C. Kun
2006
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Journal
Journal of Hubei University of Technology
Abstract
2,3,4,5-Tetrafluorobenzoic acid(TFBA),an important intermediates of fluoroquinolone antibiotics,was prepared starting from Nphenyl tetrachlorophthalimide,which reacted with potassium fluoride in the presence of DMF and hexadecyltributylammonium bromide at 140~150℃ for 7~9 h to give N-phenyl tetrafluorophthalimide(PTFP) in 87% yield.Open-ring of PTFP in 1.5 mol/L potassium hydrate with hexadecyltrimethylammonium bromide as catalyst gave N-phenyl-2-carboxy-3,4,5,6-tetrafluorobenzoyl amine(PCTFBA) in 98% yield,and decarboxylation of PCTFBA with N,N-dimethyl-ethylolamine as solvent gave N-phenyl-2,3,4,5-tetrafluorobenzoyl amine(PTFBA) in 76% yield;after hydrolysis,TFBA was obtained in 87% yield.The reactions of all steps were carried out in moderate condition to afford the total yield of TFBA up to56.4%.