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Meta directing deactivators \(\,<\,\) Ortho-Para directing deactivators (halogens) \(\,<\,\) Ortho -Para directing Activators

Activator-An atom or molecule capable of increasing electron density on benzene ring either by hyper conjugation or by mesomeric effect \(+R\).

Halogen are dectivator due \(-I\) effect so their reactivity is less than of benzene but Ortho-Para directing due to \(+R\) mesomeric effect.

Deactivates decreases electron density on benzene ring so electrophile can attack on meta position with difficulty.

Now the order

(Meta directing deactivators)

\(- NO _2\,<\,- CN \,<\,- SO _3 H\, <\,- COCH_3\,<\,- COOH \,<\,- COOCH _3\,<\,- COH \,<\,\)

( \(OP\) deactivator)

\(- I\, <\,- Br \,<\,- Cl\, <\,- F \,<\,\)

(\(OP\) activators)

\(- H \,<\,- ph \,<\,- CH _3\,<\,- COCH _3\,<\,- N \left( CH _3\right)_3\,<\,- OH \,<\,- NH _2\)