Propanone is reduced with magnesium amalgam in benzene followed by water to give P. P is heated with concentrated H2SO4 to give Q (pinacol-pinacolone rearrangement). Q is treated with NaOCl/NaOH and acidified to give R. R is

JEE Advanced levelSingle correct optionDifficulty 3 of 3co155

Propanone is reduced with magnesium amalgam in benzene followed by water to give P. P is heated with concentrated $H X_{2} SO X_{4}$ to give Q (pinacol-pinacolone rearrangement). Q is treated with $NaOCl$ / $NaOH$ and acidified to give R. R is

Bimolecular reduction gives P = 2,3-dimethylbutane-2,3-diol. Acid causes methyl migration to give Q =

(CH X_{3}) X_{3} CCOCH X_{3}

, 3,3-dimethylbutan-2-one. The haloform reaction removes the

CH X_{3}

CHCl X_{3}

, so R =

(CH X_{3}) X_{3} CCOOH

, 2,2-dimethylpropanoic acid.