Chemistry 2423
Exam 2A
O Cimene – refers toseveral isomeric compounds. The Ocimenes
are monoterpenes found within varity of plants fruits.
Instructor : Dr. Pahlavan
1
ORGANIC CHEM 2423 EXAM # 2A Sample(Chapters 5,6, and7)
Name:__________________
Score
DIRECTIONS- Please answer all questions in the space provided as completely and clearly as possible .
Show all your work for the writing portions of the exam.
PART I – Multiple Choice (3 points each)
_____ 1. Species with unpaired electrons are called ___________________ .
A. molecular ions
B. free atoms
C. radicals
D. electrophiles
_____ 2. Identify the type of the following reaction:
Br
Br2 / H2O
OH
A. elimination
B. substitution
C. addition
D. rearrangement
_____ 3. Consider the following reaction. Which species is the nucleophile?
..
O:
..
..
O:
+
(I)
A. I only
: CN
CN
( II)
B. II only
( III )
C. III only
D. none of these
_____ 4. This process occurs when both bonding electrons remain with one product fragment.
A. homolytic bond breaking
C. hemolytic bond formation
B. heterolytic bond breaking
D. radical formation
_____5. How many degree of unsaturation are in Valium (diazepam) , C16H13N2OCl ?
A. 10
B. 11
C. 7
D. 12
_____ 6. Provide the proper IUPAC name for the alkene shown below.
CH3 – CH = CH – CH2 – CH3
A. n- pentane
B. 3-pentene
C. 2- pentene
2
D. 2- pentyne
_____ 7. What is the acceptable structure for 1,2-dimethylcyclohexene?
A.
D.
C
B.
_____ 8. What two atomic orbitals or hybrid atomic orbitals overlap to form the C = C bond in ethene?
A. sp-sp
B. sp2 – sp2
C. sp-sp2
D. sp3-sp3
_____ 9. Which of the following has the highest priority?
A. –CN
B. –OH
D. – OCH3
C. - CH3
_____10. Which of the following alkenes is most stable?
A.
B.
C.
D.
_____11. Provide the reagents necessary to complete the following transformation.
OH
O
CO2
+
B. KMnO4 /H3O+
A. KOH /ethanol
C. CH2I2 /Zn(Cu)
D. none of these
_____12. bromination of an alkene occurs with:
A. anti stereochemistry
C. syn stereochemistry
B. cis stereochemistry
D. non Markovnikov addition
•
_____13. In a radical reaction, the following step Cl• + CH3 - CH2 - CH3  CH3 –CH - CH3 + HCl
is an example of______.
A. initiation
B. propagation
C. termination
_____14. Addition of HBr to 2-butene is called ___________________.
A. Hydroboration hydration
C. Hydrohalogenation
B. Hydrogenation
D. Hydration
3
D. addition
_____15. What is the major of the following reaction?
OH
H2SO4 /heat
CH3
D.
C.
B.
A.
CH3
CH2
CH3
PART II – Show your work
16. Naming and structures ( 4 points each)
a) Give the IUPAC name of the following compounds:
I
II
III
I. _______________________________________
II. _______________________________________
III. ______________________________________
b) Draw structures corresponding to the following systematic names;
(2Z)- 3-methyl-2-pentene
2,3-dimethyl-1-cyclopentene
4
17. ( 5 points) Show by a series of reactions how could you prepare the following compounds from the
indicated starting compound. Be sure to clearly indicate the reagents used in each step.
Cl
Cl
18. ( 5 points) Propose a mechanism to account for the shown product. Please show the structures of
the intermediates and using curved arrows to indicate electron flow in each step.
(Rearrangement may occur)
CH3
CH3 - C - CH = CH2
ether
+ HBr
CH3
19. (5 points) Give the average bond dissociation enthalpies below, calculate the enthalpy change for
the following reaction.
CH3 – CH2 – CH = CH2 + H2O  CH3 – CH2 – CH - CH3
OH
C = C ( 614 kJ/mol), C – O ( 358 kJ/mol), C – H ( 414 kJ/mol), O –H (463 kJ/mol),
C – C (348 kJ/mol)
5
20. Predict the major product of the following reactions. (2 points each)
CH3
a)
Br2 /H2O
CH3 - CH - CH = CH2
H2
CH3
b)
Pd /C
HBr /ether
c)
1) BH3, THF
d)
2) H2O2 , OH
Br
e)
f)
KOH/ ethanol
2 - hexene
KMnO4
H3O
g)
2 moles H2
CH2
Pd /C
h)
i)
j)
Br2 / CCl4
CH2I2 / Zn(Cu)
1) O3
2) Zn / H3O
6
Bonus Question ( 10 points) – Please show all your work for complete credit.
Write the radical mechanism for the monochlorination of 2-methylbutane to form
2-chloro- 2-methylbutane.
Cl
CH3 - CH2 - CH - CH3
CH3 - CH2 - C - CH3
+ Cl2
CH3
CH3
7
+ HCl
ORGANIC CHEM 2423 EXAM # 2A Sample Exam - Answers
PART I – Multiple Choice (3 points each)
1. C
8. B
15. B
2. C
9. D
3. B
10. A
4. B
11. B
5. B
12. A
6. C
13. B
7. B
14. C
PART II – Show your work
16. Naming and structures ( 4 points each)
a) I. 3- Methyl-1-cyclohexene II . (3Z) –2,3,4-trimethyl-3-hexene III. 3,7-dimethyl-1,3,6-octatiene
b)
(2Z)- 3-methyl-2-pentene
2,3-dimethyl-1-cyclopentene
H
CH3
CH3
C=C
CH3
CH3-CH2
CH3
17. ( 5 points) Show by a series of reactions how could you prepare the following compounds from the
indicated starting compound. Be sure to clearly indicate the reagents used in each step.
Cl
Cl
CHCl3 /KOH
Cl2 /light
Cl
KOH /ethanol
18. ( 5 points) Propose a mechanism to account for the following reaction. Please show the structures of
the intermediates and using curved arrows to indicate electron flow in each step.
(Rearrangement may occur)
CH3
CH3
ether
CH3 - C - CH = CH2
+ HBr
CH3
CH3 - C - CH - CH3
methide
shift
:Br
CH3
2 carbocation intermediate
CH3
Br
CH3
CH3 - C - CH - CH3
CH3
:Br
CH3 - C - CH - CH3
CH3
CH3
3 carbocation intermediate
8
Br
CH3 - C - CH - CH3
CH3
19. (5 points)Using average bond dissociation enthalpies table, calculate enthalpy change for the
following reaction.
(C-H)
CH3 – CH2 – CH = CH2 + H – OH  CH3 – CH2 – CH - CH3
( C=C)
(H-O)
(C-O) OH
(C-C)
C = C ( 614 kJ/mol), C – O ( 358 kJ/mol), C – H ( 414 kJ/mol)
O –H (463 kJ/mol), C – C (348 kJ/mol)
 H = [ D(C=C) + D(H-O)] – [D(C-O) + D(C-O) + D(C-H)]
= [ 614 + 463 ] – [ 348 + 358 + 414]
= 1077 – 1120 = -43 kJ
20. Predict the major product in each of the following reactions. (2 points each)
CH3
CH3
a)
Br2 /H2O
CH3 - CH - CH = CH2
CH3 - CH - CH - CH2Br
H2
CH3
b)
OH
CH3
Pd /C
HBr /ether
c)
Br
1) BH3, THF
d)
OH
2) H2O2 , OH
Br
e)
f)
KOH/ ethanol
2 - hexene
KMnO4
CH3 - CH2 - CH2 - C OOH
+
H3O
g)
2 moles H2
CH2
CH3
Pd /C
H
h)
Br2 / CCl4
Br
Br
i)
j)
CH3
CH2I2 / Zn(Cu)
O
O
O3
H3O
CH3 C - (CH2)4 - C -H
9
CH3 - COOH
Bonus Question ( 10 points) – Please show all your work for complete credit.
Write a radical mechanism for monochlorination of 2-methylbutane to form 2-chloro- 2 - methylbutane.
Cl .
I) Initiation : Cl - Cl
+ Cl .
II) Prpagation
a)
Cl .
.
CH3 - CH2 - C - CH3 + HCl
+ CH3 - CH2 - CH - CH3
b)
.
CH3 - CH2 - C - CH3
CH3
Cl
CH3
+ Cl2
CH3 - CH2 - C - CH3 + Cl .
CH3
CH3
III) Termination
a) Cl . + Cl .
b)
Cl2
Cl
.
CH3 - CH2 - C - CH3 + Cl .
CH3 - CH2 - C - CH3
CH3
.
c) CH - CH - C - CH +
3
2
3
CH3
CH3
.
CH3 - CH2 - C - CH3
CH3
10
CH3 CH3
CH3 - CH2 - C - C - CH2 - CH3
CH3 CH3
Chemistry 2423
Exam 2B
NH2
N
N
HO
O
H
H
OH
H
H
H
Instructor : Dr. Pahlavan
11
O
ORGANIC CHEM 2423 EXAM # 2B Sample
Name:__________________
Score
DIRECTIONS- Please answer all questions in the space provided as completely and clearly as possible .
Show all your work for the writing portions of the exam.
PART I – Multiple choice : (2 points each)
_____1. For which of the following compounds does radical chlorination give a single monochloro product?:
(I)
A) (I)
(II)
(III)
B) (II)
(IV)
C) (III)
D) (IV)
_____ 2. How do you classify the following reaction? :
A) rearrangement
B) elimination
C) substitution
D) addition
_____3. Which statement is not correct?
A) Radical reaction is a process involving symmetrical bond breaking and bond making.
B) Endergonic reaction is a reaction where G is negative.
C) Substitution is a reaction where two reactants exchange parts to give two new products.
D) Activation energy is the energy needed by reactants to reach the transition state.
_____4. Consider the following reaction. Which species is the nucleophile?
(I)
A) (I)
(II)
B) (II)
(III)
C) (III)
(IV)
D) (IV)
_____5. Calculate the degree of unsaturation in the formula of diazepam (Valium):C16H13N2OCl
A) 9
B) 10 

C) 11
D) 12
_____6. Use the following bond dissociation Energies in the table below to calculate Hfor
the reaction of ethyl methyl ether with hydrogen chloride and hydrogen iodide.
D (kJ/mol)
a.
b.
CH3CH2OCH3 + HCl
CH3CH2OCH3 + HI
CH3CH2OH
+ CH3Cl
H°a
CH3CH2OH
+ CH3I
H°b
12
Bond
CH3CH2OCH3
CH3CH2OH
HCl
H
CH3Cl
CH3
339
436
432
298
351
234
A) HakJ/mol; HbkJ/mol
C) HakJ/mol; HbkJ/mol
B) HakJ/mol; HbkJ/mol 
D) none of these
_____7. From the above data of Haand Hb (refer to question 6): which acid would you predict to be most
effective for the formation of ethanol?
A) HCl
B) HI  C) both acids
D) cannot predict
_____8. The reaction depicted in the energy diagram below can best be described as:
A) slow exergonic reaction
C) slow endergonic reaction
B) fast exergonic reaction
D) fast endergonic reaction
_____9. Dieldrin, C12H8Cl6O, is a pentacyclic compound formerly used as an insecticide.How many
double bonds does dieldrin have?
A) one
B) two
C) three
D) four
____10. Ocimene is a triene found in the essential oils of many plants. What is its IUPAC name, including
stereochemistry?
A) (3Z)-3,7-dimethyl-1,3,6-octatriene
C) (5Z)-2,6-dimethyl-2,5,7-octatriene
B) (3E)-3,7-dimethyl-1,3,6-octatriene
D) (5E)-2,6-dimethyl-2,5,7-octatriene
____11. A neutral molecule containing a divalent carbon with six valence electrons is called:
A) carbocation
B) carbanion
C) carbene
D) radical
____12. Arrange the following bicyclic alkenes in order of increasing stability (least stable to most stable).
A) III < II < I
B) I < II < III
C) I < III < II
13
D) II < III < I
____13. Which of the following alkene has the E configuration?:
CH3
CH3
CH3
(I)
(II)
A) (I)
(III)
B) (II)
C) (III)
D) (I) and (III)
____ 14. Arrange the following carbocations in order of increasing stability (least stable to most stable).
I
A) III < II < I
II
B) I < II < III
III
C) I < III < II
D) II < III < I
____15. In a radical reaction, the step below is an example of:
Cl-Cl
A) initiation
+
.
Cl
CH3-CH-CH3
CH3-CH-CH3
B) propagation
C) termination
+
Cl
OH
OH
Cl
A)
Cl
B)
C)
D)
____17. Suggest structure (s) for alkene (s) that give the indicated reaction product.
H2
?
Pd
(I)
A) (I)
(II)
B) (II)
(III)
C) (III)
14
Cl
D) substitution
____16. Predict the major product from the following reaction:
Cl
.
D) All of these
____18. Predict the major product of the following reaction:
OH
CH3
H2SO4/heat
A)
CH3
B)
CH2
C)
D)
____19. What alkene would you start with to prepare the 2,4-diiodopentane below:
A):
B):
C):
D):
____20. Hydroboration/oxidation of alkenes occurs with:
A) anti stereochemistry &
B) anti stereochemistry &
C) syn stereochemistry &
D) syn stereochemistry &
Markovnikov regiochemistry
non-Markovnikov regiochemistry
Markovnikov regiochemistry
non-Markovnikov regiochemistry
PART II- Show your work (8 points each)
21. Consider the reaction of 2-bromo-2-methylpropane with water:
i) Is the reaction of 2-bromo-2-methylpropane with water an example of:
a. a substitution reaction? b. a rearrangement reaction?
c. an elimination reaction?. d. or an addition reaction?.
Explain your choice:
15
CH3
ii)
The First Step of the Reaction:
Add curved arrows to indicate electron flow in the First Step.
iii)
The Second and Third Steps of the Reaction:
Label the nucleophile, Nu, and the electrophile, E+, in the blanks provided under the reactant
structures (Second and Third Steps).
iv)
Draw arrows on the structures above showing electron flow in Second and Third Steps of this
reaction.
22. Refer to the reaction of 2-bromo-2-methylpropane with water in question 21.
a. Using the bond dissociations values in the table below, calculate the H for this reaction. Show your
calculations for full credit.
16
b. Draw a qualitative reaction energy diagram for the reaction of 2-bromo-2-methylpropane with water.
The first step is the slowest step of the reaction. Fully label the diagram, including the coordinates.
23. Propose a mechanism, showing the structures of the intermediates in the following
reaction:
Cl
+
HCl
17
24. Predict the major product of each reaction. Indicate regiochemistry and stereochemistry when relevant.
25. What reagent would you use to carry out each of the following transformations? In each reaction place the
reagent above the arrow.
18
BONUS QUESTION(10 points)- Show all your work.
In an abandoned laboratory has been found a flammable liquid, A, in a bottle bearing only the label "Compound
A: C7H12." Government agents have offered you a considerable sum to determine the structure of this
compound. After verifying the molecular formula by elemental analysis, you find that Compound A reacts with
1 mol equiv of hydrogen and, after treatment with acidic KMnO4, gives the dicarboxylic acid C (see below).
Another bottle from the same laboratory is labeled "Compound B (isomer of A)." Compound B also reacts with
1 mol equiv of hydrogen, but yields cyclohexanone after treatment with acidic KMnO4.
i)
How many degrees of unsaturation does Compound A possess?
ii)
From the list below suggest structure for A and B
ii)
What was the other product formed in the KMnO4 oxidation of B?
19
ORGANIC CHEM 2423 EXAM # 2B Sample Exam - Answers
PART I :
1. C
7. B
13. A
19. B
2. A
8. B
14. D
20. D
3. B
9. A
15. B
4. B
10. B
16. C
5. C
11. C
17. D
PART II :
21.
i)
a substitution reaction: substitution of Br with OH.
ii) The First Step of the Reaction:
iii) The Second and Third Steps of the Reaction:
iv)
20
6. B
12. D
18. B
22.
a.
H=D (bonds broken) - D (bonds formed)
= (263 kJ/mol + 498 kJ/mol) - (380 kJ/mol + 366 kJ/mol)
= + 15 kJ/mol.
b. three steps = three transition states
23.
Cl
+
H-Cl
H
H
+
+
Cl-
Hydride
shift
Cl-
21
24.
25.
1. BH3, THF
2. H2O2, NaOH, H2O
OH
1. Hg(OAc)2, H2O
2. NaBH4
OH
CH2I2, Zn(Cu)
H
O
1. O3
2. Zn, H3O+
H
CH3
O
22
BONUS QUESTION:
i)
D.U. = 1 + C –1/2(H + X – N)
= 1 + 7 – 1/2(12)
=2
Compound A possesses 2 degrees of unsaturation:
ii)
Compound A reacts only with 1 mole equivalent of H2 : suggest that
Compound A has only one C=C (double bound)
Oxidation of Compound A with KMnO4 produces only one product:
suggest that Compound A is a cyclic alkene.
Finally looking at the oxidation product C, and the cyclohexanone, the structures of compounds
A & B are:
iii) The other product formed in the KMnO4 oxidation of B is: CO2
23