The Basic Concept of Reduction

What do you mean by Reduction?

There is not only one universal definition of Reduction. There are several definitions of reductions based on the chemical reaction taking place. The various definitions of Reduction are classified as: 

• Based on the oxygen transfer: The loss of oxygen from a compound is called Reduction. For example, the extraction of iron from its ore is done by the Reduction of the ore using a suitable reducing agent. 
• Based on the hydrogen transfer: The gain of hydrogen in a compound is called Reduction. For example, ethanol can be oxidized to ethanol by gaining one hydrogen atom, thus carrying out a reduction reaction.
• Based on the electron transfer: A chemical reaction in which electrons are lost is reduced.

The reduction process is helpful in many ways: 

• Reduction of ores to metal oxides.
• It is commonly used for making electrochemical cells.
• It is also used for the conversion of ammonia to nitric acid.
• It is helpful in biochemical reactions and industrial processes.

What do you understand by reducing agents?

The reducing agents are similarly classified as the Reduction. They are:

• Based on the oxygen transfer: The substance which removes oxygen from other substances is known as the reducing agent.
• Based on the hydrogen transfer: The substance that adds hydrogen to a compound is known as the reducing agent.
• Based on the electron transfer: A substance that adds electrons to other substances is known as the reducing agent.

Some Common Examples of Reducing Agent

• Lithium 
• Sodium
• Magnesium
• Aluminum
• Chromium
• Iron
• Hydrogen
• Silver
• Fluorine ion
• Sodium hydride
• Lithium hydride
• Lithium aluminum hydride
• Calcium hydride

Redox Reaction

In a chemical reaction, oxidation and Reduction take place simultaneously. This reaction is termed a redox reaction. 

Oxidation is just the reverse of Reduction. Reduction is the gain of electrons, whereas oxidation is the loss of electrons from an atom or compound. 

For example, when calcium carbonate decomposes into calcium oxide and carbon dioxide, the gain and loss of electrons take place simultaneously. Hence, the process of oxidation and Reduction takes place simultaneously.

Clemmensen Reduction Reaction

Clemmensen of Park Davis in 1913 introduced this reaction. In this process, carbonyl groups, mainly aldehyde and ketone, are reduced to the methylene group (respective hydrocarbons). Zinc amalgam and hydrochloric acid act as a catalyst in this process. 

For example, conversion of heptanal into heptane takes place via Clemmensen reduction reaction. 

Applications of Clemmensen Reduction Reaction

• Its main application is informing aromatic compounds with unbranched side hydrocarbon chains. 
• It is widely used in the conversion of carbonyl compounds into hydrocarbons.
• This reaction is widely used in reducing aliphatic and mixed aliphatic-aromatic carbonyl compounds.

Wolff Kishner Reduction Reaction

1912. Kishner introduced Wolff Kishner’s reduction reaction in 1911 and L. Wolff in 1912. This reaction is widely used in organic chemistry to reduce the carbonyl functional group to a methylene group. It is used to convert aldehyde or ketone into saturated hydrocarbons. The catalyst used in this process is hydrazine and a base. Suitable conditions are essential. It is unsuitable for base sensitive substrates because this reaction requires fundamental conditions.

For example, converting cyclopentanone to cyclopentane is done with the help of Wolff Kishner’s reduction reaction.

Applications of Wolff Kishner Reduction Reaction

• It is widely used in synthesizing various compounds, especially multiwalled carbon nanotubes. 
• It is used for the production of allylic alcohol from oxyplumbation.

Some Other Reactions in Organic Chemistry Showing Reduction

• Using metal hydride reducing agent: The carbonyl functional groups are reduced using metal hydrides in the organic laboratory. The commonly used metal hydrides are sodium borohydride and lithium aluminum hydride. 

When a sodium borohydride solution is mixed with the aldehyde or ketone, a hydride ion is added to the carbonyl compound to form two-degree alcohol or one-degree alcohol. 

• Catalytic Hydrogenation Reaction of Unsaturated Hydrocarbons: The hydrogenation process of alkenes and alkynes occurs by passing the hydrogen gas in the presence of metal such as platinum and palladium. This process is known as catalytic hydrogenation.

In this process, the double and triple bond of the unsaturated hydrocarbon breaks down, resulting in the addition of hydrogen at that place. This leads to the formation of saturated hydrocarbons.

Conclusion

This article focuses on the reduction reaction from the basics. Several examples are given to understand the process of Reduction easily and comfortably. Few named reactions are also listed to highlight the applications of the reduction process. 

By going through this article, one can easily understand the process of Reduction. We hope that this article proved to be helpful.