16

(ii)

Opposing effects

strong activators “win” over weak ones!

but approximately statistical ratio in cases where groups are of same directing ability:

2.7.Strategies for
Disubstituted Benzenes

the

Preparation

of

(i)take advantage of directing effects to determine
order of introduction of substituents:

the

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Cl

Me

weak

weak

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NO2

Br

NO2

Br

NO2

Br

Br

NO2

vs

ususally separable
by crystallisation or
distillation

brominate
then
nitrate

nitrate
then
brominate