<i>p</i>-Toluenesulfonyl Chloride

[98-59-9] C7H7ClO2S (MW 190.66) InChI = 1S/C7H7ClO2S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3 InChIKey = YYROPELSRYBVMQ-UHFFFAOYSA-N (sulfonyl transfer reagent; O-sulfonylation of alcohols2 for conversion to chlorides3 or intermolecular4 and intramolecular5 displacements, vicinal diols for epoxidation,6 1,3-diols for oxetane formation,7 carboxylic acids for esterification8 or decarboxylation,9 oximes for Beckmann rearrangements10 or fragmentations11 and Neber rearrangements,12 hydroxamic acids for Lossen rearrangements,13 nitrones for rearrangements,14 conversion of N-cyclopropylhydroxylamines to β-lactams;15 N-sulfonylation of aliphatic amines16 for subsequent deamination17 or displacement,18 aromatic amines for protection;19 C-sulfonylation of alkenes20 and silylalkynes;21 dehydration of ureas,22 formamides,23 and amides24) Alternate Names: tosyl chloride. Physical Data: mp 67–69 °C; bp 146 °C/15 mmHg. Solubility: insol H2O; freely sol ethanol, benzene, chloroform, ether. Form Supplied in: white solid, widely available. Purification: upon prolonged standing the material develops impurities of p-toluenesulfonic acid and HCl. Tosyl chloride is purified by dissolving 10 g in a minimum volume of CHCl3 (ca. 25 mL), filtering, and diluting with five volumes (ca. 125 mL) of petroleum ether (bp 30–60 °C) to precipitate impurities (mostly tosic acid, mp 101–104 °C). The solution is filtered, clarified with charcoal, and concentrated to ca. 40 mL by evaporation. Further evaporation to a very small volume gives 7 g of pure white crystals (mp 67.5–68.5 °C).25 Tosyl chloride may also be recrystallized from petroleum ether, from benzene, or from toluene/petroleum ether (bp 40–60 °C) in the cold. Tosyl chloride in diethyl ether can be washed with aqueous 10% NaOH until colorless, then dried with Na2SO4 and crystallized by cooling in powdered dry ice. It can also be purified by dissolving in benzene, washing with aqueous 5% NaOH, drying with K2CO3 or MgSO4, and distilling under reduced pressure.26 Handling, Storage, and Precautions: freshly purified tosyl chloride should be used for best results. Tosyl chloride is a moisture-sensitive, corrosive lachrymator.