CH237 ORGANIC CHEMISTRY LABORATORY EXAM
(July 5, 2006, summer I session, Blackstock)
name:__________________________
honor pledge:__________________________
This exam is worth 100 points toward your final course grade. There are 5 pts extra credit built in.
I. Chemical Structures (20 pts, 2 each)
Write the chemical structures (including stereochemistry) of the compounds listed below. All of these
chemicals were used in the laboratory this semester.
a. aspirin
b. ethylacetate
c. trans-cinnamic acid
d. trityl fluoroborate salt
e. two common drying agents used in the lab
f. two suitable solvents for NMR spectroscopy
measurements
g. the product from bromination (with Br2 in AcOH)
of cis-cinnamic acid (indicate stereochemistry)
h. the Grignard reagent used to make
triphenylmethanol
i. biphenyl
j. banana oil
II. Balanced Chemical Reactions (10 pts, 5 each)
Write balanced chemical equations for the reactions used to prepare the following organic compounds starting
from reagents used in the lab. Indicate the solvent and reaction conditions employed. (no mechanisms here!)
banana oil (experiment 3)
acetyl ferrocene (experiment 7)
III. Reaction Mechanisms (12 pts, 6 each)
Show the major organic product and the mechanism of its formation for the reactions below.
a.
CH3
OH
85% H3PO4
!
Zaitsev product
2
b.
H
O
+
2
O
NaOH, EtOH, !
IV. General Laboratory Knowledge (48 pts) - brief answers please.
1. (2 pts) Does aspirin have a higher solubility in dichloromethane or aqueous base?
2. (2 pts) Does phenacetin have a higher solubility in dichoromethane or aqueous base?
3. (2 pts) What device is used in the chemical laboratory to separate two immiscible liquids of differing density
(a device you used this session)?
4. (2 pts) What is a key feature of a good recrystallization solvent?
5. (2 pts) Impure solids generally melt at (circle one) lower / higher / the same temperature as a pure solid.
6. (2 pts) Name two ways to separate two solids from each other.
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7. (6 pts) What are the three general routes by which substances may enter the body and three accompanying
practices used in the laboratory to reduce exposure to toxic substances via these routes?
8. (2 pts) When distilling an ideal binary mixture of liquids through an efficient column the pot temperature
will be (circle one) higher / lower than the head temperature.
9. (2 pts) What term is used for a mixture of liquids whose vapor composition equals exactly its liquid
composition?
10. (2 pts) In an extraction involving dichloromethane / water, which phase will be on top?
11. (2 pts) To extract an organic material from aqueous solution, would it be better to do one extraction with
100 mL ether or 2 extractions with 50 mL each of ether?
12. (2 pts) What are two common methods of visualizing the “spots” of molecules on TLC plates?
13. (2 pts) If a polar compound gives an Rf value of 0.5 using elution with 1:1 hexane : ethylacetate, what will
happen to its Rf value if the amount of ethylacetate is increased?
14. (2 pts) What are the two common stationary chromatography phases for TLC or column chromatography?
15. (2 pts) What material is used to contain the sample for measurement if its IR spectrum?
16. (2 pts) List two ways to separate two liquids from each other.
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17. (2 pts) Write the structure of the compound which serves as a chemical shift reference for 1H- and 13CNMR (δ = 0.0 ppm).
18. (2 pts) How can one distinguish an alcohol from an ester by IR spectroscopy?
19. (2 pts) Why is fluted filter paper used in the gravity filtration of liquids?
20. (6 pts) List any problems with the following set up.
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V. Organic Spectroscopy Problem (15 pts)
Please refer to the spectral information to answer the following questions for an unknown of formula C6H6NBr
1. (2 pts) Provide the unsaturation index for this molecule.
2. (3 pts) Does the structure contain any sp3 CH's, sp2 CH's, any NH's?
3. (10 pts) Propose a structure for this molecule based on all the spectroscopic data and assign each signal in the
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H NMR spectrum to the appropriate H in the molecule.
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IR spectrum
C-NMR spectrum (in d1-chloroform)
H-NMR (in d1-chloroform)
H-NMR expansion (in d1-chloroform)
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scratch
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