Hypochlorite - (ClO⁻)

Hypochlorite, in chemistry, is described as an anion having the chemical formula, ClO−. It connects with several cations to produce hypochlorites, which can also be regarded as hypochlorous acid salts. Common examples are calcium hypochlorite (bleaching powder’s component), sodium hypochlorite (household bleach).

It can also refer to hypothetical hypochlorous acid esters, namely organic compounds having a ClO– group covalently bound to the remaining molecules. Tert-butyl is the principal example of hypochlorite, a useful chlorinating agent.

Usage of Hypochlorite

Many hypochlorite salts, in their pure form, are unstable and are handled normally as aqueous solutions. Main hypochlorite applications may be used as bleaching agents, water treatment agents, but they may also be used for chlorination and oxidation reactions.

Let us look at the important properties of Hypochlorite CLO- as tabulated below.

Properties of Hypochlorite

Structure of Hypochlorite (ClO–)

(Image will be uploaded soon)

Reactions

Acid Reaction

Acidification of the hypochlorites produces hypochlorous acid. This lives in equilibrium with chlorine gas, which can be bubbled out of solutions. Also, the equilibrium is subjected to the principle of Le Chatelier; therefore, a high pH drives the reaction to the left side by consuming the H+ ions, promoting the chlorine’s disproportionation into hypochlorite and chloride, whereas a low pH leads the reaction to the right side, by promoting the chlorine gas release.

2H⁺ + ClO^- + Cl^- ⇌ Cl₂ + H₂O

Hypochlorous acid will also exist in equilibrium with its anhydride, which is dichlorine monoxide.

2HOCl ⇌ Cl₂O + H₂O    K(at 0°C) = 3.55 x 10^-3 dm³ mol^-1

Stability

In general, hypochlorites can results in unstable, and several compounds exist only in the solution. Calcium hypochlorite Ca(OCl)2, barium hypochlorite Ba(ClO)2, Lithium hypochlorite LiOCl, has been isolated as the compounds of pure anhydrous. Here, all are solids, where a few more can be produced as aqueous solutions. Generally, the greater the dilution, the greater their own stability. It is impossible to define the trends for the alkaline earth metal salts because many of them cannot be produced.

The beryllium hypochlorite is unheard of, and the pure magnesium hypochlorite cannot be prepared; whereas, the solid Mg(OH)OCl is known. Calcium hypochlorite can be produced on an industrial scale, and it has good stability. However, the strontium hypochlorite (Sr(OCl)2) stability has not yet been determined and is not well characterized.

Hypochlorite ion can be unstable concerning the disproportionation. Still, upon heating, it degrades to a mixture of oxygen, chloride, and also the other chlorates, as equated below:

2Cl^- ➝ 2Cl^- + O₂

3 ClO^- ➝ 2 Cl^- + ClO₃^-

This reaction is completely exothermic, and in the case of concentrated hypochlorites, such as LiOCl and Ca(OCl)2, can head to a dangerous thermal runaway, including potential explosions.

The alkali metal hypochlorites decrease in the stability down to the group. Anhydrous lithium hypochlorite falls stable at room tempurature; but, the sodium hypochlorite has not been prepared drier to that of pentahydrate (NaOCl·(H2O)5). Although the more dilute solutions encountered as household bleach possess better stability, above 0 °C, this is unstable. However, the potassium hypochlorite (KOCl) is known only in the solution.

However, the lanthanide hypochlorites also unstable, and they have been reported as being more stable in their anhydrous forms than in the presence of water. This hypochlorite has also been used to oxidize the cerium from its oxidation state of +3 to +4.

Hypochlorous acid alone is not stable in isolation because it decomposes to produce chlorine.

Uses of Hypochlorite ClO–

Let us look at the important uses of Hypochlorite ClO– as listed below.

• Hypochlorite can be used as chlorinating agents. They also consist of the ability to chlorinate the aromatic hydrocarbons, which are electron-rich.

• It can be used to oxidize the primary alcohols to carboxylic acids in organic chemistry.

• It is also a strong oxidizing agent and can be used in Jacobsen epoxidation reaction to help in Mn (III) to Mn (V) conversion.

• Domestically it can be used for stain removal.

• Calcium hypochlorite and Sodium is used to whiten clothes.

• Hypochlorites can be used to lighten hair color.

Health Hazards

Let us look at a few of the health hazards that are associated with the hypochlorite compound.

• When inhaled and ingested, hypochlorite is toxic.

• It irritates mucous membranes, eyes, and skin.

• When it comes in contact with organic materials, it can ignite.

• Its fire involvement may enhance combustion or can also cause an explosion.

Industrial and Domestic Uses of Hypochlorites

There exist many uses of hypochlorites, where a few of them are mentioned below.

Hypochlorites, especially sodium (either the liquid bleach or Javel water) and calcium (otherwise called bleaching powder) are widely used for industrial and domestic purposes, lighten hair color, whiten clothes, and remove stains. These are the first commercial bleaching products, which are soon developed in 1785 after that property was discovered by the French chemist named “Claude Berthollet”.

Did You Know?

• Sodium hypochlorite is termed as a strong liquid oxidizing agent, and it has a yellowish or greenish hue. In general, it is known as bleach since it is an active ingredient in the bleach. The chemical formula is given as NaClO, which consists of 1 sodium (Na) atom, 1 chlorine (Cl) atom, and 1 oxygen (O) atom.