Chlorides

Chlorides are chemical compounds that contain chlorine in the −1 oxidation state. In inorganic chemistry, this typically means salts of chlorine anion Cl− paired with metal or metalloid cations. In organic chemistry, the term also covers organochlorine compounds in which chlorine is covalently bound to carbon.

Inorganic chlorides include sodium chloride (table salt), potassium chloride, calcium chloride, and ferric chloride. They form ionic lattices with high melting points and are generally soluble in water; some, like FeCl3, hydrolyze to acidic solutions. Industrially they are made by direct reaction of chlorine with metals or by the reaction of hydrochloric acid with metal oxides or hydroxides. Uses include food seasoning, de-icing, desiccation, and chemical manufacture.

Organic chlorides feature carbon-chlorine bonds. Common examples include chloromethane, dichloromethane, chloroform, and carbon tetrachloride; chlorinated derivatives are pervasive in solvents and intermediates. Polymers such as polyvinyl chloride (PVC) are major chlorinated materials. Many organochlorines are toxic or persistent environmental pollutants; handling requires caution.

Chloride salts occur naturally in seawater and evaporite minerals such as halite (NaCl) and sylvite (KCl). They are also produced industrially from brines. In the chlor-alkali process, electrolysis of aqueous NaCl yields chlorine gas, sodium hydroxide, and hydrogen. Chloride ions influence water chemistry and can contribute to corrosion and ecosystem effects at high concentrations.

See also halides and organochlorine compounds.