1. The Keq for the interconversion for the two chair forms of methylcyclohexane at 25 °C is 18. What % of the chair conformations feature an axial methyl group?
(A) 95
(B) 75
(C) 50
(D) 25
(E) 5

14. Find the energy cost of a 1,3-diaxial interaction for the following compounds, which has most 1,3-diaxial interaction energy? Assume the following 1,3-diaxial strains. (A) Isopropylcyclohexane (B) Fluorocyclohexane (C) Cyclohexanecarbonitrile (D) cis-1-Chloro-2-methylcyclohexane (E) trans-1-Chloro-2-methylcyclohexane.

9. 化合物 cis-1,3-dimethylcyclohexane 的最穩定結構為何？ (A) (B) (C) (D) (E)

3. 下列化合物中，何者具有最高的莫耳燃燒熱(molar heat of combustion)？ (A) trans-1,2-dimethylcyclopentane (B) cis-1,2-dimethylcyclopentane (C) trans-1,3-dimethylcyclopentane (D) methylcyclohexane

22. Which of the following Newman projection represents the most stable trans-1,2-dimethylcyclohexane? (A) (B) (C) (D) (E)

34. If one gauche interaction is 0.9 kcal/mol, what is the energy difference between cis-decalin and trans-decalin? (A) 0.9 kcal/mol (B) 1.8 kcal/mol (C) 2.7 kcal/mol (D) 3.6 kcal/mol (E) 4.5 kcal/mol

3. Which one of the following structures represents a different compound from the other three? (A) 1 (B) 2 (C) 3 (D) 4 (E) All of the above are the same.

2. What is the name of the major organic product of the following reaction?  (A) 3,3-dimethyl-1-butanol (B) 3,3-dimethyl-2-butanol (C) 2,3-dimethyl-2-butanol (D) 2,3-dimethyl-1-butanol (E) 4-methyl-2-petanol

3. How many diastereomer(s) exist for the compound below?  (A) 2 (B) 4 (C) 6 (D) 8 (E) 0

4. Which of the following statements is (are) true for the Diels-Alder reaction? (A) When the diene is electron-rich, the reaction works best when the dienophile contains one or more electron-withdrawing groups conjugated to its C=C. (B) Substituents which are cis in the dienophile remain cis in the product. (C) Dienes which cannot achieve an s-cis conformation do not react in Diels-Alder reactions. (D) Secondary orbital interactions typically cause the endo product to be favored kinetically over the exo. (E) All of the above.

5. What is the major product of the following reaction?

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