CN, or chloracetophenone, is a gas used as a riot control agent. It has the molecular form C8H13ClO. It was investigated, but not used, during the First and Second World Wars, and was used by United States forces in Vietnam. As its toxicity is apparently greater than that of CS gas, it has largely been supplanted by CS gas.
CN is still supplied to paramilitary and police forces in a small pressurized aersol can known as "Mace" or tear gas. Its use has fallen by the wayside as "pepper spray" works faster and disperses quicker than CN.
Like CS gas, this compound is irritating for the mucous membranes (oral, nasal, conjunctival and tracheobronchial). Sometimes it can give rise to more generalised reactions such as lipothymy, temporary loss of balance and orientation. More rarely, cutaneous irritating outbreaks have been observed and allergic contact permanent dermatitis.