IB Chemistry Topic R3.2.9 Oxidation of Organic Compounds Revision Notes (SL/HL)

IB Chemistry Topic R3.2.9 Oxidation of Organic Compounds Revision Notes (SL/HL) | RevisionDojo

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Oxidation of Primary Alcohols: From Aldehyde to Carboxylic Acid

Step 1: Primary Alcohol to Aldehyde

Primary alcohols, such as ethanol $CH_3CH_2OH$, can be oxidized to aldehydes.
In this process, the hydroxyl group $-OH$ is converted into a carbonyl group $C=O$, which defines the aldehyde functional group.
The reaction is represented as:
$$RCH_2OH + [O] \rightarrow RCHO + H_2O$$
Here, $[O]$ represents the oxidizing agent, commonly acidified potassium dichromate $K_2Cr_2O_7$ or potassium permanganate $KMnO_4$.

Tip

Key condition:

To stop the reaction at the aldehyde stage, the aldehyde must be distilled out of the reaction mixture as it forms.
This prevents further oxidation.

Example

Ethanol is oxidized to acetaldehyde (ethanal) when distilled during the reaction: $$CH_3CH_2OH + [O] \rightarrow CH_3CHO + H_2O$$

Step 2: Aldehyde to Carboxylic Acid

If the reaction continues, the aldehyde undergoes further oxidation to form a carboxylic acid.
In this step, the carbonyl group $C=O$ in the aldehyde is converted to a carboxyl group $-COOH$.
The reaction is expressed as:
$$RCHO + [O] \rightarrow RCOOH$$

Tip

Key condition:

To achieve full oxidation to the carboxylic acid, the reaction mixture is heated under reflux.
Reflux ensures that any aldehyde vapor condenses and returns to the reaction mixture for further oxidation.

Example

Ethanol is oxidized first to acetaldehyde and then to ethanoic acid (acetic acid) when heated under reflux with an excess of oxidizing agent: $$CH_3CH_2OH + 2[O] \rightarrow CH_3COOH + H_2O$$

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Oxidation of Primary Alcohols: From Aldehyde to Carboxylic Acid

Step 1: Primary Alcohol to Aldehyde

Primary alcohols, such as ethanol $CH_3CH_2OH$, can be oxidized to aldehydes.
In this process, the hydroxyl group $-OH$ is converted into a carbonyl group $C=O$, which defines the aldehyde functional group.
The reaction is represented as:
$$RCH_2OH + [O] \rightarrow RCHO + H_2O$$
Here, $[O]$ represents the oxidizing agent, commonly acidified potassium dichromate $K_2Cr_2O_7$ or potassium permanganate $KMnO_4$.

Tip

Key condition:

To stop the reaction at the aldehyde stage, the aldehyde must be distilled out of the reaction mixture as it forms.
This prevents further oxidation.

Example

Ethanol is oxidized to acetaldehyde (ethanal) when distilled during the reaction: $$CH_3CH_2OH + [O] \rightarrow CH_3CHO + H_2O$$

Step 2: Aldehyde to Carboxylic Acid

If the reaction continues, the aldehyde undergoes further oxidation to form a carboxylic acid.
In this step, the carbonyl group $C=O$ in the aldehyde is converted to a carboxyl group $-COOH$.
The reaction is expressed as:
$$RCHO + [O] \rightarrow RCOOH$$

Tip

Key condition:

To achieve full oxidation to the carboxylic acid, the reaction mixture is heated under reflux.
Reflux ensures that any aldehyde vapor condenses and returns to the reaction mixture for further oxidation.

Example

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Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry R3.2.9 Oxidation of Organic Compounds Notes

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

Oxidation of Primary Alcohols: From Aldehyde to Carboxylic Acid

Step 1: Primary Alcohol to Aldehyde

Step 2: Aldehyde to Carboxylic Acid

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Oxidation of Primary Alcohols: From Aldehyde to Carboxylic Acid

Step 1: Primary Alcohol to Aldehyde

Step 2: Aldehyde to Carboxylic Acid

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