Lithium permanganate (LiMnO₄) is an inorganic compound consisting of lithium cations (Li⁺) and permanganate anions (MnO₄⁻). It belongs to the family of permanganates, which are strong oxidizing agents due to the high oxidation state of manganese (+7). Lithium permanganate typically appears as a dark purple or nearly black crystalline solid, similar in appearance to other permanganates. It is highly soluble in water, producing an intensely violet solution.
It can be produced by the reaction of lithium sulfate and barium permanganate, and the trihydrate LiMnO4·3H2O can be crystallized from the solution. It decomposes violently at 199 °C to a mixture of spinel salts:
LiMnO4 → Li2MnO3 + LiMn2O4 + O2↑
As an oxidizer, LiMnO₄ is very reactive and can cause combustion or explosions when in contact with organic materials, reducing agents, or combustible substances. It decomposes upon heating or in strong acidic conditions, yielding manganese dioxide (MnO₂), oxygen, and lithium salts. Because of its instability and reactivity, lithium permanganate is less common than other alkali permanganates like potassium permanganate (KMnO₄).
Properties
- Chemical formula: LiMnO4
- Molar mass: 125.87 g·mol−1
- Appearance: purple
- Solubility in water: soluble
- Oxidizing ability: A very strong oxidizer, capable of oxidizing a wide variety of organic and inorganic substances.
- Stability: Less stable than potassium permanganate; it can decompose under heat, light, or in the presence of reducing agents, releasing oxygen and manganese oxides.
- Hygroscopicity: Can absorb moisture from the air, affecting its storage and handling.
- Thermal behavior: On heating, it decomposes into lithium manganate (LiMnO₂) and oxygen.
Occurrences
Lithium permanganate does not occur naturally; it is a synthetic compound. It is generally prepared in laboratories by reacting permanganic acid (HMnO₄) with lithium hydroxide (LiOH) or lithium carbonate (Li₂CO₃). Its natural occurrence is not observed because permanganates are highly reactive and unstable in geological environments.
It finds limited use in analytical chemistry as an oxidizing agent, in organic synthesis, and as a potential oxidant in battery research due to lithium’s role in electrochemistry.
Applications
In laboratory applications, it may be used as an oxidizing reagent for organic synthesis, though its rarity and sensitivity limit widespread use. Potential applications in specialized chemical processes and materials research have been explored, but safety concerns restrict handling. Lithium permanganate is not naturally occurring and must be synthesized artificially, typically by reacting lithium salts with permanganic acid. Proper storage requires cool, dry conditions away from organics and reducing agents.
