For the given compound,determine the number o | vedclass

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(A) The given compound is pent$-3-$en$-2-$one,which contains an $\alpha,\beta$-unsaturated carbonyl system.In the presence of a base like $\mathop O\l

Vedclass · Accepted Answer

$5$

Vedclass · Answer

(A) The given compound is pent$-3-$en$-2-$one,which contains an $\alpha,\beta$-unsaturated carbonyl system.In the presence of a base like $\mathop O\limits^\ominus D$ in $D_2O$,the $\alpha$-hydrogens are acidic and undergo keto-enol tautomerism.The compound is $CH_3-CH=CH-CO-CH_3$.The $\alpha$-hydrogens are those attached to the carbon adjacent to the carbonyl group $(C=O)$.There are $3$ $\alpha$-hydrogens on the methyl group attached to the carbonyl carbon.Additionally,the $\gamma$-hydrogens (on the $CH_3$ group at the other end of the double bond) are also acidic due to conjugation with the carbonyl group through the double bond.Thus,the $3$ hydrogens of the terminal $CH_3$ group and the $2$ hydrogens on the $\alpha$-carbon (if present,but here it is $CH_3-CH=CH-CO-CH_3$,so the $\alpha$-carbon is the carbonyl carbon,and the adjacent $CH_3$ has $3$ hydrogens) are exchangeable.Specifically,the $3$ hydrogens of the $CH_3$ group adjacent to the carbonyl and the $2$ hydrogens on the $CH$ groups of the alkene part in conjugation with the carbonyl are susceptible to exchange.However,in $CH_3-CH=CH-CO-CH_3$,the $3$ hydrogens of the acetyl group $(CH_3-CO-)$ are exchangeable.Also,the $2$ vinylic hydrogens at the $\gamma$ and $\delta$ positions are not acidic,but the $3$ hydrogens of the terminal $CH_3$ group are acidic due to vinylogous enolization.Total exchangeable hydrogens = $3$ (from $CH_3-CO$) + $2$ (from the $CH_3$ group at the other end via vinylogous enolization) = $5$.

For the given compound,determine the number of hydrogen atoms that are replaced by $D$ upon keeping it for a long time with $\mathop O\limits^\ominus D / D_2O$.

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