110877-64-0Relevant articles and documents
Syntheses of 2-chloro-4,5-difluorobenzoic acid
Li, Zhibin,Huang, Naihua
, p. 245 - 246 (1996)
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Method of preparing fluoroaromatic compounds
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, (2008/06/13)
The present invention provides a method of preparing ortho-difluorobenzene derivatives, which comprises (a) providing a mixture of cyclohexenes by reacting chlorotrifluoroethylene (CTFE) and 1,3-diene in a flow reactor and distilling the resultant, and (b) dehydrohalogenating the mixture of cyclohexenes with a phase transition catalyst in the presence of alkali metal hydroxide at temperature range of 40 to 150 °C without using any organic solvent. The distillate having low boiling point, which is obtained during distillation of the resultant, is recycled into the flow reactor. The present invention also provides a method of preparing 2-chloro-4,5-difluorobenzoic acid, which comprises (a) providing a mixture of 4-chloro-1-methyl-4,5,5-trifluorocyclohexene and 5-chloro-1-methyl-4,4,5-trifluorocyclohexene by reacting chlorotrifluoroethylene (CTFE) and isoprene and distilling the resultant, (b) dehydrohalogenating said mixture in the presence of alkali metal hydroxide and a phase transition catalyst to form 3,4-difluorotoluene, (c) reacting said 3,4-difluorotoluene with chlorine gas without using any organic solvent to form 2-chloro-4,5-difluorotoluene, (d) photo-reacting said 2-chloro-4,5-difluorotoluene with chlorine gas under a lighting mercury lamp without using any organic solvent to form 2-chloro-4,5-difluorobenzotrichloride, and (e) reacting said 2-chloro-4,5-difluorobenzotrichloride with aqueous acid solution without using any organic solvent. The present invention also provides a method of preparing 2-chloro-4,5-difluorobenzoyl chloride by reacting the 2-chloro-4,5-difluorobenzotrichloride of step (e) above with zinc oxide.
Process for the preparation of halogenated benzoic acids
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, (2008/06/13)
A process for the preparation of halogenated benzoic acids of formula (1): STR1 in which R1, R2, R3, R4 and R5 are hydrogen, fluorine, chlorine or bromine atoms or C1 -C6 -alkyl, C1 -C6 -alkoxy, nitro, cyano, trifluoromethyl, aidehyde, C1 -C4 -alkoxycarbonyl, -SO2 -C1 -C4 -alkyl, -SO2 -phenyl, -CONH2, -CON(C1 -C4 -alkyl)2, hydroxy, carboxy, -NH2 or -N(C1 -C4 - alkyl)2 groups, at least one of the substituents R1 -R5 being one of said halogen atoms, which comprises reacting 1 mol of a benzophenone, asymmetrically substituted on the benzene rings A and B, of general formula (2): STR2 in which R1 -R10 are as defined above for R1 -R5, with about 1 to about 10 mol of an oxidizing agent selected from the group comprising hydrogen peroxide, urea/hydrogen peroxide addition product, an alkali metal peroxide, ammonium, alkali metal or alkaline earth metal peroxodisulfates, pertungstates, perborates or percarbonates, ozone, alkyl- or aryl-percarboxylic acids, alkyl- or aryl-persulfonic acids or persulfuric acid, at temperatures from about -20° to about +100° C.