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Assignment CHM 6 2011
In this assignment:
- Mechanisms
- Acid/base
- Epoxide reactions
- Elimination reactions
Remember how to calculate formal charge?
F.C. = # of electrons in the neutral atoms valence # of bonds # of lone electrons
What does F.C. tell us?
If there is a + or - charge on an atom
(+ and - is determined by electronegativity differences)
1. Draw a mechanism to explain the formation of the following intermediates and
products. Note that these are not reactions that you have seen (yet) or need to
memorize (yet). Rather, you should analyze each reaction and show the reaction flow
using a mechanism (curved arrows).
a.
b.
c.
d.
e.
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f.
g.
2. Draw the following:
a. A deprotonated carboxylic acid
b. A protonated amine
c. A protonated ketone
d. A deprotonated alkyne
e. The reaction that occurs when sodium methoxide dissolved in water (include
a mechanism).
f. The reaction that occurs when lithium amide (LiNH2) dissolves in methanol.
g. The reaction that occurs when hydrochloric acid is dissolved in water
h. The reaction that occurs when sulfuric acid is dissolved in ethylamine
3. Give the major organic product for each of the following reactions. Give a
mechanism for parts a and b.
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4. Analyze the products from question 1.
a. What type of functional group always forms when an epoxide is opened?
b. What is the relative stereochemistry between the nucleophile and the oxygen
from the epoxide?
5. Predict all the elimination products of each of the following reactions. Identify the
major and minor products. Give a mechanism for parts a and b.
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6. Name the following compounds
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7. Predict the products of elimination for the following compounds. Predict the relative
amounts of each product.
8. When 1-bromomethylcylcohexene is heated in ethanol, three products are observed.
Give mechanisms to account for each product.
9. a) Design an alkyl halide that will give only 2, 4-diphenyl-2-pentene treatment
with upon potassium tert-butoxide (a strong hindered base).
b) What relative stereochemistry is required in your alkyl halide so that only the
following stereoisomer of the product is formed?
10. When 2-bromo-3-phenylbutane is treated with sodium methoxide, alkenes result in
addition to the substitution product.
a) Draw a mechanism for the reaction showing the major and minor products. Clearly
indicate the source of each product (mechanism)
b) When one pure diastereomer of the starting material reacts, one pure isomer of the
major product results. Predict which diastereomer will produce the isomer that has
the methyl groups cis.
c) Draw a Newman projection of the transition state to justify your choice in part b.
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d) Draw a Newman projection of the transition state to show the formation of the trans
isomer from the other diastereomer.
e) Predict the stereochemistry of the product produced from the enantiomer of part b.
11. Some of the following can exist as stereoisomers and some cannot. For the ones that
can, draw the isomers and assign names.
12. Explain why a strong base such as tert-butoxide cannot dehydrate an alcohol through
an E2 mechanism. What can be done to the alcohol to dehydrate it (give 2 methods)?
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13. Predict the elimination products that result when the following are heated in
alcoholic KOH. When more than one product is possible, predict the relative
amounts.
14. Explain the difference in the following reactions.
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15. For each of the following reactions, indicate if the reaction will work well, poorly or
not at all. Give mechanisms and brief justifications.
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16. Propose syntheses of the following molecules from the indicated starting materials.
You may use any reagents or solvents needed. Give mechanisms for all
transformations. Provide a retrosynthetic analysis for each.
17. Draw mechanisms and energy diagrams for the following reactions.
18. Explain the following result:
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