Account for the formation of CH3 CH=CH-CH2 CN and C=CC(C)C#N from the reactio

step 1 The portion is the reaction of propene with HOCL will lead to which intermediate. So we have to

Account for the formation of CH3 CH=CH-CH2 CN and ...

Account for the formation of $$ \mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2 \mathrm{CN} \text { and } $$ <smiles>C=CC(C)C#N</smiles> from the reaction with $\mathrm{CN}^{-}$of 1 -chloro-2-butene, $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2 \mathrm{Cl}$. Formation of 1-cyano-2-butene results from $\mathrm{S}_{\mathrm{N}} 2$ reaction at the terminal $\mathrm{C}$. $$ \mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}^{-} \mathrm{CH}_2^{-}-\mathrm{Cl}^{-\mathrm{CN}^{-}} \longrightarrow \mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2-\mathrm{CN}+\mathrm{Cl}^{-} $$ Attack by $\mathrm{CN}^{-}$can also occur at $\mathrm{C}^3$ with the $\pi$ electrons of the double bond acting as nucleophile to displace $\mathrm{Cl}^{-}$in an allylic rearrangement:

Account for the formation of
$$
\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2 \mathrm{CN} \text { and }
$$
<smiles>C=CC(C)C#N</smiles>
from the reaction with $\mathrm{CN}^{-}$of 1 -chloro-2-butene, $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2 \mathrm{Cl}$.
Formation of 1-cyano-2-butene results from $\mathrm{S}_{\mathrm{N}} 2$ reaction at the terminal $\mathrm{C}$.
$$
\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}^{-} \mathrm{CH}_2^{-}-\mathrm{Cl}^{-\mathrm{CN}^{-}} \longrightarrow \mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2-\mathrm{CN}+\mathrm{Cl}^{-}
$$

Attack by $\mathrm{CN}^{-}$can also occur at $\mathrm{C}^3$ with the $\pi$ electrons of the double bond acting as nucleophile to displace $\mathrm{Cl}^{-}$in an allylic rearrangement:

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Key Concepts

Regioselectivity in Allylic Nucleophilic Substitution

Regioselectivity in these reactions is determined by the stability of intermediates and the potential for resonance stabilization in the allylic system. Nucleophiles can attack at different sites within an allylic framework, and the most favorable site is typically the one that leads to a more stabilized transition state or intermediate, thereby influencing the distribution of the reaction products.

SN2 Reaction Mechanism

This mechanism involves a direct backside attack by a nucleophile on an electrophilic center, leading to the simultaneous displacement of a leaving group. It is characterized by a concerted one-step process, where bond formation and bond breaking occur simultaneously, resulting in inversion of configuration at the reaction center.

Allylic Rearrangement

Allylic rearrangement refers to the process where nucleophilic attack occurs at an allylic position, making use of the resonance stabilization of the allylic system. This mechanism allows for shifting of the double bond and rearrangement of the bonding framework, which can lead to different isomeric products compared to the direct substitution pathway.

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