A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1925, 5, 3
DOI: 10.15227/orgsyn.005.0003
[Sulfanilyl chloride, N-acetyl-]
Submitted by S. Smiles and Jessie Stewart.
Checked by Henry Gilman and F. Schulze.
1. Procedure
In a 500-cc. round-bottomed flask, fitted with a mechanical stirrer, is placed 290 g. (165 cc., 2.49 moles) of chlorosulfonic acid (Note 1). The flask is surrounded by a cooling bath and cooled with running water to about 12–15°. To the chlorosulfonic acid is added gradually 67.5 g. (0.5 mole) of acetanilide. This requires about fifteen minutes if the temperature is maintained at approximately 15°. Since large volumes of hydrogen chloride are evolved, the reaction should be conducted in a good hood, or a gas absorption trap (Fig. 7 on p. 97) might be used. After all the acetanilide has been added, the mixture is heated to 60° for two hours to complete the reaction (Note 2).
The sirupy liquid is poured slowly, with stirring (Note 3), into 1 kg. of ice to which just enough water has been added to make stirring easy. This decomposition of the excess chlorosulfonic acid should be carried out in the hood. The solid sulfonyl chloride which separates is collected on a suction funnel (Note 4) and washed with water. The yield of crude material is 90–95 g. (77–81 per cent of the theoretical amount based on the acetanilide).
This crude material may be used directly in many preparations such as p-acetaminobenzenesulfinic acid (p. 7). If a pure product is desired, the crude material is dried by pressing on a porous plate and then crystallized from dry benzene. The acid chloride is slightly soluble in benzene, and only 1.5 to 2 g. will dissolve in 100 cc. of hot benzene. On cooling, about 75 per cent of the material separates from the benzene in thick, colorless prisms melting at 149° (Note 5).
2. Notes
1. The chlorosulfonic acid should be freshly distilled. Smaller amounts of this reagent may be used without reducing the yield or affecting the quality of the product. However, with smaller amounts the time required for the reaction must be increased. Thus, if 175 g. (1.5 moles) of chlorosulfonic acid is used with 67.5 g. (0.5 mole) of acetanilide, an additional hour of heating is required to obtain the yields mentioned above.
2. The hydrogen chloride which is liberated during the reaction fills the mixture with tiny bubbles. When these disappear the reaction is complete.
3. Mechanical stirring is most convenient but not necessary.
4. A rather large suction funnel (125 mm. or more) should be used in the filtration as the sulfonyl chloride has a tendency to clog the filter.
5. The purification is the least satisfactory part of the preparation. The material must not be heated while water is still present, or excessive decomposition will occur. As the sulfonyl chloride is only slightly soluble in hot benzene, it is inconvenient to crystallize more than a small amount at a time. The crude product does not keep well and must be used at once. After recrystallization it may be kept indefinitely.
3. Discussion
p-Acetaminobenzenesulfonyl chloride can be prepared by the action of phosphorus pentachloride1 or chlorosulfonic acid2 on sodium p-acetaminobenzenesulfonate and by the action of chlorosulfonic acid on acetanilide.3
This preparation is referenced from:

References and Notes
  1. Schroeter, Ber. 39, 1563 (1906).
  2. Goldyrev and Postovskii, J. Applied Chem. (U.S.S.R.) 11, 316 (1938) [C. A. 32, 5800 (1938)].
  3. Stewart, J. Chem. Soc. 121, 2558 (1922).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

sulfonyl chloride

acid chloride

hydrogen chloride (7647-01-0)

Benzene (71-43-2)

Acetanilide (103-84-4)

Sulfanilyl chloride, N-acetyl-,
p-Acetaminobenzenesulfonyl chloride (121-60-8)

chlorosulfonic acid (7790-94-5)

phosphorus pentachloride (10026-13-8)

p-Acetaminobenzenesulfinic acid (710-24-7)

sodium p-acetaminobenzenesulfonate