Upload
agustin-kurniati
View
220
Download
0
Embed Size (px)
DESCRIPTION
secret
Citation preview
Exam # 2 Chpaters 5,6,,7
Chemistry 2423
Exam 2A
O Cimene refers toseveral isomeric compounds. The Ocimenes
are monoterpenes found within varity of plants fruits.
Instructor : Dr. Pahlavan
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:
A. eliminationB. substitution
C. addition
D. rearrangement
_____ 3. Consider the following reaction. Which species is the nucleophile?
( I ) ( II) ( III )
A. I only
B. II only
C. III only
D. none of these
_____ 4. This process occurs when both bonding electrons remain with one product fragment.
A. homolytic bond breaking
B. heterolytic bond breaking
C. hemolytic bond formation D. radical formation
_____5. How many degree of unsaturation are in Valium (diazepam) , C16H13N2OCl ?
A. 10B. 11
C. 7
D. 12
_____ 6. Provide the proper IUPAC name for the alkene shown below.
CH3 CH = CH CH2 CH3
A. n- pentaneB. 3-pentene
C. 2- pentene
D. 2- pentyne _____ 7. What is the acceptable structure for 1,2-dimethylcyclohexene?
_____ 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
C. - CH3
D. OCH3
_____10. Which of the following alkenes is most stable?
_____11. Provide the reagents necessary to complete the following transformation.
A. KOH /ethanol B. KMnO4 /H3O+ C. CH2I2 /Zn(Cu) D. none of these
_____12. bromination of an alkene occurs with:
A. anti stereochemistry
B. cis stereochemistry
C. syn 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
D. addition
_____14. Addition of HBr to 2-butene is called ___________________.
A. Hydroboration hydration B. Hydrogenation
C. Hydrohalogenation D. Hydration
_____15. What is the major of the following reaction?
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
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.
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)
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)
20. Predict the major product of the following reactions. (2 points each)
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.
ORGANIC CHEM 2423 EXAM # 2A Sample Exam - Answers
PART I Multiple Choice (3 points each)
1. C
2. C
3. B
4. B
5. B
6. C
7. B
8. B
9. D
10. A
11. B
12. A
13. B
14. C
15. B
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
(2Z)- 3-methyl-2-pentene 2,3-dimethyl-1-cyclopentene
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.
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)
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)
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.
Chemistry 2423
Exam 2B
Instructor : Dr. Pahlavan
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)
(II)
(III) (IV)
A) (I)
B) (II)
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)
(II)
(III)
(IV)
A) (I)
B) (II)
C) (III) 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 Hfor
BondD (kJ/mol)
CH3CH2OCH3339
CH3CH2OH436
HCl
432
H
298
CH3Cl351
CH3234
the reaction of ethyl methyl ether with hydrogen chloride and hydrogen iodide.
A) HakJ/mol; HbkJ/mol B) HakJ/mol; HbkJ/mol C) HakJ/mol; HbkJ/mol D) none of these
_____7. From the above data of Haand Hb (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 B) fast exergonic reaction C) slow endergonic 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 B) (3E)-3,7-dimethyl-1,3,6-octatriene
C) (5Z)-2,6-dimethyl-2,5,7-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 D) II < III < I
____13. Which of the following alkene has the E configuration?:
(I)
(II)
(III)
A) (I)
B) (II) C) (III) D) (I) and (III)
____ 14. Arrange the following carbocations in order of increasing stability (least stable to most stable).
I II
III
A) III < II < I B) I < II < III C) I < III < II D) II < III < I
____15. In a radical reaction, the step below is an example of:
A) initiation B) propagation C) termination D) substitution
____16. Predict the major product from the following reaction:
A)
B)
C)
D)____17. Suggest structure (s) for alkene (s) that give the indicated reaction product.
(I)
(II)
(III)
A) (I) B) (II)
C) (III)
D) All of these ____18. Predict the major product of the following reaction:
____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 & Markovnikov regiochemistry
B) anti stereochemistry & non-Markovnikov regiochemistry
C) syn stereochemistry & Markovnikov regiochemistry
D) syn stereochemistry & 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:
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.
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:
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.
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? ORGANIC CHEM 2423 EXAM # 2B Sample Exam - Answers
PART I : 1. C
2. A
3. B
4. B
5. C
6. B
7. B
8. B
9. A 10. B 11. C 12. D13. A
14. D 15. B 16. C 17. D 18. B
19. B
20. DPART 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)
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.
24.
25.
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: CO2PAGE 12
_1149677998.unknown
_1161001238.unknown
_1161006509.unknown
_1161236660.unknown
_1223897310.unknown
_1296648912.unknown
_1161510145.unknown
_1161510594.unknown
_1161236090.unknown
_1161236313.unknown
_1161229732.unknown
_1161004440.unknown
_1161006061.unknown
_1161001413.unknown
_1160895978.unknown
_1160896380.unknown
_1160898215.unknown
_1160997038.unknown
_1160900786.unknown
_1160897255.unknown
_1160896179.unknown
_1160807033.unknown
_1160845666.unknown
_1160846323.unknown
_1160895879.unknown
_1160846056.unknown
_1160845537.unknown
_1149678814.unknown
_1142189913.unknown
_1142252400.unknown
_1142834090.unknown
_1142837821.unknown
_1149677019.unknown
_1142836289.unknown
_1142832755.unknown
_1142230698.unknown
_1142231178.unknown
_1142185254.unknown
_1142186324.unknown
_1142182716.unknown