42903-81-1Relevant articles and documents
Mirror Inversion of the Low-symmetry Ground-state Structures of the Methylcyclohexane and 1,1-Dimethylcyclohexane Radical Cations
Sjoeqvist, Lars,Lindgren, Mikael,Lund, Anders,Shiotani, Masaru
, p. 3377 - 3382 (1990)
The dynamics of the methylcyclohexane and 1,1-dimethylcyclohexane radical cations in a solid perfluoromethylcyclohexane matrix at low temperature have been studied by electron paramagnetic resonance (EPR) spectroscopy.The reversible variations of the experimental EPR linewidth, observed for both cations in the temperature region 4-173 K, have been reproduced through simulations employing a dynamical model for the molecular motion.It was assumed that an interconversion between two energetically equivalent mirror images of the molecular framework occurred.The related activation energy has been determined to be 0.2 and 0.3 kcal mol-1 for the methylcyclohexane and 1,1-dimethylcyclohexane radical cations, respectively.
Catalyst on the basis of a Zr, Ti or Hf complex and process for hydrogenation of olefins or polymer
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, (2008/06/13)
The present invention relates to a catalyst composition which comprises at least: a) a metal compound cation of the formula [(A)(B)ML+] wherein M represents titanium, zirconium, or hafnium, wherein A and B represent ligands with structure I or II in which R1independently represents the same or different hydrocarbyl groups optionally containing heteroatoms, and R3independently represents the same or different hydrocarbyl groups optionally containing heteroatoms, or a halide, and in which R substituents may be shared between A and B to provide a bridge, wherein m is an integer from 0-5, p is an integer from 0-4, and q is an integer from 0-3, wherein L represents hydrogen or hydrocarbyl group optionally containing heteroatoms, with the proviso that if A and B are both ligands with structure I or II, at least one of m, p or q is at least 1, and b) a non-coordinating stable anion. The present invention further relates to a process for the preparation of a catalyst composition and to a process for the catalytic hydrogenation of olefins, oligomers, polymers or copolymers.
Radical Cations of Cyclohexanes Alkyl-substituted on One Carbon: An ESR Study of the Jahn-Teller Distorted HOMO of Cyclohexane
Shiotani, Masaru,Lindgren, Mikael,Ohta, Nobuaki,Ichikawa, Takahisa
, p. 711 - 719 (2007/10/02)
Cation radicals of cyclohexanes alkyl-substituted on one carbon have been stabilized in perfluoromethylcyclohexane and other halocarbon matrices at 4.2 K and studied by means of ESR spectroscopy.It was found that all have an electronic ground state resembling the 2Ag state of the cyclohexane cation, one of the possible states following a Jahn-Teller distortion of the D3d cyclohexane chair structure.The cations can be classified into two groups depending on the substituted alkyl group.To the first group belong the cations with a methyl group or a primary carbon (ethyl, n-propyl or isobutyl group) attached to the ring.The disubstituted cyclohexane cations of 1,1-dimethylcyclohexane and 1-methyl-1-ethylcyclohexane were also found to have a similar structure.The ESR spectra are characterized by a 1:2:1 three-line pattern with the hyperfine (hf) splitting due to two magnetically equivalent equatorial ring hydrogens.The magnitude of the splitting was found to depend on the size and number of substituents, ranging from 74 G (methylcyclohexane.+) to 55 G (isobutylcyclohexane.+).An additional doublet, 17-34 G, due to a hydrogen on the substituent could be detected in certain cases.Such hydrogens are axial with one of the elongated C-C bonds in the ring structure which contains a relatively large fraction of the unpaired electron.It follows that the substituents are located asymmetrically with respect to an ag-like SOMO in the ring.In the second group a secondary or tertiary carbon connects the substituent to the ring, such as an isopropyl or tert-butyl group.The largest hf splittings are ca. 30 G in magnitude, due to certain hydrogens on the substituent which are axial with respect to the cyclohexyl bond.It follows that an ag-like SOMO in the ring here is symmetrically arranged with respect to the position of the substituent.Hyperconjugation is the dominating mechanism for the spin transfer in all cations reported in this study.
Mechanistic aspects of the fluorination of cyclohexane and cyclohexene with acetyl hypofluorite in acetic acid
Visser, G. W. M.,Bakker, C. N. M.,Halteren, R. W. v.,Herscheld, J. D. M.,Brinkman, G. A.,Hoekstra, A.
, p. 214 - 219 (2007/10/02)
The reaction of acetyl hypofluorite in acetic acid with both cyclohexane and cyclohexene has been investigated.Analysis by GCMS and radio-HPLC, using (18)F as a tracer, revealed that apart from typical products expected from a radical reaction, several compounds originating from carbocationic intermediates were formed.On the basis of the observed products, a single-electrontransfer (SET) mechanism leading to an intermediate radical-cation is proposed.
