B. A transition state represents a maximum on the reaction path diagram and can be isolated.

Transcription

1 Practice Hour Exam 2, Chemistry 2210, Organic Chemistry I 1. The most stable carbocation is: 2. Which of the following statements is true of transition states? A. A transition state represents a minimum on the reaction path diagram and can be isolated. B. A transition state represents a maximum on the reaction path diagram and can be isolated. C. A transition state represents a minimum on the reaction path diagram and cannot be isolated. D. A transition state represents a maximum on the reaction path diagram and cannot be isolated. 3. Which of the following structures is the least stable conformation of butane? 4. Which of the following compounds is/are meso? I II III A. I only B. II only C. III only D. II and III IV

2 5. Which of the following compounds would react the fastest in an S N 1 reaction? A. (C 6 H5)3CCl B. (C 6 H5)3CCH 2 Cl C. (C 6 H5)2CHCl D. (CH3)3CCl 6. What is the IUPAC name of the following compound? A. 4-bromo-4-ethyl-2,5-dimethyloctane B. 5-bromo-4-ethyl-2,4-dimethyloctane C. 4-bromo-3-isobutyl-3-methylheptane D. 3-bromo-3-ethyl-5-methyl-2-propylhexane 7. The most stable conformation of the following compound has the methyl group in the position and the tert-butyl group in the position. A. Equatorial, Axial B. Equatorial, Equatorial C. Axial, Axial D. Axial, Equatorial 8. What is the relationship of the following compounds? CH 2 CH 3 OH H OH CH 3 CH 2 H H OH CH 3 OH CH 3 H A. Enantiomers B. Diastereomers C. Constitutional isomers D. Same compound

3 9. Which statement is true for the reaction shown here? NaOH + CH 3 CO 2 H H 2 O + CH 3 CO 2 Na A. NaOH is the base and CH 3 CO 2 Na is its conjugate base B. NaOH is the acid and H 2 O is its conjugate base C. CH 3 CO 2 H is the acid and CH 3 CO 2 Na is its conjugate base D. CH 3 CO 2 H is the base and CH 3 CO 2 Na is its conjugate acid 10. Which of the following changes will increase the rate of the following reaction? Br + SH SH + Br I. Replace SH with H 2 S II. Replace (CH 3 ) 2 CHCH 2 Br with CH 3 CH 2 CHBrCH 3 III. Replace (CH 3 ) 2 CHCH 2 Br with (CH 3 ) 2 CHCH 2 OH IV. Use the solvent DMSO instead of methanol A. I and III B. II C. I and IV D. IV 11. What is the energy of activation for the reaction of B C? kj/mol A C Series reaction coordinate B A. 6 kj/mol B. 3 kj/mol C. 9 kj/mol D. 23 kj/mol

4 12. Which of the following statements correctly describes the molecule shown below: A. It is achiral B. It is meso C. Its chirality center possesses the R configuration D. The mirror image of this molecule is its enantiomer 13. For the following reaction step, indicate the mechanistic pattern. A. Proton Transfer B. Loss of Leaving Group C. Nucleophilic Attack D. Rearrangement 14. Which of the following is/are the most likely product(s) for the following reaction? Br K acetone A. and B. C. D.

5 15. What is the IUPAC name of: H H I A. trans-1-iodo-2-vinylcyclohexane B. cis-1-iodo-2-vinylcyclohexane C. trans-2-iodo1-vinylcyclohexane D. cis-2-iodo-1-vinylcyclohexane 16. What is the configuration of the following molecule? H CH 3 H C3 C2 COOH HO CH 3 A. (2R,3R) B. (2S,3S) C. (2R,3S) D. (2S,3R) 17. What is wrong with the following mechanism? A. There is no leaving group, so there should be no arrows. B. The arrow should be removing a proton from the H 2 O group. C. An arrow is also needed to indicate the loss of the leaving group. D. The arrow indicating the formation of the C-Br bond (nucleophilic attack) should start at the bromide anion.

6 18. What is the product of the following S N 1 reaction? 19. What is the relationship between the following two molecules? A. diastereomers B. conformers C. enantiomers D. constitutional isomers 20. Which of the following compounds has the lowest boiling point? 21. Give the IUPAC name for the following compound. A. (S)-2-methyl-4-chloro-1-hexene B. (R)-2-methyl-4-chloro-1-hexene C. (S)-2-methyl-4-chloro-1-pentene D. (R)-2-methy-4-chloro-1-pentene

7 22. The major compound that will form in the following S N 1 reaction will be: 23. Your sample of Compound-X was found to have a specific rotation of +20. A sample of pure Compound-X has a specific rotation of What is the composition of the sample? A. 20% (+) isomer and 80% (-) isomer B. 80% (+) isomer and 20% (-) isomer C. 60% (+) isomer and 40% (-) isomer D. 40% (+) isomer and 60% (-) isomer 24. Which of these statements is false? A. Angle strain is a major problem in cyclopropane. B. Gauche butane has torsional strain. C. Boat cyclohexane is destabilized with respect to chair cyclohexane, partly due to flagpole steric strain. D. On a cyclohexane, 1,3-diaxial interactions are an example of steric strain. 25. What is the correct priority of these groups with respect to (R,S) determination in stereochemistry, with highest priority group first? Assume these groups are all bonded to the same chirality center. A. -CH 2 CH 2 F > -CH 2 OH > -CH=CH 2 > -C(CH 3 ) 3 B. -CH 2 OH > -C(CH 3 ) 3 > -CH=CH 2 > -CH 2 CH 2 F C. -CH 2 OH > -C(CH 3 ) 3 > -CH 2 CH 2 F > -CH=CH 2 D. -C(CH 3 ) 3 > -CH=CH 2 > -CH 2 OH > -CH 2 CH 2 F