|Systematic IUPAC name|
3D model (JSmol)
|Molar mass||114.078 g mol−1|
|Density||2.239 g cm−3|
|Melting point||45 °C|
|Tetrahedral at S|
|Main hazards||strong oxidizer|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Peroxymonosulfuric acid, H2SO5, also known as persulfuric acid, peroxysulfuric acid, or Caro's acid. In this acid, the S(VI) center adopts its characteristic tetrahedral geometry; the connectivity is indicated by the formula HO–O–S(O)2–OH. It is one of the strongest oxidants known (E0 = +2.51 V) and is highly explosive.
H2SO5 is sometimes confused with H2S2O8, known as peroxydisulfuric acid. The disulfuric acid, which appears to be more widely used as its alkali metal salts, has the structure HO–S(O)2–O–O–S(O)2–OH.
H2SO5 was first described in 1898 by the German chemist Heinrich Caro, after whom it is named.
Synthesis and production
- H2O2 + ClSO2OH ⇌ H2SO5 + HCl 
Published patents include more than one reaction for preparation of Caro's acid, usually as an intermediate for the production of potassium monopersulfate (PMPS), a bleaching and oxidizing agent. One patent for production of Caro's acid for this purpose gives the following reaction:
- H2O2 + H2SO4 ⇌ H2SO5 + H2O 
This is the reaction that produces the acid transiently in "piranha solution".
Uses in industry
Ammonium, sodium, and potassium salts of H2SO5 are used in the plastics industry as radical initiators for polymerization. They are also used as etchants, oxidative desizing agents for textile fabrics, and for decolorizing and deodorizing oils.
Pure Caro's acid is highly explosive. Explosions have been reported at Brown University and Sun Oil. As with all strong oxidizing agents, peroxysulfuric acid should be kept away from organic compounds such as ethers and ketones because of its ability to peroxidize these compounds, creating highly unstable molecules such as acetone peroxide.
- International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN:0-85404-438-8. p. 139. Electronic version.
- "Peroxysulfuric acid (CHEBI:29286)". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute. 20 November 2007. http://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:29286.
- Caro, H. (1898). "Zur Kenntniss der Oxydation aromatischer Amine". Zeitschrift für angewandte Chemie 11 (36): 845–846. doi:10.1002/ange.18980113602. http://babel.hathitrust.org/cgi/pt?id=mdp.39015073166319;view=1up;seq=855.
- "Synthesis of Caro's acid" (in en-US). 2017-02-13. http://www.prepchem.com/synthesis-caros-acid/.
- A method and apparatus for producing a peroxyacid solution, https://patents.google.com/patent/WO2005016511A1/da, retrieved 2018-10-12
- Edwards, J.O. (1955). "Safety". Chem. Eng. News 33 (32): 3336. doi:10.1021/cen-v033n032.p3336.
Original source: https://en.wikipedia.org/wiki/ Peroxymonosulfuric acid. Read more