bluuebunny/crossref_metadata_2025_split huggingface dataset:
MASSENSPEKTROMETRISCHE UNTERSUCHUNG ZUM MECHANISMUS DER METHYLABSPALTUNG AUS VICINALEN METHYLFURANCARBONSÄURE‐METHYLESTERN
Authors: Schwarz Helmut , Bornowski Hans , Petruck Gerd‐Michael 
Published: May 2005

AbstractDie Methyl‐Eliminierung aus den Titelverbindungen wird durch die Untersuchung mehrerer Modellverbindungen aufgeklärt. Es wird gezeigt, daß die Reaktion unter Nachbargruppenbeteiligung verläuft und daß der Abstand zwischen dem Wasserstoffdonator und demakzeptor von entscheidender Bedeutung für die Bildung der [M‐CH3]+‐Ionen ist.
On the formation of anisole from phenoxyacetamides
Authors: Tomer Kenneth B. 
Published: May 2005

AbstractA major fragmentation route of N‐t‐butyl‐N‐isopropyl‐and N‐ethylphenoxyacetamide is the formation of [C7H8O]+. Deuterium labeling implicates hydrogen transfer from nitrogen in all three species and from the t‐butyl groups of the t‐butylamide. The anisole structure is assigned to the [C7H8O]+· ion on the basis of its secondary fragmentation.
Electron‐impact‐induced rearrangement of organic hypophosphates
Authors: Stec W. J. , Zielińatska B. , Van Wazer J. R. 
Published: May 2005

AbstractPreliminary investigation of electron‐impact behavior of organic hypophosphates and their mono and dithio derivatives has shown that they undergo skeletal rearrangement to the anhydride type of structure magnified image,and that this anti‐Arbuzov rearrangement is of electron‐impact origin.
Mass spectral fragmentation of some phosphaaromatic compounds
Authors: Jongsma C. , Bickelhaupt F. 
Published: May 2005

AbstractThe behaviour of 2‐phosphanaphthalene, 3‐methyl‐phosphanaphthalene and 10‐methyl‐9‐phosphaanthracene upon electron‐impact has been compared with that of the carbon and nitrogen analogues. A close resemblance to the fragmentation pattern of the [M  H]+ ions of 2‐methyl‐and 2‐ethylbenzo[b]thiophene has been observed. It is concluded from the σ40 intensities of the molecular ions, the relatively high intensities of the doubly charged molecular ions and the fragmentation patterns, that these phosphorin derivatives behave as aromatic compounds under electron‐impact. From the molecular ion of 2‐phosphanaphthalene a remarkable expulsion of a phosphours atom is observed.
MASSENSPEKTROMETRISCHE UNTERSUCHUNGEN VON DIARYLMETHYLEN‐BIS‐XANTHOGENATEN UND DIARYL‐DITHIOACETALEN: II
Authors: Schumann Dieter , Frese Emil , Praefcke Klaus , Knöfel Werner 
Published: May 2005

AbstractDas massenspektrometrische Verhalten der Diarylmethylen‐bis‐xanthogenate wird beschrieben und mit dem der Dithioacetale verglichen. Charakteristisch für alle untersuchten Verbindungen ist das Auftreten eines primär gebildeten Sulfenium‐Kations, das für die Verbindungen ein den Thioestern analoges Fragmentierungsverhalten zeigt. Hervorzuheben ist das mit Thioketonstrukturen, deren Bildung mit der thermolytischen verglichen und diskutiert wird. Dabei ist bemerkenswert, dass die als Beleg dienenden metastabilen Signale für die Bildung des Fragments d aus dem 1. feldfreien Raum erst bei höheren Temperaturen auftreten und somit Abhängigkeit von der thermischen Überschussenergie zeigen.
The significance of field ionisation kinetics to ion structure: Isomerisation and decompostition of [C4H8]+· radical ions
Authors: Morgan Roger P. , Derrick Peter J. 
Published: May 2005

AbstractThe kinetics of formation of [C3H5]+[M  CH3]+, [C3H4]+·[M  CH4]+· and [C2H4]+·[M  C2H4]+· from but‐1‐ene, cis‐ and trans‐but‐2‐ene, 2‐methylpropene, cyclobutane and methylcyclopropance following field ionisation have been determined as a function of time 20 (or 30) picoseconds to 1 nanosecond and at two points in the microsecond time‐frame. The results are consistent with the supposition that at the shortest accessible times (20 to 30 picoseconds) the structure of the [C4H8]+· molecular ion qualitatively resembles that of its neutral precursor, but suggest that prior to decomposition within nanoseconds the various molecular ions (excepting cyclobutane where the processes are slower) attain a common structure or mixture of structures. Reaction pathways of the presumed known ion structures are delineated from the nature of decompostion at the shortest times.
MASSENSPEKTROMETRISCHE UNTERSUCHUNG ORGANISCHER STICKSTOFFVERBINDUNGEN XVIIIMECGABUSNEB;ndash DER NH3‐ ELIMINIERUNG AUS 3‐PHENYL‐PROPYL‐ UND 5‐PHENYLPENTYLAMIN
Authors: Schwarz Helmut , Wesdemiotis Chrysostomos , Hess Bernd , Levsen Karsten 
Published: May 2005

AbstractMit Hilfe von 2H‐markierten Verbindungen, Bestimmungen, Bestimmung der Bildungsenthalpien der [pM  NH3]+·‐Ionen aus Auftrittspotential‐Messungen und Vergleich der Stoßakitiverungs‐spektren dieser Ionen mit denen der entsprechenden Phenylalkene werden die Mechanismen der Ammoniak‐Eliminierung aus den Titelverbindungen untersucht und möliche Ionenstrukturen als Funktion der Lebensdauer diskutiert.
Mass spectrometric study of hexamethyldisilazane and some of its N‐substituted derivatives
Authors: Tamás J. , Miklós P. 
Published: May 2005

AbstractThe electron‐impact‐induced decomposition of the title compounds has been investigated in detail. Deuterium labelling was used to study the mechanisms of fragmentation and the structures of ions generated. Hydrogen, methyl and phenyl group migrations to one of the silicon atoms were observed as significant secondary processes. These processes are usually γ‐transitions, from which it is inferred that these rearrangements occur via 4‐membered cyclic transition complexes.
Formation of aniline‐like ions by electron‐impact‐induced elimination of CO from formanilide
Authors: Hammerum Steen 
Published: May 2005

AbstractThe metastable peak intensity ratios for elimination of HNC vs DNC from the [M  CO]+· ion of deuterium labelled analogues of formanilide show that the formyl hydrogen atom migrates to nitrogen prior to or during CO expulsion to form a [C6H7N]+· ion of aniline‐like structure. An examination of metastable peaks does not allow similar conclusions to be reached for methyl substituted formanilides. Low abundance [C6H6O]+· ions are formed by HNC elimination from the formanilide molecular ion in a reaction where three covalent bonds to the formyl carbon are broken.
Spectrometrie de masse d'heterocycles azotes. IV—comportement sous l'impact electronique d'iodures de pyrazoliniums‐2
Authors: Aubagnac J.‐L. , Bourgeon D. , Jacquier R. 
Published: May 2005

AbstractLe comportement d'iodures de pyrazolinium‐2 en spectrométrie de masse est étudié. Les réactions de substitution de l'anion iodure sur les substituants portés par l'azote en 1 entraǐnent la formation de quatre molécules neutres dont on observe simultanément la fragmentation. Les réactions se produisent donc tant dans des solutions protiques, ainsi que des travaux précédents l'ont montré, qu'en phase gazeuse et sous l'impact électronique.
Studies in mass spectrometry. III—formation of a common intermediate in the primary fragmentation process of 1‐phenylcyclobutene and of 2‐phenyl‐1,3‐butadiene
Authors: Derocque Jean‐Luc , Jochem Martin 
Published: May 2005

AbstractThe mass spectra of the title compounds show peaks corresponding to the primary fragmentation of H, CH3 and (H2 + C2H2). Kinetic study suggests that the molecular ion of 1‐phenylcyclobutene and 2‐phenyl‐1,3‐butadiene loses H and CH3 through formation of a common intermediate. This is confirmed by appearance potential and ionisation potential measurements, fragmentation of deuterium labelled compounds and the corrected Z values.
Fragmentation d'azoles sous l'impact electronique. X—etude de rearrangements cycliques en serie alkylamino‐1,2,4‐triazole
Authors: Maquestiau A. , Van Haverbeke Y. , Flammang R. , Cooks R. G. 
Published: May 2005

AbstractLa formation in situ de tautomères individuels par des réactions de fragmentation dans le spectromètre de masse constitue une méthode de réarrangements tels que les équilibres prototropiques. Le C‐aminotriazole est généré en ses différentes formes tautomères par élimination d'éthylène à partir des composés N‐éthylés et ces tautomères sont isomérisés en une structure commune avant fragmentation. L'élimination d'éthylène se déroule via un état de transition à quatre centres pour deux éthylaminotriazoles isomères et via un état de transition à cinq centres pour le troisième comme le montrent les termes de partition d'énergie associés aux réactions aux réactions d'ions métastables. Ces conclusions mécanistiques sont étayées par l'étude d'effects isotopiques (méthode de caractérisation de facteurs de fréquence). L'élimination de propène à partir de propylaminotriazoles est abordée par des méthodes analogues. Les termes de partition d'énergie et l'étude d'effets isotopiques primaires sont en accord avec une élimination non concertée de propène ou avec un mécanisme de transfert de l'hydrogène β via un complexe transitoire à cinq centres.
Mass spectra of some neopentylphosphorus derivatives
Authors: King R. B. , Cloyd J. C. , Reimann R. H. 
Published: May 2005

AbstractThe fragmentation patterns and major metastable ions of the mass spectra of the neopentyl‐phosphorus derivatives [(CH3)3CCH2]3P, [(CH3)3CCH2]2P(O)H, [(CH3)3CCH2]nPX3‐n (n = 1 and 2; X = H, Cl, C6H5 and CH = CH2), [(CH3)3CCH2]3PS, [(CH3)3CCH2]nP(S)R3‐n (n = 1 and 2; R = C6H5 and CH = CH2), [(CH3)3 CCH2]2PCH2CH2P[CH2C(CH3)3]2, ([CH3)3CCH2]2PCH2PCH2‐CH2P(H)C6H5 and [(CH3)3CCH2]2PCH2CH2P(S)(CH3)2 are described. Fragmentation of a neopentyl group by elimination of either C4H8 or CH3 is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C4H8 from all of the neopentyl groups occurs very readily. The resulting [(CH3)nPX]+.3‐n ions are often the most intense ions in the mass spectra.
Isomere N‐Aryltetrazole. III—Massenspektren
Authors: Könnecke A. , Lippmann E. 
Published: May 2005

AbstractDie niedrigaufgelösten massenspektren von vier Paaren isomerer N‐Aryltetrazole sind untersucht worden, um die Anwendbarkeit der Massenspektrometrie zur Unterschiedung der Isomeren zu überpuüfen. die Fragmentierung beginnt in Reihen durch aufeinanderfolgende Abspaltung von N2 und HCN unter Bildung von Ionen der gleichen Massenzahlen, die vielleicht auf Grund verschiedener Struktur mit unterschiedlicher Häufigkeit auftreten. Dies ermöglilcht die eindeutige Identifizierung der Isomeren.
Hydrogen rearrangements in cyclic phosphates during the electron impact‐induced fragmentation
Authors: Murai Asao , Kainosho Masatsune 
Published: May 2005

AbstractThe fragmentation upon electron impact of a cyclic phosphate, 5,5‐dimethyl‐2‐oxo‐2‐phenoxy‐1,3,2‐dioxaphosphorinane, was investigated. Using its deuterated analogue, it was shown that no randomization of hydrogen atoms among methyl, methylene and phenyl groups occurred within the molecular ion. The majority of the fragmentations involved single, double or triple hydrogen transfers. The origin of hydrogen(s) transferred in the formation of C‐5 ions was also estimated. The existence both specific and nonspecific hydrogen rearrangement mechanisms was also revealed. The specific hydrogen rearrangement involves a methyl hydrogen transferring to the PO group and this process seemed to be the initial step in the formation of many of the ions.
Anwendung der Massenspektrometrie zur Identifizierung isomerer Amino‐oxadiazole
Authors: Kraft R. , Henklein P. , Etzold G. , Zöpfl H.‐J. , Westphal G. , Schmidt R. 
Published: May 2005

AbstractDie massenspektrometrischen Zerfallsprodukte der vier isomeren phenyl‐substituierten Amino‐oxadiazole, 2‐Amino‐5‐phenyl‐l.3.4‐oxadiazol, 3‐Amino‐5‐phenyl‐l.2.4‐oxadiazol, 5‐Amino‐3‐phenyl‐l.2.4‐oxadiazol und 3‐Amino‐4‐phenyl‐l.2.5.oxadiazol, unterscheiden sich sowohl hinsichtlich der Art der Fragmentzusamrnensetzung als auch der Signalintensitäten so charakteristisch, daß eine eindeutige Differenzierung von Ring‐ und Stellungsisomeren moglich ist. Die wichtgsten Fragmentierungswege, die zu den strukturspezifischen Ionen führen, werden diskutiert.
Elektronestossinduzierte Fragmentierung von Acetylenverbindungen. XIV—Wasser‐Eliminierung Durch OH/OH‐Wechselwirkung bei α,ω‐DIIN‐Diolen
Authors: Schwarz Helmut 
Published: May 2005

AbstractDie Mechanismen der elektronenstroßinduzierten Wasser‐Eliminierung aus den Titelverbindungen werden untersucht. Es wird gezeigt, daß beide Hydroxylgruppen an diesem Prozeß beteiligt sind und daß die ungewöhnliche Wechselwirkung nichtgebundener Zentren wahrscheinlich durch winkeldeformationen der Diine verursacht wird.
Structure in metastable peaks arising from reactions in which[C3H3]+ ions are produced
Authors: Sen‐Sharma D. K. , Jennings K. R. , Beynon J. H. 
Published: May 2005

AbstractThe metastable peak resulting from the fragmentation of [C7H7]2+⋅ ions fram a variety of sources shows structure due to the presence of two reactions releasing different amounts of translational energy. The translational energy differences has been measured as 0.52 ± 0.04eV and is thought to be due to the formation of product ions of different structure via competing reactions from a single transition state. The possible structures of these ions are discussed, and it is proposed that the effect observed is due to the formation of [C3H3]+ ions in two forms, cyclopropenyl and proparg1. The metastable singly charged ions which also lead to product ions of formula [C3H, 3]+.
Mass spectral studies of unsaturated carboxylic acids. II—Some acids containing two double bonds
Authors: Bigley D. B. , Todd J. F. J. , Weatherhead R. H. 
Published: May 2005

AbstractThe mass spectra of some doubly unsaturated carboxylic acids are reported. Where C‐2 is quaternary, the fragmentation pathway is similar to that previously demonstrated for βγ‐unsaturated acids. The unbranched acids show different behaviour, similar to their thermal pyrolysis.
Chemical ionization of cyclopropyl ethers
Authors: Andrist A. Harry , Wilburn Bruce E. , Zabramski Joseph M. 
Published: May 2005

AbstractChemical ionization of the isomeric 2,3‐dimethylcyclopropyl methyl ethers has been examined with hydrogen, methane and ammonia as reagent gases. The relative ion intensities for loss of methanol from each protonated isomer are consistent with the operation of the DePuy‐Hoffmann‐Woodward Rule in the gas phase.
Slow metastable transitions in aromatic species
Authors: Smith Richard D. , Furtell Jean H. 
Published: May 2005

AbstractA tandem Dempster‐ion cyclotron resonance mass spectrometer was used to examine metastable transitions in benzene, toluene, anisole and anisole 1,3,5‐d3. The tandem‐ion cyclotron resonance technique examines all unimolecular reactions of the injected, mass‐selected ion, which occur between the injection time of several microseconds and the ion cyclotron resonance reaction section residence time of several milliseconds. The long sampling interval results in different relative intensities and considerably larger isotope effects than have been observed in previous studies.
Stereoselective H2O eliminations in 3‐ and 4‐arcylcyclohexanols under electron impact
Authors: Sharvit Joseph , Mandelbaum Asher 
Published: May 2005

AbstractThe elimination of H20 from the molecular ions of trans‐4‐ and trans‐3‐arylcyclohexanois takes place to a greater extent than in the corresponding cis isomers. The remarkable differences in abundance taken together with substituent effects and the results of deuterium labelling, show that configuration is retained in the molecular ions which undergo the elimination, and that this process is a cis‐1,4 and cis‐1,3 elimination in the trans‐4‐ and trans‐3‐ arylcyclohexanois, respectively. Possible mechanisms for the elimination in the cis isomers are discussed.
Die massenspektrometrische Identifizierung von Alkyl‐1, 3‐thiazolen
Authors: Haag Armin , Werkhoff Peter 
Published: May 2005

AbstractStellungsisomere Mono‐, di‐ und Trialkyl‐1,3‐thiazole Können anhand ihrer Elektronenstossmassenspektren eindeutig identifiziert und von isobaren Deivaten unterschieden werden. Die entscheidenden Kriterien hierfür ergeben sich suc den Massenzahlen und den relativen Intensitäten signifkanter schlüsselionen, isbesondere der Molkülionen, der [M – 1]+,‐Ionen, der Thiazolylmethly‐carbokationen bzw. ihrer zur Thiaziniumstruktur ringerweiterten Formen, sowkie der durchringverrengende Nitrileliminierung gebildeten Thiitren‐Radikalionen. Auf diese Weise wurden durch Gaschromatographie‐Massenspektroskopie im Glaskapillar‐Gaschromatogramm von Röstkaffeearoma 22 Thiazolderivate erkannt. Ihre Zuordnung wurde durch Messungen an einer Reihe authentischer Vergleichspräparate voll bestätigt.
Mass spectrometric identification of amino acid thiohydantoins
Authors: Suzuki Tateo , Song Kyung‐Duck , Itagaki Yasuhiro , Tuzimura Katura 
Published: May 2005

AbstractAmino acid thiohydantoins were identified using electron impact and chemical ionization mass spectrometry. Some fragmentations of thiohydantoin ring were also identified. These results suggest that the thiohydantoin method should be useful for the stepwise peptide sequence analysis starting from the carboxyl terminus. The sequence of a model tripeptide was determined by the combination of the thiohydantoin method and mass spectrometry. In the case of peptide which contained a proline residue as their C‐terminal peptide, cleavage of the peptide bond cannot be achieved.
Fragmentation in doubly charged ion mass spectra of anhydropisatin and related compounds
Authors: Eguchi Shizuko , Nakayama Mitsuru , Hayashi Shûichi 
Published: May 2005

AbstractThe doubly charged ion mass spectra of anhydropisatin, 4‐methoxyanhydropisatin, 3, 8, 9‐trimethoxypterocarpen and 3, 4, 8, 9‐tetramethoxypterocarpen were determined, and the fragmentation was explained by assuming that the paired electrons were partially localized in the fragmentations and by comparing the spectra with that of 3‐(CD3)‐anhydropisatin. Conventional mass spectra of these compounds were very simple, but the doubly charged ion spectra were sufficiently characteristic for the reliable identification.
Hydrogen migrations in mass spectrometry. I—The loss of olefin from phenyl‐n‐propyl ether following electron impact ionization and chemical ionization
Authors: Benoit Frank M. , Harrison Alex G. 
Published: May 2005

AbstractUsing specifically labelled compounds we have made a detailed study of the source of the hydrogen transferred in the elimination of C3H6 from the molecular ion of phenyln‐propyl ether following electron impact ionization and from the protonated (and ethylated) molecule following chemical ionization. The migrating hydrogen originates from all three positions of the npropyl group but not in the ratio expected for randomization of the alkyl hydrogens prior to transfer. The source of the migrating hydrogen is similar for both electron impact ionization and chemical ionization, indicating that the factors governing the rearrangement are the same for both modes of ionization. From a comparison of the results for labelled 2,6‐dimethyl phenyl n‐propyl ethers with the results for the unsubstituted ether it is concluded that hydrogen transfer occurs only to the ether oxygen and not to the phenyl ring. A two‐step mechanism involving a set of competing reversible hydrogen transfer reactions followed by CO bond cleavage is proposed to explain the results.
Hydrogen randomization and the loss of CH3N in the mass spectra of 2‐dimethylaminopyridines
Authors: Whittle C. P. , Lacey M. J. , Macdonald C. G. 
Published: May 2005

AbstractThe electron impact mass spectra of some deuterium labelled 2‐dimethylaminopyridines are consistent with hydrogen randomization within the dimethylamino group prior to the loss of the elements of methylenimine.
Charge stripping and E/2 mass spectra
Authors: Kemp D. L. , Beynon J. H. , Cooks R. G. 
Published: May 2005

AbstractThe stabilities of doubly charged ions have been investigated by comparing the relative abundances of these ions in charge stripping spectra with their precursor ions in normal mass spectra. This study reveals differences in cross‐section for charge stripping of isobaric ions with different elemental compositions, and information is presented on the competition between collisional dissociation and collisional ionization.
The analysis of mixtures: V
Authors: Halket J. McK. , Reed R. I. 
Published: May 2005

AbstractThe work previously discussed has been extended. Product‐moment correlation coefficients are shown to be useful in reducing the conditions hitherto necessary for the resolution of pure component spectra from an array of mixtures spectra. The method is illustrated by the solution of a five component calculated mixture in which there is only one unicomponent peak.
Computer‐aided interpretation of mass spectra. Increased information from neutral loss data
Authors: Dayringer Henry E. , McLafferty F. W. , Venkataraghavan Rengachari 
Published: May 2005

AbstractThe performance of the [Self‐Training Interpretive and Retrieval System] for unknown mass spectra has been improved by modifications to the data classes utilizing information concerning the masses of neutral fragments lost from the molecular ion. Modifications include use of overlapping mass ranges, sets of homologous series of losses and an arithmetic combination of the data class rankings to give an [overall match‐factor] for neutral loss data.
Mass spectra and fragmentation patterns of malonaldehydedianil and some of its metal complexes
Authors: Richards C. P. , Delderfield J. , Webb G. A. 
Published: May 2005

AbstractUnder electron impact malonaldehydedianil and its bis Co(II), Ni(II) and Zn(II) complexes produce a stable molecular ion. The Cu(II) complex appears to decompose prior to ionization. The free dianil molecular ion fragments by expulsion of the azomethine proton or by fission of C‐N bonds. The molecular ions of the metal complexes usually expel a complete ligand before undergoing demetallation.
Etude en Basse Tension de l'Androstane Dione‐3,17—Application a la Localisation du Deuterium
Authors: Viger Antoinette , Marquet Andrée , Tabet Jean‐Claude 
Published: May 2005

AbstractLes fragmentations de al (5α) androstanedione‐3,17 ont été étudiées en vue de localiser le deutérium entre les positons 4 et 6. Ceci est possible en basse tension: on trouve un pic à m/e 216, provenant d'une élimination du cycle. A qui permet le dosage de molécules deutériées en 4 et (ou) 6.
Application of molecular orbital theory to the interpretation of mass spectra study of substituent effect on a series of acetophenones
Authors: Loew Gilda H. , Kirchner Robert F. , Lawless James G. 
Published: May 2005

AbstractSemi‐empirical molecular orbital calculations have been used to study the substituent effect on the intensity of the m/e 43 peak ([COCH3]+) in the mass spectra of a series of 25 substituted acetophenones. The two most relevant molecular properties calculated appear to be the ionization potential and the bond density of the fragmenting bond. A semi‐logarithmic plot of relative peak intensities[the ratio of m/e (43/[M]+)] versus the ratio of ionization potential to bond density for these compounds produced a linear relationship with a correlation coefficient of 0.90 from the INDO method and 0.93 from the IEHT method. The use of two different semi‐empirical methods to calculate ionization potentials and bond densities, together with the qualitative agreement between the two methods and with available experimental data, substantiates the correlations obtained. In addition, the molecular orbital calculations were used to understand the anomalous behavior of the teritary butyl and para‐phenyl substitutes.