Oxidation of Alcohols, Aldehydes and Ketones, Identification, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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Oxidation of Alcohols to Aldehydes and Ketones

  • Alcohols are a group of compounds containing one, two or more hydroxyl groups that are attached to the alkane of a single bond. These compounds have a general formula -of . Reactions can leave the R-O bond or even they can leave bond.
  • The alcohols are converted to aldehydes and ketones by the process of oxidation. This is one of the most important reactions in the field of organic chemistry.
  • Oxidizing alcohols to aldehydes and ketones are one of the vital reactions in the field of synthetic organic chemistry. These reactions occur in the presence of catalysts and the best oxidants required for these conversions have high valent ruthenium acting as the catalyst for this kind of reaction.

Mechanism of Conversion Alcohols into Aldehydes and Ketones

Mechanism of Conversion Alcohols into Aldehydes and Ketones
  • The catalytic conversion of the primary type of alcohols into aldehydes and the secondary form of alcohols into ketones are important in the preparation of various synthetic intermediates in organic chemistry.
  • The result of the oxidation reaction of the alcohols depends on the types of substituents used on the carbonyl carbon. For the oxidation reaction to take place, a hydrogen atom needs to be present on the carbonyl carbon.
  • The oxidizing agents or the catalysts used in these types of reactions are normally the solutions of sodium or also potassium dichromate (VI) which is acidified with the dilute sulphuric acid. In the process of oxidation, the orange solution which contains ions of dichromate (VI) is reduced to the green solution which contains chromium (III) ions.

Making of Aldehydes

  • The preparation of Aldehydes is by oxidizing the primary alcohols. The aldehyde which is produced can be oxidized further to the carboxylic acids by the use of acidified potassium dichromate (VI) solution that is used as an oxidizing agent.
  • The net effect occurs as the oxygen atom of the oxidizing agent eliminates the hydrogen atom from the hydroxyl (-OH) group of alcohol and also one carbon atom attached to it.
Conversion of Alcohols – Making of Aldehydes

Conversion of Alcohols – Making of aldehydes

Here, R and Rβ€² are the alkyl groups or hydrogen. If these groups contain the hydrogen atom, you will get aldehyde. These aldehydes are obtained from the primary alcohols.

Making of Ketones

  • The preparation of Ketones is done by the oxidation of secondary alcohols. Consider, for example, heating the secondary alcohol propan-2-ol with the sodium or even potassium dichromate (VI) solution which is acidified with the dilute sulphuric acid, then the ketone called propanone formed.
  • The occurring reaction is as shown below-
Conversion of Alcohols – Making of Ketones

Conversion of Alcohols – Making of Ketones

The Ketones obtained cannot be further oxidized because this reaction would involve the breaking up of C – C bond, requiring too much energy.

What Are the Different Types of Alcohol?

On the basis of chemical groups attached to the carbon atom, alcohols are divided into three categories:

  • Primary alcohol: When the carbon atom attached to the hydroxyl group is bonded to only one carbon atom such type of alcohol is known as primary alcohol.
  • Secondary alcohol: When it is bonded to two carbon atoms such type of alcohol is known as secondary alcohol.
  • Tertiary alcohol: When it is bonded to three carbon atoms such type of alcohol is known as tertiary alcohol.

Each of the three types of alcohol (primary, secondary and tertiary alcohol) exhibits different physical and chemical properties.

Types of Alcohols

Types of Alcohols

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