In organosulfur chemistry, a sulfonyl group can refer either to a functional group found primarily in sulfones, or to a substituent obtained from a sulfonic acid by the removal of the hydroxyl group, similarly to acyl groups.[1]: 1470–1476 Sulfonyl groups can be written as having the general formula R−S(=O)2−R′, where there are two double bonds between the sulfur and oxygen.[1]: 53 [2]
Sulfonyl groups can be reduced to the sulfide with DIBALH. Lithium aluminium hydride (LiAlH4) reduces some but not all sulfones to sulfides.[1]: 1851
In inorganic chemistry, when the group −S(=O)2− is not connected to any carbon atoms, it is referred to as sulfuryl.[3]