Oxidation Reactions of Alcohol

  Our Objective

Study Oxidation of alcohol using (i) Complete combustion reaction (ii) Oxidation using oxidising agent.

  The Theory

Alcohols are a class of organic compounds that have one, two, or more hydroxyl (-OH) groups linked to a single alkane bond. The typical formula for these compounds is -OH. The process of oxidation transforms alcohols into aldehydes and ketones. In the discipline of organic chemistry, this is one of the most significant reactions. 

Ethanol, often known as ethyl alcohol, is a hydrocarbon fuel that is utilised in laboratories and factories. CH3-CH2-OH or C2H5-OH is the chemical formula. When ethanol is burned in air, it combines with oxygen, producing CO2 and water, much like any other hydrocarbon fuel. This is an exothermic process, meaning it produces a lot of heat energy. 

oxidation process involves gain of oxygen by the elements or compounds. 

Alcohol can be oxidised to form various products under different conditions. 

1. Complete combustion: On burning alcohol (ethanol)in an excess supply of oxygen (present in air) with a flame, gives carbon dioxide and water.

C2H5OH + 3O2 → 2CO2 + 3H2O + Heat

 

2. Oxidation using an oxidising agent: alcohol on oxidation with an oxidising agent (such as alkaline potassium permanganate solution) get oxidised to a carboxylic acid.

The completion of reaction is characterised by the decolourisation of potassium permanganate solution.

Primary alcohols, like other organic molecules, burn well in the presence of oxygen, producing carbon dioxide and water

Types of Alcohols – Oxidation Reaction 

Alcohols are classified into three types based on the chemical groups connected to the carbon atom:

  • Primary alcohol is defined as an alcohol in which the carbon atom linked to the hydroxyl group is connected to only one carbon atom.
  • Secondary alcohol is defined as a form of alcohol that has two carbon atoms linked together.
  • Tertiary alcohol is defined as a form of alcohol that has three carbon atoms linked together.

To distinguish between primary, Secondary and Tertiary. The alcohols are oxidised with sodium dichromate in the oxidation test (Na2Cr2O7). The rate of oxidation varies depending on whether the alcohol is primary, secondary, or tertiary. Alcohols are classified as follows based on their oxidation rates:

  • Primary alcohol is easily converted to an aldehyde, which can then be converted to carboxylic acids.
  • Secondary alcohol may readily be converted to ketone, but no further oxidation is feasible.
  • In the presence of sodium dichromate, tertiary alcohol does not oxidise.

As a result, the rate of oxidation when using sodium dichromate aids in the identification of primary, secondary, and tertiary alcohol.

Learning Outcomes

  • Students will be able to study the chemical structure for primary, secondary and tertiary. 
  • Students can identify the functional group that alcohols have in common. 
  • Students to study more on the functional group of other organic compounds. 
  • Students will be able to study that the primary, secondary, and tertiary alcohol can be distinguished using oxidation test. 
  • Students can learn more on the types of oxidation reaction in organic chemistry. 
  • Students can identify the oxidized species of a molecule in a chemical reaction.