Question

1-provide an sn1 mechanism between AgNO3 and bromobenzene?

2-provide an sn2 mechanism between AgNO3 and bromobenzene?

Answer 1

There will not be any reaction in both the two cases.

Reasons

Nucleophilic substitutions on substituted Benzenes dont usually dont occur, the reason being
(i) nucleophiles are negatively charged and benzene has a pi cloud which is electron rich and the pi cloud repels the nucleophiles.
(ii) C-Br bond in bromobenzene is relatively strong (compared to alkylhalides), it involves the overlap of Sp2 carbon and halogen's p-orbital. Sp2-P bond is stronger than Sp3-P bond. As the percentage of s-character increases the bond strength increases.

(iii) NO₃^- is not good nucleophiles.

For a SN1 reaction on BromoBenzene -
C-Br should dissociate to C+ and Br-. This bond is strong and it never ionizes.

SN2 reaction on bromobenzene requires an attack on the alpha-carbon. There is accessibility problem as well as the pi cloud repulsion of the nucleophile.

Substituted Benzenes are not known to undergo SN1 or SN2 reactions directly.

Substituted Benzenes do react differently to nucleophiles via Benzyne intermediate under appropriate conditions.

Hence bromobenzene can only go Aromatic nucleophilic substitution (SN_Ar)reactions.

You can get substitution reactions on halobenzenes using transition metal catalysts and these are not SN1 or SN2 reaction.

There are some name reactions that you can look up if you are interested such as Stille reaction, Suzuki reaction, Sonogashira reaction, and Buchwald reaction.