CHEMpossible 261 Exam 1 Review A. Rank the following carboxylic acids from least acidic to most acidic: B. Draw the line-angle formulas for three acylic (non-cyclic) esters with the molecular formula C 4 H 6 O 2 (structural/constitutional isomers only!) Least < < Most Acidic Acidic C. Rank the following molecules from lowest to highest boiling point (BP): Lowest < < Highest BP BP d. Answer the following questions about Clividine, shown below: 1. What is the hybridization (sp, sp 2, sp 3 ) of oxygen A? 2. In what orbital does the lone pair of oxygen B reside? 3. What is the hybridization (sp, sp 2, sp 3 ) of nitrogen C? 4. Which orbitals overlap to form the bond labeled D? (e.g. C sp -H 1s ) 5. What is the molecular formula? (list atoms in the order C, H, N, O) e. With respect to the bold hydrogen/proton, which molecule is more acidic? (A or B?) Explain your answer (using graphics and text).
2. Follow the instructions given: A. Provide the IUPAC name of the molecule shown below: b. Circle all of the chiral carbon atoms in the molecule shown below. C. Draw a line-angle formula for the molecule shown below. You must use dashes/wedges to show the absolute configuration of any chiral carbons. D. Rank the following cations from most stable to least stable. Least Most Stable < < Stable 3. Draw Newman projections down the indicated bond (from the viewpoint shown) that represent the highest and lowest energy conformations of the molecule. Estimate the energy difference between the two conformations given the interaction energies in the table below. Interactions Energy (kcal/mol) CH 3 /CH 3 gauche 0.9 CH 3 /CH 3 eclipsed 3.0 CH 3 /H eclipsed 1.3 H/H eclipsed 1.0 Highest energy conformer Lowest energy conformer Energy difference calculation
4. The structure of methyl dimethylcarbamate (A) is shown below. Answer the questions that follow. A. Add any missing lone (electron) pairs directly to structure A. B. Draw two other unique (i.e. non-identical) resonance forms of A that also obey the octet rule for all atoms. Do not forget to draw all lone pairs and appropriate formal charges! C. From the two structures that you drew, circle the major contributor and briefly explain why this is your choice. D. How many electrons are in the molecule s σ-bonding framework? E. In the space below, draw the π-framework of methyl dimethylcarbamate, carefully showing all of the atomic orbitals that contain the π-electrons. 5. Follow the instructions given: A. Circle and name four different functional groups that appear in the anticancer drug Tarceva. B. For the molecules shown below, indicate the formal charge of each boron, nitrogen, and oxygen atom (e.g., 0, +1, -1, etc.).
6. Consider the following acid-base reaction and answer the questions that follow: A. Use curved arrows to show how the acid and the base react (mechanism of electron movement) above (you will have to draw the appropriate hydrogen of the acid). Be very precise! B. Draw the products of the reaction, complete with any charges and lone pairs. C. Estimate K eq. Show your work. 7. For each of the pairs shown, indicate their relationship as conformation isomers, geometric isomers (cis/trans isomers), structural isomers, identical, enantiomers, diastereomers, or none.
8. Given the following molecule (A): a. Draw five other unique (i.e., non-identical) resonance forms of A that obey the octet rule for all carbon and nitrogen atoms. Use arrows to show the electron movement from one structure to the next. b. From the six structures drawn above, circle the top two contributors and say why (in one sentence) these are your choices. 9. Consider the three structures shown below, and answer the questions that follow. A. Assign the absolute configuration (R or S) of any chiral carbons in B. Place the assignments near the appropriate carbons in the structure above. B. Will a solution containing equal amounts of A, B, and C be optically active? (yes/no) C. What is the isomeric relationship between A and B?
10. Draw all the meso stereoisomers of the compound shown below (by using dashes and wedges; you do not need to draw chair conformations). 11. Consider the molecule shown below. It is optically pure (a single enantiomer). A. Clearly draw the two chair conformers of the molecule in equilibrium. Be sure to draw all substituents and ring hydrogens. B. Which of the two conformers is most stable? 12. Consider the molecules shown below, and answer the questions that follow. A. Which molecules, if any, are meso? B. Which molecule has the same melting point as C? C. Will a solution containing equal amounts of B and E be optically active? D. What is the isomeric relationship between B and D? E. Which molecule is the same as the one shown below?