Hinsberg reagent is an alternative name for benzene sulfonyl chloride. This name is given for its use in the Hinsberg test for the detection and distinction of primary, secondary, and tertiary amines in a given sample.

This reagent is an organosulfur compound. Its chemical formula can be written as ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{SO}}_2\mathrm{Cl}$.

In the Hinsberg Test, the amines act as nucleophiles and attack the electrophile (sulfonyl chloride). This leads to the displacement of the chloride and the generation of the sulfonamides. When primary and secondary amines form sulfonamides, this sulfonamide product is not soluble and precipitates from the solution as a solid.

$1° \text{and} 2°$ amines will give reaction with Hinsberg reagent. Compounds which gives reaction with Hinsberg reagent are as follows,