Substituent Effects: Electrophilic Aromatic Substitution Substituents that are capable of donating electrons into the benzene ring will stabilize both the carbocation intermediate and the transition state leading to its formation –Increases the rate of electrophilic aromatic substitution Substituents that withdraw electrons from the benzene ring will destabilize the carbocation intermediate and the transition state leading to its formation –Decreases the rate of electrophilic aromatic substitution

Ortho, Para, and Meta Directing Substituents All meta directing substituents have a positive or partial positive charge on atom adjacent to ring All ortho-para directing substituents have at least one lone-pair of electrons on atom adjacent to ring. ortho-parameta ortho-para

TNT, a pale yellow solid, melts at 83°C, and explodes at 240°C. Supplying TNT with activation energy produces N 2, CO, CO 2, H 2 O, and lots of energy in a chemical chain reaction.

Why is TNT so explosive?! TNT is explosive for two reasons. First, it contains the elements carbon, oxygen and nitrogen, which means that when the material burns it produces highly stable substances (CO, CO 2 and N 2 ) with strong bonds, so releasing a great deal of energy. The second fact that makes TNT explosive is that it is chemically unstable - the nitro groups are so closely packed that they experience a great deal of strain and hindrance to movement from their neighboring groups. Thus it doesn't take much of an initiating force to break some of the strained bonds, and the molecule then flies apart.

Nucleophilic Aromatic Substitution Reactions

p orbitals in a normal triple bond p orbitals in benzyne