion. The possibility for [M + H  C2H6]+ is discounted by comparison with the methane chemical ionization nass spectrum of tran,tran‐2,3‐dimethylmethoxycyclopropane. The isobutane chemical ionization nass spectrum of the diethylcyclopropyl methyl ether affords nearly exclusive electrocyclic methanol fragmentation, i.e. [M + H  CH3OH]+.
The computer processing and interpretation of mass spectral information. II—computation of the degree of isotope labelling in organic compounds
Authors: Sukharev Yu. N. , Nekrasov Yu. S. 
Published: May 2005

AbstractThe program ISOMETA which processes the low resulution mass spectra and determines the degree of labelling in the molecular and fragment ions is described. The degree of labelling for any stable isotope (D, 13C, 15N, 18O, etc.) in compounds of known molecular formulae can be estimated. The compound may contain any number of elements and atoms of each element. The mass spectra are processed in terms of peak groups of the molecular and fragment ions which have been identified as having one composition. The program is written in ALGOL, runs on a BESM‐6 computer and requires 6.5K core memory.
Study of ions with excess kinetic energy. III—Mass spectra of excess kinetic energy ions of aliphatic amines
Authors: Tsuchiya M. , Tamura K. 
Published: May 2005

AbstractThe mass spectra obtained from ions having excess kinetic energy (named the excess kinetic energy mass spectra) formed by electron impact of several aliphatic amines have been studied. Comparison with the excess kinetic energy mass spectra of the analogous alcohols shows many similarities. For example, the intensity of the [CH2OH]+ ion of an aminoalcohol is about the same as the intensity of the [CH2NH2]+ ion. The excess kinetic energy mass spectra give useful information about the presence or absence of various functional groups, such as CH2NH2, CH2OH, CH3CHNH2 and alkyl groups, and also about rearrangements. The fragmentation mechanisms are straightforward and applicable to a variety of classes of compounds. The molecular weight dependence of excess kinetic energy mass spectra is described.
Electron impact studies. CVII—Negative ion mass spectra of the oxime group. Monoximes derived from α‐dicarbonyl systems
Authors: Bowie John H. , Janposri Sompong 
Published: May 2005

AbstractSpecific losses of water are observed from the molecular anions of monoximes of α‐diketones. Labelling studies, kinetic energy release values and the +E spectra of magnified image ions have been used to aid in the elucidation of the fragmentation pathways. It is proposed that the majority of magnified image ions have α‐keto nitrile structures.
Zur Lokalisierung Funktioneller Gruppen mit Hilfe der Massenspektrometrie. XV—Massenspektren von androstanen mit Hydroxygruppen in den Positionen 3, 16 und 17
Authors: Grote Heinfried , Spiteller Gerhard 
Published: May 2005

AbstractDie Massenspektren von Androstantriolen mit Hydroxygruppen in den Positionen 3, 16 uund 17 sind im Vergleich zu isomeren Triolen durch hohe Molekülionen gekennzeichnet. Schlüsselionen zeigen den Verlust der C‐Atome 15, 16 und 17 des D‐Ringes als 75 Masseneinheiten schweres Teilchen an. Das verbleibende Spaltstück veliert leicht die 3‐städige Hydroxygruppe als wasser unter Bildung eines [M  93] Ions. Weitere Schlüsselbruchstücke zeigen die Massen 60, 84 und 110. Mit Hilfe dreier deuterierter Androstantriole und der Massenfeinbestimmung läßt sich zeigen, daß diese Ionen Teile des D‐Ringes enthalten.
Structures and formation of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions
Authors: Nishishita Takao , Bockhoff F. M. , McLafferty F. W. 
Published: May 2005

AbstractSeveral \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm\ 8}} } \right]_{}^{_.^ + } $\end{document} ion isomers yield characteristic and distinguishable collisional activation spectra: \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 1-butene} } \right]_{}^{_.^ + } $\end{document} and/or \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 2-butene} } \right]_{}^{_.^ + } $\end{document} (a‐b), \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm isobutene} } \right]_{}^{_.^ + } $\end{document} (c) and [cyclobutane]+ (e), while the collisional activation spectrum of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm methylcyclopropane} } \right]_{}^{_.^ + } $\end{document} (d) could also arise from a combination of a‐b and c. Although ready isomerization may occur for \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions of higher internal energy, such as d or e → a, b, and/or c, the isomeric product ions identified from many precursors are consistent with previously postulated rearrangement mechanisms. 1,4‐Eliminations of HX occur in 1‐alkanols and, in part, 1‐buthanethiol and 1‐bromobutane. The collisional activation data are consistent with a substantial proportion of 1,3‐elimination in 1‐ and 2‐chlorobutane, although 1,2‐elimination may also occur in the latter, and the formation of the methylcycloprpane ion from n‐butyl vinyl ether and from n‐butyl formate. Surprisingly, cyclohexane yields the \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm linear butene} } \right]_{}^{_.^ + } $\end{document} ions a‐b, not \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm cyclobutane} } \right]_{}^{_.^ + } $\end{document}, e.
Field desorption mass spectrometry of oligosaccharides in the presence of metallic salts
Authors: Prome Jean‐Claude , Puzo Germain 
Published: May 2005

AbstractIn the field desorption mass spectrometry of oligosaccharides, traces of contaminating salts in polar solvents decrease the detection sensitivity, and in some cases no ion could be detected in the molecular range. The present work shows that the addition of alkaline salts (NaI or KI) greatly increases the sensitivity, and cationized molecular ions are obtained. The influence of the molar ratio sugar/salt on the nature and relative intensity of the desorbed species has been studied on mixtures of α‐D‐trehalose and NaI. At the low salt ratio (100:1), high molecular weight clusters [XM + Na]+ are preferentially formed. At the high salt ratio (1:10), mixed clusters [M + NaI + Na]+, doubly charged ions [M + 2Na]2+ and monomeric cationized ions [M + Na]+ are observed along with salt clusters [NaI + Na]+ and [2NaI + Na]+. In the range of molar ratios sugar/salt of 10:1 to 1:1, the field desorption mass spectra exhibit a cationized ion [M + Na]+, which contributes more than 80% of Σ100. This cationization technique has been applied to the field desorption mass spectrometry of several oligosaccharides. In all cases, the salt effect causes the replacement of the [M + H]+ ion by a [M + C]+ ion. (Note: the term [M + C]+ and similar ones mean an association between the whole molecule studied (M) and an alkaline cation [C]+ ([K)]+, [Na]+, [Li]+).) Thus, di, tri‐ and tetrasaccharides exhibit intense [M + Na]+ ions in the presence of NaI and only a few fragment peaks are observed in their field desorption mass spectra. This technique has been applied successfully to the detection of the hexasaccharide ajugose in a natural sample of pentasaccharide, and has also allowed the unambiguous determination of the composition of a mixture of partially methylated trehaloses. The salt effects are dicussed in terms of selective adsorption on the emitter, pre‐existing soluble complexes sugar‐salt, interactions between these species in the electric field and dissociative desorption of ionic complexes.
The formation of a resonance stabilized oxonium ion in isoflavone and 2′‐substituted isoflavones
Authors: Eguchi Shizuko , Haze Machiko , Nakayama Mitsuru , Hayashi Shûichi 
Published: May 2005

AbstractThe predominant elimination of the hydrogen atom or the substituent from the 2′‐position in isoflavone derivatives was confirmed by the use of the metastable ion defocusing technique.
Collisional activation mass spectra of pentene and hexene molecular ions
Authors: Nishishita Takao , McLafferty F. W. 
Published: May 2005

AbstractThe collisional activation spectra of the molecular ions from fourteen pentene and hexene isomers show substantial differences, some of which can be rationalized using known ion fragmentation mechanisms. These differences, and their negligible dependence on ion internal energy, are advantageous for the structural characterization of such isomeric ions, including those produced by fragmentation of larger molecules. The decompositions of metastable ions of the pentenes were nearly identical, but those of the hexenes showed some differences useful for structural charactrization.