Permanganic acid (ormanganic(VII) acid) is the inorganic compound with the formula HMnO4. This strongoxoacid has been isolated as its dihydrate. It is the conjugate acidofpermanganate salts. It is the subject of few publications and its characterization as well as its uses are very limited.
Crystalline permanganic acid has been prepared at low temperatures as the dihydrate, HMnO4·2H2O.[3]
Although its structure has not been verified spectroscopically or crystallographically, HMnO4 is assumed to be adopt a tetrahedral structure akin to that for perchloric acid.
As a strong acid, HMnO4 is deprotonated to form the intensely purple coloured permanganates. Potassium permanganate, KMnO4, is a widely used, versatile and powerful oxidising agent.
Permanganic acid solutions are unstable, and gradually decompose into manganese dioxide, oxygen, and water, with initially formed manganese dioxide catalyzing further decomposition.[6] Decomposition is accelerated by heat, light, and acids. Concentrated solutions decompose more rapidly than dilute.[6]
^Stewart, R.; Mocek, M.M. (1963). "The Mechanisms of Permanganate Oxidation VII: The Oxidation of Fluoral Hydrate". Canadian Journal of Chemistry. 41 (5): 1160–9. doi:10.1139/v63-164.
^Bailey, N.; Carrington, A.; Lott, K.A.K.; Symons, M.C.R (1960). "Structure and Reactivity of the Oxyanions of Transition Metals Part VII: Acidities and Spectra of Protonated Oxyanions". Journal of the Chemical Society (Resumed): 290–7. doi:10.1039/JR9600000290.
^ abFrigerio, Norman A. (1969). "Preparation and properties of crystalline permanganic acid". Journal of the American Chemical Society. 91 (22): 6200–1. doi:10.1021/ja01050a058. PMID5823192.
