Chromyl chloride
Chromyl chloride is the inorganic compound with the formula CrOCl. It is a reddish brown compound that is a volatile liquid at room temperature, which is unusual for transition metal complexes. Preparation. Chromyl chloride can be prepared by the reaction of potassium chromate or potassium dichromate with hydrogen chloride in the presence of sulfuric acid, followed by distillation. The sulfuric acid serves as the dehydration agent. It can also be prepared directly by exposing chromium trioxide to anhydrous hydrogen chloride gas. The method used to prepare chromyl chloride is the basis for a qualitative test for chloride: a  sample suspected of containing chloride is heated with a mixture of potassium dichromate and concentrated sulfuric acid. If chloride is present, chromyl chloride forms as evidenced by red fumes of CrOCl. Analogous compounds are not formed with fluorides, bromides, iodides and cyanides. Reagent for oxidation of alkenes. Chromyl chloride oxidizes internal alkenes to alpha-chloroketones or related derivatives. It will also attack benzylic methyl groups to give aldehydes via the Étard reaction. Dichloromethane is a suitable solvent for these reactions. Safety considerations. CrOCl decomposes violently on contact with water to release hydrochloric acid (HCl) and chromic acid (HCrO). Although not  combustible, chromyl chloride is a strong oxidizer and can spontaneously ignite or explode on contact with flammable substances. In case of fire, no direct contact should be made with water. Additionally, chromyl chloride is severely corrosive and easily burns the skin and eyes, and ingestion would cause severe internal damage. Its vapours are also strongly irritating to all parts of the body. Chronic: Cr can produce chromosomal aberrations and is a human carcinogen via inhalation. Frequent exposure of the skin to chromyl chloride may result in ulceration.