Test: Classification of Alcohol & Lucas Test - JAMB MCQ

In Propan-1-ol, the hydroxyl (-OH) group is attached to a primary carbon atom. A primary alkanol is characterized by the presence of a hydroxyl group attached to a carbon atom bonded to only one other carbon atom.

The molecular formula of a secondary alkanol is represented by R₂CHOH, where R represents an alkyl group. It signifies that the hydroxyl group is attached to a carbon atom bonded to two other carbon atoms.

2-Propanol is a tertiary alkanol because the carbon atom bearing the hydroxyl group is attached to three alkyl groups.

The Lucas test is employed to distinguish between primary, secondary, and tertiary alkanols based on their reactivity with the Lucas reagent (concentrated sulfuric acid and zinc chloride).

Tertiary alkanols react quickly with the Lucas reagent and form an immediate turbidity or precipitate, indicating their presence.

Tertiary alkanols exhibit the highest reactivity and react the fastest with the Lucas reagent, resulting in the immediate formation of a turbidity or precipitate.

The reaction between a primary alkanol and the Lucas reagent results in the formation of an alkyl halide as the product.

2-Methyl-2-propanol is a tertiary alkanol, and it will give a positive Lucas test result within 30 minutes due to its high reactivity.

When a tertiary alkanol reacts with the Lucas reagent, it undergoes dehydration to form an alkene as the product.

In the Lucas test, primary alkanols require a longer reaction time compared to secondary and tertiary alkanols for the formation of a turbidity or precipitate due to their lower reactivity.