Question

a) explain why resonance theory would predict that anisole, chlorobenzene and diphenyl ether would all have similar rates for bromine adding to the para-position, when compared with tolunene and the three xylenes

b) Using resonance theory, which of the xylenes (ortho, meta, or para) is predicted to react fastest? Explain the answer.

Please help with this two questions, great explanation will be very necessary and helpful, thanks in advance.

Answer 1

a)According to resonance theory, anisloe,chlorobenzene and diphenyl eher all three have similar rates for the bromine addition reaction.

Because in all three the groups directly attached to the benzene ring are -OCH3, -Cl and -OC6H5 . These groups enhance the electron density on p-positin and the tendency of electrophilic substitution reaction is increased.

But in toluene no such group is present.

b)According to the analysis all three xylenes are somewhat differ to the bromine reactivity. Molecular bromination data shown below;

toluene - 480

m-xylene - 2.0*10⁵

p-xylene - 2.1*10³

This happens because the selectivity to the all molecules are different.

hope this helped. Thank you.