CHE 230-002 – Organic
Chemistry
Exam 4,
Name
________________________________ Student ID Number ________________
Before you begin this exam: First: Write your name and student ID number on this
page. Then write your name and student ID
number on the bubble sheet. Second: Note the blank page at the end
provided for scrap paper. It must be
returned at the end of the exam. Third: Place your student
identification card on your desk. A
proctor will come around to check everyone’s ID. Fourth:
The first 40 questions are in multiple choice format. The answers must be entered on the bubble sheet with a #2 pencil. Make sure that your answers correspond with
the correct problem numbers. Fifth: The final three questions are not
in multiple choice format and should be answered on
this exam. Return all of the exam
(including scrap paper and periodic table) at the end of the period. Sixth: Read
the instructions for each problem.
You will have until
Problem Score
41. _____
42. _____
43. _____
subtotal _____
1 – 40. _____
Total _______
Part A: Multiple Choice Questions (40 x 2.2 = 88)
1. Which of the following is a Newman projection of 2-bromopentane (one enantiomer only)?
(A) (B) (C) (D)
2. Which is the most stable resonance form for ozone?
(A) (B) (C) (D)
3. What is the hybridization of the underlined carbon (the CH2 group) in the following resonance-stabilized anion?
(A) sp (B) sp2 (C) sp3 (d) p
4. Which structure best shows the correct three-dimensional geometry for 2, 3-pentadiene? (Solid lines represent bonds in the plane of the paper; wedges and hashed lines represent bonds in front of or behind the plane.)
(A) (B)
(C) (D)
5. How many 13C NMR signals are expected for 2, 5-dimethylhexane?
(CH3)2CHCH2CH2CH(CH3)2
(A) three (B) six (C) seven (D) eight
6. Which one of the molecules below is not chiral?
(A) (B) (C) (D)
7. What is the relationship between the two molecules below?
(A) configurational enantiomers (B) configurational diastereomers
(C) identical (D) structural isomers
8. What notation should be used to specify the configurations in the following isomer of 3-bromo-2-chloro-1-butanol?
(A) (3R,2R) (B) (3R,2S) (C) (3S,2R) (D) (3S,2S)
9. What is the correct name for the following compound?
(A) (2E,4E)-2,4-hexadiene (B) (2Z,4Z)-2,4-hexadiene
(C) (2Z,4E)-2,4-hexadiene (D) (2E,4Z)-2,4-hexadiene
10. How many stereogenic centers does the following molecule possess?
(A) two (B) three (C) four (D) six
11. How many configurational stereoisomers exist for 1,2-dibromocyclopentane?
(A) one (B) two (C) three (D) four
12. Which of the following is the strongest base?
(A) 
(B) 
(C) 
(D) 
13. Which of the following is the best nucleophile in a polar protic solvent?
(A) F– (B) Cl– (C) Br– (D)
I–
14. Which is the lowest energy conformation for the following molecule?
(A) (B) (C) (D)
15. Which reactants would be the best choice for making 1-phenyl-2-butyne?
(A) (B)
(C) (D)
16. Choose the major product(s) of the following reaction.
(A) (B) (C) (D)
17. Which of the following does not undergo SN2 displacement readily?
(A) (B) (C) (D)
18. What term best describes the relationship between the following structures?
(A) configurational diastereomers (B) configurational enantiomers
(C) conformational diastereomers (D) conformational enantiomers
19. What is the major product of the following reaction sequence?
(A) (B) (C) (D)
20. What nucleophile could be used to react with 1, 4-dibromobutane to prepare the following compound? (You may assume that base is present to remove extra protons.)
(A) 
(B) 
(C) 
(D) 
21. What is the major product of the following reaction?
(A) (B)
(C) (D)
22. From the bond energies given below calculate the values of ΔH for each step in the following reaction mechanism. Choose one of the answers listed in A, B, C or D.
Bond dissociation energies in kcal/mol : H-CH3 105;
H-I 71; I-I
36; CH3-I 58
(A)
step 1: -71 kcal/mol, step
(B)
step 1: + 34 kcal/mol, step
(C)
step
(D)
step 1: +105 kcal/mol, step
23. Suppose that ΔH for the following reaction is – 55 kcal/mol and that ΔG is +6 kcal/mol at 25oC. Is ΔS negative or positive? Is K greater than 1 or less than 1?
9 C(s) + 10 H2(g) → C9H20(l)
(A) ΔS is positive, K > 1 (B) ΔS is positive, K < 1
(C) ΔS is negative, K > 1 (D) ΔS is negative, K < 1
24. What alkene would give acetaldehyde (CH3CHO) as the only product when the alkene is treated with ozone followed by a reducing agent?
(A) (B) (C) (D)
25. What is the major product of the following reaction?
(A) (B) (C) (D)
26. What is the major product of the following reaction?
(A) (B)
(C) (D)
27. What would be the relative rates of hydrolysis (by an SN1 mechanism) of these compounds in water-acetone at 25oC?
(A) I > II > III (B) II > I > III (C) III > II > I (D) I > III > II
28. Which reaction sequence would accomplish the following transformation in several steps?
(A)
(B)
(C)
(D)
29. What is the major product of the following reaction? (Assume that the enantiomer of the product is also formed.)
(A) (B) (C) (D)
30. What starting material would produce the following product?
(A) (B) (C) (D)
31. What is the major product of the following reaction?
(A) (B) (C) (D)
32. Which of the following is the dienophile needed to prepare the following compound using a Diels-Alder reaction.
(A) CH3-CH=CH-CH=CH-CH3 (B) CH3-CH=CH-CH3 (C) 
(D)
33. What is the structure of the monomer that would produce polyacrylonitrile (below).
(A) CH3-CH=CH-CΞN (B) CH2=CH-CH=CH-CΞN
(C) NΞC-CH2-CH2-CΞN (D) CH2=CH-CΞN
34. What
should be the product of the following reaction?
(A) (B) (C) (D)
35. Which of the following compounds should absorb at the longest wavelength in the ultraviolet?
(A) (B) 
(C) (D)
36. If a free-radical bromination were performed on the chiral molecule below (stereochemistry shown), what should be the stereochemistry of the major product (stereochemistry not shown)?
(A) (S), since free-radical brominations occur with inversion of stereochemistry.
(B) (R), since free-radical brominations occur with retention of stereochemistry.
(C) (R), since free-radical brominations occur with inversion of stereochemistry.
(D) a racemic mixture of (R) and (S), since the radical intermediate is almost planar.
37. Which is the most acidic hydrogen in the following molecule?
(A) HA (B) HB (C) HC (D) HD
38. What is the major product of the following reaction?
(A) (B) (C) (D)
39. Which of the following is a propagation step in the free radical addition of HBr to propene?
(A) RO· + H-Br → ROH + Br·
(B) Br-CH2-CH-CH3 + H-Br → Br-CH2-CH2-CH3 + Br·
(C) CH2=CH-CH3 + Br· → CH2=CH-CH2· + H-Br
(D) Br-CH2-CH-CH3 + Br· → Br-CH2-CHBr-CH3
40. Which sequence of reactions could be used to prepare the following product?
(A) (1) CH2=CH-CN + CH2=CH-CH=CH2 (2) CF3CO3H (3) HO-, H2O
(B) (1) CH2=CH-CH=CH2 + CH2=CH-CN (2)
OsO4, then Na2SO3, H2O
(C) (1) HCΞC-CN + CH3CH=CH-CH=CH2 (2) BH3, then H2O2, HO-
(D)
Part B (3 x 4 = 12)
1. Draw two additional resonance forms for the following anion.
2. Draw an energy diagram for the following rearrangement. Label A, B, C and D on the diagram.
