bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectrométrie de Masse d'Hétérocycles Azotés. X–Contribution à l'Etude du Comportement de ll'Ion Aniline et des Ions Aminopyridines avant Fragmentation par Perte de HCN
Authors: Aubagnac Jean‐Louis , Campion Philippe 
Published: May 2005

AbstractL'examen des spectres MIKE de dérivés marqués au deutérium de l'aniline, des aminopyridines et de la chloro‐2 amino‐5 pyridine montre qu'avant fragmentation par perte de HCN, le mixage, absent dans le cas des aminopyridines, est limité mais notable dans le cas de l'aniline. Pour ce dernier composé, le mixage est modifié fortement par de faibles variations de l'énergie des ions étudiés, variations situés à l'intérieur de la région d'énergies correspondant aux ions métastables. De plus, l'examen des spectres MIKE des dérivés monodeutériés des aminopyridines permet d'infirmer pour ces composés le mécanisme de perte de HCN généralement admis.
The formation of [C9H10]+˙ ions by loss of a molecule of water from molecular ions of 3‐phenylpropanol with lifetimes of 10−11 to 10−5 s
Authors: van der Greef J. , Nibbering N. M. M. 
Published: May 2005

AbstractField ionization kinetic experiments in conjunction with deuterium labelling have been shown that the molecular ions of 3‐phenylpropanol with lifetimes as short as 10−11s lose a molecule of water via a specific 1,3 elimination. At times > 10−11s two distinct hydrogen interchange processes in the molecular ions appear to complete with this reaction. One of the intechange processes involves the benzylic and hydroxylic hydrogen atoms and starts to complete with the elimination of water at shorter molecular ion lifetimes than the other interchange process in which the ortho hydrogen atoms also participate. Decomposing [C9H10]+˙ ions generated by elimination of water from the molecular ions of 3‐phenylpropanol or by direct ionization of various isomeric C9H10 compounds could not be distinguished adequately, illustrating isomerization either to a common ion structure or to a set of ions with rapidly interconverting structures. A consideration of the energetics of the elimination of water from 3‐phenylpropanol suggests that at threshold energies 1‐phenylpropene or indane type structures can be formed. Arguments for the latter have been obtained from the observation that a labile fluorine atom is present in the [M – H2O]+˙ ions generated from 3‐pentafluoro‐phenylpropanol.
Loss of hydroxyl radical from cis‐ and trans‐1‐cyclohexyl 2‐phenyl‐3‐benzoylaziridines: A unique eight‐centered rearrangement elimination
Authors: Tarburton Philip , Sun Tung , Cromwell Norman H. , Gross Michael L. 
Published: May 2005

AbstractFollowing electron impact ionization of the title compounds, a rapid electrocyclic ring opening of the [M]+˙ of both isomers occurs. A subsequent fragmentation of each is loss of hydroxyl which occurs by rearrangement to the carbonyl function. Properties of [MOH]+ are in accord with a stable structure for this ion and therefore it is assigned as the 4‐phenylisoquinium ion. The proposed mechanism and ion structures are supported by deuterium labeling and defocused metastable ion studies.
Mass spectra of 1,1‐bis(acylamido)‐1‐deoxyalditol acetates
Authors: Matulewicz María Cristina , Cerezo Alberto Saúl 
Published: May 2005

AbstractThe mass spectra of fourteen 1,1‐bis(acylamido)‐1‐deoxyalditol acetates and of two model compounds have been recorded. The most important feature of the fragmentation of these derivatives is the cleavage of the C–1–C–2 bond which produces fragment
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None of the alditol derivatives yields the molecular ion.
Oxygen rearrangement of molecular ions of 3‐phenylpropionates
Authors: Liehr Joachim G. , Caprioli Richard M. , Beynon John H. , Morgan Roger P. , Richter Wilhelm J. 
Published: May 2005

AbstractThe oxygen rearrangement in molecular ions of 3‐phenylpropionates has been investigated with the aid of mass analyzed ion kinetic energy spectra. Elimination of an allyl radical followed by expulsion of ketene from the molecular ion of allyl 3‐phenylpropionate is shown to result in formation of protonated benzaldehyde. The oxygen rearrangement has been found to be inoperative in ionized methyl 3‐methyl‐3‐phenylbutyrate. [M  CH3  CH2CO]+ ions in the spectrum of the latter compound are formed by elimination of the 3‐methyl substituent and subsequent methoxy migration.
Potential energy profiles for the unimolecular reactions of [C3H7S]+ Ions
Authors: Broer W. J. , Weringa W. D. 
Published: May 2005

AbstractAppearance energies were measured for several types of [C3H7S]+ ions. From these appearance energy values the heats of formation of the ions were calculated. For the isomeric ions that could not be generated in the mass spectrometer, the heats of formation were estimated by means of the isodesmic substitution method. Transition state energies for the decomposition to C2H4 and [CH3S]+ along two pathways were determined from the appearance energies of these ions. Using the energy values, potential energy diagrams were constructed for the rearrangements and decompositions of the [C3H7S]+ ions. A supplementary 13C Clabelling experiment is described for the determination of the rearrangement pathway of [CH3CH2CHSH]+ ions prior to decomposition.
Comparative study of pulsed laser and fission fragment induced desorption with nucleotic compounds
Authors: Schueler B. , Krueger F. R. 
Published: May 2005

AbstractMass spectra obtained under pulsed laser induced and fission fragment induced desorption of nucleosides and their nucleobases are reported and compared. No striking differences are observed. The nature of the excitation process for both methods is discussed. Fission fragment induced desorption is known to be due mainly to a sudden non‐resonant electric perturbation, which in conjunction with thermal activation also plays a major role in laser induced desorption.
Mass spectra of pyridine monoamidoximes and their O‐trimethylsilyl ether derivatives
Authors: Pearse George A. , Jacobsson Sven 
Published: May 2005

AbstractThe mass spectra of pyridine‐2‐, ‐3‐, and ‐4‐amidoxime and their O‐trimethylsilyl derivatives have been investigated. Also included in this study were the deuterated derivates. Main pathways of fragmentation of these compounds have been proposed. A comparison with the mass spectra of the corresponding pyridine aldoximes has been made.
Mass spectrometry of organic compounds of the group V elements: V‐Cyanamides, cyanphosphines, cyanarsines and vinylogues
Authors: Kostyanovsky R. G. , Pleshkova A. P. , Voznesensky V. N. , El'natanov Yu. I. 
Published: May 2005

AbstractNew data have been obtained confirming distinct differences in fragmentation of compounds of trivalent nitrogen and other group V elements under electron impact. These data have been obtained for the fragmentation of the cyanamides, cyanphosphines and cyanarsines, as well as of their vinylogues.
The fragmentation behaviour of some spirobenzthiazoles under electron impact
Authors: Herzig Ulrike , Krenmayr Peter , Varmuza Kurt 
Published: May 2005

AbstractThe electron impact induced fragmentations of ten spiro‐benzthiazoles have been studied. The principal decomposition reactions have been elucidated by metastable studies, exact mass measurements, and by deuterium exchange of the imino hydrogen. The primary fragmentation step is an α‐cleavage reaction, which leads to ring opening of the ring fused to the benzthiazole moiety of the molecule. The subsequent decompositions resemble those of cyclohexylamines. They follow a general pattern, the details of which are discussed with respect to the nature and position of the heteroatom in the saturated ring.
Application of a secondary ion mass spectrometer as a detector in liquid chromatography
Authors: Benninghoven A. , Eicke A. , Junack M. , Sichtermann W. , Krizek J. , Peters H. 
Published: May 2005

AbstractRecently developed new techniques of ion formation from organic solids may become very useful in the application of mass spectrometers as detector units in liquid chromatography. Details of a liquid chromatograph mass spectrometer coupling device are presented. Some features of this device, combined with a quadrupole secondary ion mass spectrometer, are demonstrated experimentally by the analysis of aqueous solutions of leucine and cytosine. It is demonstrated that the sensitivity of the liquid chromatography secondary ion mass spectrometry combination covers the concentration range occurring in liquid chromatography.
Fragmentation of alkylbenzoates by electron impact: Transposition and rearrangement of the alkyl chain
Authors: Audier Henri E. , Milliet Arielle 
Published: May 2005

AbstractThe electron impact induced fragmentation of alkylbenzoates produces an ethylenic ion in a stepwise reaction. The first step is exothermic and involves the transfer of one hydrogen radical from the chain to the oxygen atom on the carboxyl; several intermediate ions having a large energy excess can be formed. The orientation of the reaction is directed by the relative breaking rates of these different intermediate ions. At low energy the transferred H is the one which leads to the most stable ion and consequently to the most substituted ethylenic fragment. In several cases chain rearrangements take place during the reaction. This phenomenon is the result of both the exothermic character of the first step and the large difference between the ΔH of the monosubstituted, disubstituted or trisubstituted ethylenic ion which is the final state of this fragmentation.
Electron impact mass spectra of some substituted aromatic boronate derivatives of bifunctional compounds
Authors: Singhawangcha Sureerat , Pooie Colin F. , Zlatkis Albert 
Published: May 2005

AbstractThe electron impact mass spectra of the 3,5‐bis(trifluoromethyl)benzeneboronate, 2,4‐dichlorobenzene‐boronate and 4‐bromobenzeneboronate derivatives of some bifunctional diols and aminoalcohols are characterized by prominent molecular ions with diagnostically useful modes of fragmentation. Many of the principal ions in the mass spectra retain boron in their structure.
Mass spectrometry of nitrogen heterocycles:XI—Loss of HCN from indazole studied by 15N labelling
Authors: Atmani Aziz , Aubagnac Jean‐Louis , Pellegrin Valdo 
Published: May 2005

AbstractA small preference for the N‐1 nitrogen atom is observed in the loss of HCN from the molecular ion of 15N labelled indazole. In addition there is a small isotope effect.
A novel mass marker for metastable ion scans in a double focusing mass spectrometer
Authors: Porter C. J. , Brenton A. G. , Beynon J. H. , Popplestone A. 
Published: May 2005

AbstractCharacterization and assignment of the products of metastable decompositions which are transmitted by a double focusing mass spectrometer, is often complicated by the inability to measure precisely the parent/daughter ion mass values directly from the spectra which appear on chart paper. This is often because there are considerably fewer peaks in these types of spectra compared with a normal mass spectrum obtained from high energy reactions in the ion source. Electronic circuits are described which permit accurate parent/daughter ion mass values to be obtained when the products of metastable decompositions are transmitted through the ZAB‐2F double focusing mass spectrometer. Digital logic circuitry is also described which is used to mark mass values during a scan by driving either a solenoid pen drive unit for a chart recorder or a galvanometer on a multi‐range ultraviolet oscillograph recorder.
Mass spectrometry: XI—Electron impact induced fragmentation of some amides of F‐acids and their deuterated homologues
Authors: Greiner Jacques , Pastor Raphael , Cambon Aimé 
Published: May 2005

AbstractThe mass spectrometry of perfluoro compounds (F‐alkyl compounds) has seldom been the subject of systematic studies. Fluorocarbons excepted, only a few mass spectra of such compounds have been analysed and corresponding fragmentations correlated. In this paper we report the mass spectra of 19 amides of perfluoro acids (RFCONHR) with R=benzyl, 2‐phenylethyl, 2‐phenylpropyl, 3‐phenylpropyl, 2‐(N‐phenylamino)ethyl, and RF=F‐methyl, n‐perfluoropropyl, n‐perfluoropentyl and n‐perfluoroheptyl. These compounds exhibit quite different behaviour from their hydrocarbon homologues under electron impact (for instance no [RFCO]+ fragment was found). Specific deuterium labelling and high resolution measurements have been used to show typical rearrangements and to establish the fragmentation routes.
Rearrangement reactions of 2‐nitrothiobenzamides upon electron impact
Authors: Clausen K. , Scheibye S. , Lawesson S.‐O. , Bowie J. H. , Blumenthal T. 
Published: May 2005

AbstractThe decomposing molecular cations derived from (substituted) 2‐nitrothiobenzamides fragment by complex rearrangement reactions. When the alkyl substituents (R) attached to N are methyl, the major fragmentations are [M]+˙ → [MSO]+˙ and [MSO]+˙ → [(MSO)+˙–R˙]+. This remains a basic pathway when R ⩾ Et, but other rearrangements are also observed. For example, when R=Et, additional competitive processes are [M]+˙ → [MHO˙]+ and [M]+˙ → [MC2H4O]+˙.
Fragmentation of dihydro‐ and tetrahydro‐1,5‐benzothiazepines under electron impact
Authors: Wen‐Gang Chai , Guang‐Hui Wang , Sheng Jin , Heng‐Liang Jin 
Published: May 2005

AbstractThe fragmentation mechanisms of dihydro‐ and tetrahydro‐1,5‐benzothiazepines under electron impact have been studied in detail using high resolution mass spectrometry, metastable decompositions and deuterium labelling techniques. Both kinds of the benzothiazepines possess high stability. The [MSH]+ and the cyclic benzothiazole ions derived from the fragmentation and severe skeletal rearrangement of the molecular ion comprised the main features of the spectra. Some doubly charged ions were noticed in the low resolution electron impact mass spectra.
Water loss from [C5H10O]+˙ isomers: A reassessment
Authors: Holmes John L. , Dakubu Mumuni , Rye Robin T. B. 
Published: May 2005

AbstractFrom a detailed analysis of metastable peak shapes it is proposed, contrary to earlier conclusions, that the loss of H2O from the molecular ions of the C5H10O isomers cyclopentanol, pentanal and pent‐1‐en‐3‐ol yields only [penta‐1,3‐diene]+˙ in the metastable time frame. Therefore the composite metastable peak for this process arises from two competing reaction channels yielding a common daughter ion. The observation that the first two isomers also produce [penta‐1,4‐diene]+˙ as a daughter ion is attributed to a high energy (ion source) reaction which contributes negligibly to first field free region fragmentations.
Chemical ionization desorption mass spectrometry of some quaternary ammonium salts
Authors: Hasiak Bruno , Ricart Guy , Barbry Didier , Couturier Daniel , Hardy Michel 
Published: May 2005

AbstractThe ammonia chemical ionization desorption spectra of N,N‐dimethyl quaternary ammonium iodides in addition to high protonated molecular ion [M + H]+ intensity, show signals for an ion radical composed of N‐methyl abstracted salt cation and ammonia [C + NH3CH3]+˙. These ions corresponding to the cation +2 show increased importance in the chemical ionization mode, using the same reagent gas. The technique of chemical ionization desorption appears suitable for the analysis of salts, and thus for the determination of the molecular weight of both anion and cation.
The computer processing and interpretation of mass spectral information. V—generation of a table of isotopic spectra of structural fragments
Authors: Sukharev Yu. N. , Molgachova N. S. , Nekrasov Yu. S. 
Published: May 2005

AbstractA package of dialogue programs intended for generation of isotopic spectra from specified elemental compositions containing any number of elements is described. Structural fragments (super‐elements), once in the table, acquire the status of a separate chemical element. All operations with super‐elements are analogous to those with polyisotopic elements of the periodic table. The user can modify the table at his discretion to suit his purpose. The table increases the flexibility of interactive data processing programs and thus the dialogue is made to approach the natural chemist's language. The programs written in FORTRAN IV are intended for a minicomputer with a core memory of about 24 K words.
Mass spectrometry of thio analogues of pyrimidine bases: Benzylthiouracils and p‐nitrobenzylthiouracils
Authors: Wyrzykiewicz E. , Stobiecki M. , Golankiewicz K. 
Published: May 2005

AbstractThe mass fragmentation of twelve new 2‐ and 4‐benzylthio substituted derivatives of uracils is discussed and fragmentation pathways, elucidation of which was assisted by accurate mass measurements and metastable transitions, are proposed. It has been found that the position of uracil ring thiation may be deduced on the basis of mass spectral fragmentation patterns.
Secondary ion mass spectra of oligosaccharides
Authors: Kambara Hideki , Hishida Shinzaburo 
Published: May 2005

AbstractThe mass spectra of oligosaccharides such as glucose, sucrose, lactose and raffinose obtained by static secondary ion mass spectrometry operated at 10−6 Torr are presented. Cationized molecular ions are observed in high intensity. Fragment ions are compared with daughter ions produced by collision induced dissociation of field desorbed cationized molecular ions.
Site of protonation and bifunctional group interactions in α,ω‐hydroxyalkylamines
Authors: Davis D. V. , Cooks R. G. 
Published: May 2005

AbstractChemical ionization mass spectrometry and mass analyzed ion kinetic energy spectrometry in conjunction with collision induced dissociation are used to study the fragmentation behavior of a series of α,ω‐hydroxyalkylamines. The difference between the ionic population present at equilibrium in the source, and that which is sampled under nonequilibrium conditions, is revealed in the striking differences observed in product distributions in the chemical ionization mass spectra and the mass analyzed ion kinetic energy spectra. The major fragmentations in the mass analyzed ion kinetic energy spectra, loss of NH3 and H2O, show large variations in intensity as a function of the chain length between the hydroxy and amino functionalities. These results are rationalized through analysis of the relevant thermochemical data.
Mechanisms of water elimination and other degradations of 2‐hydroxy‐5‐ketobornane cations in the gas phase
Authors: Fraefel A. , Mändli M. , Seibl J. 
Published: May 2005

AbstractThe mechanisms of water elimination in 2‐hydroxy‐5‐ketobornanes have been investigated and compared with those in borneol and isoborneol in order to ascertain whether and how such processes are affected by incorporation of a remote second functional group of lower ionization energy. Analysis of metastable ion peak shapes and specific labelling with 2H and 18O are employed as methods for differentiating between individual reaction paths. In addition, those degradation reactions which give rise to the most prominent fragments and pattern differences in the mass spectra of the epimeric keto alcohols were scrutinized. The elimination of water is shown to exhibit entirely different features due to the presence of the carbonyl group. The other most important degradation reactions all proceed by hydrogen transfer from the hydroxyl group onto the charged product and concomitant loss of the hydroxyl oxygen in a neutral entity. The results are interpreted in terms of initial charge radical localization on the carbonyl group initiating the relevant chemical reactions. Peak shape analysis proves a very valuable, and at times the only useful way to distinguish individual reactions.
Novel cluster ions from magnesium and zinc acetates in filament heated in‐beam electron impact mass spectrometry
Authors: Matsumoto Kozo , Kosugi Yoshio 
Published: May 2005

AbstractMass spectral peaks of cluster ions believed to be due to penta‐μ‐acetato‐μ4‐oxo‐tetramagnesium and tri‐μ‐acetato‐μ3‐oxo‐trimagnesium, or the corresponding zinc compounds, were detected when magnesium acetate or zinc acetate was heated on a tungsten filament and impacted at the same time by an electron beam. Structures of these non‐transition metal complexes are analogues of the so‐called ‘electron‐sponge’ complexes, [Ru3O(OAc)6L3]. Previously reported new cluster ions from lithium acetate are formulated by similar structures.
Fast atom bombardment mass spectrometry of two isomeric tripeptides
Authors: Barber Michael , Bordoli Robert S. , Sedgwick R. Donald , Tetler Lee W. 
Published: May 2005

AbstractFast atom bombardment of solids is presented as the basis of a new ion source for mass spectrometry. This novel technique is particularly useful for obtaining mass spectra from involatile and thermally labile materials. The ion source produces both positive and negative ions with equal facility, and examples of both are presented for two underivatized tripeptides. The normal second field free region metastables are observed in a double focusing mass spectrometer and comprehensive metastable pathways have been traced using Barber‐Elliott (V‐scan) techniques.
Electron impact induced migrations of aryl groups in substituted 4(3H)‐quinazolinones
Authors: Tureček František , Světlík Jan 
Published: May 2005

AbstractElectron impact mass spectra of 2‐diphenylmethyl‐3‐aryl‐4(3H)‐quinazolinones display ions arising from migrations of different aryl groups in the molecular and [MH]+ ions. The most abundant ion due to rearrangement, [C13H9NO]+˙, is formed by migration of a phenyl from the benzhydryl group onto N‐1 and subsequent cleavage of the heterocyclic ring. Other rearrangements involve initial migration of the N‐3 aryl group to the benzylic carbon. The mechanisms of migrations were elucidated by means of deuterium and 15N labelling and are supported by metastable spectra.
Mass spectral behaviour of some m‐dimethoxybenzene and sym‐trimethoxybenzene sulphur derivatives
Authors: Bottino Francesco , Fradullo Rosa , Pappalardo Sebastiano 
Published: May 2005

AbstractThe mass spectra of fifteen m‐dimethoxybenzene and sym‐trimethoxybenzene sulphur derivatives (including thiols, sulphides, disulphides and trisulphides) have been investigated. Main fragmentation pathways have been proposed for each class of sulphur compound. Primary skeletal rearrangements of the molecular ions occurring in (poly)sulphur‐bridged derivatives can provide a sensitive diagnostic tool both in structure elucidation and in the problem of locating methoxy substituents.
The formation of [CH3CH2C(OH)CH2]+˙ from 1‐hepten‐3‐ol
Authors: McAdoo David J. , Hudson Charles E. 
Published: May 2005

AbstractThe [C4H8O]+˙ ion in the mass spectrum of 1‐hepten‐3‐ol is shown to be \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} {\rm{CH}}_{\rm{2}} {\rm{C(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}})\mathop {\rm{C}}\limits^{\rm{.}} {\rm{H}}_{\rm{2}} $\end{document} by collisional activation spectra, appearance energies and comparison of the ratios of the intensities of metastable decompositions. [C4H8O]+˙ appears to be formed by rearrangement of ionized 1‐hepten‐3‐ol to \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} \mathop {\rm{C}}\limits^{\rm{.}} {\rm{HC(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H)CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{3}} $\end{document} followed by γ‐hydrogen rearrangement‐β‐cleavage.
A revised mechanism for the structure‐specific gas phase enol cation‐cyclobutanol reaction
Authors: Bouma Willem J. , MacLeod John K. , Radom Leo 
Published: May 2005

AbstractIon cyclotron resonance studies using deuterium labelled substrates have revealed a more complex mechanism than previously proposed for the structure‐specific ion/molecule reaction of the [C2H4O]+˙ and [C3H6O]+˙ enol ions with neutral cyclobutanol. This requires the intermediacy of a species in which all of the methylene groups present in both the reactant ion and neutral can become equivalent.