Indian Forest Service (Mains), Chemistry optional · 2024 · Paper II

Q2(c)(i). Hofmann elimination

10 marks
Topic: Elimination reactions
Answered

Question

Define the Hofmann product. Explain the major product from the drawn sec-butyltrimethylammonium ion with potassium tert-butoxide on heating, using a Newman projection. [structure given in the paper]

Answer in brief

The Hofmann product is the less substituted alkene: but-1-ene is favoured, with trimethylamine as the leaving molecule.

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Topic notes: elimination reactions (E1, E2, E1cB, Saytzeff and Hofmann, anti-periplanar, Chugaev, Cope), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversHofmann eliminationHofmann rulequaternary ammonium saltanti-periplanar E2Newman projection

All parts of Question 2

2(a)(i) A para-Claisen crossover experiment5 marks
2(a)(ii) Kinetic and thermodynamic enolates5 marks
2(b)(i) Photolysis of an ortho-methyl diazo compound5 marks
2(b)(ii) Bridgehead carbocation stability5 marks
2(b)(iii) Rearrangement during solvolytic elimination5 marks
2(c)(i) Hofmann elimination10 marks
2(c)(ii) Chugaev elimination5 marks