3D model (JSmol)
|Molar mass||116.52 g mol−1|
|Appearance||colorless liquid that fumes in air|
|Density||1.753 g cm−3|
|Melting point||−80 °C (−112 °F; 193 K)|
|Boiling point||151 to 152 °C (304 to 306 °F; 424 to 425 K) (755 mmHg or 100.7 kPa)|
|Solubility in other solvents||reacts with alcohols|
soluble in chlorocarbons
Refractive index (nD)
|Safety data sheet||ICSC 1039|
|R-phrases (outdated)||R14, R35, R37|
|S-phrases (outdated)||(S2), S26, S45|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Chlorosulfuric acid (IUPAC name: sulfurochloridic acid) is the inorganic compound with the formula HSO3Cl. It is also known as chlorosulfonic acid, being the sulfonic acid of chlorine. It is a distillable, colorless liquid which is hygroscopic and a powerful lachrymator.
Structure and properties
Chlorosulfuric acid is a tetrahedral molecule. The formula is more descriptively written SO2(OH)Cl, but HSO3Cl is traditional. It is an intermediate, chemically and conceptually, between sulfuryl chloride (SO2Cl2) and sulfuric acid (H2SO4). The compound is rarely obtained pure. Upon standing with excess sulfur trioxide, it decomposes to pyrosulfuryl chlorides:
- 2 ClSO3H + SO3 → H2SO4 + S2O5Cl2
- HCl + SO3 → ClSO3H
It can also be prepared by chlorination of sulfuric acid, written here for pedagogical purposes as HSO3(OH), vs. the usual format H2SO4:
- PCl5 + HSO3(OH) → HSO3Cl + POCl3 + HCl
The latter method is more suited for laboratory-scale operations.
- ROH + ClSO3H → ROSO3H + HCl
- CH3C6H5 + 2 ClSO2OH → CH3C6H4SO2Cl + H2SO4 + HCl
ClSO3H reacts violently with water to yield sulfuric acid and hydrogen chloride, commonly seen as vapors fuming from the liquid. Precautions, such as proper ventilation, associated with HCl should be observed.
Related halosulfuric acids
- Fluorosulfonic acid, FSO2OH, is a related strong acid with a diminished tendency to evolve hydrogen fluoride.
- Bromosulfonic acid, BrSO2OH, is unstable, decomposing at its melting point of 8 °C to give bromine, sulfur dioxide, and sulfuric acid.
- Iodosulfonic acid is not known to occur.
- Cremlyn, R. J. (2002). Chlorosulfonic Acid. Royal Society of Chemistry. ISBN 978-0-85404-498-6.
- Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. pp. 549–550.
- Maas, J.; Baunack, F. (2002). "Chlorosulfuric Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_017.
- The Royal Navy at War (DVD). London: Imperial War Museum. 2005.
- Amos, Jonathan (2018-04-11). "Nazi legacy found in Norwegian trees". BBC News Online. Retrieved 2018-04-17.