Search results for "PolyAT"

showing 3 items of 53 documents

A new general fragmentation reaction in mass spectrometry: The hydrogen-carbon, carbon-carbon double rearrangement of 2 heteroalkyl substituted diphe…

1995

Diphenylmethyl cations formed by benzylic cleavage of the molecular ions of ortho heteroalkyl substituted 1,1-diphenylalkanes undergo the double rearrangement process (H to C followed by C to C) previously reported for ortho-methoxy derivatives. Hence the formation of substituted benzyl (or tropylium) ions allowing this double rearrangement process constitutes an interesting type of fragmentation reaction characteristic for 1,1-diphenylalkanes bearing ortho substituents (OMe, OEt, OiPr, SMe, NHMe, NMe2) which are able to transfer a hydride to the charged benzyl carbon of diphenylmethyl cations formed by benzylic cleavage of the molecular ion.

inorganic chemicalsCollision-induced dissociationHydrogenChemistryHydrideorganic chemicalsPolyatomic ionReinforced carbon–carbonAnalytical chemistrychemistry.chemical_elementMass spectrometryMedicinal chemistryIonFragmentation (mass spectrometry)heterocyclic compoundsSpectroscopyEuropean Journal of Mass Spectrometry
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Resonance in Interacting Induced-Dipole Polarizing Force Fields: Application to Force-Field Derivatives

2009

The Silberstein model of the molecular polarizability of diatomic molecules, generalized by Applequist et al. for polyatomic molecules, is analyzed. The atoms are regarded as isotropically polarizable points located at their nuclei, interacting via the fields of their induced dipoles. The use of additive values for atom polarizabilities gives poor results, in some cases leading to artificial predictions of absorption bands. The molecular polarizability of methane and its derivative are computed. The agreement with experimental mean molecular polarizabilities is within 1–5%. A hypothesis is indispensable for a suitable representation of polarizability derivative.

lcsh:T55.4-60.8Molecular physicsForce field (chemistry)lcsh:QA75.5-76.95Theoretical Computer Scienceelectric field gradientPolarizabilityAtomPhysics::Atomic and Molecular ClustersMoleculederivativelcsh:Industrial engineering. Management engineeringPhysics::Atomic PhysicsPhysics::Chemical PhysicsPhysicspolarizing force fieldNumerical AnalysisPolyatomic iondipole momentDiatomic moleculepolarizabilityelectric fieldComputational MathematicsDipoleComputational Theory and Mathematicsresonanceinteracting induced-dipole polarizationlcsh:Electronic computers. Computer scienceElectric field gradientAlgorithms
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Studies in organic mass spectrometry. Part 23. Role of the aroyl group on the competitive fragmentation reactions of the molecular ion of aroylanilid…

1999

The 70 eV and mass-analysed ion kinetic energy (MIKE) spectra of some thiophenecarboxanilides and benzoylanilides (1–10) have been compared in order to investigate the role of the aroyl (or heteroaroyl) moiety on the abundance of the competitive fragmentation reactions occurring in their molecular ions (amide–bond cleavage and phenol radical ion formation). It has been shown that the electron ionisation induced decompositions with high (70 eV) and low (MIKE) internal energy excess are qualitatively similar, but remarkable quantitative differences have been observed that can be accounted for in terms of the different effectiveness in the transmission of electronic effects of substituents in …

substituent effectsChemistryrearrangement processesPolyatomic ionAnalytical chemistryaroylanilidesMass spectrometryPhotochemistryelectron ionisation; positive ions; ion chemistry; aroylanilides; substituent effects; rearrangement processesIonchemistry.chemical_compoundRadical ionFragmentation (mass spectrometry)positive ionsThiopheneElectronic effectMoietyion chemistryelectron ionisationSpectroscopy
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