dodecane-1-thiol, ≥98% (Sigma-Aldrich)

trichloroisocyanuric acid, ≥95% (Fluka)

acetonitrile

water, deionized

sodium sulfate, anhydrous

petroleum ether (bp 40–60 °C)

hydrochloric acid

To a stirring solution of dodecane-1-thiol (1.74 g, 86 mmol) in a mixture of acetonitrile and water (4 : 1 vol., 40 mL) on an ice-bath was added portion-wise trichloroisocyanuric acid (2.90 g, 125 mmol) at such a rate to maintain the temperature at no more than 5 °C. The mixture was left stirring for 30 min in the ice-bath. The precipitated cyanuric acid was then removed by filtration and washed with ethyl acetate (30 mL). The combined filtrate was evaporated under reduced pressure at the bath temperature not higher than 30 °C (to minimize the losses from hydrolysis). The so obtained crude product was dissolved in petroleum ether (50 mL), washed with cold 1% HCl(aq) (50 mL), dried over Na₂SO₄ and again evaporated under reduced pressure to give the product as a white powder (1.40 g, 61%).

The oxidation of thiols to sulfonyl chlorides is traditionally performed with chlorine (see Katritzky et al. for a review). Disulfides, isothiocyanates, isothioureas, thiosulfates, xanthates and related derivatives of thiols are also suitable substrates for the analogous oxidations to sulfonyl chlorides with chlorine, but the above method was not tested on any of these. A continuous rapid stream of gaseous chlorine needs to be applied, which makes the reaction hazardous and unpractical under laboratory-scale reaction conditions. Trichloroisocyanuric acid was therefore tried out of convenience, because it can substitute chlorine and other electrophilic chlorinating reagents in many reactions. The product was needed for use in synthesis and the procedure was thus applied only this once. Consequently, it should be considered a non-optimized synthetic method. The scope might be expected to be similar to the scope of the original method using chlorine, but is yet to be verified experimentally on other substrates.

mp 38–39 °C (lit. 42–43 °C, Sprague and Johnson).

¹H NMR (300 MHz, 302 K, CDCl₃) δ 0.883 (t, J = 6.8, 3H), 1.20–1.40 (m, 16H), 1.49 (m, 2H), 2.07 (m, 2H), 3.66 (m, 2H).

IR (KBr) 1618, 1467, 1416, 1356, 1153 cm^-1.

Ed.: A. R. Katritzky, S. V. Ley, O. Meth-Cohn, C. W. Rees: Comprehensive organic functional group transformations, vol. 2., 1995, Elsevier, Oxford, 177–180.

J. M. Sprague, T. B. Johnson: Preparation of alkylsulfonyl chlorides from isothioureas. II. J. Am. Chem. Soc. 1937, 59, 1837–1840.