The sodium permanganate is a chemical compound of Formula NaMnO 4. It is mainly available in a monohydrate form. Its structure is shown in figure 1. This salt is hygroscopic and has a low melting point.
It has the same properties as potassium permanganate (KMnO 4), although sodium permanganate is approximately 15 times more soluble in water. Despite this, potassium permanganate is more commonly used since its production costs are lower.
Figure 1: Structure of sodium permanganate.
Sodium permanganate readily dissolves in water to give deep purple solutions, evaporation of which gives bright purple-black prismatic crystals of NaMnO4 · H2O monohydrate. The potassium salt does not form a hydrate. Due to its hygroscopic nature, it is less useful in analytical chemistry than its potassium counterpart.
It can be prepared by the reaction of manganese dioxide with sodium hypochlorite and sodium hydroxide or sodium carbonate as follows:
2MnO 2 + 3NaClO + 2NaOH → 2NaMnO 4 + 3NaCl + H 2 O
2MnO 2 + 3NaClO + Na 2 CO 3 → 2NaMnO 4 + 3NaCl + CO 2
Using sodium carbonate, the yield is lower and the reaction must be heated to obtain the product (vapid, 2016).
Physical and chemical properties
Sodium permanganate has a similar appearance to potassium permanganate. They are prismatic crystals or purple spheres that in aqueous solution form a colored liquid that ranges from pink to purple depending on the concentration. Its appearance is shown in figure 2.
Figure 2: appearance of sodium permanganate
The anhydrous form of the compound has a molecular weight and a melting point of 141.9254 g / mol and 36 ° C respectively, and the monohydrate form has a molecular weight and a melting point of 159.94 g / mol and 170 ° C respectively.
Its density is 1,972 g / ml and it is very soluble in water, being able to dissolve 900g per liter at room temperature (National Center for Biotechnology Information, 2017).
Reactivity and hazards
Sodium permanganate is not combustible, but it accelerates the combustion of combustible materials. If the combustible material is finely divided, the mixture may be explosive.
May spontaneously ignite in contact with liquid combustible materials. Contact with sulfuric acid can cause fire or explosion.
Acetic acid or acetic anhydride can explode with permanganates if not kept cold. Explosions can occur when permanganates that have been treated with sulfuric acid come into contact with benzene, carbon disulfide, diethyl ether, ethyl alcohol, petroleum, or organic matter (SODIUM PERMANGANATE, 2016).
These substances accelerate burning when involved in a fire. Some can decompose explosively when heated or involved in a fire. It can explode from heat or contamination.
Some will react explosively with hydrocarbons (fuels). It can ignite fuels (wood, paper, oil, clothing, etc.). Containers may explode when heated. Runoff may create fire or explosion hazard (SODIUM PERMANGANATE, SF).
Potassium permanganate reacts with water to produce manganese dioxide, potassium hydroxide, and oxygen. Potassium hydroxide is a strong corrosive. In severe cases, systemic effects including intravascular coagulation, hepatitis, pancreatitis, and failure can occur.
Chronic ingestion can cause paresthesias, tremors due to manganese toxicity. Manganese neurotoxicity is the result of depletion of dopamine and neurotoxins, dopamine quinone and peroxide (SODIUM PERMANGANATE, 2014).
Sodium permanganate damages eye tissue on contact, causing burns. It can be irritating on contact with the skin, leaving purple spots on it. In case of inhalation it may cause damage to the respiratory tract (material data safety sheet sodium permanganate, SF).
If the compound comes into contact with the skin, it should be rinsed with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.
In case of ingestion, vomiting should not be induced. Tight clothing such as a collar, belt or tie should be loosened. If the victim is not breathing, mouth-to-mouth resuscitation should be given.
In case of inhalation, the victim should be removed from the place of exposure and moved to a cool place. If it is not breathing, artificial respiration should be given. If breathing is difficult, oxygen should be given.
In all cases, immediate medical attention should be obtained (Material Safety Data Sheet Sodium permanganate monohydrate, 2013).
Applications
Sodium permanganate, like the potassium compound, is a disinfectant and bactericidal antiseptic. Its uses include bleaching resins, waxes, fats, straw, cotton, silk and other fibers and suede.
It is also used as a disinfectant, deodorizer, chemical disinfectant in photography, and reagent in synthetic organic chemistry.
Illicit uses have included the production of drugs of abuse and abortion by topical application to the vaginal wall. Historically, permanganate solutions have been used as a urethral irrigant and flushing fluid for poisoning.
Sodium Permanganate acts as an oxidizing agent in the oxidation of o-toluene sulfonamide to produce saccharin and purification of toluene amide. It is also an antidote to morphine and phosphorus, and synthetic organic / pharmaceutical reactions.
Sodium permanganate has been used in water treatment and soil rehabilitation because it is capable of degrading BTEX (benzene, toluene, ethylbenzene and xylene), phenols, polycyclic aromatic hydrocarbons (PAH), chlorinated ethenes and explosives, and remove hydrogen sulfide.
Due to its high solubility in water, sodium permanganate is preferred for applications requiring high concentrations of permanganate ions, such as etching plastic parts of the printed circuit board.
Other uses of sodium permanganate include metal surface treatment agent and metal cleaning formulation etc (Sodium Permanganate Aqueous Solution (NaMnO4), SF).
Sodium permanganate can replace potassium permanganate in some applications, since it is the permanganate ion that is the oxidizing agent.
However, since sodium permanganate exists in a monohydrate form, it cannot be used for analytical applications such as redox titrations.
References
- Material data safety sheet sodium permanganate. (SF). Retrieved from dogee.org: dogee.org.
- Material Safety Data Sheet Sodium permanganate monohydrate. (2013, May 21). Retrieved from sciencelab: sciencelab.com.
- National Center for Biotechnology Information. (2017, March 4). PubChem Compound Database; CID = 23673458. Retrieved from PubChem: pubchem.ncbi.nlm.nih.gov.
- SODIUM PERMANGANATE. (2014, December 5). Retrieved from toxnet: toxnet.nlm.nih.gov.
- SODIUM PERMANGANATE. (2016). Retrieved from cameochemicals: cameochemicals.noaa.gov.
- Sodium Permanganate Aqueous Solution (NaMnO4). (SF). Retrieved from changyuancorp: en.changyuancorp.com.
- SODIUM PERMANGANATE. (SF). Retrieved from chemicalbook: chemicalbook.com.
- (2016, June 27). Sodium permanganate from manganese dioxide and sodium hypochlorite. Retrieved from chemistry.stackexchange: chemistry.stackexchange.com.