CHEMISTRY 212 EXAM 3 Monday, March 8, 2004 Answer Key
1. (3) The first step of a reaction between a ketone and a Wittig reagent is:
a) Protonation of the ketone O
b) Attack by the ketone O upon the P of the Wittig reagent
c) Attack by the Wittig C anion on the C of the ketone C=O
d) Loss of an alkene
e) Attack by the Wittig P atom on the C of the ketone C=O
2. (3) The first step of a reaction between an epoxide (cyclic ether) and H3O+ is:
a) Attack by the epoxide O upon the O of H3O+
b) Loss of water
c) Addition of H anion to the epoxide O
d) Attack by water upon a ring C
e) Protonation of the epoxide O
3. (3) Compound A (shown below) would react faster than B with MeMgBr because:
4. (8) Carvone is a major constituent of spearmint oil. Draw the products you would expect from reaction of carvone with each of the reagents shown:
5. (3) One of the following is true about BH3. Which one?
a) it reacts with nitro groups
b) it is a strongly electron-deficient species
c) it reduces carboxylic acids to esters
d) it is an initial source of H-
e) it is a very weak reducing agent
6. (5) Draw the carbonyl compound and the diol that would have been used to form the acetal shown:
7. (5) Show the ylide and carbonyl species necessary to make the molecule shown below via the Wittig reaction:
8. (14) For each of the following, indicate with an asterisk (*) the atom or atoms which could be attacked by a nucleophile / base (without the addition of any catalyst). In some cases, more than one site is a possible answer.
9. (10) For each of the molecules shown below, indicate with an asterisk (*) the atom that would attack an acid such as hydrochloric acid. There is only one answer in each case.
10. (3) True or False. The OH peak in the proton-NMR spectrum of a carboxylic acid or an alcohol will disappear on addition of D2O.
11. (5) Circle any of the following reagents that are not reducing agents?
a) LiAlH4 b) HOCH2CH2OH c) Zn / Hg, H+ d) NaBH4 e) BH3
12. (11) Name the following molecules using a method that would not be frowned on by the International Union of Pure and Applied Chemists.
7-bromo-2-butylheptanoic acid 1-isopropoxy-1-butene
13. (33) Fill in the missing products or reactants in the following reactions.
a)
b)
c)
d)
14. (6) In each of the following pairs, assign an appropriate infrared C=O stretching vibration value (choose from the numbers to the right) to each molecule.
15. (6) In each of the following pairs, circle the compound which will react faster with the reagent indicated. You need not explain why.
16. (15) In each of the following, use arrows to show the first complete step of a reaction between the molecules shown. You need not show the consequence of your arrows.
17. (9) In each of the following pairs circle the species that would have the more acidic H.
18. (3) Hexane boils more than 100°C lower than hexanoic acid. What is the most important factor contributing to the difference in boiling points?
(A) Hexane has a lower molecular weight than hexanoic acid.
(B) Hexanoic acid has more oxygen atoms than hexane.
(C) Hexane has a less branched structure than hexanoic acid.
(D) Hexane molecules do not engage in hydrogen bonding.
19. (2.5) True or False. Reactions between amides and nucleophiles are typically carried out in the presence of an acid catalyst to speed up the reaction.
20. (2.5) True or False. A primary amine reacts with a ketone to form a product with a C=C bond.