Final Examination
Name _________________________________
ID# ___________________________________
Final Examinations can be picked up starting Monday, Dec. 22nd in my office, Kolthoff 455. Grades will be posted on line no later than Saturday, Dec 20th.
Final Examination Organic Chemistry 2302 Fall Semester 2008
11 pages including last page to tear off for scratch paper ♦ ♦ ♦ ♦ ♦ ♦ ♦
Do not open the exam until you are asked to do so. Have your ID visible on the desk beside you. Place your last name on all subsequent pages in case pages get separated. You may NOT use calculators, models, or any notes for this exam. Raise your hand if you have a question and TA or I will help you. Exam begins at 8:00 a.m. and ends at 10:00 a.m. When time is called by the TAs, all pens are to be down and no more written work done. TAs are authorized to deduct 5 points from the exam of any student that does NOT following these rules. ♦ Good luck! 1) _________/ 15 pts
Total
2)
_________/ 23 pts
3)
_________/ 14 pts
4)
_________/ 32 pts
5)
_________/ 30 pts
6)
_________/ 24 pts
7)
_________/ 20 pts
8)
_________/ 26 pts
9)
_________/ 16 pts
_________/200 points
Last Name ____________________________
Applications of Organic Chemistry to Biological Molecules 1.
Carbohydrates and Protecting Group Chemistry – Consider the reaction sequence below where β-D-Glucose is protected at its 4-OH and 6-OH groups. H
6
H OH
Ph H
O
HO
OH H
OH
H
O
4
5
O
B
HO
7
O
2
3
HO
H+, remove water
H
OH H
OH
H
H
1 H
β-D-Glucose protected at 4-OH and 6-OH (C)
β-D-Glucose (A) a.
Supply the missing compound B required for the protection (note we first learned this reaction as a protection of compound B). 3 pts
b.
Which carbon atom in product (C) represents the center of a HEMIACETAL? Circle one. 2 pts C1
c.
C2
C3
C4
C5
C6
C7
Which carbon atom in product (C) represents the center of an ACETAL? Circle one. 2 pts C1
C2
C3
C4
C5
C6
C7
d.
What conditions would you use to reverse the reaction and convert compound (C) back to (A)? 2 pts
e.
Alternatively, ALL of the hydroxyl groups can be protected in the reaction below. Complete the template on the right adding the correct functional groups. 3 pts H OH
O H
O
H3C
HO HO
OH H
OH
H
H
β-D-Glucose (A) f.
O
O
H H
CH3
Pyridine
O
H H
H
Complete template f or expected product
Explain why glucose is considered a reducing sugar and gives a positive Tollens test (Ag(NH3)2+, OH). What physical observation indicates a positive Tollens test? 3 pts
______ 15 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 1
Last Name ____________________________
2.
Amino Acids – Racemic alanine (written in its neutral form) can be prepared from the α-ketoacid given below. Though the synthesis can be performed in one step using ammonia, hydrogen, and palladium, draw the intermediate that would form in the reaction (Hint: two steps occur) 3 pts
O O H 3C C C OH
excess NH 3
H 2 , Pd
Ha O H 2N C C OH CH 3
Alanine
(b)
b.
Though alanine has a molecular weight of only 89.09, its mp is extremely high (265 oC with decomposition). Succinctly explain why using words and structure(s). 3 pts
c.
The 1H NMR of alanine obtained in D2O (so the amine and carboxylate hydrogens are not observed) gives two sets of peaks for Ha and Hb. Circle the expected peaks considering chemical shift and splitting pattern. 3 pts a. 1.4 (singlet), 1.8 (triplet) b. 2.4 (quartet), 3.8 (doublet) c.
3.
1.4 (doublet), 3.8 (quartet)
d. 3.5 (doublet), 4.0 (triplet)
Lipids - Complete the roadmap problem below which centers on l-carvone, a component of spearment oil, by drawing the products that would result for each reaction A-D. 12 pts O 1 eq H 2
NaBH 4
Pt A
CH 3OH l-carvone
B
O
Raney Ni excess H2
NO2
Michael Reaction Assume neutral product D
C
e.
Which class of lipids does l-carvone represent? (Circle one) 2 pts a. terpenes
b. prostaglandins
c. waxes
d. steroids _____ 23 pts
Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 2
Last Name ____________________________
Cumulative portion of the exam 4.
Mechanisms: Draw the full mechanism for each specific reaction below from starting material to product (ignore other possible products). Use proper arrow notation and show all intermediates and proton transfers. Note any specific directions for each problem.
a. (Include reaction of Br2 with light) 5 pts CH3 Br 2, light Br
b. (Cyclic transition state required for full credit) 4 pts O H CH3CH2 C C OH C O OH
heat
O CH3CH2 CH C
H OH
+
CO2
H+, H2O
O CH3CH2 CH2 C
OH
c. Including all intermediate resonance structures. 5 pts
_____ 14 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 3
Last Name ____________________________
d.
Mechanisms, continued. 8 pts N OH
O H+ +
5.
NH 2OH
H 2O
+ pH 4.5
Aromatic Systems – For each molecule below, circle the appropriate classification – aromatic, antiaromatic or nonaromatic. 12 pts H H N aromatic antiaromatic nonaromatic
aromatic antiaromatic nonaromatic
O N
aromatic antiaromatic nonaromatic N H
6.
O
B H
aromatic antiaromatic nonaromatic
N
H
aromatic antiaromatic nonaromatic (pyrimidine base of RNA)
aromatic antiaromatic nonaromatic
Acidity and Basicity – For each compound below, circle the most ACIDIC hydrogen(s) in the first row or most BASIC nitrogen (for all structures with nitrogen). 12 pts O
O
O
HO
H 3C OH
Cl Cl NH 2
CH2
O OH
H3C
O
O CH 2
OH H N
CH 3 N NH2
C H N CH 3
H N
_____ 32 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 4
Last Name ____________________________
7. Contrasting Reactions – Write the product of the reaction of the center molecule with each reagent – one to left and one to the right. Be careful to count all carbons and indicate if no reaction will occur. For EAS reactions, if both ortho and para are expected draw the para and write “+ ortho” a.
6 pts
CH 3 O
NaOCH 3 CH 3OH
H+ CH3 OH
b.
6 pts HN
O C
CH3
NH2
HNO3, H2SO4
c.
6 pts
d. 6 pts O
POCl3
1) LiAlH 4 2) H2 0
NH 2
e. 6 pts
_____ 30 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 5
Last Name ____________________________
8.
Reagents - Consider each reaction below and choose the ONE best reagent that would successfully complete the reaction without complication. Place the letter of the reagent in the box. Zero credit will be given for ambiguous letters or multiple letters. Not all reagents will be used and some may be used twice. O
O
H
H O
OH
O
O
OCH 3
O
O
OH
O O
NH2
O
O
O
Br
CH 2Br
CH 3
Br
CO 2H
NH 2
O
OH
OH
H
OH
OH
O CH3
CH3
OH
OH
O
O CH3
CH3
A. i) 3 CH3I ii) Ag2O, heat
B.
NaBH4, CH3OH
C.
HCN, cat NaCN
D. CH3CO3H, H+, H2O (aq peroxyacidic acid)
E.
NBS, light
F.
CH2=PPh3
G.
Na2Cr2O7, H2SO4
H. Zn(Hg), HCl
I. i) NaH ii) CH3I
J.
NaOH, heat Remove water
K.
i)NH2OH, H+ ii) H2, Ni
L. i) NH2NH2, H+ ii) KOH, heat
M.
i) CH3Mg Br ii) H3O+
N. i) Mgo, ii) CO2
O.
PCC, CH2Cl2
P.
Br2, H2O
H2, Pt
R.
T.
POCl3
Q.
iii) H3O
+
i) LiAlH4 , ii) H3O+
S. HOAc, Br2
_____ 24 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 6
Last Name ____________________________
9.
Name Reactions - Complete the examples of NAME reactions below by filling in the boxes with either the product, reactants, or reagents required.
a. Stork reaction O
4 pts Cl
H N
H+
+
O
H 3O +
-H 2 O enamine
b. Wittig Reaction
4 pts
c. Sandmeyer Reaction
4 pts
d.
4 pts
Crossed Claisen Condensation
e. Friedel-Crafts Acylation Reaction (Anhydride version)
4 pts
_____ 20 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 7
Last Name ____________________________ Problem 9, Continued
f.
Diels-Alder reaction
g.
4 pts
Robinson Annulation
4 pts -
OH
+
O a cyclohexanone
a Michael acceptor
h. Temporary Ester Synthesis – Acetoacetic Ester
10.
4 pts
EAS Reactivity – Consider the mononitration of each compound below and add the nitro group to the position where substitution will occur in the highest yield. 6 pts O O
HO
11.
SO3 H
F
F
Huckel’s rules of Aromaticity - Use the polygon rule to demonstrate Huckel’s 4N + 2 rule for benzene. Label each π molecular orbital, add * to antibonding orbitals, and add the appropriate number of electrons. Use the diagram to explain benzene’s super-duper stability. For π4∗, identify the number of bonding, antibonding, and/or bonding interactions present. 8 pts * Polygon Rule for Benzene π4
_________
26 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 8
Last Name ____________________________
12.
Synthetic Transformations – Choose two of the three synthetic transformation problems given below to summarize your knowledge of 2302 learned this semester. Check the boxes of the two you want graded. Nothing else will be considered. Give reagents for each step and the intermediate compounds. WORK BACKWARDS for most efficient use of time! 16 pts (8pts each)
______ 16 pts - THE END – Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 9
ID# ___________________________________
Final Examinations can be picked up starting Monday, Dec. 22nd in my office, Kolthoff 455. Grades will be posted on line no later than Saturday, Dec 20th.
Final Examination Organic Chemistry 2302 Fall Semester 2008
11 pages including last page to tear off for scratch paper ♦ ♦ ♦ ♦ ♦ ♦ ♦
Do not open the exam until you are asked to do so. Have your ID visible on the desk beside you. Place your last name on all subsequent pages in case pages get separated. You may NOT use calculators, models, or any notes for this exam. Raise your hand if you have a question and TA or I will help you. Exam begins at 8:00 a.m. and ends at 10:00 a.m. When time is called by the TAs, all pens are to be down and no more written work done. TAs are authorized to deduct 5 points from the exam of any student that does NOT following these rules. ♦ Good luck! 1) _________/ 15 pts
Total
2)
_________/ 23 pts
3)
_________/ 14 pts
4)
_________/ 32 pts
5)
_________/ 30 pts
6)
_________/ 24 pts
7)
_________/ 20 pts
8)
_________/ 26 pts
9)
_________/ 16 pts
_________/200 points
Last Name ____________________________
Applications of Organic Chemistry to Biological Molecules 1.
Carbohydrates and Protecting Group Chemistry – Consider the reaction sequence below where β-D-Glucose is protected at its 4-OH and 6-OH groups. H
6
H OH
Ph H
O
HO
OH H
OH
H
O
4
5
O
B
HO
7
O
2
3
HO
H+, remove water
H
OH H
OH
H
H
1 H
β-D-Glucose protected at 4-OH and 6-OH (C)
β-D-Glucose (A) a.
Supply the missing compound B required for the protection (note we first learned this reaction as a protection of compound B). 3 pts
b.
Which carbon atom in product (C) represents the center of a HEMIACETAL? Circle one. 2 pts C1
c.
C2
C3
C4
C5
C6
C7
Which carbon atom in product (C) represents the center of an ACETAL? Circle one. 2 pts C1
C2
C3
C4
C5
C6
C7
d.
What conditions would you use to reverse the reaction and convert compound (C) back to (A)? 2 pts
e.
Alternatively, ALL of the hydroxyl groups can be protected in the reaction below. Complete the template on the right adding the correct functional groups. 3 pts H OH
O H
O
H3C
HO HO
OH H
OH
H
H
β-D-Glucose (A) f.
O
O
H H
CH3
Pyridine
O
H H
H
Complete template f or expected product
Explain why glucose is considered a reducing sugar and gives a positive Tollens test (Ag(NH3)2+, OH). What physical observation indicates a positive Tollens test? 3 pts
______ 15 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 1
Last Name ____________________________
2.
Amino Acids – Racemic alanine (written in its neutral form) can be prepared from the α-ketoacid given below. Though the synthesis can be performed in one step using ammonia, hydrogen, and palladium, draw the intermediate that would form in the reaction (Hint: two steps occur) 3 pts
O O H 3C C C OH
excess NH 3
H 2 , Pd
Ha O H 2N C C OH CH 3
Alanine
(b)
b.
Though alanine has a molecular weight of only 89.09, its mp is extremely high (265 oC with decomposition). Succinctly explain why using words and structure(s). 3 pts
c.
The 1H NMR of alanine obtained in D2O (so the amine and carboxylate hydrogens are not observed) gives two sets of peaks for Ha and Hb. Circle the expected peaks considering chemical shift and splitting pattern. 3 pts a. 1.4 (singlet), 1.8 (triplet) b. 2.4 (quartet), 3.8 (doublet) c.
3.
1.4 (doublet), 3.8 (quartet)
d. 3.5 (doublet), 4.0 (triplet)
Lipids - Complete the roadmap problem below which centers on l-carvone, a component of spearment oil, by drawing the products that would result for each reaction A-D. 12 pts O 1 eq H 2
NaBH 4
Pt A
CH 3OH l-carvone
B
O
Raney Ni excess H2
NO2
Michael Reaction Assume neutral product D
C
e.
Which class of lipids does l-carvone represent? (Circle one) 2 pts a. terpenes
b. prostaglandins
c. waxes
d. steroids _____ 23 pts
Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 2
Last Name ____________________________
Cumulative portion of the exam 4.
Mechanisms: Draw the full mechanism for each specific reaction below from starting material to product (ignore other possible products). Use proper arrow notation and show all intermediates and proton transfers. Note any specific directions for each problem.
a. (Include reaction of Br2 with light) 5 pts CH3 Br 2, light Br
b. (Cyclic transition state required for full credit) 4 pts O H CH3CH2 C C OH C O OH
heat
O CH3CH2 CH C
H OH
+
CO2
H+, H2O
O CH3CH2 CH2 C
OH
c. Including all intermediate resonance structures. 5 pts
_____ 14 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 3
Last Name ____________________________
d.
Mechanisms, continued. 8 pts N OH
O H+ +
5.
NH 2OH
H 2O
+ pH 4.5
Aromatic Systems – For each molecule below, circle the appropriate classification – aromatic, antiaromatic or nonaromatic. 12 pts H H N aromatic antiaromatic nonaromatic
aromatic antiaromatic nonaromatic
O N
aromatic antiaromatic nonaromatic N H
6.
O
B H
aromatic antiaromatic nonaromatic
N
H
aromatic antiaromatic nonaromatic (pyrimidine base of RNA)
aromatic antiaromatic nonaromatic
Acidity and Basicity – For each compound below, circle the most ACIDIC hydrogen(s) in the first row or most BASIC nitrogen (for all structures with nitrogen). 12 pts O
O
O
HO
H 3C OH
Cl Cl NH 2
CH2
O OH
H3C
O
O CH 2
OH H N
CH 3 N NH2
C H N CH 3
H N
_____ 32 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 4
Last Name ____________________________
7. Contrasting Reactions – Write the product of the reaction of the center molecule with each reagent – one to left and one to the right. Be careful to count all carbons and indicate if no reaction will occur. For EAS reactions, if both ortho and para are expected draw the para and write “+ ortho” a.
6 pts
CH 3 O
NaOCH 3 CH 3OH
H+ CH3 OH
b.
6 pts HN
O C
CH3
NH2
HNO3, H2SO4
c.
6 pts
d. 6 pts O
POCl3
1) LiAlH 4 2) H2 0
NH 2
e. 6 pts
_____ 30 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 5
Last Name ____________________________
8.
Reagents - Consider each reaction below and choose the ONE best reagent that would successfully complete the reaction without complication. Place the letter of the reagent in the box. Zero credit will be given for ambiguous letters or multiple letters. Not all reagents will be used and some may be used twice. O
O
H
H O
OH
O
O
OCH 3
O
O
OH
O O
NH2
O
O
O
Br
CH 2Br
CH 3
Br
CO 2H
NH 2
O
OH
OH
H
OH
OH
O CH3
CH3
OH
OH
O
O CH3
CH3
A. i) 3 CH3I ii) Ag2O, heat
B.
NaBH4, CH3OH
C.
HCN, cat NaCN
D. CH3CO3H, H+, H2O (aq peroxyacidic acid)
E.
NBS, light
F.
CH2=PPh3
G.
Na2Cr2O7, H2SO4
H. Zn(Hg), HCl
I. i) NaH ii) CH3I
J.
NaOH, heat Remove water
K.
i)NH2OH, H+ ii) H2, Ni
L. i) NH2NH2, H+ ii) KOH, heat
M.
i) CH3Mg Br ii) H3O+
N. i) Mgo, ii) CO2
O.
PCC, CH2Cl2
P.
Br2, H2O
H2, Pt
R.
T.
POCl3
Q.
iii) H3O
+
i) LiAlH4 , ii) H3O+
S. HOAc, Br2
_____ 24 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 6
Last Name ____________________________
9.
Name Reactions - Complete the examples of NAME reactions below by filling in the boxes with either the product, reactants, or reagents required.
a. Stork reaction O
4 pts Cl
H N
H+
+
O
H 3O +
-H 2 O enamine
b. Wittig Reaction
4 pts
c. Sandmeyer Reaction
4 pts
d.
4 pts
Crossed Claisen Condensation
e. Friedel-Crafts Acylation Reaction (Anhydride version)
4 pts
_____ 20 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 7
Last Name ____________________________ Problem 9, Continued
f.
Diels-Alder reaction
g.
4 pts
Robinson Annulation
4 pts -
OH
+
O a cyclohexanone
a Michael acceptor
h. Temporary Ester Synthesis – Acetoacetic Ester
10.
4 pts
EAS Reactivity – Consider the mononitration of each compound below and add the nitro group to the position where substitution will occur in the highest yield. 6 pts O O
HO
11.
SO3 H
F
F
Huckel’s rules of Aromaticity - Use the polygon rule to demonstrate Huckel’s 4N + 2 rule for benzene. Label each π molecular orbital, add * to antibonding orbitals, and add the appropriate number of electrons. Use the diagram to explain benzene’s super-duper stability. For π4∗, identify the number of bonding, antibonding, and/or bonding interactions present. 8 pts * Polygon Rule for Benzene π4
_________
26 pts Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 8
Last Name ____________________________
12.
Synthetic Transformations – Choose two of the three synthetic transformation problems given below to summarize your knowledge of 2302 learned this semester. Check the boxes of the two you want graded. Nothing else will be considered. Give reagents for each step and the intermediate compounds. WORK BACKWARDS for most efficient use of time! 16 pts (8pts each)
______ 16 pts - THE END – Wissinger, Chemistry 2302, Final Examination Fall 2008, Page 9
