Give reasons why the reaction between benzoylchloride and methanol do not attack carbon from the ring
The reaction between benzoyl chloride (C6H5COCl) and methanol (CH3OH) is typically used to form esters, specifically benzoyl methanol. However, this reaction does not attack the carbon atoms directly attached to the benzene ring. Here are a few reasons explaining why this occurs:
1. Electrophilic Aromatic Substitution: Benzoyl chloride contains an acyl chloride group (–COCl), which is highly reactive due to the presence of an electron-withdrawing chlorine atom. However, because benzene is an aromatic system, it undergoes electrophilic aromatic substitution reactions rather than nucleophilic additions. In this type of reaction, the electrophile attacks the aromatic ring and substitutes one of the hydrogens attached to the carbon atoms in the ring.
2. Resonance Stabilization: The benzene ring is a highly stable aromatic system due to its delocalized π bonds. This stability arises from the resonance of the p-orbitals, which allows for electron density to disperse across all carbon atoms in the ring. The presence of this resonance stabilization makes it energetically unfavorable for nucleophilic attacks to occur on the carbon atoms directly attached to the aromatic ring. Instead, nucleophilic attacks generally target other reactive groups present in the molecule, such as the acyl chloride group.
3. Substituent Effects: The presence of electron-donating or electron-withdrawing substituents on the benzene ring can affect the reactivity of the carbon atoms towards nucleophilic attacks. In the case of benzoyl chloride, the chlorine atom is an electron-withdrawing group, which enhances the electrophilic nature of the acyl chloride group. This electron withdrawal effect directs the nucleophilic attack away from the carbon atoms attached to the ring and towards other reactive sites, such as the carbonyl carbon (C=O) of the acyl chloride.
In summary, the reaction between benzoyl chloride and methanol does not attack the carbon atoms directly attached to the benzene ring due to the preference for electrophilic aromatic substitution, the resonance stabilization of the aromatic system, and the electronic effects of the substituents present in the molecule.
The reaction between benzoyl chloride (C6H5COCl) and methanol (CH3OH) typically leads to the formation of an ester, benzoyl methanol (C6H5COOCH3). The reaction proceeds through a nucleophilic acyl substitution mechanism, where the nucleophile (methanol) attacks the carbonyl carbon of the benzoyl chloride.
However, the reaction does not attack the carbons in the benzene ring for several reasons:
1. Aromaticity: The benzene ring is stabilized by aromaticity, a ring of conjugated pi electrons. Aromatic compounds tend to be relatively unreactive because disrupting the delocalized electrons would require a substantial amount of energy. Thus, the carbons in the benzene ring are less reactive than the carbonyl carbon.
2. Electronegativity of the oxygen: The oxygen atom in the methanol molecule is highly electronegative compared to the carbon atoms in the benzene ring. As a result, the oxygen atom attracts the electron density towards itself, making it less likely to attack the carbon atoms in the ring.
3. Steric hindrance: The substitution reaction is sterically hindered because the benzene ring is planar and its aromaticity is maintained by a specific arrangement of single and double bonds. This planar arrangement of atoms creates limited space around the ring, making it difficult for nucleophiles to approach the carbons directly.
Therefore, in the reaction between benzoyl chloride and methanol, the nucleophilic attack primarily occurs at the carbonyl carbon of the benzoyl chloride, leading to the formation of an ester, benzoyl methanol.