Chem 6B-4 Experiment 2 Questions
Answer the following 4 questions and include them in your report for Experiment 2
following your Discussion / Conclusion:
1.
What is the KI-starch test testing for?
2.
In this experiment, we neutralize the acid by adding sodium carbonate. You will
have observed fizzing on this addition. i.e. a gas is produced. What is the gas?
3.
Briefly explain what is meant by the term “salting out”.
4.
Explain why there are only three sets of signals in the 1H NMR spectrum of
cyclohexanone. (Make sure you assign these signals in your results section).
Chem 6B-4 Experiment 3 Questions
Answer the following 3 questions and include them in your report for Experiment 3
following your Discussion / Conclusion:
1.
Aqueous sodium hydroxide is needed in this experiment in order to generate the
carbanion intermediate. However, it is not miscible with hexane, the solvent used
to dissolve the phosphonate and benzaldehyde. How is this problem solved?
2.
Why is a drying tube not used during the one hour of refluxing in this experiment?
3.
Which isomer of stilbene would be preferentially formed if the corresponding
Wittig reaction were used?
Chem 6B-4 Experiment 4 Questions
Answer the following 2 questions and include them in your report for Experiment 4
following your Discussion / Conclusion:
1.
Explain why it is important to use a calcium chloride-charged drying tube in the
first part of this experiment.
2.
The product was not purified in this experiment. Describe how the relative
amounts of each component present in your product mixture were determined.
Chem 6B-4 Experiment 5 Questions
Answer the following 2 questions and include them in your report for Experiment 5
following your Discussion / Conclusion:
1.
Explain why we wash the triphenylmethanol crystals with petroleum ether at the
end of the product purification procedure in this experiment.
2.
Discuss three important experimental parameters for the successful preparation of
the Grignard reagent in this experiment.
Chem 6B-4 Experiment 6 Questions
Answer the following 2 questions and include them in your report for Experiment 6
following your Discussion / Conclusion:
1.
Give an example of another Diels Alder reaction, including the mechanism.
2.
The maleic anhydride used in this experiment may not be pure. What else is likely
to be present?
Chem 6B-4 Experiment 7A Questions
Answer the following 2 questions and include them in your report for Experiment
7A following your Discussion / Conclusion:
1.
The formation of the tetraphenylcyclopentadienone in Part 3 is the result of an
aldol condensation between benzil and dibenzyl ketone, followed by an
intramolecular aldol condensation. Write a mechanism for these reactions.
2.
Give the other aldol condensation that could also occur in Part 3 of this
experiment.
Chem 6B-4 Experiment 7B Questions
Answer the following question and include it in your report for Experiment 7B
following your Discussion / Conclusion:
1.
The formation of hexaphenylbenzene in Part 6 is the result of the Diels-Alder
reaction of diphenylacetylene and tetraphenylcyclopentadienone, followed by carbon
monoxide extrusion. Write a mechanism for these reactions.
Chem 6B-4 Experiment 8 Questions
Answer the following question and include them in your report for Experiment 8
following your Discussion / Conclusion:
1.
Label the following in terms of increasing reactivity with bromine in acetic acid
(1-3, where 1 is the most reactive). Explain your answer.
O
N
H
C
H
H
N
2
aniline
acetanililde
2.
3
benzene
Fill in the missing 3 resonance contributors which show why –NHAc is an
ortho/para director. Include arrows to show the movement of electrons.
O
N
H
O
C
H
3
N
H
C
H
3.
Briefly explain why only para-bromoacetanilide was formed in this experiment.
i.e. why was there no ortho-bromoacetanilide produced?
Name: ___________________
Chem 6B-4 Laboratory Quiz Number One
Answer the following 5 questions. Total: 10 points
Experiment 1: Fischer esterification.
1.
(2 pts) Excess ethanol is used in this experiment. Briefly explain why.
2.
(2 pts) The acid catalyst used in this experiment is acetyl chloride (CH3COCl).
Write the reaction that shows how this compound is a source of acid under the
conditions of the experiment.
3.
(2 pts) Briefly explain the purpose of CaCl2 in the tube on top of the reflux
condenser in this experiment.
Experiment 2: Oxidation of cyclohexanol.
4.
(2 pts) Fill in the missing word: This experiment aims to convert a secondary
alcohol to a ______________________.
5.
(2 pts) Name the oxidizing agent in this reaction.
Chem 6B
Lab Quiz 1
Name:_________________
The experiment performed the first week was a Fischer Esterification to form ethyl laurate.
How could you tell from the IR analysis if you formed the product?
O
EtOH
OH
H+
O
O
Chem 6B
Lab Quiz 1
Name:_________________
The experiment performed the first week was a Fischer Esterification to form ethyl laurate.
How could you tell from the IR analysis if you formed the product?
O
EtOH
OH
H+
O
O
Name: ___________________
Chem 6B-4 Laboratory Quiz Number Two
Answer the following 5 questions. Total: 10 points
Experiment 2: Oxidation of cyclohexanol.
1.
(2 pts) This experiment involves the oxidation of the secondary alcohol
cyclohexanol to what ketone? (Give the name and the structure of this ketone).
2.
(2 pts) Name one of the other reagents in this experiment (excluding the alcohol
and ketone mentioned in question 1).
Experiment 3: The Horner-Wadsworth-Emmons Reaction: (E)-Stilbene.
3.
(2 pts) This reaction is a modification of which well known reaction used to form
a double bond?
4.
(2 pts) Explain briefly what solubility property of the phase-transfer catalyst
Aliquot 336 makes it so useful in this experiment.
5.
(2 pts) Why is anhydrous sodium sulphate added to the remaining organic layer
after the aqueous layer has been removed?
Chem 6B
Lab Quiz 2 Name:_________________
1) Describe a simple test to distinguish between the aqueous and organic layers during a
work-up.
2) In what situation would you use a steam distillation, versus say a short path distillation?
Chem 6B
Lab Quiz 2 Name:_________________
1) Describe a simple test to distinguish between the aqueous and organic layers during a
work-up.
2) In what situation would you use a steam distillation, versus say a short path distillation?
Chem 6B-4 Laboratory Quiz Number Three
Answer the following 5 questions. Total: 10 points
Experiment 3: The Horner-Wadsworth-Emmons Reaction: (E)-Stilbene.
1.
(1 pt) Name the reagent that transported the hydroxide ion into the organic phase
in this reaction.
2.
(3 pts) Complete the names of the two major reagents in this experiment:
benz______________, diethyl benzyl______________.
Which of these reagents is the limiting reagent in the experiment?
Experiment 4: Olefin hydroboration-Oxidation: 1-Octanol.
3.
(2 pts) Why is it crucial that all glassware be dry in the first step of this reaction?
4.
(2 pts) Name a characteristic stretch you would expect to see in the IR spectrum
of the product in this experiment, and state approximately where you would
expect to see it (in cm-1).
5.
(2 pts) True or false: peak area in a gas chromatography trace is proportional to
the relative amount of each component present.
Chem 6B
Lab Quiz 3 Name:_______________________
(4 points)
Provide the answers to the blank spaces in the Horner-Wadsworth-Emmons
olefination reaction seen below.
O
(EtO)2P
(1 point)
-
O
OH
H
+
The reagent generated in the first step above is referred to as what?
Chem 6B
Lab Quiz 3 Name:_______________________
(4 points)
Provide the answers to the blank spaces in the Horner-Wadsworth-Emmons
olefination reaction seen below.
O
(EtO)2P
(1 point)
-
O
OH
+
H
The reagent generated in the first step above is referred to as an ________ ?
Chem 6B-4 Laboratory Quiz Number Four
Answer the following 5 questions. Total: 10 points
Experiment 4: Olefin hydroboration-Oxidation: 1-Octanol.
1.
(2 pts) Briefly describe one way of estimating the relative peak areas on a GC
trace.
2.
(2 pts) Name a product other than 1-octanol that was obtained in this experiment.
Experiment 5: Grignard Reaction with a Ketone:Triphenylmethanol.
3.
(2 pts) In a Grignard reagent (RMgX), is the carbon bonded to magnesium
nucleophilic or electrophilic in character?
4.
(2 pts) Why is all glassware used in the first part of this experiment oven dried?
5.
(2 pts) True or false: in the 1H NMR spectrum of the purified product in this
experiment you should see a peak for the proton in the OH group.
Chem 6B
(3 points)
Lab Quiz 4
What is the theoretical yield of 1-octanol in the following reaction?
1) XS BH3
OH
2) H2O2 / - OH
100 mg, MW=112
a)
You will get the same amount, ~100 mg
b)
You will get more, ~120 mg
c)
Excess borane is used, so an indeterminate amount will be formed.
d)
In the first step of the reaction above, the boron adds to the terminal carbon and the
hydride goes to the inside carbon. What is this called?
(2 points)
a)
Markovnikov addition
b)
c)
Anti-Markovnikov addition
Chem 6B
(3 points)
MW=130
Lab Quiz 4
What is the theoretical yield of 1-octanol in the following reaction?
1) XS BH3
OH
2) H2O2 / - OH
100 mg, MW=112
a)
b)
You will get the same amount, ~100 mg
You will get more, ~ 120 mg
MW=130
c)
(2 points)
Excess borane is used, so an indeterminate amount will be formed.
In the first step of the reaction above, the boron adds to the terminal carbon and the
hydride goes to the inside carbon. What is this called?
a) Markovnikov addition
b) Anti-Markovnikov addition
Chem 6B-4 Laboratory Quiz Number Five
Answer the following 5 questions. Total: 10 points
Experiment 5: Grignard Reaction with a Ketone:Triphenylmethanol.
1.
(2 pts) Give the two products A and B in the following reaction:
Et2O
r
B
2.
A
Mg
+
B
(2 pts) Give the product C in the following reaction:
O
g Br
M
1. Et2O
+
C
+
BrMgOH
2. aq. HCl
Experiment 6: Diels-Alder Reaction: 4-Cyclohexene-cis-1,2-dicarboxylic Acid
Anhydride
3.
(2 pts) Fill in the missing word: The Diels-Alder cycloaddition leads directly to
_____- membered rings with control of regiochemistry and stereochemistry.
4.
(2 pts) Are there any intermediates involved in this reaction?
5.
(2 pts) Why is it very important to do the first part of this experiment in the hood?
Chem 6B
(3 points)
Lab Quiz 5
When you performed the Grignard reaction below, the initial alkoxide product formed
needed to be protonated before the isolation steps. What problem would you have run
into during the work-up had you not protonated it? (Where would it end up?)
O
r
B
g
M
H+
h
P
O
h
P
+
h
P
(2 points)
In the Diels-Alder reaction below, some people had a large, broad peak around
3500cm-1 in their IR spectrum. What functional group shows up in this region? And,
draw the structure of the contaminant responsible for this stretch. (Hint: The answer is
the product of hydrolysis.)
O
O
O
O
+
O
O
Chem 6B-4 Laboratory Quiz Number Six
Answer the following 4 questions. Total: 10 points
Experiment 6: Diels-Alder Reaction: 4-Cyclohexene-cis-1,2-dicarboxylic Acid
Anhydride
1.
(3 pts) Give the two products A and B in the following reaction, and show the
movement of electrons on 3-sulfolene that is responsible for the formation of
these products (i.e. give the mechanism):
O
heat
S
A
+
B
O
3-sulfolene
2.
(2 pts) Give the product C in the following reaction, including the mechanism:
heat
C
O
Experiment 7: A Multi-Step Synthesis: Hexaphenylbenzene.
3.
(1 pt) True or False: Hexaphenylbenzene is a planar molecule.
4.
(4 pts) Give the structures and names of the products D and E below:
H
CND
2
O
Chem 6B
Cu(OAc)2
E
NH4NO3
CH3CO2H
Lab Quiz 6 Name:_______________________
(3 points) Recrystallizations are often useful in purifying organic compounds. And
there are several things that go into doing a good recrystallization. For example,
you need to choose the solvent well, so that your compound is soluble at higher
temperatures, but not soluble when you cool it back down.
Talk about 2 other things that need to be done to ensure a good recrystallization.
Chem 6B
Lab Quiz 6 Name:_______________________
(3 points) Recrystallizations are often useful in purifying organic compounds. And
there are several things that go into doing a good recrystallization. For example,
you need to choose the solvent well, so that your compound is soluble at higher
temperatures, but not soluble when you cool it back down.
Talk about 2 other things that need to be done to ensure a good recrystallization.
Chem 6B-4 Laboratory Quiz Number Seven
Answer the following 5 questions. Total: 10 points
Experiment 7: A Multi-Step Synthesis: Hexaphenylbenzene.
1.
(4 pts) Give the name and structure of product A in the following reaction, and
show the movement of electrons responsible for its formation (i.e. give the
mechanism):
-
HO
H
+
Br
Ph
C
C
H
Ph
Br
-H2O
-
-Br
Br
C
C
Ph
H
Ph
+
-
-H2O
OH
-Br
-
meso-stilbene dibromide
2.
(1 pt) True or False: In part four (bromination of (E)-stilbene to give mesostilbene dibromide) a single diastereomeric dibromide is obtained.
3.
(1 pt) What is the purpose of adding solid sodium carbonate to a solution “until
foaming ceases”?
4.
(2 pts) In Part 6, what well known reaction is used to form the central sixmembered ring of hexaphenylbenzene?
5.
(2 pts) Draw the structure of hexaphenylbenzene.
Chem 6B-4 Laboratory Quiz Number Eight
Answer the following 4 questions. Total: 10 points
1.
(1 pt) In an IR spectrum, what are the highest and lowest values you would expect
to see along the x-axis? (Give numbers and units).
2.
(2 pts) Many of the compounds synthesized in this course have a monosubstituted benzene functionality. Where in an IR spectrum would you expect to
see two strong absorption bands as a result of this functional group? (Include
units in your answer).
Experiment 8: Amide Synth. & Electrophilic Aromatic Substitution: 4Bromoacetanilide.
3.
(4 pts) Show the movement of electrons responsible for the formation of 4bromoacetanilide from acetanilide and bromine on the reaction scheme below (i.e.
give the mechanism):
A
O
O
Br Br
N
H
+
H
C
Br
3
-
+
Br
+
N
H
H
H
C
3
acetanilide
O
Br
N
H
H
C
3
+
HBr
4-bromoacetanilide
4.
(3 pts) The carbocation intermediate in the above reaction is resonance stabilized
via the lone pair of electrons on nitrogen. Draw the resonance contributor A
below, including the mechanism responsible for its formation.
O
Br
H
+
N
H
H
C
A
3
Quiz Questions
Why is it necessary to use an excess of ethyl alcohol in order to effectively perform the reaction below?
O
xs EtOH
H
O
acetyl chloride
O
O
The acid catalyst in experiment 1 was HCl. How was it generated?
During experiment # 2, the distillate collected (about 1 mL) right after distillation consisted of water,
cyclohexanone, and acetic acid. How were you able to separate the undesired products from the
desired one? Explain what components were in each of the layers.
Explain the function of the phase-transfer catalyst (Aliquat 336) in experiment #3.
Complete the mechanism (don’t forget to draw the arrows):
O
P
O
O
O
P
O
O
O
H
Fill in the empty boxes:
1)BH3.THF
2) H202/OH
1)BH3.THF
Show the stereochemistry
2) H202/OH
O
H
O
P
O
O
H
O
O
O
Explain the function of H2O2/OH- in the above reactions.
Explain the terms regioselectivity and syn-addition (using an example may help).
According to the stoichiometry of the reaction, 1.3 mmoles of 1-octene reacted with 0.5 mmoles of
BH3.THF. Explain why less than one equivalent of borane is enough to carry out the transformation.
The gc trace for the hydroboration should have given 3 peaks. What could they be and how would you
determine the relative amounts of each component?
Why must the Grignard reactions be prepared with oven-dried apparatus?
The purification of organic compounds can be accomplished by recrystallization of an impure solid.
Describe the process of recrystallization.
Account for the stereochemistry observed in the synthesis of meso-stilbene dibromide from (E)stilbene. Use the mechanism for the reaction to illustrate your point and explain why it is a meso
compound.
What is the function of the Triton B, which is a strong base? Why not use NaOH?
How many 13C signals should there be for hexaphenylbenzene? How many 1H signals?