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Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
Columbia University 92CORG24.DOC CHEM S3444Q Summer 1992 Professor Irving J. Borowitz Exam No. 4 August13, 1992 Name: Grade: Please use a non-red pen. Answer questions in the provided space. If you write any answers on the back of the page, indicate this on the front of that page. Points appear in parentheses ( ). Good Luck! Question Max. Pts. Points
- 2 +( 2 + 2 ) = 6
- 3 + 3 + 3 + 3 + 2 + 2 = 16
- 2 + 3 + 3 + 2 + 4 = 14
- 1 + 2 + 3 + 2 + 2 = 10
- ( 2 + 2 + 1 ) + 3 + 2 = 10
- 2 + 2 + 1 + 1 + 2 + 4 = 12
- 3 + 3 + 2 = 8
- 4 + 4 + 2 + 2 = 12
- 3 + 5 + 2 + 2 = 12
Total = 100
- (06) Consider the following two isomers of C11 H 14 O 2. A: IR - 1710 cm -1^ and 830 cm -1. NMR - (CDCl 3 /TMS) ë 1.25 (triplet, 3H), ë 2.3 (quartet, 2H), ë 2.8 (singlet, 2H), ë 3.7 (singlet, 3H), ë 7.4 (AB quartet, 4H). B: IR - 1740 cm -1^ and 750, 700 cm - NMR - (CDCl 3 /TMS) ë 1.0 (triplet, 3H), ë 1.3 (multiplet, 2H), ë 2.8 (singlet, 2H), ë 3.8 (triplet, 2H), ë 7.2 (singlet, 5H). a. Calculate ê, the Index of Hydrogen Deficiency for the molecular formula C 11 H 14 O 2.
b. Sketch the NMR spectra for isomers A and B.
A.
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
B.
(^9 876543210) δ
(^9 8 7 6 5 4 3 2 1 0) δ
- (16) a. Determine the structure of isomer A, C11 H 14 O2, in Problem 1 above. Fully support your choice by explaining the IR and NMR spectra.
b. Determine the structure of isomer B, C11 H 14 O2, in Problem 1 above. Fully support your choice by explaining the IR and NMR spectra.
c. Starting with Ph-CH 2 COOH synthesize C:
CH 2 C
O
OCH(CH 3 ) 2
d. Starting with Ph-CH 2 COOH synthesize D:
CH 2 C
O
CH(CH 3 ) 2
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
- (14) a. If one wishes to prepare 5-methyl-2-hexanone using the acetoacetic ester synthesis, one would use the following alkyl halide(s).
(1) CH 3 CH 2 -Br (2) (CH 3 ) 2 CH-CH 2 -CH 2 -Br
(3) CH 3 CH 2 -CH 2 -Br (4) (CH 3 ) 2 CH-CH 2 -Br
b. Show the above synthesis in detail, using arrows to show the direction of electron flow in the mechanism and including the steps and reagents as well as the structure of the final product.
c. Rank the following compounds in order of decreasing acidity (strongest acid to weakest acid). Briefly rationalize your choice.
CH 3
O
OCH 2 CH 3
CH 3
O
CH 2
O
OCH 2 CH 3
CH 3
O
OH
CH 3
O
CH 2
O
CH 3
Cl 3 C
O
OH
CH 3 CH 2 OH
Order:
Rationale:
d. Fill in the structure for the aldol condensation product formed from 3-pentanone and sodium ethoxide in ethanol after heating and dehydration. Show how it was formed and select the IUPAC name: (1) 4-Methyl-4-nonen-3,7-dione (2) 5-Ethyl-4-methyl-5-hepten-3-one (3) 5-Ethyl-4-methyl-4-heptene-3-one (4) 3-Ethyl-4-methyl-3-heptene-5-one (5) 3-Ethyl-4-methyl-2-heptene-5-one
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
- (10) a. Which reagent would serve as the basis of a simple chemical test that would distinguish between the pair of compounds listed below:
NH CH 3 CH 3 NH 2
(1) AgNO 3 in H 2 O (2) Dilute NaOH (3) Dilute Na HCO (^3) (4) PhSO 2 Cl, -OH, then H 3 O+^ (5) Dilute HCl
b. Give the equations for the reaction chosen, showing the organic product and noting the differing visible results.
c. Complete the following reaction sequence.
CH 3 NH 2 1. HONO
- Cu 2 (CN) 2
A
H 3 O+^ / H 2 O,∆
B
B
Br 2
FeBr 3 , ∆
C
d. Show and explain the fact that glucose exists in two forms that are interconvertible, à-D-glucopyranose and á-D-glucopyranose.
e. Which of the following is/are true of the disaccharide sucrose?
(1) It reacts with Benedict’s Solution. (2) It hydrolyzes to yield fructose and glucose. (3) It undergoes mutarotation in aqueous solution.
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
c. Give a simple chemical test and its visible result that would distinguish the two polysaccharides.
- (12) a. Which of the following statements regarding lipids is not true?
(1) Lipids are soluble in non-polar organic solvents. (2) All lipids have the same functional groups. (3) Lipids have very little in common except their solubility. (4) Lipids include waxes, terpenes, steroids, and triglycerides. (5) Many lipids have biological roles.
b. Natural "fatty acids" are biosynthesized in living organisms from:
(1) Glycerol (2) Alkenes with cis- double bonds (3) Acetyl-S-CoA (4) Isopentyl pyrophosphate (3-methyl-3-butenyl-OPP) and dimethylallyl pyrophosphate (3-methyl-2-butenyl-OPP) (5) Unbranched alkanes with even numbers of carbon atoms.
c. Which of the following is a female sex hormone?
(1) Ergosterol (2) Cortisone (3) Androsterone (4) Cholic acid (5) Estradiol (6) Cortisol
d. Which of the following is a male sex hormone?
(1) Ergosterol (2) Testosterone (3) Estradiol (4) Cortisone (5) Cholic Acid (6) Estrone
e. Cholesterol and other steroids are made biosynthetically from the triterpene:
(1) Caryophyllene (2) á-Carotene (3) à-Farnesene (4) Squalene (5) Cholic Acid.
f. Outline the key steps by which a C-4 sample small acid is biosynthesized on the way to becoming a "fatty acid."
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
- (08) a. Define isoelectric point giving its important characteristics.
b. Using the following table of pKa values, find the amino acid which would have its isoelectric point pI closest to 3.0. Calculate the exact pI and show your calculation.
amino acid pKa1 (-COOH)^ pKa2 (-NH^3 +)^ pK^3 (-R)
alanine 2.3 9. lysine 2.2 9.0 10. phenyl alanine 1.8 9. tyrosine 2.2 9.1 10. glutamic acid 2.2 9.7 4. cysteine 1.7 10.8 8.
c. Choose the structure that corresponds to the answer you have chosen. (The structures are randomly placed below compared to the order in the table above).
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
c. The secondary structure of proteins is derived from:
(1) peptide linkages (2) disulfide linkages (3) hydrogen bond formation (4) hydrophobic reactions (5) acid-base interaction
d. The primary structure of proteins refers to its .
- (12) a. Which reagent(s) below are used to "protect " the amino group of an amino acid which is to be joined to a second amino acid by a peptide bond.
CH 3
O
Cl
(1)
O
Cl
(2)
O
CH 3 CH 2 O Cl
(3)
CH 2 -^ O
O
Cl
(4)
O
(CH 3 ) 3 CO Cl
(5)
b. Synthesize the dipeptide gly-val using either the straight organic synthetic method with the mixed anhydride as the activating group or the Merrifield automated solid state peptide synthesis with DCCI (dicyclohexylcarbodiimide) as the activating group. Show all steps including protection, activation, reaction, and removal of the protecting groups. (Ignore the fact that in the standard synthetic method, the valine is used as the methyl ester).
:NH 2
H
H
O
NH H
(CH 3 ) 2 CH
O
O
Gly -^ Val
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
c. Which of these amino acid residues is expected to prefer the interior of a protein to the exterior when the protein is in aqueous medium?
(1) threonine (2) valine (3) serine (4) aspartic acid (5) lysine
d. The occurrence of this amino acid in a chain disturbs the à-helix:
(1) proline (2) alanine (3) histidine (4) methionine (5) tyrosine
Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J.
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Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J. Borowitz 13
