Carbon tetrachloride. Molecular model of the inorganic carbon compound carbon tetrachloride (CCl4). This chemical was formerly used in fire extinguishers, as a dry cleaning solvent and as a refrigerant. Its production has declined due to environmental concerns about chemicals derived from it, such as CFCs (chlorofluorocarbons). Atoms are represented as spheres and are colour-coded: carbon (grey) and chlorine (green)