- MECHANISTIC CONSIDERATIONS ON PHOTOREACTION OF ORGANIC COMPOUNDS VIA EXCITATION OF CONTACT CHARGE TRANSFER COMPLEXES WITH OXYGEN
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Reactions of various organic compounds induced by excitation of their contact charge transfer (CCT) pairs with oxygen were classified into three types of behaviour on the basis of reaction products.It is proposed that the excited state of the CCT pairs gives the products through the most isoenergetic course along the plausible exothermic pathway.
- Onodera, Kazuyuki,Furusawa, Gen-ichi,Kojima, Masanobu,Tsuchiya, Masahiro,Aihara, Shin,et al.
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- Remarkable effect of water on functionalization of the phenyl ring in methyl-substituted benzene derivatives with F-TEDA-BF4
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Various N-F reagents reacted with hexamethylbenzene (1) forming side chain substituted alkoxides or esters in protic solvents, Ritter type side chain functionalization was observed in acetonitrile in the presence of trifluoroacetic acid, while in aqueous
- Kralj, Petra,Zupan, Marko,Stavber, Stojan
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p. 3880 - 3888
(2007/10/03)
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- Attempts at Direct Detection of Reactive Species in Selective Excitation of the Contact Charge Transfer Pairs of Hexamethylbenzene and Oxygen
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Pulsed laser excitation of contact charge transfer pairs of hexamethylbenzene (HMB) and oxygen in methanol-acetonitrile gave no evidence for intermediacy of reactive species such as HMB radical cations and penthamethylbenzyl cations (ArCH2+), though stationary irradiation of the pair in hydroxylic solvents afforded distinct products arising from the cationic species.The mechanism of reactions was discussed in comparison with 9,10-dicyanoanthracene-sensitized oxygenation of HMB.
- Komatsu, Toshiki,Tsuchiya, Masahiro,Furusawa, Gen-ichi,Kuriyama, Yasunao,Sakugari, Hirochika,et al.
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p. 277 - 281
(2007/10/02)
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- Synthesis and Reactions of 5-Methylenebicyclohex-2-ene Derivatives from Hexamethyl(Dewar benzene)
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Treatment of hexamethyl(Dewar benzene) (HMDB) with tert-butyl hypochlorite provides a rearranged chlorinated derivative, exo-6-chloro-1,2,3,4,6-pentamethyl-5-methylenebicyclohex-2-ene (1).Thermal rearrangement of 1 gives pentamethylbenzyl chloride (4); the activation energy decreases in more polar solvents, suggesting an ionic intermediate during the chloride migration and/or ring opening.The intermediate is postulated to be a delocalized carbocation that can be intercepted by nucleophiles to give substitution products.Treatment of 1 with NaOCH3 in methanol gives two isomeric methoxide substitution products, 2 and 3, in 60:40 ratio.The structure of 2 involves the same skeletal structure and retention of stereochemistry relative to 1; the structure of 3 indicates neighboring group participation of the transannular ? bond.The rate law for the formation of 2 and 3 is first order in 1 and independent of NaOCH3 concentration.A common ion rate depression is observed, added chloride ion causing a decreased rate of formation of both 2 and 3 equally, indicating reversible ionization to a common delocalized carbocation.Thermolysis of 2 gives hexamethylbenzene plus formaldehyde; NMR spectra provide evidence for a methylenecyclohexadiene intermediate, indicating that the ring opening precedes loss of formaldehyde.Inclusion of basic alumina in the thermolysis of 2 diverts the reaction to formation of pentamethylbenzyl methyl ether (5).Thermolysis of 3 gives a complex mixture of products, including 5.
- Wamser, Carl C.,Ngo, David D.,Rodriguez, Michael J.,Shama, Sami A.,Tran, Thuan L.
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p. 2162 - 2168
(2007/10/02)
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- OXIDATION OF HEXAMETHYLBENZENE AND 2,3,4,5,6-PENTAMETHYLBENZYL CATION IN FLUOROSULFONIC ACID
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The oxidation of hexamethylbenzene in HSO3F-PbO2 takes place with the participation of the 1-H+-1,2,3,4,5,6-hexamethylbenzenonium ion and the intermediate formation of the 2,3,4,5,6-pentamethylbenzyl cation, which is capable of entering into further oxidative transformations leading to substitution of the hydrogen atom in two and three methyl groups.The structure of the final products from the observed transformations were established, and a mechanism is proposed for their formation.
- Rudenko, A. P.,Zarubin, M. Ya.,Fedorova, E. M.
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p. 1609 - 1618
(2007/10/02)
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- EFFECT OF LIGHT WAVELENGTH ON PHOTOOXYGENATION OF HEXAMETHYLBENZENE
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Irradiation of the charge transfer complex of hexamethylbenzene with oxygen at 313 nm in a mixture of methanol and benzene afforded methoxymethyl-pentamethylbenzene and methoxypentamethylbenzene.
- Onodera, Kazuyuki,Sakuragi, Hirochika,Tokumaru, Katsumi
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p. 2831 - 2832
(2007/10/02)
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