Problem Set 5
Chapter 6
Due: Monday, October 10, 2005
1. Study #2 and #3 in the Alkyl Halide
module and #1 in the Ether module in ORGO. 2. Hydrocarbon A forms only two
monochlorinated compounds B and C in nearly
equal amounts as predicted by calculation. B is a
racemate and C is achiral. Compound B reacts
with aqueous NaOH to give alcohol D and compound
E. C reacts with water to give alcohol
F and compound G. Both E and G
react with hydrogen and a catalyst to give a saturated
hydrocarbon with a heat
of formation of -42.5 kcal/mol.
What are the structures A-G? Explain and
illustrate. Biot
examining Pasteur's tartrate crystals b) A student recognizes that ΔGo
is not quite ΔHo but at 400oK, ΔGo=-1.84log10Keq.
The difference in the heats of formation of the two
geometrical stereoisomers translates into a calculated ratio
of 3.5:1. Is he using the correct analysis in spite of the
fact that his ratio is not the observed ratio?
Explain. c) A and B represent two
relevant, staggered conformations of 2-bromobutane. Assign
A and B as Newman projections. Explain your
choice. d) Why is the third staggered
conformation C not included on the
diagram? e) What are the two fastest processes in
this diagram: A-->B,
B-->E, E-->B,
B-->A, A-->D, or
D-->A? Explain. f) Another student suggests that the
observed ratio is determined by the difference in the rate
of formation of D vs. E. Show how this
difference is reflected in the diagram. 4. Provide the products in each of the
following questions and mechanisms for their formation. Pay
attention to stereochemistry. Be explicit about
enantiomers. 5. Compound A reacts very slowly
with hot KOH to form alcohol B. No products of
elimination are formed. When A is heated with aqueous
AgNO3, AgBr is formed in addition to C
(C5H12O), D (major) and
E (minor). D and E absorb 1 equiv. of
H2 in the presence of a Pd catalyst to form
2-methylbutane. What are the structures of A-E?
Explain and illustrate. 6. Compound A, (1S, 2R,
5S)-1-chloro-2-isopropyl-5-methylcyclohexane, and
compound B, (1S, 2S,
5R)-1-chloro-2-isopropyl-5-methylcyclohexane both react
with C2H5ONa in ethanol to give
products of elimination. A gives only C while
B gives a 1:3 ratio of D and E,
respectively. Compounds C, D, and E are
reduced with H2 to give cyclohexanes. Reduction
of C or D gives F, while reduction of
E affords F and G. a) What are the structures A-G?
Explain and illustrate. Provide clear mechanisms for the
formation of C-E. b) What is the relationship between
C and D? c) Which compounds are optically active?
Which ones are not? d) Imagine that an equimolar mixture of
A and B reacts with half as much sodium
ethoxide. Does a A or B react faster? Why?
What is formed?
3. When 2-bromobutane is treated with alcoholic KOH at
400oK, trans- and cis-2-butene (and some
1-butene) are formed in a ratio of 6:1, respectively. In a
separate experiment, the two 2-butenes are found to be
stable to the reaction conditions.
a) Using the Heats
of Formation and the reaction
coordinate diagram on the right, predict which product is
E and which one is D. Explain.