Table of Contents
Why do aromatic compounds undergo electrophilic substitution reaction?
Explanation: The aromatic structure provides significant additional stability to the molecule. Substitution reactions allow the aromatic structure to remain, whereas additions would change the C-C bonding away from being aromatic. This would be unfavourable.
Why is electrophilic substitution of benzene slow?
Because the benzene acts as a nucleophile in electrophilic aromatic substitution, substituents that make the benzene more electron-rich can accelerate the reaction. Substituents that make the benzene moor electron-poor can retard the reaction.
What is the purpose of electrophilic addition?
Electrophilic addition reactions are an important class of reactions that allow the interconversion of C=C and C≡C into a range of important functional groups including alkyl halides and alcohols. Conceptually, addition is the reverse of elimination (see Chapter 5) which can be used to prepare alkenes.
Why do aromatic hydrocarbons undergo electrophilic?
Explanation: Aromatic hydrocarbons have pi electrons but does not undergo addition reaction because resonance of compound get altered. So, the aromatic hc prefers substitution reaction and due to its nucleophile nature, it attracts electrophile. So, the aromatic hc undergo electrophile substitution reaction.
Is benzene electrophilic or nucleophilic?
Benzene is a nucleophile because of its delocalized electrons. The molecule has electron rich areas which allow it to donate them to electrophiles.
Where does electrophilic substitution occur?
1.1 Electrophilic substitution. Electrophilic substitution usually occurs preferentially in the aryl group (Figure 3). In compounds containing both an aryl group and a fused benzene ring, electrophiles usually attack the aryl group exclusively.
What are the conditions for electrophilic substitution?
The three steps involved in the electrophilic substitution reaction are the generation of an electrophile, then the formation of carbocation that acts as an intermediate, and the removal of a proton from the medium.
Why do aromatic compounds undergo electrophilic substitution rather than electrophilic addition?
Although aromatic compounds have multiple double bonds, these compounds do not undergo addition reactions. Their lack of reactivity toward addition reactions is due to the great stability of the ring systems that result from complete π electron delocalization (resonance).
Why is Benzyne electrophilic?
Bonding in o-arynes Geometric constraints on the triple bond in ortho-benzyne result in diminished overlap of in-plane p-orbitals, and thus weaker triple bond. Hence, benzyne possesses electrophilic character and undergoes reactions with nucleophiles.
Why does phenol undergo electrophilic substitution?
Electron deficient species is known as an electrophile. Thus, due to the electron-donating effect of the hydroxyl group in phenol, electron density increases at the ortho and para position of the aromatic ring. So, phenol undergoes electrophilic substitution more easily than benzene.
Is benzene addition or substitution more favorable?
Recall that the resonance energy of benzene is about 152 kJ / mol (36 kcal / mol) and a conjugated diene is 16 kJ / mol (4 kcal/mol). This extra stability of the aromatic system is responsible for favouring the substitution reaction – substitution retains the aromatic unit whereas addition removes the C=C.
Why benzene does not undergo nucleophilic substitution?
Nucleophiles are electron-rich. Due to the presence of an electron cloud of delocalized electrons on the benzene ring nucleophilic attack is difficult. Hence, they are repelled by benzene. Hence, benzene undergoes nucleophilic substitutions with difficulty.