The major product H of the given reaction sequence is:
$$ CH_3-CH_2-CO-CH_3 \xrightarrow{HCN} G \xrightarrow{9

Question

The major product H of the given reaction sequence is:
$$ CH_3-CH_2-CO-CH_3 \xrightarrow{HCN} G \xrightarrow{95\% H_2SO_4, \Delta} H $$

Accepted Answer

The reaction proceeds in two main stages:
1.  **Cyanohydrin Formation:** The reaction of Butanone ($CH_3-CH_2-CO-CH_3$) with HCN is a nucleophilic addition reaction. The cyanide ion ($CN^-$) attacks the carbonyl carbon, forming a cyanohydrin intermediate (G): 2-hydroxy-2-methylbutanenitrile.
    $$ G: CH_3-CH_2-C(OH)(CH_3)-CN $$
2.  **Hydrolysis and Dehydration:** Heating with concentrated (95%) $H_2SO_4$ performs two functions:
    *   **Hydrolysis:** The nitrile group ($-CN$) is hydrolysed to a carboxylic acid group ($-COOH$).
    *   **Dehydration:** The acid acts as a dehydrating agent, removing a water molecule (the $-OH$ group and a hydrogen from an adjacent carbon). According to **Zaitsev's rule**, the major product is the more substituted alkene. Thus, hydrogen is removed from the $CH_2$ group (C3) rather than the $CH_3$ group, forming a double bond between C2 and C3.

The final product H is **2-Methylbut-2-enoic acid** ($CH_3-CH=C(CH_3)-COOH$).

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