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| Names | |||
|---|---|---|---|
| IUPAC name Sulfurochloridic acid | |||
| Other names Chlorosulfuric acid, Chlorosulfonic acid, Chlorosulphonic acid, Chlorinesulfonic acid, Chlorinesulphonic acid, Chloridosulfonic acid, Chloridosulphonic acid, Sulfuric chlorohydrin | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChemSpider |
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| ECHA InfoCard | 100.029.304 | ||
| EC Number |
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| RTECS number |
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| UNII | |||
| UN number | 1754 | ||
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| Properties | |||
| HSO3Cl | |||
| Molar mass | 116.52 g mol−1 | ||
| Appearance | colorless liquid, but commercial samples usually are pale brown | ||
| 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) | ||
| hydrolysis | |||
| Solubility in other solvents | reacts with alcohols soluble in chlorocarbons | ||
| Acidity (pKa) | −5.9 (inCF3CO2H)[1] | ||
Refractive index (nD) | 1.433 | ||
| Structure | |||
| tetrahedral | |||
| Hazards | |||
| GHS labelling: | |||
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| Danger | |||
| H314,H335 | |||
| P260,P261,P264,P271,P280,P301+P330+P331,P303+P361+P353,P304+P340,P305+P351+P338,P310,P312,P321,P363,P403+P233,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Safety data sheet (SDS) | ICSC 1039 | ||
| Related compounds | |||
Related compounds | Sulfuryl chloride Sulfuric acid | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Chlorosulfuric acid (IUPAC name:sulfurochloridic acid) is theinorganic compound with the formula HSO3Cl. It is also known aschlorosulfonic acid, being thesulfonic acid ofchlorine. It is a distillable, colorless liquid which ishygroscopic and a powerfullachrymator. Commercial samples usually are pale brown or straw colored.[3]
Salts andesters of chlorosulfuric acid are known aschlorosulfates.
Chlorosulfuric acid is atetrahedral molecule. Its structure was debated for many decades until in 1941 Shrinivasa Dharmatti proved bymagnetic susceptibility that chlorine is directly bonded to sulfur.[4][5]
The formula is more descriptively written SO2(OH)Cl, but HSO3Cl is traditional. It is an intermediate, chemically and conceptually, betweensulfuryl chloride (SO2Cl2) andsulfuric acid (H2SO4).[6] The compound is rarely obtained pure. Upon standing with excess sulfur trioxide, it decomposes to pyrosulfuryl chlorides:[7]
The industrial synthesis entails the reaction ofhydrogen chloride with asolution ofsulfur trioxide insulfuric acid:[7]
It can also be prepared by the method originally used by acid's discovererAlexander William Williamson in 1854,[4] namely chlorination of sulfuric acid, written here for pedagogical purposes as HSO3(OH) vs. the usual format H2SO4:
The latter method is more suited for laboratory-scale operations.
Williamson's discovery disproved then-popular hypothesis that sulfuric acid is a compound of water (which was incorrectly assumed to have formula of HO) andsulfur trioxide.[8]
ClSO2OH is used to preparealkyl sulfates, which are useful asdetergents and as chemical intermediates:[7]
One historical synthesis ofsaccharin begins with the reaction oftoluene with ClSO2OH to give theortho- andpara-toluenesulfonyl chloride derivatives:
Oxidation of theortho isomer gives thebenzoic acid derivative that then is cyclized withammonia and neutralized with base to afford saccharin.
Chlorosulfonic acid has been used as an anti-contrail agent inRyan Model 147 reconnaissance drones,[9] and to producesmoke screens.[10][11]
ClSO3H reacts violently with water to yield sulfuric acid and hydrogen chloride, which are corrosive:
