CHM 225: Organic Chemistry I
Exam I
Name: ________________________________________________
15 February 2013
This exam will be graded out of 114 possible total points. (Yes, I know that’s a little
strange.) Your score on this exam will be worth 15% of your total CHM 225 grade.
Question #
Points possible
1
10
2
4
3
18
4
9
5
9
6
22
7
10
8
10
9
8
10
8
11
6
This exam includes 6 numbered pages, including this page
Any form of cheating or attempted cheating or copying will result in a grade of zero on the exam, and may lead
to further disciplinary action.
1. (10 pts) Expand the line-angle (“skeletal”) structures shown below, clearly showing all atoms
(including hydrogens), all covalent bonds, and all lone pairs.
(Viz., draw these as Lewis structures)
a)
b)
2. (4 pts) Draw a line-angle (skeletal) structure of:
n-Octane
n-Undecane
1
3. (18 pts) Match each amine to its common name; write the appropriate letter in the space at left.
(One you may not have seen before, but you should be able to deduce its name.)
_____
A n-Butyl amine
_____
B sec-Butyl amine
_____
C tert-Butyl amine
CH3NH2
_____
D Ethyl amine
_____
E Isobutyl amine
_____
F Isopropyl amine
_____
G Methyl amine
_____
H n-Propyl amine
_____
I Triethyl amine
4. (9 pts) Draw an electron-pushing mechanism for the following molecule reacting with H–Br.
Include formal charges as necessary.

5. (9 pts) Draw an electron-pushing mechanism for the following anionic molecule reacting with
H–Br. Add in all formal charges as necessary.

2
6. (22 pts) Consider the following molecule (A).
A
B
C
a. Draw two resonance structures (you will refer to them as (B) and (C) ). Use proper
brackets and resonance arrows. If there are non-zero formal charges on any atoms,
clearly indicate them. Note: this molecule has more than two valid resonance
structures; you only need to show two here.
b. Concerning molecule A and the resonance structures you drew (B and C), indicate
whether they are major contributors (more important) or minor contributors (less
important) to the overall structure of the molecule. Give a brief justification for your
choice.
A:
B:
C:
c. Molecule A has ______ π bonds.
d. (Circle any that apply) Molecule A includes a/an
aryl ring
carbonyl
hydroxyl
3
7. (10 pts) Consider the structure of Molecule A again. Five atoms are indicated; determine the
hybridization of each of these atoms.
This carbon:
This hydrogen:
This oxygen:
This carbon:
This carbon:
8. (10 pts) Compare the following structures to molecule A. Predict whether the molecule will have a
higher boiling point or a lower boiling point, and give a brief justification for your choice.
A
I predict that this
molecule will have a
Higher
Lower
boiling point than
molecule A
I predict that this
molecule will have a
Higher Lower
boiling point than
molecule A
4
9. (8 pts) Molecule A is shown on the screen with surface calculations done in Spartan. Similar
calculations for water and hexane are also shown. Predict the solubility of molecule A in each
of these solvents, and provide a short (~3 sentence) justification.
Water:
Hexane
10. (8 pts) You and your lab partner, Ben Zene, are in organic chemistry together and are working
on developing a recrystalization protocol for Molecule A. Ben takes a ~500 mg sample of 90%
pure molecule A, and adds it to a 250 mL Erlenmeyer flask. He boils about 150 mL of
isopropanol and adds all of it to the flask of molecule A. Swirling it a few times, you observe it
dissolve. Ben is clearly thrilled and exclaims: “Well, I think we’re ready to go—let’s get our 5 g
sample!”
Do you feel confident enough to proceed? Is there other information you might want to try to
learn first?
5
11. (6) You have a 2:1 mixture of the following two molecules
Napthalene
2-Napthylamine
To isolate the napthalene I would
A. Dissolve both molecules in ether, then add 2 M NaOH, mix, and allow the
layers to separate in a sep funnel. Keep the aqueous layer, add conc. HCl to it,
and filter the precipitate.
B. Dissolve both molecules in ether, then add 2 M HCl, mix, and allow the layers
to separate in a sep funnel. Keep the aqueous layer, add 6 M NaOH to it, and
filter the precipitate.
C. Dissolve both molecules in ether, then add 2 M NaOH, mix, and allow the
layers to separate in a sep funnel. Keep the ether layer, dry it with Na2SO4,
filter, and rotovap the solvent.
D. Dissolve both molecules in ether, then add 2 M HCl, mix, and allow the layers
to separate in a sep funnel. Keep the ether layer, dry it with Na2SO4, filter, and
rotovap the solvent.
E. Attempt to find a recrystalization procedure using a variety of different solvents.
To isolate the 2-napthylamine I would
A. Dissolve both molecules in ether, then add 2 M NaOH, mix, and allow the
layers to separate in a sep funnel. Keep the aqueous layer, add conc. HCl to it,
and filter the precipitate.
B. Dissolve both molecules in ether, then add 2 M HCl, mix, and allow the layers
to separate in a sep funnel. Keep the aqueous layer, add 6 M NaOH to it, and
filter the precipitate.
C. Dissolve both molecules in ether, then add 2 M NaOH, mix, and allow the
layers to separate in a sep funnel. Keep the ether layer, dry it with Na2SO4,
filter, and rotovap the solvent.
D. Dissolve both molecules in ether, then add 2 M HCl, mix, and allow the layers
to separate in a sep funnel. Keep the ether layer, dry it with Na2SO4, filter, and
rotovap the solvent.
6