Q11 · CSIR NET Chemistry, December 2012
Paper: CSIR NET December 2012 · Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: Conformational Analysis · Marks: 2 · Difficulty: Medium
Given the energy of each gauche butane interaction is $0.9\,\mathrm{kcal/mol}$, G value of the following reaction is 
(e,e conformer) 
(e,e conformer) (a)$0.9 \mathrm{kcal} / \mathrm{mol}$
(b)$1.8 \mathrm{kcal} / \mathrm{mol}$
(c)$2.7 \mathrm{kcal} / \mathrm{mol}$
(d)$3.6 \mathrm{kcal} / \mathrm{mol}$
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
trans-1,2-Dimethylcyclohexane (e,e) has 1 gauche interaction; cis (a,e) has 3 (two from the axial CH₃, one between the methyls). trans → cis: ΔG = 2 × 0.9 = +1.8 kcal mol⁻¹ (b).
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