Chromyl chloride fuming in air
| Preferred IUPAC name
Chromium(VI) dichloride dioxide
| Systematic IUPAC name
| Other names
Chromic oxychloride, chromium chloride oxide, chromium dioxychloride, chromium dichloride dioxide, chromium dioxide dichloride, chromium oxychloride, chlorochromic anhydride
|Molar mass||154.9008 g/mol|
|Appearance||Viscous fuming blood-red liquid|
|Density||1.96 g/cm3 (at 20 °C)|
|Melting point||−96.5 °C (−141.7 °F; 176.7 K)|
|Boiling point||117 °C (243 °F; 390 K)|
|Solubility|| Reacts with alcohols|
Soluble in glacial acetic acid, benzene, carbon disulfide, carbon tetrachloride, chloroform, dichloromethane, diethyl ether, nitrobenzene, phosphoryl chloride
|Vapor pressure||20 mmHg (at 20 °C)|
|Safety data sheet||Acros|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Chromyl chloride is an inorganic chemical compound, used as an oxidizing agent, mostly in organic chemistry. It is an opaque dark blood-red liquid at standard conditions.
First, a chromium compound is formed from the chromyl chloride and toluene:
- C6H5CH3 + 2 CrO2Cl2 → C6H5CH[CrO2Cl2]2
The complex is hydrolyzed with water to yield benzaldehyde.
- C6H5CH[CrO2Cl2]2 + 2 H2O → C6H5CH=O + Cr2O3 + 4 HCl
- CrO2Cl2 + 2 H2O → H2CrO4 + 2 HCl
Chromyl chloride is a deep red viscous liquid, which fumes in air. It reacts with water, alcohols, but soluble in chlorinated carbons and carboxylic acids.
Chromyl chloride is hard to find and it's best to make it yourself.
- K2Cr2O7 + 4 NaCl + 6 H2SO4 → 2 CrO2Cl2 + 2 KHSO4 + 4 NaHSO4 + 3 H2O
A good procedure can be found here.
- Make benzaldehyde
- Spontanous ignition of sulfur
Chromyl chloride is extremely corrosive and will fume in contact with air. Proper protection must be worn when handling the compound. As it is a Cr(VI) compound, it is also carcinogenic.
Chromium chloride must be stored in glass containers, away from any moisture or organic compounds. A round bottom flask with a glass stopper can be used. Inspect it periodically to make sure there's no leak and check if the ground joint froze.
Adding a supersaturated solution of sodium sulfite or some other reducing agent will neutralize the compound to less toxic Cr(III).