Disulfur Dichloride


[10025-67-9]  · Cl2S2  · Disulfur Dichloride  · (MW 135.04)

(synthesis of thioketones and thioaldehydes from hydrazones;1 synthesis of dithiazoles2 and episulfides3)

Alternate Name: sulfur monochloride.

Physical Data: mp -77 °C; bp 138 °C; d 1.688 g cm-3; nD20 1.6700.

Solubility: sol benzene, ether; readily sol CS2.

Form Supplied in: golden yellow, oily liquid; pungent odor; fumes in moist air; impure sample can be reddish orange due to SCl2; commercially available.

Purification: distillation of 500 g from 20 g of sulfur and 5 g of charcoal; fraction from 135 to 137 °C is collected.

Handling, Storage, and Precautions: refrigerate in dark bottle; air and moisture sensitive; incompatible with acids, bases, alcohols, and amines. Avoid contact with metals; harmful if swallowed; inhalation may be fatal. Use in a fume hood.

Synthesis of Thioketones and Thioaldehydes.

Based on the resulting tautomers from a synthesis of hindered N-thiosulfinylanilines (Ar-N=S=S) from anilines (eq 1),4 a synthesis for thioketones and thioaldehydes has been worked out from hydrazone derivatives and S2Cl2.5

Hydrazone derivatives are treated with S2Cl2 to produce an N-thiosulfinylamine which undergoes cyclization, followed by molecular extrusion of N2 (g) to give an S-thioxothioketone. The S-thioxothioketones (R2C=S=S) are not isolable, as they decompose to the thioketones and sulfur (eq 2).2,6 The yield of 2,2,4,4-tetramethylthiopentanone is the isolated yield; spectra showed near quantitative conversion.

2,4,6-Tri-t-butylthiobenzaldehyde was the first stable thiobenzaldehyde synthesized. It was prepared from the corresponding hydrazone in 40% yield using S2Cl2 in the presence of Triethylamine (eq 3). In the absence of oxygen, no decomposition was observed after 1 year at rt in the solid phase. In the presence of air, it is quantitatively converted to 2,4,6-tri-t-butylbenzaldehyde.7

Synthesis of Dithiazoles.

Treatment of unsaturated oxime derivatives with disulfur dichloride in the presence of Hünig's base gives high yields of cyclopenta-1,2,3-dithiazoles (eq 4).3 Treatment of saturated oximes such as cyclopentanone oxime gives unsaturated, perchlorinated dithiazoles (eq 5) in significantly reduced yield.

Episulfides from Alkenes.

Disulfur dichloride adds to alkenes to form b-chloroalkyl mono-, di-, and trisulfides. The monosulfides, however, cannot be converted into episulfides. Their production is minimized by the addition of dichloropolysulfanes, SxCl2. The b-chloroalkyl sulfides are then reduced with Aluminum Amalgam or Sodium Sulfide to the episulfide (eq 6).3b


Disulfur dichloride can also be used to synthesize N,N-dithiobissulfoximines,7 to synthesize macrocyclic, polysulfur compounds,8 and is part of an extremely powerful chlorinating agent for perchlorination of aromatic systems (see also Aluminum Chloride and Sulfuryl Chloride).9 It is also a reagent for the synthesis of aranotins, a small group of sulfur-bridged diketopiperazines,10 and it was tried in conjunction with sulfur dichloride for one-step episulfide synthesis.11

1. Okazaki, R.; Inoue, K.; Inamoto, N. TL 1979, 3673.
2. Plater, M. J.; Rees, C. W.; Roe, D. G.; Torroba, T. JCS(P1) 1993, 769.
3. (a) Fieser, M.; Fieser, L. FF 1972, 3, 275. (b) Lautenschlaeger, F.; Schwartz, N. V. JOC 1969, 34, 3991.
4. (a) Inagaki, Y.; Okazaki, R.; Inamoto, N. TL 1975, 4575. (b) Inagaki, Y.; Okazaki, R.; Inamoto, N. BCJ 1979, 52, 1988.
5. Okazaki, R.; Inoue, K.; Inamoto, N. BCJ 1981, 54, 3541.
6. (a) Fieser, M. Fieser, L. FF 1984, 11, 495. (b) Okazaki, R.; Ishii, A.; Fukuda, N.; Oyama, H.; Inamoto, N. CC 1982, 1187.
7. Okahara, M.; Yoshikawa, E.; Ikeda, I.; Komori, S. S 1975, 521.
8. (a) Bottino, F.; Foti, S.; Pappalardo, S. T 1977, 33, 337. (b) Bottino, F.; Pappalardo, S. JCS(P1) 1981, 718.
9. Ballester, M.; Molinet, C.; Castaner, J. JACS 1960, 82, 4254.
10. Coffen, D. L.; Katonak, D. A.; Nelson, N. R.; Sancilio, F. D. JOC 1977, 42, 948.
11. Tolstikov, G. A.; Lerman, B. M.; Belogaeva, T. A. ZOB 1986, 563.

Brian C. Austad

University of Wisconsin, Madison, WI, USA

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