Why hcl don't used in preparation of methyl m nitrobenzoate?

HCl is not used in the preparation of methyl m-nitrobenzoate because the presence of a strong acid like HCl can lead to unwanted side reactions, such as hydrolysis or nitration of other functional groups on the molecule. Instead, a milder acid catalyst like sulfuric acid is typically used in these types of reactions to promote the esterification process efficiently.