Which of the following oxyacids of Sulphur have a peroxy –O–O– linkage?
Caro’s acid & Marshall’s acid
Can you recall what are Caro’s acid and Marshall’s acid?
Caro’s acid is also known as peroxy monosulphuric acid and it has the formula H2SO5. Try and draw the structure yourself. It definitely has a peroxy –O–O– linkage.
I will help you figure out the structure of the other acid. Marshall’s acid is H2S2O8. It is prepared by the action of Chlorosuphonic acid on Hydrogen peroxide.
2ClSO3H+H2O2→H2S2O8+2HCl
Marshall’s acid has the structure:
The central atom of sulphurous acid is sp3 hybridized. Can you draw the structure?
In the above image, the central S atom’s lone pair has not been shown. But it is definitely there. The Sulphur atom has a pyramidal shape but tetrahedral geometry.
Caro’s acid has the following structure:
It is also prepared by the action of chlorosulphonic acid and hydrogen peroxide:
H2O2+ClSO2OH⇌H2SO5+HCl
It may also be prepared by a piranha solution, which is a mixture of concentrated sulphuric acid and hydrogen peroxide.
Cleary, Caro’s acid and Marshall’s acid are correct answers. Now, benzoyl peroxide definitely has a –O–O– linkage. Why do you reckon it is not a correct answer? Also what is picric acid? Picric acid is 2,4,6 – trinitrophenol.
In case you are still wondering, benzoyl peroxide is not an oxyacid of Sulphur. It has the structure: