bluuebunny/crossref_metadata_2025 huggingface dataset:
Étude D'une Série de Phénoxazines et D'azaphénoxazines par Spectrométrie de Masse
Authors: Cassan J. , Rouillard M. , Azzaro M. , Mital R. L.
Published: May 2005

Nous avons effectué les spectres de masse de phénoxazines et d'azaphénoxazines substituées. Ces composés sont caractérisés par la présence d' un hydrogéne sur l'azote hétérocyclique et la position de substituants NO2et Cl sur les cycles aromatiques. A l'aide de mécanismes classiques, nous avons rationalisé les processus de fragmentation et expliqué les pics principaux de ces specters. La présence de substituants Cl et NO2perturbent totalement la fragmentation observée dans le cas de la molécule de phénoxazine. Ils favorisent la localisation de la charge suivant leur position sur le cycle, soit sur l'azote, soit sur l'oxygéne hétérocycliques. Quant au gropement NO2par isomérisation (forme nitroso), il donne lieu éa une fragmentation spécifique.
A comparative, vapor‐phase (G.L.C.‐M.S.) study of various derivatives of prostaglandins A and B
Authors: Watson J. Throck , Sweetman Brian J.
Published: May 2005

The isomeric prostaglandins, A and B, can be readily distinguished by differences in the mass spectra of their derivatives. The mass spectra of the PGA1‐ or PGA2‐methyl ester (ME)‐trimethyl silyl (TMS) ether derivatives have a prominent ion at [M − 71]+ or [M − C5H11]+ while those of the PGB1‐ or PGB2‐ME‐TMS derivatives have a predominant ion at [M − 99]+ or [M − C6H11O]+ in addition to that at [M − 71]+. Ions of similar origin characterize the spectra of the PGA1‐ or PGA2‐TMS ether‐TMS ester and PGB1‐ or PGB1‐TMS‐TMS derivatives, respectively. The fragmentation of other derivatives of PGA1, PGA2, PGB1 and PGB2 such as the ME‐t‐Bu‐DMS (t‐butyl‐dimethylsilyl ether); ME‐MO (methoxime)‐TMS; ME‐MO‐Ac (acetate), and ME‐Ac are also described comparatively. The composition of important ions was confirmed by deuterium labeling and/or high resolution mass spectroscopy, where appropriate. The potential advantages and limitations of the derivatives for quantitative analysis of prostaglandins by the specialized technique of multiple ion detection (MID) are described.
Etude Comparée de la Fragmentation de Trois Composés Médicamenteux a Structure Hétérocyclique: la Primaclone, le Glutethimide et le Phenobarbital
Authors: Bourgeois G. , Brachet‐Liermain Mme A. , Ferrus Mlle L.
Published: May 2005

Les spectes de masse de ces trois composés ont éteacute; comparé. L'utilisation de la haute résolution et de la méthode de marquage au deuté a permis de mettre en évidence un mécanisme de fragmentation particulier commun aux trois dérivés. Ce mécanisme consiste en un transfert électronique cyclique á six centres donnant naissance á un ion radical aromatique. Les mécanismes de fragmentation propres aux barbituriques ont également été observé.
Nachbargruppeneffekte bei der Elektronenstoß‐Induzierten Fragmentierung von Acetylierten 2.2′‐Diamino‐Diphenylmethanen
Authors: Eckhardt G. , Fehlhaber H.‐W. , Volk H. , Welzel P.
Published: May 2005

Die mono‐und bis‐acetylierten 2.2′‐Diamino‐diphenylmethane (I bis V) spalten beim Elektronenstoß‐induzierten Zerfall in starkem Maße aus den Molekúlionen Wasser ab. Die zugrundeliegenden Fragmentierungsprozesse wurden mit Hilfe deuterierter Verbindungen untersucht.
Charge localization and aromatic stabilization in large ring ions: Mass spectra of ms‐porphyrins
Authors: Meot‐Ner M. , Adler A. D. , Green J. H.
Published: May 2005

The major mass spectrometric fragments of ms‐tetraphenylporphin and ms‐tetra(p‐chloro)phenylporphin are [M  H]+˙ and [M  Cl]+˙, respectively. Metal derivatives of these compounds give a modified characteristic fragmentation pattern with peak groups ending in the ions [M  4H]+˙, [M  ϕ  5H]+˙ and [M  2ϕ  2H]+˙ for the metallo ms‐tetraphenylporphins, and [M  ϕCl  2Cl  3H]+˙ and [M  2ϕCl  Cl  H]+˙ for Mgms‐tetra(p‐chloro)phenylporphin. Deuterated metal derivatives indicate random hydrogen loss from both phenyl and pyrrole carbons. However, metal substituents do not significantly modify the fragmentation pattern in the case of ms‐tetra(p‐methoxy)phenylporphin. These patterns can be explained in terms of aromatic stabilization of the fragmentation products, coupled with charge localization on the π system in the free base, on the metal atom in the metallo derivatives and on the methoxy function in the p‐methoxyphenyl derivative.
Massenspektroskopische Fragmentierungsreaktionen. V—Zur Frage des Quasi–Thermischen RDA–Zerfalls
Authors: Budzikiewicz H. , Linscheid M.
Published: May 2005

Am Beispiel von verschieden substituierten Steroiden wird geziegt, daß auch beim RDA‐Zerfall quasithermische Reaktionen nicht zur Deutung des Fragmentierungsverhaltens herangezogen werden müssen, daß Ergebnisse gegen eine erhebliche Beteilgung solcher Prozesse sprechen.
Mass spectrometry of insect moulting hormones: Trimethylsilyl‐methoxime derivatives of ecdysone and 20‐hydroxyecdysone
Authors: Morgan E. D. , Woodbridge A. P.
Published: May 2005

The mass spectra of trimethylsilyl‐methoxime derivatives of the two insect moulting hormones, ecdysone and 20‐hydroxyecdysone are described together with some model compounds. These steroid derivatives are volatile in the gas chromatograph and their mass spectra provide a sensitive means of detection and structure recognition.
The mass spectra of the trimethylsilyl derivatives of some alkyl and aminoalkyl phosphonates
Authors: Harvey D. J. , Horning M. G.
Published: May 2005

The mass spectra of the trimethylsilyl derivatives of a series of alkyl and aminoalkyl phosphonates were investigated with the aid of deuterium labeling and high resolution mass measurements. The spectra contained several prominent ions characteristic of the phosphonate system and a number of ions produced by inter and intra molecular migration and interaction of trimethylsilyl groups.
Mass spectra of organoarsenic compounds. III—Electron‐impact‐induced fragmentation of trialkylarsenates and penta‐alkoxyarsoranes
Authors: Frøyen Paul , Møller Jørgen
Published: May 2005

The mass spectra of a series of trialkylarsenates are reported, together with those of dimethyl methylarsonate, pentamethoxyarsorane and pentaethoxyarsorane. Their behaviour under electron‐impact is discussed and compared with that reported for trialkylphosphates.
Orientation de la Fragmentation en Spectrométrie de Masse Par Introduction de Groupements Fonctionnels. XII—Ethylene Acetals Derives de Cyclopentanones et Cyclopentanones α Substituees
Authors: Audier Henri‐Edouard , Fétizon Marcel , Tabet Jean‐Claude
Published: May 2005

La fragmentation des éthylénecétals des cétones α substituées a été étudiée. Un nou‐veau type de transposition en spectrométrie de masse a été mis en évidence.
Elektronenstossinduzierte Fragmentierung von Acetylenverbindungen. XIII—Acyclische [C7H7]+‐Ionen Als Intermediate bei der Acetylen‐Eliminierung aus dem [M  Cl]+‐Fragment von Heptin‐(6)‐Dien‐(2.4)‐Ylchlorid‐(l)
Authors: Köppel Claus , Schwarz Helmut , Bohlmann Ferdinand
Published: May 2005

[C7H7]+‐Ionen aus offenkettigen Verbindungen isomerisieren unter Elektronen‐stoss nur partiell zu einem Tropylium‐Ion, wobei die Lebensdauer τ bzw. die innere Energie E das Ausmass der Cyclisierung bestimmt.
Mass spectrometric studies of diterpenes: VIII—Epimers
Authors: Enzell Curt R. , Wahlberg Inger , Gunnarsson Lars‐Erik
Published: May 2005

Diterpene epimers differing with respect to orientation of a secondary hydroxyl group, ring fusion or configuration at an asymmetric centre carrying carbon–carbon linked substituents were studied, and certain stereostructural‐spectral correlations were achieved for the first two groups. Each of the compounds examined was subjected to multiple scanning at both high and low electron voltage to allow computer assisted statistical calculation and comparison of intensity intervals at a predetermined confidence level for total ion currents and selected peaks.
Zum Mechanismus massenspektrometrischer Fragmentierungsreaktionen: XII‐Einfluß einer sterischen Hinderung der Mesomerie bei der Fragmentierung von N,N‐Dimethyl‐N′‐4‐Biphenylformamidinen
Authors: Kuschel Heinz , Grützmacher Hans‐F.
Published: May 2005

Die Entstehung cyclischer [M  H]+Ionen (a) in den Massenspektren von N,N‐Dimethyl‐N′‐arylforrnamidinen wird durch elektronenabgebende Substituenten an der Aryl‐gruppe in para‐Stellung zur Formamidingruppe wegen der Ausbildung von Resonanzstrukturen des Typs c unterdrückt. Dieser Effekt wird auch in den Massenspektren von in 4′‐Stellung substituierten N,N‐Dimethyl‐N‐4‐biphenylformamidinen (III) beobachtet. Durch Finführung von Substituenten in die 2‐, 2′‐, 6‐ und 6′‐Stellung von III wird die Ausbildung der Resonanzstrukturen c′ in den Molekül‐Ionen so erschwert, daß diese Derivate ein noi males massenspektrometrisches Fragmentierungs‐verhalten aufweisen. Dafür reichen zwei Methylgruppen in 2‐ und 2′‐Stellung aus.
Perte Stereoselective du Groupe Methyle 20‐α de la Methyl‐20 Conanine sous L'impact Electronique
Authors: Longevialle P. , Alazard J. P. , Lusinchi X.
Published: May 2005

Des expériences de marquage au deuterium des méthyles en 20 de la méthyl‐20 conanine ont permis de montrer la perte stéréosélective du méthyle 20‐α sous l'impact électronique. La perte de l'un ou l'autre méthyle conduisant à des fragments identiques, ce résultat ne peut être interprété qu'en considérant l'état de transition de la réaction de fragmentation.
Mass spectra of aryl substituted N‐t‐ butylbenzamides: Substituent effects on unimolecular ion decomposition
Authors: Tsai S.‐C. , Rubottom G. M.
Published: May 2005

The major reactions of aryl substituted N‐t‐butylbenzamides upon electron‐impact involve direct cleavage of a methyl radical, the loss of a butene molecule with the transfer of one hydrogen, or the loss of a butenyl radical with the transfer of two hydrogens. The last of these processes parallels the mass spectral behavior of aliphatic amides. Substituent effects indicate that electron‐withdrawing groups on the aromatic ring enhance the two hydrogen transfer process, while electron‐donating groups enhance the single hydrogen transfer process. Ion abundances, ionization potentials and appearance potentials are discussed with respect to correlation with σ+ values.
Notiz Über die Elektronenstossinduzierte Fragmentierung 2H‐Markierter Phenylsilane
Authors: Bohlmann Ferdinand , Köppel Claus , Schwarz Helmut
Published: May 2005

Bei der Bildung der [M  H]+‐Ionen aus Phenylsilan wird sowohl ein Isotopeneffekt i als auch ein Präferenzfaktor p beobachtet. Die Entstehung intensiver [M – 2]+‐ und [M – 3]+‐Ionen ist mit der Vorstellung offenkettiger Systeme verträglich. Eine Entscheidung für oder gegen die Struktur eines Silatropylium‐Ions ist durch die Untersuchung 2H‐markierter Verbindungen nicht möglich.
Susbstituent effects in mass spectrometry IV—an evaluation of empirical methods for calculating the ionisation potentials of para and meta disubstituted benzenes
Authors: Benoit Frank M.
Published: May 2005

Three empirical equation which have been used to calculate ionisation potentials of para and meta disubstituted benzenes are evalyated according to their ability to predict the IP's of para and meta YC6H4COX, (where x  OH, NH2, CL).
3‐aryl‐2‐isoxazolines: Electron‐impact fragmentation and substituent effects
Authors: Bettinetti G. F. , Facchetti S.
Published: May 2005

The mass spectra were investigate of six 3‐aryl‐2‐isoxazolines, and three main fragmentation pathways were found to occur through loss of 28 and 30 a.m.u. The losses of 28 (C2H4)and 30 (CH2O) are seen as competitive mass spectrometric retro‐1,3‐dipolar cycloaddition processes. These reactions are also repeated successively, and take place in different ions either following the degradation of the substituent or the attack of the benzene ring. The substituents in the para position influence both these reactions and also the attack upon the rings. A quantitative study has been carried out on the effect of the substituent on the [M‐28] reaction, which can be interpreted in terms of the first ionisation energies. These terms are linearly intercorrelated, for the compounds under examination, with the Hammett type σ‐constants.
The effect of molecular geometry on the fragmentation of methyl esters of cyclobut‐3‐ene‐1,2‐dicarboxylic acids
Authors: Weinstein S. , Gil‐Av E. , Leftin J. H. , Levy E. C. , Mandelbaum A.
Published: May 2005

Elimination of CH3OH from the molecular ions of the methyl esters of cyclobut‐3‐ene‐1, 2‐dicarboxylic acids under electron‐impact occurs to a much greater extent in stereoisomers having a trans configuration than in the cis analogues. Deuterium labelling shows that this process takes place via different mechanisms in the stereoisomeric esters. The abundance ratio [M  CH3OH]˙+/[M  CH3O]+ is suggested as the most sensitive criterion for the deduction of configuration in this system. Determination of the geometry of the cyclobutene esters by n.m.r. spectroscopy as well as by pyrolysis to corresponding isomeric muconates is also discussed.
The mass spectra of six fluorinated β‐diketones and their monothio analogues
Authors: Das M. , Livingstone S. E.
Published: May 2005

The mass spectra of the fluorinated β‐diketones RCOCH2COCF3 (R = Ph, p‐FC6H4, p‐ClC6H4, p‐BrC6H4, p‐MeC6H4 and 2‐thienyl) and their monothio analogues RC(SH)CHCOCF3 have been obtained. The replacement of one oxygen by sulphur in the β‐diketones brings about a greater complexity in the mass spectra. The β‐diketones fragment by first losing a ·CF3 radical and then successively lose CH2CO and CO to yield \documentclass{article}\pagestyle{empty}\begin{document}${\rm [R}\mathop {\rm C}\limits^{\rm + } {\rm = O]} $\end{document} and [R]+. The monothio‐β‐diketones also fragment by an analogous reaction pathway: viz. the initial loss of ·CF3 is followed by the successive loss of CH2CO and CS to yield \documentclass{article}\pagestyle{empty}\begin{document}${\rm [R}\mathop {\rm C}\limits^{\rm + } {\rm = S]} $\end{document} and [R]+. However, they also fragment by two other pathways involving the initial loss of ·H and ·X (X=F, Cl, Br, Me), the latter occurring only with those monothio‐β‐diketones having R=p‐XC6H4.
The mass spectra of the trimethylsilyl esters of acetyl, schiff base and isothiocyanate derivatives of some aminoalkylphosphonic acids
Authors: Harvey D. J. , Horning M. G.
Published: May 2005

Trimethylsilyl esters of acetyl, Schiff base and isothiocyanate derivatives of a series of aminoalkylphosphonic acids were prepared for the purpose of characterizing these phosphorus compounds by combined gas chromatography and mass spectrometry. The mass spectra of these derivatives were investigated by means of high resolution mass measurments and deuterium labeling. Ions characteristic of the presence of the trimethylsilylphosnate group were observed at m/e 121, 195, 211 and 225 to 227 in the spectra of all the derivatives. Several ions produced by interaction between the trimethylsilyl group and the derivatized amino function were present, particularly in the spectra of the acetate derivatives ([M — 56]+, [M — R]+ and [M — 153]+, where R is the side chain attached to C‐1), and the isothiocynate derivatives (m/e 268, 253, 241, 190 and 116).
Mass spectrometric studies of alkyl‐, phenyl‐ and chloropyrimidines
Authors: Kato T. , Yamanaka H. , Abe H. , Sasaki S. , Ichikawa H.
Published: May 2005

The mass spectra of alkyl‐ and chloropyrimidines are recorded. A generalised fragmentation mechanism for the derivatives of pyrimidine is proposed. The principle of α‐cleavage for heterocyclic compounds as proposed in the previous paper is shown to be valid for pyrimidine derivatives. Electronic structures of some molecular and intermediate ions are calculated by the openshell CNDO/2 and INDO methods.
Massenspektrometrische Untersuchung Organischer Stickstoffverbindungen. XII—H‐übertragungen Durch Nachbargruppen‐Wechselwirkung bei αω′‐bis‐(N‐Piperidyl)‐Aromaten
Authors: Schwarz Helmut
Published: May 2005

Mit Hilfe von 2H‐markierten Modellverbindungen werden die durch Nachbargruppenwechselwirkung beeinflußten Fragmentierungen von verschiedenen Dipiperidinen aufgeklärt. Neben einer neuartigen McLaffery‐Umlagerung werden sowohl spezifische als auch selektive H‐übertragungen vor der Abspaltung von Peperidin nachgewiesen. Die Jeweils isomeren Diamine Können mit Hilfe der Massenspektrometrie eindeutig unterschieden und identifiziert werden.
Electron‐impact studies. LXXXVII—ortho effects in the negative ion mass spectra of salicylates and anthranilates
Authors: Bowie J. H. , Ho A. C.
Published: May 2005

The molecular anions of the methyl and phenyl esters of 4‐nitrosalicylic acid and 5‐nitroanthranilic acid eliminate ROH (R  Me or Ph) by an ortho rearrangement. The molecular anions of phenyl 3‐hydroxy‐5‐nitrobenzoate and phenyl 3‐amino‐5‐nitrobenzoate lose PhOH to a lesser extent, and a study of the pressure dependence of these eliminations indicates the operation of simultaneous two‐stage cleavage reactions. The competitive ortho effects observed when the nitro group is adjacent to either the ester or hydroxyl functions are described.
Mass spectral studies of some aryl and aroyl derivatives of glyoxime
Authors: Terent'ev P. B. , Kost A. N. , Lange Jerzy
Published: May 2005

Mass spectra of two diaroylglyoximes (Ia and Ib) are reported and compared with those of the corresponding dehydration products, 3,4‐diaroyl‐1,2,5‐oxadiazoles (IIIa and IIIb, respectively). In Ia and Ib, unlike in diarylglyoximes (Id and Ie), the largest ion is [M — 18]+, but this does not form in the ion source by a simple thermal dehydration. Similar spectra have been obtained for an alkyl aroyl derivative of glyoxime (Ic) and an isonitroso‐β‐diketone (II). A specific electron‐impact‐induced rearrangement leading to the formation of carboxylic acids has been observed in the mass spectra of all the acylated oximes under investigation.
Ein Computerverfahren für die Massenspektrometrische Untersuchung Organischer Proben bei Fraktionierter Direktverdampfung
Authors: Hillig H. , Riepe W. , Kwiatkowski J.
Published: May 2005

Es wird ein Computerverfahren beschrieben, das es ermüglicht, die ‘Lebensgeschicht’ einer organischen Probe während der Totalverdampfung im Direkteinlaßsystem eines Massenspektrometers durch Zyklische Aufnahme von Massenspektren und Beobachtung der Verdampfungstemperatur zu verfolgen. Die Aufnahme der Spektren wird durch ein Datensystem gesteuert, das auch die Weiterverarbeitung übernimmt; es liefert darüber hinaus Beurteilungsmöglichkeiten fü die Entscheidung, ob die Probe einheitlich ist oder nicht. Liegt ein Gemisch vor, gibt der Rechner Hinweise, in wieviele Komponenten die probe durch die fraktionierte Verdampfung zerlegt wurde und welche aufeinanderfolgenden Spektren den einzelnen Fraktionen zugeordnet werden müssen.
Massenspektrometrische Untersuchungen von Isomeren Stickstoffverbindungen des Dibenzofurans
Authors: Riepe W. , Florea S. , Fǎrcǎşan V. , Cristea I.
Published: May 2005

Die Massenspektren von isomeren Amino‐, Acetamino‐ und Nitrodibenzofuranen wurden aufgenommen und das Fragmentierungsverhalten untersucht. Es wurden zwischen einigen Isomeren deutliche Unterschiede gefunden, die zum Teil durch intramolekulare Wasserstoffbrücken, ortho‐Effekte oder durch Resonanzstabilisierung erklärt werden.
Electron‐impact‐induced fragmentation of morellin and related compounds
Authors: Yemul S. S. , Rao A. V. Rama
Published: May 2005

The mass spectra of morellin and other related natural products, isolated from the various Garcinia species, have been recorded and the data has been rationalised. The characteristic cleavage is the opening of the bicyclo(2.2.2) octenone ring system by a retro‐Diels‐Alder reaction. The γ‐pyrone ring also undergoes the retro‐Diels‐Alder fragmentation. These two modes of cleavage indicate the different substituents on the main skeleton of morellin. The hydrogenated derivatives show slight variations in their fragmentation modes. The mass spectral data assists considerably in the structural elucidation of similar complex molecules, if isolated in minute quantities.
Mass spectral studies of cycloheptatrienes. II—The monochlorocycloheptatrienes
Authors: Hoffman Michael K. , Friesen Marlin D.
Published: May 2005

The mass spectra of isomeric chlorocycloheptatrienes have been studied at high and low electron beam energies. Ion kinetic energy spectrometry was utilized to examine the major decomposition pathways. The extreme similarity found in the spectral characteristics of these compounds provides information about the structure of the decomposing molecular ion.
Massenspektroskopische Fragmentierungsreaktionen. VII.—Abbau der Polyenkette bei Carotinoiden
Authors: Johannes B. , Brzezinka H. , Budzikiewicz H.
Published: May 2005

Der Ablauf der verschiedenen Zerfallsreaktionen der Polyenkette bei Carotinoiden wird and Hand von deuterierten Analogen diskutiert.
The electron‐impact‐induced fragmentations of some substituted 3‐aminopropionitriles
Authors: Gay M. L. , Molton P. , Ponnamperuma C.
Published: May 2005

As a part of our study of the chemistry of simulated Jovian atmospheres, we have synthesized a series of twelve alkyl aminopropionitriles to serve as model compounds. The spectra of these compounds have been obtained, and the transitions which are observed have been further investigated by scanning in the metastable mode and by obtaining the spectra of deuterium labeled 3‐(N‐ethylamino)propionitrile. The fragmentations which are observed are dominated by the amine group.
Mass spectrometry of 4‐amino‐4′‐nitroazobenzene compounds
Authors: Gilland J. C. , Lewis J. S.
Published: May 2005

The mass spectra of 32 substituted 4‐amino‐4′‐nitroazobenzene compounds have been recorded and the most intense peaks have been used to characterize these spectra. It was found that the spectra of 4‐amino‐4′‐nitroazobenzene compounds are characterized by peaks due to: (1) molecular ions, (2) fragment ions formed by cleavage of one of the carbon‐nitrogen bonds adjacent to the azo linkage with the positive charge remaining with the amine fragment, (3) ions formed by cleavage alpha to the amine nitrogen with the charge remaining with the amine substituent, (4) ions formed by cleavage beta to the amine nitrogen with the loss of the amine substituent fragment, (5) secondary ions formed by cleavage beta to the amine nitrogen with the loss of the amine substituent fragment from the primary amine fragment (2), and (6) ions formed by loss of NO from the molecular ion. This work shows that 4‐amino‐4′‐nitroazobenzene compounds exhibit fragmentation which is dependent in a consistent manner on the types of substituents. This work provides a basis for a systematic approach to the identification of 4‐amino‐4′‐nitroazobenzene compounds.
Analytical application of ion‐molecule reactions. Reactions of various substituted cyclopropane molecular ions with ammonia
Authors: Gross Michael L. , Lin Ping‐Huang
Published: May 2005

By ion cyclotron resonance it is found that various substituted cy clopropanes after ionization react with ammonia to give products which allow identification of the degree and kind ofsubstitution on the cyclopropl ring. For example, cyclopropyle reacts to give [CH2NH2]+ (m/e 30), methylcyclopropane gives [CH2NH2]+ (m/e 30) and the ethyl substituted [CH(C2H3)NH2]+ (m/e 44) and ethylopropane gives [CH2NH2]+ (m/e 30) and the ethyl substituted [CH(C2H5)NH2]+ (m/e 58). It is suggested that reactions of stable molecular ions with reagent neutrals may be a source of highly specific structural information for organic compounds.
Mass spectrometry of cycloheptatriene derivatives. III—skeletal rearrangements in the molecular ion of 7‐cyano‐7‐methylcycloheptatriene and in some of its fragment ions
Authors: Venema A. , Nibbering N. M. M.
Published: May 2005

It is shown by carbon and deuterium labelling experiments that a substantial part of the molecular ions of 7‐cyano‐7‐methylcycloheptatriene has rearranged to a tolylacetonitrile, both in the ion source and in the second field free region. The evidence follows from a comparative study of α‐methylbenzylcyanide, o‐ and p‐tolylacetonitriles and their labelled analogues. The decomposing [M — CH3]+ ion from 7‐cyano‐7‐methylcycloheptatriene presumably has a cyanomethylphenyl cation, instead of a cyanotropylium structure.
Mass spectrometry of onium compounds. XXX—Ionisation potentials in structure analysis of sydnones
Authors: Undheim Kjell , El‐Gendy Mahmoud A. F. , Hurum Torgeir
Published: May 2005

Comparative studies of the ionisation potentials of some sydnones indicate that these molecules are largely present in the gaseous phase as their valence isomeric N‐nitroso ketenes.
Field desorption mass spectra of phthalocyanines
Authors: Games D. E. , Jackson A. H. , Taylor K. T.
Published: May 2005

Mass spectr of phthalocyanines are readily obtainable by field desorption mass spectrometry. Molecular ions are normally the base peaks in the spectra and minimal fragmentation is observed. The technique provides a rapid method for the qualitative exmination of mixtures of phthalocyanines.
Mass spectra of some isopropyl benzene derivatives. A study of the ortho effect
Authors: Smith J. G. , Wilson G. L. , Miller J. M.
Published: May 2005

The mass spectra of a series of ortho, meta and para substituted isopropyl benzene derivatives have been determined where the second substituent is COOH, C(O)NH2, C(O)C6H5, C(Ph)(=NPh) or CH(Ph)(NHPh). Two bis‐isopropylbenzophenones have also been studied. The spectra are characterized by prominent ortho effects which distinguish the ortho derivatives from the meta and para.
The mass spectra of (trimethylstannyl)x methanes: Occurrence of tin‐carbon double bonds
Authors: Dimmel Donald R. , Wilkie Charles A. , Lamothe Paul J.
Published: May 2005

The mass spectra of (Me3Sn)nCH4−n, where n varies from 1 to 4, (Me3Sn)2CClX, where X equals H, Cl, Br or I, together with some tetraalkyltin compounds and Me3SnCCl3, are presented. Comparisons with mass spectra of the silicon analogs1 show a large number of similarities, including the appearance of allylic ions which require Group IV metal to carbon π‐bonding. Multiple rearrangements are observed with the halogenated tin compounds which bring the α‐halogen into direct bonding with the tin atom.
Mass spectral structure elucidation of substituted 4‐oxazolidones, the photocycloexpansion products of 2,4‐azetidindiones
Authors: Compernolle F. , Schutyser J. , De Schryver F. C.
Published: May 2005

Abstract‐2‐Methoxy‐4‐oxazolidone structures are assigned to the photocycloexpansion products of the substituted 2,4‐azetidindiones on the basis of mass spectral evidence. A discussion is given of the mass spectra of 2‐methoxy‐4‐oxazolidones and of their hydrolysis products, the 2‐hydroxy‐4‐oxazolidones and the ring opened substituted 2‐hydroxy‐N‐formyl acetamides. Ring and chain forms, when both isolated, yield completely different mass spectra, indicating that no rapid tautomeric equilibrium is established in the gas phase.
Electron‐impact fragmentation of isobutyronitrile
Authors: Heerma W. , Versluis C.
Published: May 2005

The mass spectrum of isobutyronitrile‐2‐d1 was studied. The results support an earlier proposal of isomerisation of the molecular ion, prior to fragmentation.
Fragmentation d'azoles sous l'impact electronique VII –N‐ethylbenzimidazoles
Authors: Maquestiau A. , Van Haverbeke Y. , Flammang R. , Pardo M. C. , Elguero J.
Published: May 2005

Par marquages isotopiques (13C et D), on montre que l'ion [M  CH3]+ observé dans le spectre de masse du l‐éthylbenzimidazole se réarrange quantitativement en une structure quinoxalinium avant l'élimination d'acide cyanhydrique.
Hydrogen cyanide elimination and rearrangement upon electron‐impact from schiff bases of benzaldehyde and aliphatic amines
Authors: Hanuš V. , Vereš K. , Cabák J.
Published: May 2005

The Schiff bases of benzaldehyde and aliphatic amines form immonium ions on electron‐impact, which rearrange and eliminate hydrogen cyanide in a different way than the corresponding derivatives of pyridine‐2‐aldehyde. The presence of at least one hydrogen on the α‐carbon atom in the amine moiety is a necessary condition for this rearrangement. A mechanism is suggested for this process.
Spectral properties of organometallic transition metal complexes I–Mass spectra of haloacteophenones haloacetylferroce, FcCO–CH2X, and related ferrocence complexes FcCOCI and FcCH2CI
Authors: Pannell K. H. , Bittman Linda J.(Russwinkle)
Published: May 2005

The mass spectral properties of the title compounds have been recorded and compared. For the haloacetyl systems ring expansions to tropylium ions and π‐benzene iron ions are observed. A major ion present in all haloacetyl spectra is that derived from the corresponding acetyl compound, CH3CO‐, formed via an instrument catalyzed reduction of the halo compounds by residual water. Some substituent effects are observed. Considerable halogen migration to iron is observed for the ferrocene complexes.
Fragmentation d'azoles sous l'impact electronique VI–indazole
Authors: Maquestiau A. , Van Haverbeke Y. , Flammang R. , Pardo M. C. , Elguero J.
Published: May 2005

Une ismérisation des ions molécularies précéde la fragmentation de l'indazole sous l'impact.
[C]+· and [CH]+ from doubly charged ions formed from malononitrile
Authors: Beynon J. H. , Caprioli R. M. , Cooks R. G. , Nibbering N. M. M. , Molenaar‐Langeveld T. A.
Published: May 2005

The metastable ions [M]2+, [M – H]2+· and [M – H2]2+ from malononitrile fragment by loss of [CH]+, [C]+· and [C]+·, respectively. The reaction of the molecular ion involves the methylene and nitrile carbon atoms in the statistical probability ratio, while that of [M – H]2+· involves exclusively the nitrile carbon and that of [M  H2]2+ involves an approximately equal contribution, from both sources. It is suggested that the metastable molecular ion fragments through a bipyrimidal intermediate.
Untersuchungen in der Thiazolreihe. III—massenspektrometrische Untersuchung von 2‐Amino‐3‐hydroxythiazoliumchloriden
Authors: Entenmann G.
Published: May 2005

Der massenspektrometrische Zerfall von 2‐Aminothiazol‐3‐oxiden ist durch die Abspaltung von O und OH aus dem Molekülion charakterisiert. Deutliche Unterschiede zwischen 4‐Alkyl und 4‐Arylderivaten sowie die ausgeprägte Substituentenabhängigkeit des [M – OH]+·: [M – OH]+‐Verhältnisses lasses sich mit einer Stabilisierung des [M – O]+·‐Radikalkations durch aromatische Substituenten deuten. Die Temperaturabhängigkeit der Spektren weist auf ein Tautomeriegleichgewicht im Einlaßsystem hin.
Electron‐impact studies. XCIX—negative ion mass spectrometry of the o‐NO2C6H4XC6H5 systems. Aryl hydrogen scrambling and proximity effects
Authors: Wilson Joe C. , Bowie John H.
Published: May 2005

We report the first example of aryl hydrogen scrambling occurring in a molecular anion prior to or accompanying fragmentation, i.e. for the reaction [M]−· → [M  H2NO2.]− from o‐NO2C6H4XC6H5 (X = O or S). Proximity effects occur in these spectra when X = CO, NH, O, or S, and certain of these have been substantiated by 2H and 18O labelling.
The dissimilarity between the electron‐impact and photochemical or thermal behaviour of some methyl cyclobut‐3‐ene‐1,2‐dicarboxylates and muconates
Authors: Mandelbaum Asher , Weinstein S. , Gil‐Av E. , Leftin J. H.
Published: May 2005

Comparison of the mass spectral behaviour of the dimethyl esters of the epimeric (cis‐ and trans‐) cyclobut‐3‐ene‐1,2‐dicarboxylic acids and the isomeric muconates (cis, cis‐, cis, trans‐ and trans, trans‐) and some substituted analogues shows that no correlation exists between the electron‐impact‐induced fragmentation and the predicted photochemical or thermal transformations in these systems. The comparison involved fragmentation patterns (supported by deuterium labelling), metastable transitions, and also kinetic energy release in the field free region.
Mass spectra of 4‐substituted‐1,2,6‐trimethyl‐3,5‐diethoxycarbonyl‐1,4‐dihydropyridines
Authors: Esmans E. L. , Dommisse R. A. , Alderweireldt F. C.
Published: May 2005

The mass spectra of 4‐substituted‐1,2,6‐trimethyl‐3,5‐diethoxycarbonyl‐1,4‐dihydropyridines have been studied. The detailed fragmentation mechanisms, supported by high resolution measurements, the study of metastable ions and the use of deuterium labelling, are discussed.
Metastable ion studies. III—composite metastable peaks in fragmentations of some small hydrocarbon cations
Authors: Holmes John L. , Osborne Alexander D. , Weese Gwyneth M.
Published: May 2005

Composite metastable peaks are generated in the unimolecular fragmentations (i) [C3H5]+ → [C3H3]+ + H2 (flat‐top upon flat‐top) and (ii) [C4H9]+ → [C3H5]+ + CH4 (flat‐top and gaussian). The measurement of appearance potentials and kinetic energy releases lead us to conclude, in agreement with earlier proposals, that in (i) the components can arise from the generation of the isomeric cyclopropenium and propargyl daughter cations. In (ii) the components are proposed to arise from the fragmentation of tert‐ and sec‐butyl cations yielding allyl as the common daughter ion.

The composite peak observed in the fragmentation (iii) [C3H4]+· → [C3H3]+ + H· is shown to be present only if the decomposing molecular ion is large enough to also produce [C6H8]2+ ions. The second component in (iii) then arises from the reaction [C6H8]2+ → [C6H6]2+ + H2.
Isomerisation de l'ion moleculaire de derives substitues polycycliques du benzodioxinne‐1,4
Authors: Dagaut Jacques , Dizabo Pierre , Pompon Alain , Fillaux Joelle
Published: May 2005

Trois dégradations (petre de phényle, d'hydrogé, d'un radical RCO) de dérivés benzocyclobuténiques du bemnzodioxinne‐1,4 diversement substitué ont été étudiés. Ces molécules deutériées en position spécifique ont permis, dans certains cas, de mettre en évidence l'existence de plusieurs isomères de l'ion moléculaire.
Application of mass spectrometry to the structural investigation of triterpenes. II—3,4‐A‐seco‐triterpenoids
Authors: Aplin R. T. , Cox I. R.
Published: May 2005

The mass spectral behaviour of a series of naturally occurring and synthetic 3,4‐A‐seco‐triterpenes has been examined and fragmentations characteristic of the 3,4‐A‐seco function observed. Deuterium labelling has been used to investigate the origins of their characteristic fragments.
Massenspektroskopische Fragmentierungsreaktionen. IX—Ringkontraktion bei 6‐ und 7‐ringen: eine überischt
Authors: Budzikiewicz H. , Lenz U.
Published: May 2005

Die für mögliche Ringkontraktionen bei 6‐ und 7‐gliedrigen Perhydroheterocyclen in der Literatur vorhandenen Hinweise werden kritisch zusammengefaßt.
Substituent effects in the mass spectra of acetanilides
Authors: Gilbert J. R. , Stace A. J.
Published: May 2005

The kinetic shifts for an ion decomposition involving loss of CH2CO from a series of substituted acetanilide ions have been calculated using the Rice‐Ramsperger‐Kassel‐Marcus theory. The results indicate that in the main the observed changes in appearance potential‐ionisation potential for this reaction are due to a change in the number of degrees of freedom on introducing the substituent and not due to a substituent effect on the critical energy of reaction.
Analysis of carotenoids by field desorption mass spectrometry
Authors: Watts C. D. , Maxwell J. R. , Games D. E. , Rossiter M.
Published: May 2005

The mass spectra of a variety of authentic carotenoids covering a range of structural types have been studied using the field desorption technique. All the compounds examined show the molecular ion as the base peak, even where this ion is of very low intensity in the electron‐impact spectra. Little fragmentation is observed, but thermal decomposition can be induced in certain cases by using higher emitter currents. Application to a simple mixture of authentic compounds and a more complex mixture of sedimentary origin shows the potential of the method in the rapid qualitative screening of carotenoids in crude extracts.
Further investigation of the Ramberg‐Bäcklund process
Authors: Langler R. F. , Mantle W. S. , Newman M. J.
Published: May 2005

A further examination of the Ramberg‐Bäcklund process in the mass spectra of β‐disulfones is reported. An alternative rationale is dismissed from consideration and additional evidence adduced for preferential abstraction of benzylic hydrogens by γ‐sulfonyl groups.
Untersuchungen zum Einfluss der Stereochemie auf die Elektronenstossinduzierte ‘Retro‐Diels‐Alder’‐Reaktion
Authors: Bohlmann Ferdinand , Fischer Christian‐Herbert , Förster Jürgen , Mather Wolfgang , Schwarz Helmut
Published: May 2005

Durch die Untersuchung geeigneter Modellverbindungen wird belgt, daß eine Generalisierung der Mechanismen der elektronenstoßinduzierten ‘Retro‐Diels‐Alder’‐Reaktion aufgrund sterischer Effekte unmöglich ist.
An intermolecular methyl transfer during field desorption mass spectrometry. Identification of the [M + 14] peak in choline chloride
Authors: Wood Gordon W. , Lau P.‐Y.
Published: May 2005

Choline chloride, bromide and iodide all contain a peak at m/e 118 [M + 14] in their field desorption mass spectra. Comparison with choline(methyl‐d9) chloride demonstrates that this peak arises from an intermolecular transfer of a methyl group. Partial exchange of hydroxyl hydrogen on choline chloride does not displace the m/e 118 peak, suggesting that this hydrogen is lost during methyl transfer. The structure of the [M + 14] species should then correspond to choline methyl ether.
Analytical ion cyclotron resonance spectrometry. Spectereochemical factors and a functional group interaction in some norbornyl systems
Authors: Kao Jar‐Lin , Simonton Charles A. , Bursey Maurice M.
Published: May 2005

Ion cyclotron resonance results show that the rate of the acetylation of endo‐bicyclo‐[2.2.1]hept‐5‐en‐2‐ol by [(CH3CO)3]+ in the gas phase is similar to that of its exo‐isomer and greater than that of endo‐norborneol by the same ion. This suggests that steric interference of the 6‐endo hydrogen is removed by making it vinylic. Additionally, the acetates of the isomeric norborneols and of exo‐ and endo‐bicyclo[2.2.1]hept‐5‐en‐2‐ol have relative rates 1.0, 0.9, 1.1 and 0.5; these figures may be interpreted to indicate that acetylation may occur on the carbonyl oxygen here and that in the last compound the carbonyl function is protected by interaction with the olefinic bond.
The mass spectra of some chromans
Authors: Middleditch Brian S. , Macnicol David D.
Published: May 2005

The mass spectra of 4‐p‐hydroxyphenyl‐2,2,4‐trimethylchroman and of its thia, selena and sulphonyl analogues are reported and discussed. Formal charge localization on the oxygen atom of the oxo compound is reflected in the production of an abundant [M ‐ 15]+ ion. Lack of charge location on the heteroatom of the seleno compound leads to a retro‐Diels‐Alder reaction. The thio compound exhibits intermediate behaviour, but charge localization on the oxygen atoms is preferred in the sulphone.
Mass spectrometry of organic compounds of the group V elements. IV—new data on amines, phosphines, arsines and the corresponding acyl derivatives
Authors: Kostyanovsky R. G. , Pleshkova A. P. , Voznesensky V. N. , Elnatanov Yu. I.
Published: May 2005

Further investigations have given new data confirming differences in fragmentation under electrol impact of compounds of trivalent nitrogen and other group V elements. These data have been obtained by comparision of the fragmentation of the amines, phosphines, arsines, benzyl derivatives, geminal systems and acyl derivatives. Mass spectra of tetraethyl derivatives of the group IV elements and acetyl triethyl germane have also been taken and compared with the previous ones.
Chain length effects in the competition between intramolecular hydrogen migrations in the molecular ions of hydrogen migration in the molecular ions of α‐benzylamino‐ω‐benzyloxyalkanes as studied by deuterium labelling
Authors: Bruins Andries P. , Nibbering Nico M. M.
Published: May 2005

The unimolecular decompositions upon electron impact of the bifunctional compounds ØCH2‐NH(CH2)n‐OCH2Ø(n=2 to 7)have been studied by deuterium labelling. The molecular ions lose a benzyl radical and/or a benzaldehyde molecule, depending on the length of the aliphatic chain. Both reactions appear to be the result of the transfer of a hydrogen atom to the charge localized amino function in a cyclic transition state. The ring size of this transition state turns out to play a far more important role than the difference in reactivity of the migrating hydrogen atoms.
Mass spectra of some thioamide vinylogues and of their thiopyran derivatives
Authors: Pradère Jean‐Paul , Duguay Guy , Quiniou Hervé
Published: May 2005

The analysis of metastable ions which decompose in the second field free region of a reversed geometry double focusing mass spectrometer is used to study the fragmentation of a series of thioamide vinylogues and their thiopyran derivatives. The fragmentation processes are discussed and the expected occurrence of an electron impact‐induced retro‐Diels‐Alder reaction is confirmed.
Chelation reactions of acetylacetone on a field ion emitter
Authors: Röllgen F. W. , Schulten H.‐R.
Published: May 2005

Reactions of metal chlorides adsorbed on a field ion emitter with acetylacetone admitted from the gas phase lead to the formation of a number of different acetylacetonate ions. It is shown that these ions originate mainly from chelation reactions in which acetylacetonate molecules are formed prior to field ionization.
Mass spectrometric investigation of ethyl‐containing siloxanes and aromatic silyl ethers
Authors: Mysov E. I. , Akhrem I. S. , Avetisyan D. V.
Published: May 2005

The mass spectra of four linear ethylsiloxanes and eight aromatic silyl ethers are reported. General fragmentation patterns for the benzyltriethylsilyl ethers and their vinylogues are discussed. The spectra of the ethylsiloxanes and ethers are compared with those of their methyl analogues.
Spectres de masse de P‐anisyl‐6 2H‐Thiopyrannes Substitues ou non en 2 et Comportant en 3 un Groupement Fonctionnel
Authors: Pradère Jean‐Paul , Quiniou Hervé
Published: May 2005

Les p‐anisyl‐6 2H‐thiopyrannes substitués en 3 par les groupements fonctionnels R3 = CHO, COCH3, CONH2, et CONCHN(CH3)2 ont des pics de base [M ‐ R3]+ (cationsthiopyrylium) correspondant à l'élimination du groupement fonctionnel. Lorsque R2 = OC2h5, l'élimination de R2 fournit d'autres cations thiopyrylium. Avec R2 = OC2h5 et R3 = COCH3, l'élimination de C2H6 fournit l'acétyl‐3 2H‐tyiopyrannone‐2 substituée contractée ultérieurement en dérivé thiophénique. Lorsque R3 ‐ SCHN2 ou CSN=SHN(CH3)2, les pics moléculaires sont les pics de base; dans cette série, fragmentations corespondant à l'elimination de H2S ou de HCSN (CH3)2 convertissent R3 en CN; dans la mémem série el la Série et la série oxygénée homologue, des fragmentations correspondent à l'élimination de NH2 ou de C3H7N2 portant sur R3.
Massenspektroskopische Fragmentierungsreaktionen. XI‐,β‐Spaltung von 2‐Alkylpyridinen‐Umlagerung zu einer Azachinodimethanstruktur?
Authors: Budzikiewicz H. , Besler U.
Published: May 2005

Deuterium and 13C labelling shows that the β‐cleavage product of 2‐alkyl pyridines loses inter alia in the next step the 2′‐methylene group together with the ring nitrogen.
Pilzpigmente. XXV—Massenspektrometrische Untersuchung Polyisoprenoider Ansabenzochinone
Authors: Schwarz Helmut , Pasupathy Vinayagar , Steglich Wolfgang
Published: May 2005

Die Massenspektren von Tridentochinon und seinen Derivaten sind charakteristisch verschieden von denen der biogentisch verwandten Bovichinone. Ein Teil des komplexen Fragmentierungsverhaltens konnte durch hochauflösende Massenspektrometrie, Verwendung der Defokussierungstechnik und im Fall des Secotridentochinons durch Untersuchung der [OD]‐ markierten Verbindung aufgeklärt werden.
The electron impact‐induced fragmentation of perchlorylbenzene
Authors: Giumanini Angelo G. , Lunelli Bruno
Published: May 2005

The modes of fragmentation of perchlorylbenzene (C6H5ClO3) and its perdeutero derivative under electron impact are reported and discussed. The occurrence of the [C6H5O]− and [C6H5O]+ ions is accounted for in terms of a novel phenyl migration from chlorine to oxygen.
A comparison of negative and positive ion mass spectrometry
Authors: Large Robert , Knof Hans
Published: May 2005

Negative ion mass spectrometry using a conventional mass spectrometer with a special ion source and a sample pressure of approximately 2 × 10−5 Torr is shown to be an excellent method for the qualitative analysis of lower mass alcohols, mercaptans, ketones, aldehydes, aliphatic carboxylic acids and esters, the spectra of which are characterized by intense [M – H]− ions. The method may be termed a ‘selective’ low energy ionization technique, being suitable for the above organic compounds, but not for nitriles, nitro compounds, hydrocarbons, ethers, amines, amides, nitrogen heterocycles and chlorinated compounds. This method can be looked upon as a complementary method, to positive ion mass spectrometry.
The loss of water from isotopically labelled heptanals on chemical ionization
Authors: Fales Henry M. , Fenselau Catherine , Duncan James H.
Published: May 2005

The chemical ionization spectra of a series of deuterated heptanals has been studied using methane and isobutane. Loss of water from the [MH]+ ion follows the same pattern as in electron ionization; hydrogen (deuterium) is lost from all positions except C‐1 and C‐2. The reagent proton is found in the water lost only to the extent of 28% and this is confirmed using deuteriomethane. Possible mechanisms are discussed.
Note on the application of low voltage mass spectrometry to stereochemical problems
Authors: Zaikin V. G. , Smetanin V. I. , Wulfson N. S.
Published: May 2005

Using the stereoisomeric 1,2‐dimethyl‐4‐alkyldecahydroquinol‐4‐ols and various examples described elsewhere it was shown that there are many cases when decreasing of the electron energy does not lead to an increase in the quantitative differences between the mass spectra of stereoisomers.
Rearrangements 1,3 en Serie Heterocyclique. VI—Fragmentation, en Spectrometrie de Masse, des Aryl‐2 Alkyl‐4 Oxadiazol‐1,3,4 Ones‐5 et des Aryl‐2 Alcoxy‐5 Oxadiazoles‐1,3,4
Authors: Golfier Michel , Milcent René , Bouchoux Guy , Henry Yannik
Published: May 2005

Les spectres de masse des aryl‐2 alkyl‐4 oxadiazol‐1,3,4 ones‐5 et de leurs isoméres aryl‐2 alcoxy‐5 oxadiazoles‐1,3,4 ont été étudiés. La fragmentation de ces composés ne semble pas faire intervenir d'isomérisation unimoléculaire d'origine électronique. Pour chaque type d'hétérocycle, les transferts d'hydrogéne accompagnant la pete de la chaîne alcoylée sont principalement induits par l'azote 4.
Etude en Serie as‐Triazine. XIX—Fragmentations Principales de s‐Triazolo‐as‐Triazinones en Spectrometrie de Masse
Authors: Daunis Jacques , Follet Michel
Published: May 2005

Les fragmentations principales de s‐triazolo[4,3‐b]‐, [3,4‐c]‐ et ‐[3,2‐c]‐as triazinones ainsi que celles de leurs dérivés N‐méthylés ont été élucidées grâe á l'étude des spectres de masse des différents composés mono, di‐et triméthylés. Dans tous les cas nous avons observé en premier lieu uniquement la dèradation du cycle triazine qui expulse CO, RCN ou RCN CO selon la structure isomére des triazolo‐triazinones. La comparaison des specres de ces composés avec ceux de leurs dérivés N‐méthylés de structure fixe permet de préciser la participation de chaque forme á l'équilibre tautomére.