JEE Main levelSingle correct optionDifficulty 2 of 3co120
Assertion (A): A methyl ketone treated with excess IX2 in aqueous NaOH is converted to the triiodo ketone and cannot be stopped at the monoiodo stage.
Reason (R): Each iodine atom introduced on the alpha carbon makes the remaining alpha hydrogens more acidic through its −I effect.
Choose the correct option.
ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true
Answer: A
The −I effect of iodine stabilises the enolate, so each successive halogenation is faster than the previous one. The monoiodo and diiodo ketones therefore react further at once and the triiodo ketone results. R explains A.