3551-27-7

Upstream product

• 831-18-5 ditropenyl 
• 35430-15-0 norborna-2,5-dien-7-yl 
• 1609-39-8 7-chlorobicyclo<2.2.1>hepta-2,5-diene 
• 2422-86-8 bicyclo[3.2.0]hepta-2,6-diene 
• 35369-45-0 bicyclo<3.2.0>hepta-2,6-dien-4-yl radical 
• 110-05-4 di-tert-butyl peroxide 
• 544-25-2 Cyclohepta-1,3,5-triene 
• 108058-57-7 homobenzvalenyl radical 
• 4087-50-7 1,2,3,4,5,5-Hexamethyl-cyclopenta-1,3-diene 

Relevant academic research and scientific papers

REARRANGEMENTS OF FREE RADICALS X: C7H7 - RADICALS AND RELATED SYSTEMS

7-Norbornadienyl radical rearranges in matrix to tropylium radical.Deuterated and cyano substituted bicyclo(3.2.0)heptadienyl radicals do not undergo 1.2-vinyl shifts prior to electrocyclic ring opening.

GAS-PHASE RADICALS IN CO-CONDENSED ADAMANTANE MATRIX: PROTON SPLITTING IN THE ESR SPECTRUM OF THE CYCLOHEPTATRIENYLPEROXYL RADICAL

The cycloheptatrienyl (tropenyl) radical was generated by the gas-phase pyrolysis of ditropenyl at 473-723 K and was trapped in co-condensed adamantane at 77 K.Well-resolved isotropic ESR spectra of the tropenyl radical showed a linear temperature dependence of aiso in the range 77-226 K.The tropenylperoxyl radical was obtained if the ditropenyl pyrolysis was carried out in the presence of dioxygen.The anisotropic ESR spectrum of the tropenylperoxyl radical obtained in the adamantane matrix at 77 K was characterized by g1=2.035, g2=2.009, g3=2.002 and a1=8.4 G, a2=9.6 G and a3=5.35 G.The values of giso and aiso were found experimentally in the freely rotating radical at 130 K to be g=2.0157 and a=7.5 G respectively.The hyperfine coupling arises from coupling to the β-H atom via a hyperconjugative mechanism.

Radical-Stabilization-Energy - the MMEVBH Force Field

Making use of the VB method of Malrieu et al. a force field has been developed, which allows to calculate heats of formation of hydrocarbons (conjugated and non-conjugated olefins, radicals and diradicals) with high accuracy.With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock-tube measurements of dissociation energies or from rotational barriers of substituted olefins.A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented. - Key Words: Resonance energy / Heats of formation / Single pulse shock tube / Intrisic rotational barrier

Rearrangements of Free Radicals, XII. - ESR Spectroscopic Study of the Ring Opening of the Homobenzvalenyl Radical

Abstraction of an allylic hydrogen atom in homobenzvalene (4) either in solution by photolytically generated tert-butoxyl radicals or in an adamantane matrix by X-rays produces the homobenzvalenyl radical (5), which thermally rearranges to the tropylium radical (7).In solution the activation energy for the rate determining step of the reaction sequence was determined to be 13.4 +/- 0.5 kcal/mol.

Rearrangements of Free Radicals, XI. Sigmatropic and Electrocyclic Reactions of Bicycloheptadienyl Radicals, 3-Quadricyclanyl Radicals, and 7-Norbornadienyl Radical

The rearrangement of matrix-isolated organic radicals with bicycloheptadienyl structure (2, 5, 11a, b), 3-quadricyclanyl structure (16,26, 27), and of 7-norbornadienyl radical 15 is studied.Final rearrangement products are radicals with tropylium structure. 16, 26, and 27 isomerize to radicals with bicycloheptadienyl skeleton before electrocyclic ring opening to tropylium radicals takes place. 7-Norbornadienyl radical 15 is the least stable radical on the C7-hypersurface.Sigmatropic 1,2-vinyl shifts in bicycloheptadienyl radicals could not be observed.Substituents do not influence the rearrangement behaviour.

The Photolysis of Cyclopentadienyl Compounds of Tin and Mercury. Electron Spin Resonance Spectra and Electronic Configuration of the Cyclopentadienyl, Deuteriocyclopentadienyl, and Alkylcyclopentadienyl Radicals

Cyclopentadienyl derivatives of tin(IV) and mercury(II) and alkylcyclopentadienyl derivatives of mercury(II) are photolysed in solution to show the e.s.r. spectra of the appropriate radicals RC5H4. (R = H, D, Me, Et, Pri, or But).The C5H5. radical is a planar ?-radical with average D5h symmetry, and its spectrum is broadened in the presence of organic bromides, perhaps by a charge-transfer mechanism.The introduction of alkyl groups breaks the degeneracy of the ψA and ψS molecular orbitals of the ?-system by electron release, destabilising the ψS MO, and the e.s.r. spectrum reflects the spin density distribution in the configuration ψA2ψS1.Deuterium has a small but detectable perturbing effect: the ψA MO is destabilised by ca. 100 J mol-1, and thermal mixing of the two energy levels results in the configuration ψS1.515ψA1.485.This is compatible with the model of a vibrational perturbation of the resonance integral β, rather than of the Coulomb integral α.

Substituent Effects by Deuterium and Alkyl Groups and 13C Hyperfine Coupling Constants of Cyclopentadienyl Radicals as Studied by Electron Spin Resonance

ESR spectra of the parent and six substituted cyclopentadienyl radicals (RC5H4; R = H, D, Me, Et, i-Pr, t-Bu, Me3SiCH2), generated from the corresponding RC5H4SnMe3 by an SH2 attack on Sn with the photochemically generated tert-butoxy radical, have been recorded over the temperature range -95 to +24 deg C.Judging from the proton coupling constants, the electron-releasing perturbation of alkyl groups is in the order (CH3)3SiCH2 > CH3 > C2H5 > (CH3)2CH > (CH3)3C.Preferred conformations of these alkyl groups are discussed from the temperature effects on the spectra.Notably, the methyl group rotates freely, while the (CH3)3SiCH2 group has a fixed conformation in which the (CH3)3Si group eclipses the p orbital on the C1 atom of the cyclopentadienyl.The resonance-integral perturbation effect is more important than the Coulomb-integral perturbation in the deuterium substitution.Finally the coupling constants of 13C for CnHn (n = 5-8) radical species are discussed.