Org. Synth. 1955, 35, 99
DOI: 10.15227/orgsyn.035.0099
p-TOLUENESULFENYL CHLORIDE
Submitted by Frederick Kurzer and J. Roy Powell
1.
Checked by Richard S. Schreiber and Fred Kagan.
1. Procedure
Caution! This preparation should be conducted in a good hood.
Chlorine (Note 1) is passed into 300 ml. of anhydrous carbon tetrachloride (Note 2) contained in a 500-ml. three-necked round-bottomed flask equipped with a mechanical stirrer, a dropping funnel protected from atmospheric moisture by a calcium chloride tube, and a gas-inlet tube equipped with a sintered-glass tip (Note 3). The amount of chlorine contained in the resulting yellow-green liquid, estimated volumetrically (Note 4), varies between 25 and 32 g. The gas-inlet tube is replaced by a calcium chloride tube, and the reaction vessel is cooled externally with ice water and protected from light by being covered with a towel.
One or two crystals of iodine are added to the chlorine solution, and a solution of p-toluenethiol (7.3 g. per 10 g. of dissolved chlorine, i.e., halogen in 140% excess) (Note 5) in 50 ml. of anhydrous carbon tetrachloride (Note 2) is added dropwise over a period of approximately 1 hour. The initial slight turbidity disappears gradually, a bright orange solution being formed (Note 6). After an additional 30 minutes' stirring, the solvent and excess chlorine are rapidly removed under reduced pressure at the lowest possible temperature (Note 7), the crude sulfenyl chloride being left as an orange-red mobile liquid (Note 8). For batches starting with 24.8 g. (0.2 mole) of p-toluenethiol, the yield varies between 27 and 30.5 g. (85–96%).
Rapid distillation under reduced pressure affords p-toluenesulfenyl chloride as a red mobile liquid boiling at 66–68°/0.8 mm. (74–76°/1.5 mm.; 82–84°/3.5 mm.) (Note 9). The yield of redistilled material varies between 24.5 and 28 g. (77–88%).
2. Notes
1.
The checkers used tank
chlorine obtained from the Ohio Chemical and Surgical Equipment Company, Detroit, Michigan. The gas was dried with concentrated
sulfuric acid and used with no further purification. The rate of
chlorine addition was regulated so that no
chlorine escaped from the
carbon tetrachloride solution. After 1.5–2.0 hours,
27–33 g. of chlorine was absorbed. The submitters generated
chlorine by the action of concentrated
hydrochloric acid on
potassium permanganate.
2.
The
carbon tetrachloride is treated with a small quantity of
phosphorus pentoxide, and the suspension is set aside for 1–2 hours. The clear supernatant liquid is first decanted into a dry flask and gently shaken. Any droplets of
phosphoric acid are retained on the walls of this vessel; the anhydrous solvent is then easily decanted.
3.
During the slow absorption of
chlorine, the solution is satisfactorily protected from atmospheric moisture by means of a plug of cotton wool through which the gas-inlet tube passes. The temperature of the solution does not rise, and external cooling is not required.
4.
A 2-ml. aliquot of the solution, withdrawn by means of a safety pipet, is added to 20 ml. of water containing
2 g. of potassium iodide, and the liberated
iodine is titrated with good shaking with standard
sodium thiosulfate solution.
5.
When a smaller excess of
chlorine is used poorer yields of
sulfenyl chloride are obtained, a larger proportion of
p-tolyldisulfide being formed.
6.
The checkers found that the turbidity persisted throughout the addition of the
p-toluenethiol and that a small amount of an orange-yellow solid was present at the end of the addition. This material dissolved during the concentration under reduced pressure.
7.
Since traces of
sulfenyl chloride are carried over with the
carbon tetrachloride, the distillate varies from light to deep yellow during the concentration. Recovery of this material by repeated distillation is not economical.
8.
This material is suitable for use in further synthesis without purification by distillation, particularly if the presence of a few per cent of
p-tolyl disulfide is of no consequence.
9.
The checkers found that
76% of the product boiled at
64–66°/1.1 mm. and
24% boiled at
66–74°/1.1 mm.; however, the index of refraction of the two fractions was constant (
n20D 1.6018–1.6019). As the first few drops of distillate were green, they were discarded.
3. Discussion
p-Toluenesulfenyl chloride has been prepared by the action of
chlorine on a solution of
p-toluenethiol or
p-tolyl disulfide in
anhydrous carbon tetrachloride.
2,3,4 Benzenesulfenyl chloride has also been obtained by the interaction of
hydrogen chloride and
N,N-diethylbenzenesulfenamide5 and by reaction of
benzenethiol with
N-chlorosuccinimide.
6 A comprehensive review dealing with sulfenyl halides and related compounds is available.
7
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
sulfenyl chloride
calcium chloride (10043-52-4)
sulfuric acid (7664-93-9)
hydrogen chloride,
hydrochloric acid (7647-01-0)
potassium permanganate (7722-64-7)
carbon tetrachloride (56-23-5)
potassium iodide (7681-11-0)
sodium thiosulfate (7772-98-7)
iodine (7553-56-2)
chlorine (7782-50-5)
phosphoric acid (7664-38-2)
N-chlorosuccinimide (128-09-6)
Benzenethiol (108-98-5)
Benzenesulfenyl chloride (931-59-9)
N,N-diethylbenzenesulfenamide
phosphorus pentoxide (1314-56-3)
p-Toluenesulfenyl chloride (933-00-6)
p-toluenethiol (106-45-6)
p-tolyl disulfide,
p-tolyldisulfide (103-19-5)
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