tert-Butyl ethanoate is hydrolysed in dilute aqueous acid in which the water is H2^18O (the ester itself contains only ^16O). Under these conditions hydrolysis occurs by alkyl-oxygen cleavage through the tert-butyl cation (AAL1). The ^18O label is found in

both ethanoic acid and 2-methylpropan-2-ol

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tert-Butyl ethanoate is hydrolysed in dilute aqueous acid in which the water is $H X_{2} X_{18} X_{2}^{218} O$ (the ester itself contains only $X_{16} X_{2}^{216} O$ ). Under these conditions hydrolysis occurs by alkyl-oxygen cleavage through the tert-butyl cation (AAL1). The $X_{18} X_{2}^{218} O$ label is found in

Aneither product
B2-methylpropan-2-ol only
Cboth ethanoic acid and 2-methylpropan-2-ol
Dethanoic acid only

Answer: B

In AAL1 the protonated ester ionises to ethanoic acid (retaining its original oxygens) and the tert-butyl cation. Water, here the labelled water, captures the cation, so the labelled oxygen appears only in 2-methylpropan-2-ol.

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tert-Butyl ethanoate is hydrolysed in dilute aqueous acid in which the water is HX2​X18​X2218​O (the ester itself contains only X16​X2216​O). Under these conditions hydrolysis occurs by alkyl-oxygen cleavage through the tert-butyl cation (AAL1). The X18​X2218​O label is found in

Answer: B

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