3. a. The reaction sequence shown in Figure 4 demonstrates the synthesis of a disubstituted benzene derivative $\mathbf{O}$ from compound $\mathbf{M}$ through two Electrophilic Aromatic Substitution reactions.
(i) Draw the chemical structure of compound $\mathbf{M}$.
[2 marks]
(ii) Draw the mechanism for the transformation of compound $\mathbf{M}$ to intermediate $\mathrm{N}$ using curly arrows.
[6 marks]
(iii) Draw the chemical structure of compound $\boldsymbol{O}$.
[2 marks]
(iv) Draw the mechanism for the transformation of intermediate $\mathrm{N}$ to compound $\mathrm{O}$ using curly arrows.
[6 marks]
(v) Account for the regiochemical outcome observed in compound $\mathbf{O}$.
[4 marks]

Question

Accepted Answer

∻Solution∻ ‖ 1 ⋮ **Draw the chemical structure of compound $M$**: Compound $M$ is given as $C_6H_5Cl$, which is chlorobenzene. The structure is a benzene ring with a chlorine atom attached to one of the carbon atoms. ‖ ‖ 2 ⋮ **Draw the mechanism for the transformation of compound $M$ to intermediate $N$ using curly arrows**: The reaction of chlorobenzene ($M$) with $AlCl_3$ is an example of an electrophilic aromatic substitution (EAS) reaction. The $AlCl_3$ acts as a Lewis acid, facilitating the formation of the electrophile $Cl^+$. The mechanism involves the following steps: 1. Formation of the electrophile: $AlCl_3$ reacts with $Cl_2$ to form $Cl^+$ and $AlCl_4^-$. 2. The benzene ring donates a pair of $\pi$ electrons to the $Cl^+$, forming a sigma complex (arenium ion). 3. The $AlCl_4^-$ abstracts a proton from the sigma complex, restoring the aromaticity and forming the product $N$ (chlorobenzene). ‖ ‖ 3 ⋮ **Draw the chemical structure of compound $O$**: Compound $O$ is given as $C_6H_4ClNO_3$, which is a benzene ring with a chlorine atom and a nitro group ($NO_2$) attached. The structure is a benzene ring with a chlorine atom at one position and a nitro group at another position. ‖ ‖ 4 ⋮ **Draw the mechanism for the transformation of intermediate $N$ to compound $O$ using curly arrows**: The reaction of chlorobenzene ($N$) with $HNO_3$ and $H_2SO_4$ is another example of an electrophilic aromatic substitution (EAS) reaction. The $H_2SO_4$ acts as a catalyst, facilitating the formation of the electrophile $NO_2^+$. The mechanism involves the following steps: 1. Formation of the electrophile: $HNO_3$ reacts with $H_2SO_4$ to form $NO_2^+$ and $HSO_4^-$. 2. The benzene ring donates a pair of $\pi$ electrons to the $NO_2^+$, forming a sigma complex (arenium ion). 3. The $HSO_4^-$ abstracts a proton from the sigma complex, restoring the aromaticity and forming the product $O$ (chloronitrobenzene). ‖ ‖ 5 ⋮ **Account for the regiochemical outcome observed in compound $O$**: The regiochemistry of the nitration of chlorobenzene is influenced by the electron-withdrawing nature of the chlorine substituent. Chlorine is an ortho/para-directing group due to its lone pairs, which can donate electron density through resonance. However, it is also an electron-withdrawing group through induction. The net effect is that nitration occurs preferentially at the ortho and para positions relative to the chlorine substituent. In this case, the product $O$ is likely to be a mixture of ortho- and para-chloronitrobenzene, with the para product being more predominant due to steric hindrance at the ortho position. ‖ ∻Answer∻ ⚹ The chemical structures and mechanisms for the transformations of compounds $M$ to $N$ and $N$ to $O$ involve electrophilic aromatic substitution reactions, with the regiochemistry influenced by the substituents on the benzene ring. ⚹ ∻Key Concept∻ ⚹ Electrophilic Aromatic Substitution (EAS) ⚹ ∻Explanation∻ ⚹ EAS reactions involve the substitution of a hydrogen atom on an aromatic ring with an electrophile. The regiochemistry of the substitution is influenced by the nature of the substituents already present on the ring. ⚹◊What is the regiochemical outcome observed in compound $O$ and how does it relate to the reaction mechanism?⍭ Generate me a similar question◊

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