Organic Chemistry Exam at Columbia University, Exams of Organic Chemistry

Download Organic Chemistry Exam at Columbia University and more Exams Organic Chemistry in PDF only on Docsity! Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J. Borowitz 1 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 1. 2 +( 2 + 2 ) = 6 2. 3 + 3 + 3 + 3 + 2 + 2 = 16 3. 2 + 3 + 3 + 2 + 4 = 14 4. 1 + 2 + 3 + 2 + 2 = 10 5. ( 2 + 2 + 1 ) + 3 + 2 = 10 6. 2 + 2 + 1 + 1 + 2 + 4 = 12 7. 3 + 3 + 2 = 8 8. 4 + 4 + 2 + 2 = 12 9. 3 + 5 + 2 + 2 = 12 Total = 100 1. (06) Consider the following two isomers of C11H14O2. A: IR - 1710 cm-1 and 830 cm-1. NMR - (CDCl3/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-1 NMR - (CDCl3/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 C11H14O2. 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. Borowitz 2 B. 0123456789 δ δ9 8 7 6 5 4 3 2 1 0 2. (16) a. Determine the structure of isomer A, C11H14O2, in Problem 1 above. Fully support your choice by explaining the IR and NMR spectra. b. Determine the structure of isomer B, C11H14O2, in Problem 1 above. Fully support your choice by explaining the IR and NMR spectra. c. Starting with Ph-CH2COOH synthesize C: CH2 C O OCH(CH3)2 d. Starting with Ph-CH2COOH synthesize D: CH2 C O CH(CH3)2 Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J. Borowitz 5 4. (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 CH3 CH3 NH2 (1) AgNO3 in H2O (2) Dilute NaOH (3) Dilute Na HCO3 (4) PhSO2Cl, -OH, then H3O+ (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. CH3 NH2 1. HONO 2. Cu2(CN)2 A H3O + / H2O,∆ B B Br2 FeBr3, ∆ 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. Borowitz 6 (4) It gives a dark blue color with iodine/KI solution. (5) It is a non-reducing sugar. 5. (10) a. A D-aldotetrose sugar D could be oxidized with HNO3 to an optically inactive dicarboxylic acid E. Compound D is subjected it to the modified Kiliani-Fischer Synthesis, whose reaction sequence is: 1. HCN, 2. H2, Pd/BaSO4, H2O. The result of this reaction sequence is the formation of two isomeric aldopentoses F and G. One of the aldopentoses F could then be oxidized with HNO3 to give an optically active diacid H, while G, in an analogous oxidation gave rise to an optically inactive acid I. (1) What is the structure of the aldopentose F? C C C CH2OH H H OH H OH OH O H C CH2OH H OH C H C OHH C O H HO C CH2OH H OH CHO H C HHO C O H C CH2OH H OH CH OH C HHO C O H (3) (4)(1) (2) (2) What is the structure of the aldotetrose D? (3) What is the structure of the optically active diacid H? b. By showing a part of the amylose portion of starch and of cellulose, and by giving an explanation, differentiate amylose starch and cellulose. Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J. Borowitz 7 c. Give a simple chemical test and its visible result that would distinguish the two polysaccharides. 6. (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. Borowitz 10 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 . 9. (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. CH3 O Cl (1) O Cl (2) O ClCH3CH2O (3) CH2 -O O Cl (4) O Cl(CH3)3CO (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). :NH2 H H O NH H (CH3)2CH O O Gly-Val Organic ChemI 3444Q, Columbia U, Su92, Exam 4 - Final Exam, 08/13/92; Dr. I.J. Borowitz 11 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. Borowitz 12 Scrap Paper Best wishes for a successful career and an enjoyable remainder of the summer. 08/13/92 Grace and Irv Borowitz