Name:
Chem 22
Exam 3
05/03/00
1.
Give the product (s) of each of the following reactions. For the reactions that have multiple steps
give the product(s) for each step.
a) benzaldehyde + butanal + 1) sodium hydroxide 2) H2O
(hint: mixed aldol condensation)
b)
C)
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d)
Is this reaction an oxidation or a reduction reaction?
e)
Is this reaction an oxidation or a reduction reaction?
2.
Give the reagent (s) for each of the following reactions
a)
2
b)
c)
d)
3)
Using the given starting material, any necessary inorganic reagents, and any carbon containing
compounds , indicate how the following synthesis could be carried out.
a)
3
b)
4.
Propose a mechanism for the following reaction. Show arrows for each step and include
important resonance structure.
5.
Draw the structures or give the names of each of the following compounds
a)
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b)
c)
6. For each of the following sets of compounds indicate which one is the most acidic and give a grief
expanation.
a)
i)
ii)
i)
ii)
b)
5
7.
The ketone whose 1H NMR spectrum is shown below was obtained as the product of an
acetoacetic ester synthesis.
Analyze the spectra in terms of
a. integration
b. splitting pattern (coupling pattern)
c. chemical shift
and then draw the structure and indicate which peak belong to which protons
6
.
Multiple Choice (Choose only one answer)
1.Which of the following does NOT describe a mechanism by which a molecule of hydrogen can be added
to an organic compound?
a)
b)
c)
d)
addition of two hydrogen atoms
addition of a hydride ion and a proton
addition of two hydrogen radicals
addition of two electrons and two protons
2.Which of the following reagents is commonly referred to as DIBAH (DIBALH)?
a)
b)
c)
d)
e)
LiAl(iso-butyl)4
LiALH(O-tert-butyl)3
LiAlH2(O-tert-butyl)2
LiALH(iso_butyl)3
LiAlH2(iso-butyl)2
3.What does reduction do to a compound?
a)
b)
c)
d)
e)
it increases the number of carbon-oxygen bonds
it increases the number of carbon-halogen bonds.
It decreases the number of carbon-hydrogen bonds
It increases the number of carbon-hydrogen bonds
a and c
4.Which of the following regents will convert 2-methyl-2-butene to one equivalent of acetone and one
equivalent of acetaldhyde?
a) i) O3 ii) (CH3)2S
b) HIO4
c) KMnO4, HO-, heat
d)
KMnO4, H+
e) MMPP
5. What compound is formed when ethanol is treated with PCC in dry methylene chloride?
a)
b)
c)
d)
e)
ethane
acetone
acetaldehyde
acetic acid
ethyl chloride
6.What product is formed when a ketone reacts with a peroxyacid?
a)
b)
c)
d)
e)
an ester
a carboxylic acid
No reaction will occur
An aldehyde
An alcohol
7.Which of the following reagents can be used to reduce a carboxylic acid?
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a)
b)
c)
d)
e)
KMnO4/H2O4
PCC
H2/Pt
1. LiAlH4/ 2. H2O
1. NaBH4/2. H2O
8.Which of the following is not an oxidizing agent?
a)
b)
c)
d)
e)
CrO3
H2O2
KMnO4
LiAlH4
Ag2O
9. An ester is reduced by lithium aluminum hydride to form:
a)
b)
c)
d)
e)
two alcohols
an aldehyde and an alcohol
a ketone
an aldehyde
a carboxylic acid and an alcohol
10. What product is formed in the dissolving metal reduction (Na/NH 3) of 2-butyne?
a)
b)
c)
d)
e)
cis-2-butene and butane
equal amounts of trans-2-butene and cis-2-butene
trans-2-butene, cis-2-butene, and butane
cis-2-butene
trans-2-butene
11.Which of the following is NOT a true statement?
a)
b)
c)
d)
in a reduction reaction, the number of carbon-hydrogen bonds increase
in a reduction reaction, the reducing agent is reduced
in a reduction reaction, the compound that is oxidized loses electrons
In a reduction reaction, the compound that is reduced gains electrons
12.what is the approximate pKa of ethane?
a)
b)
c)
d)
e)
–5
+50
+25
+5
0
13.What product is formed when butanal is treated with chlorine in a basic solution?
a) 2,2-dichlorobutanoyl chloride
b) 2,2-dichlorobutanal
c) 2-chlorobutanal
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d) butanoyl chloride
e) 2,2,3,3,4,4-hexachlorobutanal
14. Which of the following is LDA? (Me =CH3)
a) Li+ -N(CHMe2)
b) Li+ -N(CMe3)
c) Li+ -N(CH2Me)
Li+ -N(CH2Me)2
e)
f) Li+ -N(CHMe2)2
15. In Michael reaction, nucleophilic addition occurs at the:
a)
b)
c)
d)
e)
beta carbon
alpha carbon
gamma carbon
delta carbon
carbonyl carbon
16.Which of the following compounds will be most apt to undergo decarboxylation when it is heated?
a)
b)
c)
d)
e)
2-oxopropanoic acid
3-ocopentanoic acid
butanoic acid
5-oxohexanoic acid
3-oxobutanoic acid
17.What ring sizes are possible when a 1.6-dietone undergoes an aldol addition; what ring(s) are actually
formed?
a)
b)
c)
d)
e)
5-and 7- membered rings; both are formed
4- and 6- membered rings; 6-membered ring is formed
5- and 7- membered rings; 7-membered ring is formed
6- and 8- membered rings; 6-membered ring is formed
5- and 7- membered rings; 7-membered ring is formed
18.What is the approximate pKa of carbonyl compounds such as aldehydes, ketones and esters?
a)
b)
c)
d)
e)
-5 to 5
15 to 25
–15 to –5
–5 to 15
25 to 35
19.What stabilizes the keto form of acetylacetone?
a)
b)
c)
d)
e)
the C = C double bond is conjugated with a C = O bond
the enol engages in intermolecular hydrogen bonding
the enol enagaes in intramolecular hydrogen bonding
both (a) and (b) play a role
both (a) and (c) play a role
20. What kind of compound can undergo a halofrom reaction?
a) a compound that contains: R-CH2–C (=O)-CH2-R
b) a compound that contains: CH3C (=O)-R
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c) a compound that contains: CH3C (=O)-OR
d) a compound that contains: R-CH2–C (=O)-R
e) a compound that contains: CH3C (=O)-NHR
21.Which of the following are true about a Claisen condensation?
a)
b)
c)
d)
e)
the reactants are two molecules of an ester and an equivalent of a base
the base is the same as the leaving group of the ester
the products are a bet-keto ester and an alcohol
all of the above
only a and c
22. What is the main reason that a hydrogen bonded to a carbon adjacent to a carbonyl crbon is more acidic
than a hydrogen of an alkane?
a) the negative charge is stabilized by its proximity to the negatively charged carbonyl carbon
b) The carbonyl group is an electron-withdrawing group and weakens the C_H bond in the
alpha-position
c) The negative charge is delocalized, and most of the charge resides on the alpha-carbon
d) The carbonyl group is an electron-donating group and weakens the C_H bond in the alphaposition.
e) The negative charge is delocalized, and most of the charge resides on the electronegative
carbonyl oxygen.
23.Which statement best describes keto-enol interconversion?
a)
b)
c)
d)
the reaction is not affected by catalysts
it is always a base-catalyzed reaction
it is always an acid-catalyzed reaction
it can be either an acid-catalyzed or a base-catalyzed reaction
24.What is Robinson annulation?
a)
b)
c)
d)
e)
an intramolecular aldol reaction follwed by a Michael reaction
Claisen reaction followed by a Michael reaction
A Michael reaction followed by an intermolecular aldol reaction
A Michael reaction followed by an intramolecular aldol reaction
An intermolecular aldol reaction foolowed by a Michael reaction
25. What class of compounds is prepared using a malonic ester synthesis?
a)
b)
c)
d)
e)
a beta-hydroxyester
a carboxylic acid
a 1,2-dicarbonyl compound
a bet-keto ester
a 1,3-dicaronyl compound
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1.
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