Chlorosulfuric acid

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. 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. Salts and esters of chlorosulfuric acid are known as chlorosulfates. 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: The industrial synthesis entails the reaction of hydrogen chloride with a solution of sulfur trioxide in sulfuric acid: It can also be prepared by chlorination of sulfuric acid, written here for pedagogical purposes as HSO3(OH), vs. the usual format H2SO4: