Review Problems

2. Under the following conditions,

   

   1-bromo-4-methylpentane will most probably react via

   1. S_N1.
   2. S_N2.
   3. both S_N1 and S_N2.
   4. neither S_N1 nor S_N2.

3. The following molecule can be classified as having

   

   1. 4 primary, 2 secondary, 4 tertiary, and 3 quaternary carbon atoms.
   2. 3 methyl groups, 2 ethyl groups, and 4 secondary carbon atoms.
   3. 4 primary, 6 secondary, 2 tertiary, and 1 quaternary carbon atoms.
   4. 3 primary, 3 secondary, 4 tertiary, and 3 quaternary carbon atoms.

4. The following reactions are part of a free-radical halogenation sequence:

   	ΔH (kcal/mol)
   (A) Cl2→ 2 Cl•	+58
   (B) Cl• + CH4→ •CH3 + HCl	+1
   (C) •CH3 + Cl2→ CH3Cl + Cl•	−26
   (D) •CH3 + Cl• → CH3Cl	−84

   Identify the initiation, propagation, and termination steps.

5. S_N1 reactions show first-order kinetics because

   1. the rate-limiting step is the first step to occur in the reaction.
   2. the rate-limiting step involves only one molecule.
   3. there is only one rate-limiting step.
   4. the reaction involves only one molecule.

6. The following reaction sequence is typical of S_N1 reactions. Which is the rate-limiting step(s)?

   

   1. Step 1
   2. Step 2
   3. Step 3
   4. Steps 1 and 2

7. Which of the following would be the best solvent for an S_N2 reaction?

   1. H₂O
   2. CH₃CH₂OH
   3. CH₃SOCH₃
   4. CH₃CH₂CH₂CH₂CH₂CH₃

8. What choices for X and Y would most favor the following reaction?

   
   1. X = I⁻, Y = Cl⁻
   2. X = EtO⁻, Y = tosylate (CH₃C₆H₄SO₂)
   3. X = tosylate, Y = CN⁻
   4. X = OH⁻, Y = H₂O

9. What would be the major product of the following reaction?

   
   1. CH₃CH₂CH₂Br
   2. CH₃CH₂CH₂CH₂CH₂CH₃
   3. H₃CCHBrCH₃
   4. CH₃CH₂Br

10. Treatment of (S)-2-bromobutane with sodium hydroxide results in the production of a compound with an (R) configuration. The reaction has most likely taken place through

    1. an S_N1 mechanism.
    2. an S_N2 mechanism.
    3. both an S_N1 and S_N2 reaction.
    4. a reaction that cannot be determined.

11. What is the correct decreasing order of the boiling points of the following compounds?

    1. n-hexane
    2. 2-methylpentane
    3. 2,2-dimethylbutane
    4. n-heptane
    1. I > IV > II > III
    2. IV > III > II > I
    3. IV > I > II > III
    4. I > II > III > IV

12. The reaction of isobutane with an unknown halogen is catalyzed by light. The two major products obtained are:

    

    What is the unknown halogen?

    1. Cl₂
    2. Br₂
    3. I₂
    4. F₂

13. Place the following species in order of increasing stability.

    1. 1. CH₃CH₂CH₂^•
       2. 
       3. CH₃^•
       4. (CH₃)₃C•
    2. 1. 
       2. R₃C⁺
       3. H₃C⁺
       4.