Directive influence of substituents in benzeneबेन्ज़ीन में प्रतिस्थापियों का निर्देशात्मक प्रभाव

NCERT Sec 9.5.5 · interactive diagram

Parts and their functions

• Ortho/para directors (ऑर्थो/पैरा निर्देशक) — Groups with a lone pair or alkyl groups (–OH, –NH₂, –OCH₃, –CH₃) push electrons into the ring; electron density rises most at the ortho and para positions, so E⁺ enters there and the ring reacts faster than benzene (activation).
• Meta directors (मेटा निर्देशक) — Electron-withdrawing groups (–NO₂, –CN, –CHO, –COOH, –SO₃H) pull electrons out; ortho and para lose the most density, so E⁺ goes to meta. The ring reacts slower than benzene (deactivation).
• Positions on the ring (वलय पर स्थितियाँ) — Relative to the group at C-1: ortho = 2 and 6, meta = 3 and 5, para = 4.
• Halogens — the exception (हैलोजन — अपवाद) — Halogens withdraw electrons strongly by −I, so they deactivate the ring, but their lone pairs (+R) still raise density at ortho/para, so they are o/p directing.

Original diagram drawn by Simple Learning Hub, based on NCERT Sec 9.5.5. Report a mistake