- Cross-conjugated compounds: microwave spectrum and ring planarity of 3-methylene-1,4-cyclohexadiene
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The unstable 3-methylene-1,4-cyclohexadiene, an isomer of toluene, has been prepared from benzoic acid.The hydrocarbon can be handled quite easily in the solid state, and in the gas phase at low pressures.Rotational transitions have been measured from 12
- Hutter, Wolfgang,Bodenseh, Hans-Karl,Koch, Andreas
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- Tautomerization energetics of benzoannelated toluenes
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The energy of tautomerization of some isotoluene structures has been measured by gas-phase ion/molecule reactions and by solution calorimetry. Benzoannelation appreciably destabilizes the aromatic tautomer, relative to the isotoluene form. An inverse saturation effect on the acidities of toluene, 1 -methylnaphthalene, and 9-methylanthracene is observed. The p-isotoluene 3-methylene-1,4-cyclohexadiene appears to have the weakest C-H bond dissociation energy known, 64 ± 3 kcal/mol. Molecular orbital calculations bear out these results.
- Bartmess, John E.,Griffith, Sharon S.
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p. 2931 - 2936
(2007/10/02)
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- Bimolecular Reactions of 3-Methylene-1,4-cyclohexadiene (p-Isotoluene), 5-Methylene-1,3-cyclohexadiene (o-Isotoluene), 1-Methylene-1,4-dihydronaphthalene (Benzo-p-isotoluene), and 9-Methylene-9,10-dihydroanthracene (Dibenzo-p-isotoluene)
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3-Methylene-1,4-cyclohexadiene, 1, 5-methylene-1,3-cyclohexadiene, 2, 1-methylene-1,4-dihydronaphthalene, 5, and 9-methylene-9,10-dihydroanthracene, 8, react with second-order kinetics in benzene solution.The activation parameters for the reaction of 1,5,and 8, especially the frequency factor, suggest a nonconcerted reaction with little orientational demand in the transition state.The frequency factor for the reaction of 2 suggests a concerted pathway.The product distribution from each compound reinforces the kinetic observations.The products from the pyrolysisof 1 could be rationalized by a radical cage intermediate, which could combine or disproportionate.The reaction products from 5 indicate a radical chain oligomerization.The reaction of 8 gives an insoluble solid. o-Isotoluene (2) gives ene dimers.
- Gajewski, Joseph J.,Gortva, Andrea M.
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p. 373 - 378
(2007/10/02)
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