Chemistry 332 - Spring 1996
Elements of Organic Chemistry II
Professor Carl C. Wamser
EXAM 1 - Answer Key
April 30, 1996
1. (15 points) Write a complete name for each of the following compounds:
a) 
(R)-6-hydroxy-3-methylhexanal
b) 
4-cyclobutyl-N,N-dimethylbutanamide
c) 
cyclohexyl 2-propenoate or cyclohexyl acrylate
d) 
3-methoxybenzoyl chloride or m-methoxybenzoyl chloride
e) 
6,6-dimethyl-2,4-cyclohexadienone
2. (15 points) Write accurate structures for each of the following names:
a) 3-oxohexanenitrile
b) protonated acetone (two resonance forms)
c) deprotonated formic acid (two resonance forms)
d) cyclopentanone imine
e) diethyl cis-1,2-cyclohexanedicarboxylate
3. (15 points) Complete each of the following reactions by adding the missing
part:
a) 
b) 
c) 
d) 
e) 
4. (15 points) Compound X is a product obtained from the reaction of formaldehyde
with ethanol.
The infrared spectrum of X shows no absorptions in the 4000-3000 cm-1
range nor in the 2500-1500 cm-1 range.
The 13C NMR spectrum shows just three absorptions.
The 1H NMR spectrum is shown on the next page.
Identify compound X and explain each of the points of information above,
including a balanced reaction showing how it is formed.
The IR spectrum shows no O-H bonds or C=O bonds.
(Also probably no C=C double bonds either).
The C NMR spectrum shows three different kinds of carbon - a, b, and c.
The H NMR spectrum shows three absorptions:
a - 2H singlet at 6 ppm
b - 2H quartet at 3.7 ppm
c - 3H triplet at 1 ppm
5. (15 points) Compound Y has the formula C10H11ClO
, and gives the 1H NMR spectrum shown on the previous page.
Identify compound Y and assign each of the NMR absorptions to specific hydrogens
in the structure.
aromatic - 5H multiplet at about 7 ppm
a - 2H singlet at 3.6 ppm
b - 2H triplet at 2.8 ppm
c - 2H triplet at 3.4 ppm
6. (15 points) Write a complete mechanism for the reaction of acetyl chloride
with sodium benzoate. (CH3COCl + C6H5COO-
Na+)
This reaction is typically carried out with neither acid nor base catalysis.
Explain.
No base: Added base is just likely to act as a competitive nucleophile towards
the acid chloride.
No acid: Acid is not needed to activate the acid chloride, which is already
highly reactive.
Also acid would protonate the benzoate anion and make it less nucleophilic.
7. (10 points) D-Ribose is shown below in its hemiacetal form. When it attaches
to the nitrogen bases of nucleic acids, it forms a linkage as shown on the
right below. Write a mechanism using acid catalysis and showing all steps.
This is a substitution reaction analogous to the formation of an acetal
from a hemiacetal.
Acid is used to set up the OH to leave, then the amine nucleophile adds.
