[aj45]

If someone could help me explain these results id be very grateful.

In the first experiment, both methylbenzene and methoxybenzene were reacted with bromine in 1,1,1- trichloroethane and only the methoxybenzene decolourised the bromine water.

In the second experiment the methylbenzene and methoxybenzene were heated with concentrated sulphuric acid and a few drops of water. With the methoxybenzene the solutions turned yellow, with the methyl benzene there was no reaction.

i Know the methoxy group on the benzene ring causes it to become more reactive than the methyl group but why?

[Winga]

The methoxy oxygen donates a lone pair to the benzene ring which makes the ring system more nucleophilic (the initial state is raised in energy as the e- density of the ring system increases).

The oxygen takes part in resonance and stabilizes the benzonium ion (intermediate).

In this case, stabilizing the intermediate will also stabilize the transition state, lower in energy.

Therefore, the activation energy is smaller and faster reaction rate.