(c) A substituted benzene can undergo electrophilic aromatic substitution, discuss the effect of a substituent on; 1) Reactivity 2) Orientation ?

1) Reactivity: The presence of a substituent on a benzene ring can greatly affect the reactivity of the ring towards electrophilic aromatic substitution reactions. Substituents can either increase or decrease the reactivity of the benzene ring depending on their electronic nature. Electron-donating substituents such as alkyl groups or phenyl groups increase the electron density on the benzene ring, making it more nucleophilic and therefore more reactive towards electrophilic aromatic substitution reactions. On the other hand, electron-withdrawing substituents such as nitro groups or carbonyl groups decrease the electron density on the benzene ring, making it less nucleophilic and less reactive towards electrophilic aromatic substitution reactions.

2) Orientation: The presence of a substituent on a benzene ring can also affect the orientation of the incoming electrophile in an electrophilic aromatic substitution reaction. Substituents can be either ortho-, meta-, or para-directing based on their electronic nature. Electron-donating substituents such as alkyl groups or phenyl groups are ortho- and para-directing, meaning they direct the incoming electrophile to the ortho and para positions relative to the substituent. Electron-withdrawing substituents such as nitro groups or carbonyl groups are meta-directing, meaning they direct the incoming electrophile to the meta position relative to the substituent. This orientation effect is known as the directing effect of substituents on electrophilic aromatic substitution reactions.