Indian Forest Service (Mains), Chemistry optional · 2016 · Paper II

Q2(a)(i). (S)-2-Bromobutane with HCOOH and with HCOO⁻Na⁺/DMSO

5 marks
Topic: Substitution reactions
Answered

Question

Write the outcome of the reaction and predict the reaction to SN1 or SN2 in each case.

Answer in brief

A = (±)-butan-2-yl formate, SN1 (racemisation) ; B = (R)-butan-2-yl formate, SN2 (inversion) . The protic solvent ionises the substrate; the aprotic solvent sharpens the nucleophile.

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Read the whole 2016 solution 2016 question paper

Topic notes: nucleophilic substitution (SN1, SN2, SNi, neighbouring group participation, solvent effects, rearrangement), with every Civil Services, IFoS and Geo-Scientist PYQ →

Covers(S)-2-bromobutanepolar proticweak nucleophile(±)-butan-2-yl formatepolar aprotic

All parts of Question 2

2(a)(i) (S)-2-Bromobutane with HCOOH and with HCOO⁻Na⁺/DMSO5 marks
2(a)(ii) 7-Norbornyl and anti-7-norbornenyl tosylates: participation of a C=C5 marks
2(b) E2 in a locked trans-decalin and in locked 1,2-dibromocyclohexanes10 marks
2(c)(i) Bromolactonisation of endo-norbornene-carboxylic acid5 marks
2(c)(ii) Octalin to the tertiary and the secondary decalol5 marks
2(d) Aromatic character of sydnones10 marks