- Rate constant ratios in the consecutive chlorination of liquid-phase p-xylene with Cl2 and an iron(III) chloride catalyst
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Given that p-xylene is an important chemical feedstock for many final products in the market from pesticides, pharmaceuticals, peroxides to dyes, its chlorinated derivatives are of interest in the chemical industry. In this paper, the rate constant ratios of the consecutive chlorination of p-xylene at 70°C in a gas–liquid semibatch reactor using molecular chlorine and iron(III) chloride as a catalyst was investigated up to the fourth successive reaction (tetrachloro-p-xylene production). The ratios were determined with both mathematical expressions and a graphical method proposed recently in the literature by use of the maxima of the successive products. The ratios found for monochloro-p-xylene (2-chloro-p-xylene), dichloro-p-xylene (the sum of 2,3-dichloro-p-xylene and 2,5-dichloro-p-xylene), trichloro-p-xylene (2,3,5-trichloro-p-xylene), and tetrachloro-p-xylene (2,3,5,6-tetrachloro-p-xylene) are k2/k1=?0.295, k3/k1=?0.0826, and k4/k1=?0.00383. The ratio of the dichlo-isomers produced was also determined as 2.12 in favor of 2,5-dichloro-p-xylene, which is reasonable since 2,3-dichloro-p-xylene is highly hindered by the adjacent groups on the aromatic nucleus. The existing knowledge found in the literature on the rate constant ratios of consecutive reactions was also extended in this paper with a new mathematical expression for the determination of the third stage product peak concentration. The standard uncertainties of the rate constant ratios, the standard deviation of the means, as well as the expanded uncertainties of the means, were calculated. Finally, the propagation of uncertainties for the trichloro-p-xylene was estimated using the partial derivatives of this product for each of the rate constants.
- Rigas, Fotis P.
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- MANUFACTURING METHOD OF HIGH PURITY 2,5-DICHLORO-P-XYLENE
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PROBLEM TO BE SOLVED: To provide a manufacturing method of high purity 2,5-dichloro-p-xylene capable of providing high purity 2,5-dichloro-p-xylene with a purity of 99.9% or more at excellent yields. SOLUTION: There is provided a method of manufacturing high purity 2,5-dichloro-p-xylene by reacting p-xylene and chlorine in presence of a catalyst consisting of ferric chloride and/or antimony trichloride and a cocatalyst consisting of diaryl sulfide under a chlorination condition with a chlorination degree of 2.0 to 2.8, separating the 2,5-dichloro-p-xylene from an obtained reaction product by a distillation treatment or the combination of a distillation treatment and a recrystallization treatment to obtain 2,5-dichloro-p-xylene with a purity of 99.9% or more. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPO&INPIT
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Paragraph 0024
(2018/03/07)
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- Phosphonium nitrate ionic liquid catalysed electrophilic aromatic oxychlorination
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Trioctylmethylphosphonium nitrate (P8,8,8,1NO3), an ionic liquid made via a green synthesis, catalyses electrophilic aromatic chlorination of arenes with HCl and air at 80 °C. The aromatic oxychlorination is truly catalytic in nitrate, proceeds without added solvents, and uses atmospheric oxygen as oxidant. The extent of chlorination can be controlled to yield selectively mono or dichlorinated products, and the ionic liquid catalyst can be recycled. Dependence of the chlorination rate on HCl and nitrate concentrations as well as on the rate of re-oxidation of the nitrogen intermediates by air, allowed us to propose a reaction mechanism.
- Noe, Marco,Perosa, Alvise,Selva, Maurizio,Zambelli, Luca
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experimental part
p. 1654 - 1660
(2010/12/19)
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- Novel process for generating useful electrophiles from common anions using Selectfluor fluorination agent
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In the present work, the electrophile equivalents C1+, Br+, SCN+, and NO2+ are generated from their respective sodium, potassium, and in some cases ammonium salts (M+X-) by reaction with Selectfluor electrophilic fluorination agent in acetonitrile solution at room temperature. These generated electrophilic species subsequently react in situ with a variety of aromatic substrates containing one or more substituent groups including H, F, C1, CH3, COOH, C(O)CH3, NO2, and OR′ and NR′R″ where R′ and R″ are H or CH3. The resulting substitution products are, in most cases, isolable as pure compounds in high yield. Variations in the process include the use of other anions, electrophilic fluorination agents, and solvents.
- Syvret, Robert G.,Butt, Kathleen M.,Nguyen, Tung P.,Bulleck, Victoria L.,Rieth, Ryan D.
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p. 4487 - 4493
(2007/10/03)
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- Addition-Elimination Reactions in Heterolytic Chlorinations of p-Xylene
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Chlorinations of p-xylene and chloro-p-xylene with molecular chlorine at 20-21 deg C in the dark and im acetic acid and, second, of p-xylene in nitrobenzene and neat with or without weak catalysts, have been carried out.The results are compared with those obtained for the FeCl3-catalysed chlorinations of p-xylene and chloro-p-xylene and reveal that dichloro derivates (especially 2,3-dichloro-p-xylene) are obtained directly from p-xylene, probably by an addition-elimination mechanism wich occurs in the all media used except for the FeCl3-catalysed chlorination.The direct formation of dichloro derivates from p-xylene, as well as that of trichloro-p-xylene from chloro-p-xylene, is shown by chlorination of an equimolar mixture of 2H10>-p-xylene and chloro-p-xylene.The separation and evaluation of deuteriated and non-deuteriated chloro derivatives are carried out by g.l.c. on capillary columns.
- Bermejo, Jenaro,Blanco, Carlos G.,Martinez, Amelia,Moinelo, Sabino R.
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p. 1993 - 1996
(2007/10/02)
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- Process for producing 2,5-dichloro-p-xylene
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Reaction of ferric chloride with 2-chloro-p-xylene yields dichloro-p-xylene having a high ratio of 2,5-dichloro-p-xylene isomer to 2,3-dichloro-p-xylene isomer.
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