Riot control grenades take two basic forms, chemical and kinetic.
Chemical grenades are designed to emit fumes that irritate or disable to the extent that they prevent persons from carrying out a chosen course of action, i.e. they quell rioters.
The primary requirement demanded of such agents is that they irritate or disable, but also that they do no permanent damage.
For many years, the chosen irritant agent in riot control was tear gas, a relatively harmless substance that des little more than bring tears to the eyes and impart a general feeling of choking and helplessness.
Tear gas is now generally known as CN, but its proper chemical name is alpha chloroacetophenon