Question

Write the classification of aliphatic ketones with example. What is the action of sodium hypoiodite on acetone?

Hint:

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Answer 1

Step 1: Classification of Aliphatic Ketones: Aliphatic ketones have the general formula R–CO–R', where R and R' are alkyl groups. They are classified as: - Symmetrical ketones: Both alkyl groups are identical, e.g., acetone (CH\(_{3}\)COCH\(_{3}\)). - Unsymmetrical ketones: The alkyl groups differ, e.g., methyl ethyl ketone (CH\(_{3}\)COCH\(_{2}\)CH\(_{3}\)).
Step 2: Action of Sodium Hypoiodite on Acetone: Sodium hypoiodite (NaOI, formed in situ from NaOH and I\(_{2}\)) reacts with acetone (CH\(_{3}\)COCH\(_{3}\)) in the iodoform test. Acetone, containing a methyl ketone group (CH\(_{3}\)CO–), undergoes haloform reaction: \[ \text{CH}_{3}\text{COCH}_{3} + 3\text{NaOI} \rightarrow \text{CHI}_{3} (\text{iodoform}) + \text{CH}_{3}\text{COONa} + 2\text{NaOH}. \] Iodoform (CHI\(_{3}\)) is a yellow precipitate, confirming the presence of a methyl ketone.