scholarly journals Relative Rates of Hydrogen Shift Isomerizations Depend Strongly on Multiple-Structure Anharmonicity

2018 ◽  
Vol 140 (50) ◽  
pp. 17556-17570 ◽  
Author(s):  
Lili Xing ◽  
Junwei Lucas Bao ◽  
Zhandong Wang ◽  
Xuetao Wang ◽  
Donald G. Truhlar
Keyword(s):  
Hydrogen Shift ◽  
Multiple Structure

Perturbations by Phenyl on the 1,5-Hydrogen Shift in 1,3(Z)-Pentadiene. Another Chameleonic Transition Region?

2004 ◽  
Vol 126 (43) ◽  
pp. 14206-14216 ◽  
Author(s):  
William von E. Doering ◽  
Edmund J. Keliher ◽  
Xin Zhao
Keyword(s):  
Transition Region ◽  
Hydrogen Shift

scholarly journals Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

2015 ◽  
Vol 11 ◽  
pp. 576-582 ◽  
Author(s):  
Grzegorz Mlostoń ◽  
Paulina Grzelak ◽  
Maciej Mikina ◽  
Anthony Linden ◽  
Heinz Heimgartner
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Thermal Conditions ◽  
Alder Reaction ◽  
Diels Alder ◽  
Hydrogen Shift ◽  
Diels Alder Reaction ◽  
Shift Sequence

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.

Automated multiple structure alignment and detection of a common substructural motif

2001 ◽  
Vol 43 (3) ◽  
pp. 235-245 ◽  
Author(s):  
Nathaniel Leibowitz ◽  
Zipora Y. Fligelman ◽  
Ruth Nussinov ◽  
Haim J. Wolfson
Keyword(s):  
Structure Alignment ◽  
Multiple Structure

Synthesis of polysubstituted pyridines under combined microwave and ultrasound irradiation: K2CO3-promoted tandem addition/cyclization/hydrogen shift process

2012 ◽  
Vol 53 (9) ◽  
pp. 1160-1162 ◽  
Author(s):  
Huangdi Feng ◽  
Yuan Li ◽  
Erik V. Van der Eycken ◽  
Yanqing Peng ◽  
Gonghua Song
Keyword(s):  
Ultrasound Irradiation ◽  
Hydrogen Shift

Iminoacyl Alkyl Complexes of Zirconium Supported by a Ferrocene-Linked Diphosphinoamide Ligand Scaffold

2016 ◽  
Vol 69 (5) ◽  
pp. 555 ◽  
Author(s):  
Nathan R. Halcovitch ◽  
Michael D. Fryzuk
Keyword(s):  
General Formula ◽  
Mechanistic Studies ◽  
Hydrogen Shift ◽  
Alkyl Complexes ◽  
Rate Determining Step ◽  
Zirconium Complexes ◽  
Alkyl Derivatives ◽  
Benzyl Substituent

Zirconium dialkyl complexes of the general formula fc(NPiPr2)2ZrR2 (where fc = 1,1′-ferrocenyl, R = CH3, CH2Ph, CH2tBu, tBu) have been synthesized and characterized via the addition of alkyl lithium or potassium benzyl derivatives to the dichloride complex fc(NPiPr2)2ZrCl2(THF). Addition of 2,6-dimethylphenylisocyanide to these alkyl derivatives generates the corresponding mono iminoacyl alkyl zirconium complexes. On thermolysis, the iminoacyl moiety containing a benzyl substituent undergoes rearrangement to yield a new complex that contains an alkene-amido fragment. Mechanistic studies point to a 1,2 hydrogen shift as the rate-determining step.

Die kinetische Energie ionisierter MolekülfragmenteIII. Quasithermische Ionen von einfachen Paraffinen

1964 ◽  
Vol 19 (7-8) ◽  
pp. 911-925
Author(s):  
Rolf Taubert
Keyword(s):  
Activation Energy ◽  
Statistical Theory ◽  
Mass Spectra ◽  
Transition Energy ◽  
Bond Cleavage ◽  
Theoretical Data ◽  
Initial Energy ◽  
Transition Energies ◽  
Hydrogen Shift ◽  
Reverse Process

From the monotonic increase of the average initial energy of paraffin fragment ions formed by electron impact the existence of unimolecular dissociation sequences is concluded as it is assumed by the statistical theory of mass spectra. For primary decomposition steps the total kinetic energies set free during the respective dissociation processes (transition energies) have been deduced from measured initial energies. The transition energies obtained in this way may be compared with theoretical data for the translational energies in the transition states (statistical energies) as calculated by means of the statistical theory of mass spectra. In case of—C bond cleavage theoretical data are close to the experimental values (≈ 0.1 ev). In case of a C—H bond cleavage, however, theoretical values are always lower than the experimental ones.In rearrangement reactions an activation energy for the reverse process may exist, which should show up, at least partly, in the transition energy. For a primary H2-abstraction process the activation energy for the reverse process aE can be calculated from thermochemical data. The observed transition energies are always lower than the calculated values. A C—C skeleton rearrangement also shows some influence of aΕ on the transition energy. The absolute effect, however, is small—less than 0.1 ev. For hydrogen shift reactions no indication of an aE-contribution was found.

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