FALL05 Midterm2

FALL05 Midterm2 - Chemistry 140A Whitesell Fall Quarter,...

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Unformatted text preview: Chemistry 140A Whitesell Fall Quarter, 2005 Second Midterm Exam, Monday November 14 first name middle initial last name Student ID Number Quest 1 2 3 4 5 6 7 8 9 10 11 12 13 total Regrade Points 4 4 4 4 4 4 10 8 10 10 14 10 14 100 score Your answers to this exam are to be only your own work. You may use no written information during this test period other than the five pages of this exam. You may not use the back of any pages for answers. Up to one week after your exam is returned you may submit it for regrading if and only if you have made NO marks on the exam except for a star (*) next to the number(s) of the question(s) you would like regraded. your signature (read the above before signing) To request regrading, sign below and check the appropriate boxes. your signature I would like the questions marked with a star (*) regraded (check box at right) If you feel that we have made an addition error in your score, check the box at the right 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1. The corrected ordering of the rates of reactions of alkyl halides in an SN2 reaction is: Methyl > 1° > 2° > 3° 3° > 1° > 2° > methyl 3° > 2° > 1° > methyl Methyl > 3° > 2° > 1° 2. The corrected ordering of the rates of reactions of alkyl halides in an SN1 reaction is: Methyl > 1° > 2° > 3° 3° > 1° > 2° > methyl 3° > 2° > 1° > methyl Methyl > 3° > 2° > 1° 3. Axial methylcyclohexane is less stable than is equatorial methylcyclohexane by: 2.5 kcal/mole 0.9 kcal/mole 5.5 kcal/mole 1.7 kcal/mole 4. The C—C—C bond angle in planar cyclobutane is: 60° 120° 90° 109.5° 5. A molecule with 4 centers of chirality can have at most: 2 stereoisomers 8 stereoisomers 4 stereoisomers 16 stereoisomers 6. In organic chemistry, resolution is: formation of radicals marriage counseling 7. separation of enantiomers separation of diastereomers Mark each center of chirality with the correct stereochemistry (R or S). Each is worth 1 point. Do NOT guess as 1 point will be subtracted for each wrong answer. Br Br Cl HO H H H OH OH OH Your signature (in ink)______________________________________________ 2 8. Show the mechanism for the following reaction using curved arrows to show the flow of electrons. H3C Cl NaOH H3C OH 9. Show the mechanism for the following reaction using curved arrows to show the flow of electrons. Br H2O OH Your signature (in ink)______________________________________________ 3 10. Draw a clear, three-dimensional representation for the transition state for the following reaction. H3C Cl NaOH H3C OH 11. Draw the more stable chair conformations of trans-1,4- and cis-1,3dimethylcyclohexane (shown below) using the chairs provided. trans-1,4-dimethylcyclohexane cis-1,3-dimethylcyclohexane Your signature (in ink)______________________________________________ 4 12. Draw a picture of a t-butyl cation showing the hyperconjugation that makes this cation more stable than a methyl cation. 13. Draw the structures show all stereochemistry for all of the monobromination products of (S)-2-bromopentane using the structures shown below (caution: there are more structures provide than there are products). Indicate for each structure if it is chiral or achiral and indicate if any compound(s) is meso. Do not guess. If you mark a chiral molecule as achiral (or the other way around or mark a non-meso as meso), you will have a point subtracted from you score for this question. Br Br Br Br Br Br Br Br Br Your signature (in ink)______________________________________________ 5 ...
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This note was uploaded on 10/04/2009 for the course BILD BILD 2 taught by Professor Schroeder during the Spring '08 term at UCSD.

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