- An "ortho effect" in electrophilic aromatic nitrations: Theoretical analysis and experimental validation
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Usually, a π-donor substituent acts as an ortho/para directing group in an electrophilic aromatic substitution reaction, and a π-acceptor substituent acts as a meta directing group. Interestingly, when a π-acceptor substituent is meta to a π-donor substituent, certain electrophilic aromatic nitration occurs ortho to the π-acceptor substituent rather than para . The "ortho effect", highlighted in various textbooks, has been tentatively analyzed here based on ab initio calculations. The reliability of the calculations was verified by the corresponding experimental data, including a newly-designed electrophilic aromatic nitration that also gave reasonable product distributions.
- Li, Hui-Jing,Wu, Yan-Chao,Dai, Jian-Hong,Song, Yan,Cheng, Runjiao,Qiao, Yuanyuan
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p. 1307 - 1312
(2015/02/05)
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- Competition between electron-donor and electron-acceptor substituents in nitrotoluene isomers: A photoelectron spectroscopy and ab initio investigation
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We present an investigation of the close relationship between chemical structure, physical properties and reactivity of the three nitrotoluene isomers: a joint experimental and theoretical study, based on X-ray photoelectron spectroscopy (XPS) measurements and ab initio calculations, addressing the complex interplay between the competing electron-donor and electron-acceptor effects of the nitro- and methyl-substituents on the chemical properties of the nitrotoluene isomers. As the main results of the investigation we: (i) point out that accurate ab initio calculations play a key role in the complete assignment of photoemission measurements, as well as in the estimate of proton affinities in the case of all the eligible sites; (ii) revisit, at a more quantitative level, textbook models based on inductive and resonant effects of different substituents of the aromatic ring, as well as on the hyper-conjugative connection of the methyl group to the π-conjugated system; (iii) provide an accurate analysis of correlation patterns between calculated proton affinities and core-ionization energies, which represent a powerful tool, capable of predicting site-specific reactivities of polysubstituted molecules in the case of electrophilic aromatic substitution reactions.
- Rondino, Flaminia,Catone, Daniele,Mattioli, Giuseppe,Bonapasta, Aldo Amore,Bolognesi, Paola,Casavola, Anna Rita,Coreno, Marcello,O'Keeffe, Patrick,Avaldi, Lorenzo
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p. 5272 - 5282
(2014/01/23)
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- PROCESS FOR THE PREPARATION OF NITRATED AROMATICS AND MIXTURES THEREOF
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A process for the preparation of mononitroaromatics and dinitroaromatics, in which a hydrate melt of at least one metal nitrate M(NO3)3 is used as a nitrating medium, it being possible for M to be the metals Fe, Cr, Y, La, Ce, Al, Bi and In, and the metal nitrate having a water content of from 4 to 9 mol of water per M(NO3)3, leads to simplifications of the process and improved yields.
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Page/Page column 5
(2012/01/03)
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- A new procedure for preparing 3,4-dinitrobenzoic acid
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A new efficient procedure of synthesis of 3,4-dinitrotoluene from 3-nitro-4-aminotoluene was developed. Oxidation of 3,4-dinitrotoluene with an ozone-oxygen mixture to 3,4-dinitrobenzoic acid in the presence of cobalt(II) acetate was studied.
- Andreev,Potapenko,Pogorelova,Krasil'nikov,Band
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p. 503 - 505
(2008/09/20)
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- 6-Lithioquinoxalines and Their Transformations
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6-Bromo-2,3-diphenylquinoxaline reacts with butyllithium to give the 6-lithio derivative in a yield of more than 80%, which reacts with electrophiles such as benzophenone, Michler ketone, methyl ethyl ketone, iodine, selenium, and dimethylformamide to give the corresponding quinoxaline derivatives. 6-Bromo-2,3-dimethylquinoxaline is metallated with butyl- and phenyllithium at the methyl groups and benzene ring. These organolithium compounds react with benzophenone to give the corresponding diphenyl- and triaryl-carbinols, whose yield and ratio were determined by HPLC. These results open prospects for preparing new quinoxaline derivatives substituted at the annelated benzene ring.
- Dobrodei,El'tsov
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p. 620 - 629
(2007/10/03)
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- Process for the production of nitro derivatives of aromatic compounds
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Nitroderivates of aromatic compounds which are difficult to nitrate, can readily be obtained by nitration providing that the aromatic compound is treated with nitric acid or another nitrating agent in the presence of aliphatic or cycloaliphatic hydrocarbons monosubstituted or polysubstituted by halogen, the nitro group or an alkyl sulphonyl group, and the nitro derivative formed subsequently isolated.
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