University of New England CHEM 1020 Chapter 6 -- Organic Halogen Compounds MULTIPLE CHOICE 1)What is the IUPAC name of the following alkyl halide?           2-bromo-6-methylheptane 6-methyl-2-bromoheptane 2-methyl-6-bromoheptane 2-bromo-2-methylheptane 2-bromo-5-isopropylpentane                                              What is the IUPAC name of the following alkyl halide?           trans-p-bromotoluene trans-4-methylcyclohexyl bromide trans-4-methyl-1-bromocyclohexane trans-1-bromo-4-methylcyclohexane trans-p-bromomethylcyclohexane                                              Which of the following structures represents 2,4,4-trichloroheptane?             I II III IV   V                                              Which of the following is the best nucleophile? H2O HO- HS- H3S all are the same                                              Which of the following is the strongest base? H2O -OH NH3 -NH2 F-                                              Which of the following is the best leaving group? F- Cl- I- Br- H2N-                                              Which of the following is the best nucleophile? H2O CH4 NH3 HF                                              Which of the following is an incorrect representation of relative nucleophile strength? —NH2 > F— HO— > HS—   3 CH — > HO— CH3O— > CH3OH I— > Br—                                              The reactivity order of the following as nucleophiles is:   CH3S- CH3O- CH3OH   A) 1 > 2 > 3 B) 2 > 3 > 1 C) 2 > 1 > 3 D) 3 > 2 > 1 E)   1 > 3 > 2                                                  What is the mechanism of the following reaction?   SN1 SN2 E1 E2 both A and B                                              Which statement is true for SN2 reactions? The rate of the reaction is dependent on the stability of a carbocation

University of New England

CHEM 1020

Chapter 6 -- Organic Halogen Compounds

MULTIPLE CHOICE

1)What is the IUPAC name of the following alkyl halide?

1. 1. 2-bromo-6-methylheptane
   2. 6-methyl-2-bromoheptane
   3. 2-methyl-6-bromoheptane
   4. 2-bromo-2-methylheptane
   5. 2-bromo-5-isopropylpentane

2. What is the IUPAC name of the following alkyl halide?

1. 1. trans-p-bromotoluene
   2. trans-4-methylcyclohexyl bromide
   3. trans-4-methyl-1-bromocyclohexane
   4. trans-1-bromo-4-methylcyclohexane
   5. trans-p-bromomethylcyclohexane

3. Which of the following structures represents 2,4,4-trichloroheptane?

1. 1. I
   2. II
   3. III
   4. IV

1. 5. V

4. Which of the following is the best nucleophile?
   1. H₂O
   2. HO^-
   3. HS^-
   4. H₃S
   5. all are the same

5. Which of the following is the strongest base?
   1. H₂O
   2. ^-OH
   3. NH₃
   4. ^-NH₂
   5. F^-

6. Which of the following is the best leaving group?
   1. F^-
   2. Cl^-
   3. I^-
   4. Br^-
   5. H₂N^-

7. Which of the following is the best nucleophile?
   1. H₂O
   2. CH₄
   3. NH₃
   4. HF

8. Which of the following is an incorrect representation of relative nucleophile strength?
   1. ^—NH₂ > F^—
   2. HO^— > HS^—
   3.  

1. 4. CH₃O^— > CH₃OH
   5. I^— > Br^—

9. The reactivity order of the following as nucleophiles is:

1. CH₃S^-
2. CH₃O^-
3. CH₃OH

A) 1 > 2 > 3

B) 2 > 3 > 1

C) 2 > 1 > 3

D) 3 > 2 > 1

E)   1 > 3 > 2

10. 
    What is the mechanism of the following reaction?

1. 1. S_N1
   2. S_N2
   3. E1
   4. E2
   5. both A and B

11. Which statement is true for S_N2 reactions?
    1. The rate of the reaction is dependent on the stability of a carbocation.
    2. The rate of reaction is dependent on just the substrate.
    3. The fastest reaction will occur with a tertiary halide.
    4. Displacement occurs with inversion of configuration.
    5. The mechanism is a two step process.

12. Which bromide reacts fastest in S_N2 reactions?
    1. CH₃Br
    2. (CH₃) ₂CHBr
    3. (CH₃) ₃CBr
    4. (CH₃) ₃CCH₂Br
    5. CH₃CH₂Br

13. Which of the following is a polar aprotic solvent?
    1. H₂O
    2. CH₃CN
    3. CH₃OH
    4. (CH₃) ₂S=O
    5. both B and D

14. Which statement(s) is/are true of an E1 elimination?
    1. it is a two-step process and has the same first step as a S_N1 mechanism
    2. it involves the formation of the carbocation from elimination of a good leaving group
    3. a common competing reaction is rearrangement of a less stable carbocation to a

more stable carbocation

1. 4. the loss of a proton by the carbocation is a fast step
   5. all of the above

15. 
    When (R)-3-bromo-3-methylhexane is treated with H₂O, racemic is produced. By what mechanism does this reaction occur?

1. 1. S_N1
   2. S_N2
   3. E1
   4. E2
   5. cannot be explained by one mechanism

16. The slowest step of an S_N1 reaction involves:
    1. attack of the nucleophile on the substrate to form a pentavalent carbon.
    2. breaking the bond between the carbon and the leaving group to give a carbocation.
    3. combination of a nucleophile with the carbocation to give the product.
    4. loss of a proton from the nucleophile to give the product.
    5. none of the above.

17. Which of the following bromides will react faster with CH₃OH in an S_N1 reaction?

B)

C)

E)

18. The S_N2 mechanism for nucleophilic substitution reactions
    1. involves two steps and occurs with inversion of configuration.
    2. involves one step and occurs with inversion of configuration.
    3. involves two steps and occurs with racemization.
    4. involves one step and occurs with retention of configuration.

1. 5. involves one step and occurs with racemization.

19. The S_N1 mechanism for nucleophilic substitution reactions
    1. involves one step and occurs fastest with primary halides.
    2. involves one step and occurs fastest with tertiary halides.
    3. involves two steps and occurs fastest with tertiary halides.
    4. involves two steps and occurs fastest with primary halides.
    5. involves one step and occurs fastest with aromatic halides.

20. 
    The expected S_N2 reactivity order of the following is:

A) 2 > 1 > 3

B) 2 > 3 > 1

C) 1 > 2 > 3

D) 1 > 3 > 2

E)   3 > 1 > 2

21. CH₃CH₂C(CH₃)₂Br + (CH₃)₃CO

^—K⁺ are most likely to react by

1. 1. a free radical chain mechanism.
   2. the S_N1 mechanism.
   3. the S_N2 mechanism.
   4. the E1 mechanism.
   5. the E2 mechanism.

22. are most likely to react by

1. 1. a free radical chain mechanism.
   2. the S_N1 mechanism.
   3. the S_N2 mechanism.
   4. the E1 mechanism.
   5. the E2 mechanism.

23. The structure below represents the transition state for the reaction of

1. 1. methanol with 2-bromopropene.
   2. methoxide with 2-bromopropane.
   3. sodium bromide with isopropyl methyl ether.
   4. methanol with 2-bromopropane.
   5. methoxide with 1-bromopropane.

24. 
    The energy-reaction diagram below is for

1. 1. an S_N2 reaction only.
   2. an S_N1 reaction only.
   3. an E2 reaction only.
   4. an E1 reaction only.
   5. an S_N1 or E1 reaction.
   6. an S_N2 or E2 reaction

ANS: F                           

25. The major product of the following reaction is:

1. 1. I
   2. II
   3. III
   4. I and II
   5. there is no major product

26. When 1-bromobutane is reacted with the bulky base, potassium tert-butoxide, in tert-butyl alcohol, the major elimination product is:
    1. 1-butene
    2. cis-2-butene
    3. trans-2-butene
    4. butyl tert-butyl ether
    5. butyl alcohol

27. How many different E2 products can form from the dehydrohalogenation of 2-bromopentane?
    1. 1
    2. 2
    3. 3
    4. 4
    5. 5

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

A)

B)

C)

E) none of these

29. What is the final product of the following sequence of reactions?

1. 1. I
   2. II
   3. III
   4. IV
   5. III and IV

30. What alkyne is produced when sodium acetylide reacts with CH₃CH₂CH₂I?
    1. 2-pentyne
    2. 1-pentyne
    3. 2-pentene
    4. 1-pentene
    5. butyne

31. 1-Butanethiol, CH₃CH₂CH₂CH₂SH, is produced by the reaction of 1-bromobutane with:
    1. NH₃
    2. CH₃OH
    3. CH₃S^-
    4. ^-SH
    5. CH₃O^-

32. Which Fischer projection represents the product of the following reaction?

1. 1. 
      D)
   2. E)

C)

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

1. 1. D)

1. 2. E)

C)

34. The major product of the reaction below is:

is

1. 1. 
      D)
   2. E)

C)

35. The products of the following reactions are:

1. 1. I, III
   2. I, II, III
   3. III, V
   4. II, IV, V
   5. II, III