CHEM 233 Final Review

1. Final Review Session
12:30 pm – 2:00 pm

2. The terminal hydrogens on allene, pictured below, lie in planes that are
perpendicular to each other. Draw the σ and π-bonding framework to
explain why.

3. Arrows!

4. Circle all true statements about stereochemistry.
i) Two molecules that are enantiomers are chiral
ii) A 50:50 mixture of diastereomers will not rotate plane polarized
light.
iii) Meso compounds have no chiral centres.
iv) Enantiomers have different physical properties
v) Achiral compounds can exist as diastereomers
vi) Switching the methyl and hydrogen on propene leads to a new
stereoisomer.
vii) A meso compound can have a chiral diastereomer

5. Major contributing resonance structure

6. Which of the following molecules are aromatic?

7. Which of the following molecules are aromatic?

8. Identify the molecule with the lowest pKa
a) b)
c) d)

9. Identify the molecule with the lowest pKa (pKa of hydrogen in red)
a)
b)

10. Rank the following from least to most acidic.

11. Which of the following in each pair is more basic?

12. Rank the following electrophiles in order from slowest to fastest SN2
reaction rate.

13. Rank the following carbocations from slowest to fastest-forming from their
respective alkenes.

14. Fischer to chair

15. E2
Complete the template which would react under the noted conditions to
provide the alkene product as the only stereoisomer

16. The reaction of alcohol D and acetone in the presence of anhydrous HCl in an
attempt to prepare ketal E led to the formation of unexpected side product F.
Write a mechanism for the formation of F.

24. Using any of the molecules in the box, synthesize the following
compound.

25. Draw the product(s) of the following reaction:
Stereochemically, how are the products related?
a) Enantiomers
b) Diastereomers
c) There is no stereochemistry
d) There is only one product
e) None of the above
Δ

26. Provide a mechanism for the following reaction:
H2O

27. Draw the product(s) of the following reaction:

28. The expected product of the following reaction was not isolated. Explain
why.
cat. H2SO4
Δ

29. The expected product of the following reaction was not isolated. Explain
why.
cat. H2SO4
Δ

30. Under E1 conditions, the top molecule yields two isomers, while the lower
molecule gives only one isomer. Provide the outcome of each reaction, and
explain the differences in regioselectivity.
cat. H2SO4
Δ
cat. H2SO4
Δ

31. The following reaction does not give any aldol products. Explain why.
NaOMe
HOMe
Δ

32. The following synthesis does not yield the desired products. (i) Explain why
and (ii) propose an alternative synthesis.
cat. H2SO4
H2O

33. The following synthesis does not yield the desired product. (i) Explain why
and (ii) propose an alternative synthesis.
NaOH
H2O

34. The following synthesis does not yield the desired product. (i) Explain why
and (ii) propose an alternative synthesis.
NaOEt
HOEt

35. The following synthesis does not yield the desired product. (i) Explain why
and (ii) propose an alternative synthesis.
1 equiv. LDA
iPrBr

36. The following synthesis does not yield the desired product. (i) Explain why
and (ii) propose an alternative synthesis.
NaOH, H2O
CH3I

37. Thiols can be added to ketones, under acidic conditions, to form an acetal
equivalent known as a thioacetal. Propose a mechanism for this process.

38. • Provide a mechanism for the following transformation.

39. In seawater, CO2 and H2O react to form carbonic acid. Draw a mechanism for
this process. Assume catalytic acidic conditions.

40. Provide a mechanism for the following transformation:

41. Provide a mechanism for the following transformation:

42. Provide a mechanism for the following transformation:

43. Provide a mechanism for the following transformation:

44. For each set, rank the following from least to most reactive to nucleophiles.

45. Synthesize the following molecule from (i) diethyl malonate and (ii)
acetoacetic ester.

46. Synthesize the following molecule from (i) a single organic compound
and (ii) two separate organic compounds.

47. Synthesize the following (racemic mixture), starting with an aldehyde
or ketone.

48. The Wieland-Miescher ketone (below) is a molecule used in the
synthesis of several natural products, including steroids. Propose a
synthesis of this molecule.

49. Identify which compounds can be made directly from a/ an (multiple
answers possible):
(A) Aldol addition (B) Aldol condensation
(C) Claisen condensation (D) Dieckmann cyclization
(E) NAS reaction (excluding Claisen)(F) Alpha alkylation
(G) None of the above

50. Identify which compounds can be made directly from a/ an (multiple
answers possible):
(A) Aldol addition (B) Aldol condensation
(C) Claisen condensation (D) Dieckmann cyclization
(E) NAS reaction (excluding Claisen)(F) Alpha alkylation
(G) None of the above

51. Alcohol A (C6H14O) is chiral. Reacting A with PBr3, NaSCH2CH3 in DMSO gives
optically pure compound B (C8H18S). Compound A additional reacts with cat.
H2SO4, CH3O to give an optically active mixture of ether C (C7H16O). Draw
compounds A, B and C. Any stereoisomer of A is sufficient, but B and C must
be consistent with A.
A C
B

52. Carbonyl A (C5H10O) gives a negative Tollens test. Treatment of A with LDA
and ethyl bromide gives a racemic mixture of compound B (C7H14O). Draw
compounds A and B.
A B