Showing papers by "Samsung published in 1967"

Method of preparing fluoroaromatic compounds

Abstract: 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 :he 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, to 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.