Organic Chemistry CHE230-001 EXAM 4 Page 1 of 11 Cover Sheet! EXAM4 CHEM230-001 FALL 2002 PRINT your name legibly on the line below. _____________________________________________________Organic Chemistry CHE230-001 EXAM 4 Page 2 of 11 Name: ______________________ Student ID No:____________ First: You are allowed to have a writing utensil, a calculator and molecular model set at your seat. Please put away all other materials. Second: Place your student identification on your desk. A proctor will come around to check everyone’s ID. Is your name and number on your test? Third: Quickly read through the entire exam. Your goal, as always, is to score as many points as possible. Do not waste time on problems that you can’t do if there are easy questions to do first. Fourth: It is critically important that your answers be written in a clear, unambiguous manner. Answers in which your intentions are unclear will not receive credit. SHOW YOUR WORK! Fifth: READ THE INSTRUCTIONS FOR EACH PROBLEM. answer each question Problem Number Points possible Score 1. 40 _____ 2. 10 _____ 3. 10 _____ 4. 15 _____ 5. 10 _____ 6. 10 ______ 7. 05 ______ subTotal 100 _____ 8. 10 _____ 9. 10 _____ 10. 10 _____ 11. 10 _____ 12. 10 _____ 13. 15 ______ 14. 10 ______ 15. 10 _____ 16. 15 ______ subTotal 100 _____ Total 100 _____Organic Chemistry CHE230-001 EXAM 4 Page 3 of 11 Cumulative Part (100 pts) 1. (40 pts) Match the reagents z-q with products A-J. There is one best product for each reaction. This molecule Br is the starting material for all reactions in problem 1. Do the ones you know first and then tackle the rest by deductive reasoning. z) H2O heat, pH 7. ________ y) OF3COOH ________ x) tBuOK, polar aprotic solvent ________ w) 1) O3, ether 2) H2O, NaOH, H2O2 ________ v) Br2, CCl4 ________ u) NBS, hv, CCl4 ________ t) 1) H3O(+) 2) NaOH, H2O ________ s) 1) BH3, ether 2) H2O2 ________ r) 1) OsO4 2) NaOH, H2O ________ q) 1) PdC, EtOH, H2 ________ OHOHBrOOOBrBrBrBrBrBrOHBrBrBrBrBrHOHOABCDEFGHIJHOOrganic Chemistry CHE230-001 EXAM 4 Page 4 of 11 2. (10 pts.)OHHH Upon treatment with H3O(+) the bicyclic carbon framework at left rearranges to make a diastereomeric pair of bicyclic alcohols. Please draw the two structures below. 3. (10 pts.) On the reaction diagram below, draw the energy profile of an exergonic reaction (Keq>1). Starting material 3A produces a carbocation 3B that rearranges once to a more stable carbocation 3C and then produces product 3D. Label the points on your diagram 3A-3D. Hint 1: How many intermediates will there be on the energy diagram? Hint 2: What will be the relative energies of the transition states and species involved? ∆GRxn CoordinateOrganic Chemistry CHE230-001 EXAM 4 Page 5 of 11 Energy MO energy diagram of the transition state of 4a. Energy MO energy diagram of the transition state of 4b. 4. Let’s consider two hypothetical rearrangements, 4a and 4b. HHHH4a4bHHH4c4d 4e 4fH The transition state 4c has the H atom half way between the carbon atoms. 4d, 4e and 4f are molecular orbitals pertinent to the transition state of rearrangements 4a and 4b. Answer the following questions. You can avoid redrawing the MO’s by referring to them as 4d, 4e and 4f. 4.1 (10 pts) In the space below construct two Molecular Orbital Energy diagrams of the transition states of reactions 4a and 4b. You need to order the MO’s by lowest to highest energy and fill in the electrons. 4.2 (5 pts) Which rearrangement occurs easiest? Why? (Give a very brief answer)Organic Chemistry CHE230-001 EXAM 4 Page 6 of 11 6. Work space: 5. (10 pts) How many 13C signals are there in the following cis-bicyclic molecules? OOOOOOOOOOHHHHHHHHHH ____ ____ ____ ____ ____ 6. (10 pts) Consider the formula C9H7NO. It is a bicyclic structure with no triple bonds. You’re your work. How many double bonds does the structure have? _______ 7. NNONHNNONH7a. lysergic acid diethylamide7b. isolysergic acid diethylamide The following is an entry in Dr. Albert Hofmann’s lab book. “On Friday afternoon, April 16, 1943, while working in the laboratory, I was seized by a peculiar sensation of vertigo and restlessness. Objects, as well as the shapes of my associates appeared to undergo optical changes. I was unable to concentrate. . .” The compound he was working with was, at that time, a new compound with structure 7a, LSD. 7.1 (5 pts) Why doesn’t 7b produce the same effect since one could argue that 7a and 7b have the same physical properties? 7.1 My answer:Organic Chemistry CHE230-001 EXAM 4 Page 7 of 11 8 9 10 Chapters 10-12 8. (10 pts.) Draw the product of this reaction. HClROORheat 9. (10 pts.) Cyclopentadiene undergoes Diels-Alder cycloaddition to form a dimer. Please draw the structure of the dimer. Stereochemistry is important. dimer 10. (10 pts.) Draw the Diels-Alder product. Stereochemistry is important. OOOO+Organic Chemistry CHE230-001 EXAM 4 Page 8 of 11 11. (10 pts.) Complete the molecular orbital energy diagram below for the pi-system of benzene. We are looking down at the atomic p orbitals. I have drawn one of the MO’s for you and I put it in its proper place on the energy scale. Hint: If you can not remember the MO’s of benzene you can derive them easily from constructive and destructive linear combinations of the MO’s of allyl like I did in lecture. EABCDEF 12. Even though you get problem 11 totally wrong you should be about to answer the following questions. 12.1 (5 pts.) Which orbital(s) above is (are) the most bonding? ________ 12.2 (5 pts.) Which orbital(s) above is (are) the most antibonding? ________Organic Chemistry CHE230-001 EXAM 4 Page 9 of 11 13.2 13. Consider the hydrocarbon azulene. 13.1 (5 pts.) Is azulene aromatic, antiaromatic or neither? On what are you basing your opinion? Give a short answer that lets the grader know that you know what you are talking about. Your answer does not even have to be in a complete sentence. Be brief!! The arrow next to acetone (left, below) represents the dipole moment of acetone. The arrow points to the O atom because that is where most of the electron density is. The resonance structure shows how the electron density gets there. Hydrocarbons usually lack dipole moments because they lack
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