- A 2, 4 - difluoro - 3, 5 - dichloro nitrobenzene synthesis of 1, 3, 5 - trichloro - 2, 4, 6 - trifluorobenzene
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The invention discloses a method for synthesizing 1,3,5-trichloro-2,4,6-trifluorobenzene from 2,4-difluoro-3,5-dichloronitrobenzene. The method comprises performing chlorination reaction on 2,4-difluoro-3,5-dichloronitrobenzene in chlorine atmosphere to obtain a chloride, and controlling the chlorination reaction temperature to 160-195 DEG C; performing nitration reaction on the chloride in a mixed acid solution of sulfuric acid and nitric acid to obtain a nitro compound, and controlling the nitration reaction temperature to 60-110 DEG C; and performing fluorination reaction on the nitro compound with a fluoride under a waterless condition so as to obtain 1,3,5-trichloro-2,4,6-trifluorobenzene, and controlling the fluorination reaction temperature to 80-200 DEG C. The product synthesized by the method is high in selectivity, and the yield and the purity of products of all steps are relatively high, and operation is simple.
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Paragraph 0052; 0053; 0054; 0055; 0056; 0057
(2017/08/25)
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- Process for preparing a quinolone-carboxylic acid
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The present invention provides a process for preparing quinolonecarboxylic acid derivatives having the formula (I): wherein R1 is H, halogen, or amino; R2 is halogen; R3 is H, halogen, C1-4 alkoxyl, or CN; R4 is selected from the group consisting of C3-6cycloalkyl, C1-4alkyl, C1-4alkoxyC1-4alkyl, and C1-4alkylaminoC1-4alkyl. The invention also provides new acetophenones having the formula (II) that are intermediates for preparing the compound of the formula (I).
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- Fluorinated biphenyls from aromatic arylations with pentafluorobenzenediazonium and related cations. Competition between arylation and azo coupling
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High yields of the mixed perfluorinated biaryls (C6F5-Ar) are obtained by the catalytic dediazonlatlon of the pentafluorobenzenediazonium salt (C6F5N2+BF4-) in acetonitrile solutions containing various aromatic substrates (ArH) together with small amounts of iodide salts. Activated (electron-rich) as well as deactivated (electron-poor) arenes are successfully pentafluorophenylated by this method. The arylation is distinct from the azo coupling of the same substrates, which takes place in the absence of the iodide catalyst and yields the corresponding diazene (C6F5N=N-Ar) as product. The catalytic role of iodide, and the isomeric product distributions obtained with this procedure indicate that the arylation proceeds via the pentafluorophenyl radical in a efficient homolytic chain process. Since azo coupling involves electrophilic aromatic substitution of electron-rich ArH by C6F5N2+, the two competing pathways are distinct and do not have reactive intermediates in common.
- Kosynkin, Dmitry,Bockman, T. Michael,Kochi, Jay K.
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p. 2003 - 2012
(2007/10/03)
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- Thermal (iodide) and photoinduced electron-transfer catalysis in biaryl synthesis via aromatic arylations with diazonium salts
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The dediazoniative arylation of various aromatic hydrocarbons (Ar'H) with diazonium salts (ArN2+) in acetonitrile can be readily effected to biaryls (Ar-Ar') in high yields, simply by the addition of small (catalytic) amounts of sodium iodide. [In the absence of Ar'H, the competitive iodination to ArI is nearly quantitative.] Iodide catalysis of biaryl formation is efficiently mediated by aryl radicals (Ar') that participate in an efficient homolytic chain process in which ArN2+ acts as a 1-electron oxidant. The complex kinetics of such an electron-transfer chain or ETC process (Scheme I) is quantitatively verified by computer simulation of the Ar'H-dependent (a) competition between arylation vs iodination and (b) catalytic efficiency of iodide. using the GEAR algorithms. ETC catalysis also pertains to the alternative photochemical procedure for arylation (in the absence of iodide), in which the deliberate irradiation of the charge-transfer band of the precursor complex (ArN2+, Ar'H) initiates the same homolytic chain arylation. The latter underscores the mechanistic generality of the ETC formulation for various types of catalytic dediazoniations of aromatic diazonium salts.
- Kosynkin,Bockman,Kochi
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p. 4846 - 4855
(2007/10/03)
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