I cant remember where I have seen this...
For electrophilic substituition, if say you have 3-methylbenzoic acid reacting with the conc. nitric acid and conc. sulphuric acid, where will the NO2 group be added since there's no common position?
Will the acid group take priority or will the methyl group take priority?
Is there a list of priority of groups in this case? Is this the same priorities as when naming?
I googled and this is the priority list for aromatic cpds I have found out:
1. R group
2. NH2 grp
3. OH gp
4. aldehyde grp
5. COOH gp
6. SO3H gp
Originally posted by intothewild:I cant remember where I have seen this...
For electrophilic substituition, if say you have 3-methylbenzoic acid reacting with the conc. nitric acid and conc. sulphuric acid, where will the NO2 group be added since there's no common position?
Will the acid group take priority or will the methyl group take priority?
Is there a list of priority of groups in this case? Is this the same priorities as when naming?
I googled and this is the priority list for aromatic cpds I have found out:
1. R group
2. NH2 grp
3. OH gp
4. aldehyde grp
5. COOH gp
6. SO3H gp
The carboyxl group is deactivating and meta directing, due to a partial positive charge on its C atom. The methyl group is electron donating by induction and activating, and is hence ortho and para directing.
Activating directors outweigh (ie. are more influential than) deactivating directors.
Therefore, in this case, the nitronium cation, a sufficiently electrophilic species,will substitute away a proton on a position ortho or para to the methyl group.
Considering that the carboxyl group presents a greater steric hinderance as compared to the methyl group, the major product will be the nitro group substituting ortho to the methyl group (ie. 4th C on the benzene), and the minor product will be the nitro group substituting para to the methyl group (ie. 6th C on the benzene).