Let’s review the potassium hydroxide agenda in the reactions. Potassium is a member of the first group of the periodic table. Physically, it is a soft, silvery-white element. Like other alkali metals, potassium is highly reactive. Therefore, it cannot be dealt with in nature. Reacts easily with many substances, especially water. Forms of potassium hydroxide (potash caustic) in air react with metal very quickly. Due to its high reactivity, the metal is stored under a layer of kerosene or Vaseline.
Metallic potassium is a good reducing agent. Reacts easily with many simple ingredients: Reacts strongly with water, alkali – potassium hydroxide forms:
2K + 2H₂O = 2KOH + H₂
Potassium is widely used in organic synthesis for the production of fertilizers and insulating materials. Potassium compounds (mainly hydroxide and salt) are used in plating, catalysis, food production, detergent bases and paints.
Potassium hydroxide KOH is a strong alkaline that has strong basic properties. Accordingly, reactions with potassium hydroxide occur as usual Potassium hydroxide agenda. It acts as the main raw material to obtain metal-free potassium without alloys (electrolysis of potassium hydroxide alloy is performed according to a summary equation):
4KOH = 4K + O₂ + 2H₂O
Like other bases, KOH reacts with neutralizing acids to form salts and water:
KOH + HCl = KCl + H2O (with hydrochloric acid)
KOH + HI = KI + H2O (with hydroidic acid)
Salts also form acidic oxides in the reaction of potassium hydroxide:
2KOH + SO₃ = K₂SO₄ + H2O (potassium sulfate)
Reaction with carbon dioxide may:
2KOH + CO₂ = K₂CO₃ + H₂O
With amphoteric oxides, potassium hydroxide forms dual salts:
2KOH + ZnO = K₂ZnO₂ + H2O (formed on potassium with zinc oxide).
2KOH + Al₂O₃ = 2KAlO₂ + H2O (product of reaction with aluminum oxide is potassium aluminate).
Dual and complex salts are also formed in the reaction of potassium hydroxide with amphoteric metals:
2KOH + Zn = K₂ZnO₂ + H₂
2KOH + 2Al + 2H₂O = 2KAlO₂ + 3H₂
2KOH + 2Al + 6H₂O = 2K [Al (OH) ₄] + 3H₂
If an insoluble compound forms as a result of the reaction, potassium hydroxide can also react with the salts:
2KOH + CuSO₄ = K₂SO₄ + Cu (OH)
Copper (II) hydroxide – a base that is insoluble in water.
Potassium salts behave in a similar way. Reacts with other salts to form an insoluble compound.
Such as the reaction of potassium hydroxide with potassium phosphate:
2K₃PO₄ + 3Ca (OH) ₂ = Ca₃ (PO₄) ₂ + 6KOH
The following reaction occurs with phosphorus:
4Р + 3KOH + 3Н₂О = РН₃ + 3KН₂РО₂
A disproportionate reaction occurs. Phosphorus is both oxidized and reduced.
In some cases, potassium hydroxide acts as a mediator to react with potassium permanganate:
2KMnO₄ + K₂SO₃ + 2KOH = K₂SO₄ + 2K₂MnO₄ + H2O
Potassium manganate with the formula K₂MnO₄ is obtained only in the presence of alkali.
Reactions of metal potassium and its hydroxide with organic compounds
The metal is able to react with some organic compounds. For example, the basis of Wurtz synthesis is the reaction between haloalkenes and alkali metals. With this reaction, we can obtain longer hydrocarbon chains from shorter chains:
2K + 2CH₃Cl = C₂H₆ (CH₃-CH₃) + 2KCl
This is an example of Wurtz symmetric synthesis, because the same haloalkene is used as the reagent. Accordingly, this product has a symmetrical structure.
When different halo alkanes are linked together, the products are different. Wurtz synthesis can be done symmetrically or asymmetrically:
6K + 3CH₃Cl + 3C₂H₅Cl = CH₃-CH₃ + CH₃-C₂H₅ + C₂H₅-C₂H₅ + 6KCl
Potassium hydroxide is widely used in nuclear replacement reactions and the removal of halogen derivatives:
With an aqueous solution of potassium hydroxide, when a halogen atom in a halogen derivative is replaced by the OH group, a nuclear substitution occurs:
CH₃-CH₂-Br + KOH (blue) = CH₃-CH₂-OH + KBr (ethyl alcohol is obtained from bromic ether).
With an alkaline alcoholic solution, the reaction takes place differently: an alkene is formed due to the loss of halogen and hydrogen atoms from neighboring atoms (often).
Dual bonded hydrocarbons:
CH₃-CH₂-Br + KOH (alcohol) = CH2 = CH2 + KBr + H2O (ethylene forms).