Title: Caro's Acid
CAS Registry Number: 7722-86-3
CAS Name: Peroxymonosulfuric acid
Additional Names: sulfomonoperacid; persulfuric acid
Molecular Formula: H2O5S
Molecular Weight: 114.08
Percent Composition: H 1.77%, O 70.12%, S 28.11%
Literature References: Dry reagent is prepd by stirring 10 g potassium persulfate into 11 g concd H2SO4 for 10 min and adding 30 g finely powdered potassium sulfate; liquid reagent is obtained by triturating potassium persulfate with three times as much (by weight) of H2SO4; dil reagent is prepd by stirring 10 g potassium persulfate into 11 g concd H2SO4 and adding 50 cc ice: Baeyer, Villiger, Ber. 32, 3625 (1899); another prepn by reacting 90% H2O2 with chlorosulfonic acid at -40 to -50°: Ball, Edwards, J. Am. Chem. Soc. 78, 1125 (1956).
Properties: The product is a sirupy liquid consisting of about equal amounts of Caro's acid and H2SO4. pK2 of Caro¢s acid 9.4 ± 0.1. Oxygen is evolved at room temp; should be stored at dry ice temp.
pKa: pK2 of Caro¢s acid 9.4 ± 0.1
CAUTION: Can be dangerously unstable, like most peroxides. Description of explosion at Brown University: J. O. Edwards, Chem. Eng. News 33, 3336 (1955). Explosion at Sun Oil, ibid. 38, 59 (Nov. 21, 1960). May be highly irritating to skin, eyes, mucous membranes.
Use: In prepn of dyes; oxidation of olefins to a-glycols; oxidation of ketones to lactones or esters; treating woolens to prevent felting and shrinking; in bleaching compositions. |