Cleavage of ethers by HI: mechanismHI द्वारा ईथरों का विदलन: क्रियाविधिCleavage of ethers by HI: mechanism

Class 12 Chemistry · Chapter 7 · interactive diagram

Parts and what they mean

• Protonated ether (oxonium ion) (प्रोटॉनित ईथर (ऑक्सोनियम आयन)) — HBr and HI are acidic enough to protonate the ether O.
• Iodide ion (good nucleophile) (आयोडाइड आयन (अच्छा नाभिकस्नेही)) — I⁻ is a better nucleophile than Br⁻ or Cl⁻, so HI reacts fastest.
• SN2 curved arrows (SN2 वक्र तीर) — I⁻ attacks the CH₃ carbon (less hindered); the C–O bond pair moves to O.
• Products: iodomethane + ethanol (उत्पाद: आयोडोमेथेन + एथेनॉल) — With 1°/2° groups the LOWER alkyl group becomes the alkyl iodide.
• With excess HI the alcohol is also converted (अधिक HI से ऐल्कोहॉल भी परिवर्तित) — Overall, a dialkyl ether gives two alkyl halide molecules.
• Tertiary alkyl group: SN1 path (तृतीयक ऐल्किल समूह: SN1 मार्ग) — The stable 3° carbocation forms, so the halide is the tertiary one: (CH₃)₃C–I + CH₃OH.
• Alkyl aryl ether (anisole) + HI → phenol + CH₃I (ऐल्किल ऐरिल ईथर (ऐनिसोल) + HI → फ़ीनॉल + CH₃I) — O–CH₃ is weaker than O–C₆H₅ (sp² carbon, partial double bond). Phenol does not react further because its sp² carbon cannot undergo nucleophilic substitution.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake