Search results
Results from the WOW.Com Content Network
The reagent is an alkaline solution of potassium permanganate. Reaction with double or triple bonds (R 2 C=CR 2 or R−C≡C−R) causes the color to fade from purplish-pink to brown. Aldehydes and formic acid (and formates) also give a positive test. [43] The test is antiquated. Baeyer's reagent reaction
Crystalline potassium permanganate (KMnO 4) is placed in an evaporating dish. A depression is made at the center of the permanganate powder and glycerol liquid is added to it. The white smoke-like vapor produced by the reaction is a mixture of carbon dioxide gas and water vapor.
Potassium permanganate will decompose into potassium manganate, manganese dioxide and oxygen gas: 2 KMnO 4 → K 2 MnO 4 + MnO 2 + O 2. This reaction is a laboratory method to prepare oxygen, but produces samples of potassium manganate contaminated with MnO 2. The former is soluble and the latter is not.
The chemical chameleon reaction shows the process in reverse, by reducing violet potassium permanganate first to green potassium manganate and eventually to brown manganese dioxide: [1] [2] [5] KMnO 4 (violet) → K 2 MnO 4 (green) → MnO 2 (brown/yellow suspension) Blue potassium hypomanganate may also form as an intermediate. [6]
According to theory, permanganate is strong enough to oxidize water, but this does not actually happen to any extent. Besides this, it is stable. It is a useful reagent, but it is not very selective with organic compounds. Potassium permanganate is used as a disinfectant and water treatment additive in aquaculture. [6]
The reaction has been demonstrated to proceed in water as reaction solvent and with direct aromatization by ferric chloride, manganese dioxide or potassium permanganate in a one-pot synthesis. [4] Hantzsch reaction with ammonium acetate, ethyl acetoacetate, formaldehyde and ferric chloride
Sodium permanganate behaves similarly to potassium permanganate. It dissolves readily in water to give deep purple solutions, evaporation of which gives prismatic purple-black glistening crystals of the monohydrate NaMnO 4 ·H 2 O. The potassium salt does not form a hydrate.
Potassium permanganate (KMnO 4) is an oxidizing, bleaching and purification substance and is used for production of saccharin. Potassium chlorate (KClO 3) is added to matches and explosives. Potassium bromide (KBr) was formerly used as a sedative and in photography. [14]