# The increasing order of reactivity of substituted benz0yl chlorides towards nucleophilic substitution

Arrange the following compounds in the order of their increasing reactivity towards nucleophilic substitution:

The answer to this question is $$[3<2<1<4]$$. We have to compare the positive charge density on the carbons to which leaving group is connected. In $$(1)$$, the phenyl ring shows negative inductive effect but my teacher did not mention anything for that. In $$(3)$$ and $$(4)$$ the connected groups ($$\ce{OCH3}$$ and $$\ce{NO2}$$) show +M and -M respectively. But, they also show -I effect. Why are we ignoring the inductive effect?

• You're kind of overcomplicating it. The rate-determining step is attack of a nucleophile on the electrophilic C=O. The more electrophilic it is, the faster the reaction. You don't need to care about the inductive effect of the phenyl group, because all of them have phenyl groups. The only thing that matters is the 4-substituent. Jun 4, 2020 at 12:05
• The person who decided it was OK to teach students that +ve and -ve are acceptable abbreviations is one of the worst people of the last century. + and - already mean positive and negative!
– Zhe
Jun 4, 2020 at 12:58
• rate of reaction is proportional to the concentration of the nucleophile. But in this question, we don't know which nucleophile is being used. Jun 4, 2020 at 14:43