Tamu Chem 238 final, CHEM 238 FINAL, Ochem 2 Lab
Final Questions With Complete Solutions
1. Reaction of ethyl magnesium bromide with water will
generate?
a. ethanol
b. ethane
c. butane
d. ethyl magnesium hydroxide
e. a peroxide Correct Answers b
2. Under conditions of thermodynamic control, product
distribution is governed by:
a. the relative stabilities of the products
b. the relative energies of the transition states leading to the
products
c. the rate at which each product is formed
d. a and b
e. b and c Correct Answers a
3. Which of the following statements is false for the reduction of
camphor?
a. A hydride is transferred from the borohydride ion to the
carbonyl of camphor.
b. Isoborneol is the major product.
c. One mole of NaBH4 can reduce four moles of camphor.
d. The borohydride ion can approach the camphor more easily
from the exo side.
,e. If LiAlH4 is used instead of NaBH4, ethanol cannot be used
as a solvent. Correct Answers d
4. In an aqueous organic extraction,
a. the less dense layer is on top
b. the more dense layer is on top
c. aqueous layer is always on top
d. the phase with less sample dissolved is always on top
e. the organic layer is always on top Correct Answers d
5. The dimeric structure of diphosphomevalonate decarboxylase
involves:
a. Covalent amide linkages
b. Van der Waals interactions of non-polar side chains
c. Interactions of polar sidechains of amino acids
d. Hydrogen bonding of amide carbonyls with nearby amide N-
H bonds
e. Covalent disulfide linkages Correct Answers c
6. A good classification test (reaction which provides easy
detection of positive result) for a carboxylic acid is
a. the Hinsberg test
b. treatment with 2,4-dinitrophenylhydrazine solution
c. sodium fusion
d. the evolution of carbon dioxide upon addition of sodium
bicarbonate
e. reaction with thionyl chloride Correct Answers d
,7. What will happen if you don't cool the diazonium chloride
salt before addition of phenol?
a. It will still produce same diazonium compound
b. It will be converted to a phenol
c. It will be converted to an amine
d. It will produce a different diazonium compound
e. It will react with unreacted amine present in solution Correct
Answers b
8. Which statement best describes the first steps in the aldol
condensation?
a. a-hydrogen abstraction followed by enolate formation
b. nucleophilic attack by hydroxide on carbonyl carbon followed
by hydride transfer
c. aldehyde hydrogen abstraction followed by enolate formation
d. aldehyde hydrogen abstraction followed by hydride transfer
e. a-hydrogen abstraction leading to enolate formation Correct
Answers e
9. Which combination might give an ester that will not be
volatile enough to have significant odor?
a. benzyl alcohol and salicylic acid
b. methyl alcohol and formic acid
c. methyl alcohol and acetic acid
d. acetic acid and 2-methyl-1-propanol
e. formic acid and ethyl alcohol Correct Answers a
, 11. The purpose of spotting a mixture of all possible products on
the TLC plate is to:
a. identify which product was synthesized by comparing your
product to the Rf values from
the mixture
b. demonstrate which products you should have had
c. identify the dinitration product
d. identify any impurities
e. for comparison of the crude product Correct Answers a
12. Which of the following chemicals will not react with
Grignard Reagent?
a. water
b. carbon dioxide
c. ethyl ester
d. diethyl ether
e. acetone Correct Answers d
13. In both the Reactions of Aldehydes and Ketones Experiment
and Borohydride Reduction of Camphor Experiment, the
purification method of the crude products is recrystallization
from aqueous ethanol. What is the main purpose of adding water
to the hot ethanol solution of products?
a. to dissolve insoluble impurities
b. to dissolve the organic products
c. to produce turbidity so that impurities can come of the
solution
d. to decrease the polarity of the solvent, thus reduce the
solubility of the organic products
Final Questions With Complete Solutions
1. Reaction of ethyl magnesium bromide with water will
generate?
a. ethanol
b. ethane
c. butane
d. ethyl magnesium hydroxide
e. a peroxide Correct Answers b
2. Under conditions of thermodynamic control, product
distribution is governed by:
a. the relative stabilities of the products
b. the relative energies of the transition states leading to the
products
c. the rate at which each product is formed
d. a and b
e. b and c Correct Answers a
3. Which of the following statements is false for the reduction of
camphor?
a. A hydride is transferred from the borohydride ion to the
carbonyl of camphor.
b. Isoborneol is the major product.
c. One mole of NaBH4 can reduce four moles of camphor.
d. The borohydride ion can approach the camphor more easily
from the exo side.
,e. If LiAlH4 is used instead of NaBH4, ethanol cannot be used
as a solvent. Correct Answers d
4. In an aqueous organic extraction,
a. the less dense layer is on top
b. the more dense layer is on top
c. aqueous layer is always on top
d. the phase with less sample dissolved is always on top
e. the organic layer is always on top Correct Answers d
5. The dimeric structure of diphosphomevalonate decarboxylase
involves:
a. Covalent amide linkages
b. Van der Waals interactions of non-polar side chains
c. Interactions of polar sidechains of amino acids
d. Hydrogen bonding of amide carbonyls with nearby amide N-
H bonds
e. Covalent disulfide linkages Correct Answers c
6. A good classification test (reaction which provides easy
detection of positive result) for a carboxylic acid is
a. the Hinsberg test
b. treatment with 2,4-dinitrophenylhydrazine solution
c. sodium fusion
d. the evolution of carbon dioxide upon addition of sodium
bicarbonate
e. reaction with thionyl chloride Correct Answers d
,7. What will happen if you don't cool the diazonium chloride
salt before addition of phenol?
a. It will still produce same diazonium compound
b. It will be converted to a phenol
c. It will be converted to an amine
d. It will produce a different diazonium compound
e. It will react with unreacted amine present in solution Correct
Answers b
8. Which statement best describes the first steps in the aldol
condensation?
a. a-hydrogen abstraction followed by enolate formation
b. nucleophilic attack by hydroxide on carbonyl carbon followed
by hydride transfer
c. aldehyde hydrogen abstraction followed by enolate formation
d. aldehyde hydrogen abstraction followed by hydride transfer
e. a-hydrogen abstraction leading to enolate formation Correct
Answers e
9. Which combination might give an ester that will not be
volatile enough to have significant odor?
a. benzyl alcohol and salicylic acid
b. methyl alcohol and formic acid
c. methyl alcohol and acetic acid
d. acetic acid and 2-methyl-1-propanol
e. formic acid and ethyl alcohol Correct Answers a
, 11. The purpose of spotting a mixture of all possible products on
the TLC plate is to:
a. identify which product was synthesized by comparing your
product to the Rf values from
the mixture
b. demonstrate which products you should have had
c. identify the dinitration product
d. identify any impurities
e. for comparison of the crude product Correct Answers a
12. Which of the following chemicals will not react with
Grignard Reagent?
a. water
b. carbon dioxide
c. ethyl ester
d. diethyl ether
e. acetone Correct Answers d
13. In both the Reactions of Aldehydes and Ketones Experiment
and Borohydride Reduction of Camphor Experiment, the
purification method of the crude products is recrystallization
from aqueous ethanol. What is the main purpose of adding water
to the hot ethanol solution of products?
a. to dissolve insoluble impurities
b. to dissolve the organic products
c. to produce turbidity so that impurities can come of the
solution
d. to decrease the polarity of the solvent, thus reduce the
solubility of the organic products
