[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]([F:11])([F:10])[F:9])=[CH:4][C:3]=1[CH2:12][S:13]([OH:16])(=O)=[O:14].[Na].P(Cl)(Cl)(Cl)(Cl)[Cl:19]>>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]([F:11])([F:10])[F:9])=[CH:4][C:3]=1[CH2:12][S:13]([Cl:19])(=[O:16])=[O:14]A mixture of sodium (2-chloro-5-trifluoromethyl-phenyl)-methanesulfonic acid (Example 1.1) (9.4 g) and phosphorous pentachloride (13.5 g) was heated to 80-90° C. for 4 hours. The reaction mixture was concentrated. The residue was poured onto a mixture of ice and water and the mixture extracted twice with dichloromethane. The combined organic extracts were washed with water and brine, dried over magnesium sulfate and concentrated to give (2-chloro-5-trifluoromethyl-phenyl)-methanesulfonyl chloride as an off-white solid (8.480 g). 1H-NMR (400 MHz, CDCl3): 7.87 (m, 1H), 7.68 (m, 2H), 5.15 (s, 2H) ppm.
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