tert-Butyl acetate is hydrolysed in dilute aqueous acid enriched in H2^18O by the AAL1 pathway (alkyl-oxygen cleavage, the tert-butyl cation is captured by water). The ^18O label is found in

both acetic acid and tert-butyl alcohol

JEE Advanced levelSingle correct optionDifficulty 3 of 3ro049

tert-Butyl acetate is hydrolysed in dilute aqueous acid enriched in $H X_{2} X_{18} X_{2}^{218} O$ by the AAL1 pathway (alkyl-oxygen cleavage, the tert-butyl cation is captured by water). The $X_{18} X_{2}^{218} O$ label is found in

AAL1: the protonated ester ionises to

CH X_{3} COOH

(carrying the original oxygens) and

(CH X_{3}) X_{3} C X^{+}

. The cation then adds

H X_{2} X_{18} X_{2}^{218} O

to give

(CH X_{3}) X_{3} C - X_{18} X_{2}^{218} OH

. Hence the label is only in the alcohol.