- Facile synthesis of 2,3,5,6-tetrabromo-4-methyl-nitrocyclohexa-2,5-dien-1- one, a mild nitration reagent
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Nitrocylcohexadienones have been applied as nitration reagents for mild, mono-nitrating reactions. The original synthesis of 2,3,5,6-tetrabromo-4-methyl- 4-nitrocylcohexa-2,5-dien-1-one appeared to be difficult to pursue due to both the solvent system and
- Arnatt, Christopher K.,Zhang, Yan
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scheme or table
p. 1592 - 1594
(2012/04/10)
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- Dual Reactivity of 2,3,5,6-Tetrabromo-4-methyl-4-nitrocyclohexa-2,5-dienone
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2,3,5,6-Tetrabromo-4-methyl-4-nitrocyclohexa-2,5-dienone in acetone solution nitrates 4-methoxyphenol by a radical mechanism, but acts mainly as a brominating agent towards phenol, after rearrangement.
- Coombes, Robert G.
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p. 1007 - 1008
(2007/10/02)
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- POLYBROMINATED AROMATIC COMPOUNDS V. REACTION OF PENTABROMOTOLUENE WITH SODIUM METHOXIDE IN PYRIDINE
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During the reaction of pentabromotoluene with sodium methoxide in pyridine, together with the products from methoxydebromination and protodebromination, the products from substitution of both the bromine atom in the aromatic ring and hydrogen atom in the methyl group by methoxy groups are formed.The directing effect of the methyl and methoxymethyl groups during substitution of the bromine in the pentabromophenyl ring by the methoxide ion was studied, and it was shown that the directing selectivity of these substituents is low.The methyl group is predominantly a meta-orientant, whereas the methoxymethyl group is predominantly a para-orientant.
- Shishkin, V. N.,Lapin, K. K.,Tanaseichuk, B. S.,Butin, K. P.
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p. 1882 - 1887
(2007/10/02)
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- TETRAHALOBENZENES AS DI-ARYNE EQUIVALENTS IN POLYCYCLIC ARENE SYNTHESIS
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1,2,4,5-Tetrabromobenzenes and analogous naphthalenes react with one or two equivalents of n-butyllithium and various dienes (furans, pyroles, cyclopentadienes, fulvenes) to form mono- or bis-cycloadducts.Highly substituted arenes can be obtained by removing the oxygen or nitrogen bridges from the furan or pyrrole adducts.By choice of conditions, two identical or two different rings can be fused to the di-aryne equivalent.Improved short syntheses of permethylnaphthalene, -anthracene and -naphthacene are described.A new triphenylene synthesis is presented.
- Hart, Harold,Lai, Chung-yin,Nwokogu, Godson Chukuemaka,Shamouilian, Shamouil
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p. 5203 - 5224
(2007/10/02)
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- Nitrocyclohexadienones : a new class of nitrating agents
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Various nitrocyclohexadienones are proposed as new nitrating agents. These compounds are easy to prepare from corresponding phenols, easy to handle and stable. Nitrocyclohexadienones act as nitronium carriers using rearomatization as the driving force and permit nitration of highly activated substrates under mild conditions and with good yields.
- Lemaire, Marc,Guy, Alain,Roussel, Jacques,Guette, Jean-paul
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p. 835 - 844
(2007/10/02)
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- Bis- or poly-(bromo-4-methyl-phenoxy)-alkanes and -alkenes, process for preparing same and use thereof as uv-stable fireprotective agents for synthetic materials
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Disclosed are novel bis- or poly-(bromo-4-methylphen-oxy)-alkanes and -alkenes having the formula (1) wherein, n is an integer of from 1 to 6,m is 2 (n + z) - y,x is an integer of from 1 to 4,y is an integer of from 2 to 4 and, z is 0 or 1,and a process for preparing said compounds by reacting alkali salts of nucleus-brominated p-cresols with bis- or poly-haloalkanes or -alkenes, preferably in a glycol monoalkylether as reaction medium. The materials are employed as UV-stable low-migrating fire-protective agents for thermoplastic synthetic materials, and more specifically for polybutylene terephthalate or acrylo-nitrile-butadiene-copolymer molding compositions, in combination with antimony trioxide.
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- Electrophilic Substitution with Rearrangement. Part 9. Dienones derived from Brominations of o-, m-, and p-Cresol
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Regiospecific protodebromination of ring-substituted bromophenols derived from 2-, 3-, or 4-methylphenol can be effected by heating them with aqueous hydrogen iodide; the synthetic scope of this reaction has been explored.These di- and poly-bromophenols can generally be converted by further bromination in aqueous acetic acid into dienones , which have now been shown to have the 4-bromo-2,5-dienone rather than the 2-bromo-3,5-dienone structure.The rearrangemens of these dienones to ring-substituted polybromophenols by treatment with sulfuric acid have been investigated; where more than one product is formed, the regioselectivity differs from that prevailing in the corresponding direct bromination of the phenol with liquid bromine.The alternative rearrangements of these dienones in aprotic solvents with and without illumination have been compared with results obtained by reaction of methylphenols with bromine under the same conditions.Characteristic differences between the behaviours of 2-, 3-, and 4-methyl-substituted compounds reflect the specific reactions available to the particular dienones.
- Brittain, Judith M.,Mare, Peter B. D. de la,Newman, Paul A.
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