Sulfanilic acid

Sulfanilic acid is an organic compound with the formula H2NC6H4SO3H. It is a white solid that is soluble in water and slightly soluble in organic solvents. Sulfanilic acid is used in the synthesis of dyes, sulfonamides, and other organic compounds.

History

Sulfanilic acid was first synthesized in the 19th century by the German chemist August Wilhelm von Hofmann. He discovered that when aniline, a primary aromatic amine, is treated with sulfuric acid, it forms sulfanilic acid.

Properties and Structure

Sulfanilic acid is a white crystalline solid at room temperature. It is soluble in water and slightly soluble in organic solvents such as ethanol and acetone. The compound has a melting point of 288 °C and a boiling point of 300 °C.

The structure of sulfanilic acid consists of a benzene ring with an amino group (NH2) and a sulfonic acid group (SO3H) attached. The amino group is in the para position to the sulfonic acid group.

Synthesis

Sulfanilic acid is synthesized by the sulfonation of aniline. This process involves the reaction of aniline with sulfuric acid at high temperatures. The resulting product is then neutralized with an alkali to yield sulfanilic acid.

Applications

Sulfanilic acid is used in the synthesis of a variety of organic compounds. It is a key intermediate in the production of many dyes, including azo dyes and sulfa drugs. It is also used in the manufacture of resins, plastics, and rubber.

In addition, sulfanilic acid is used as a laboratory reagent in various chemical reactions. It is particularly useful in the detection of nitrites and nitrates in solution.

Safety

Sulfanilic acid is considered a low hazard substance. However, it can cause irritation to the skin and eyes, and prolonged exposure can lead to respiratory problems. It is recommended to handle the compound with care and use appropriate personal protective equipment.

See also

• Aniline
• Sulfonation
• Azo dye
• Sulfa drug