Homework answers / question archive / Chem 24 Makeup Exam 5/7/21 100 pts 50 pts Multiple choice: Choose the one best answer

Chem 24 Makeup Exam 5/7/21 100 pts 50 pts Multiple choice: Choose the one best answer

Sociology

Share With

Chem 24 Makeup Exam 5/7/21 100 pts 50 pts Multiple choice: Choose the one best answer. 1. Vinylic halides undergo: a. SN2 b. SN1 c. E1 d. None of the above 2. Which of the following has no effect on reaction rate for SN2 reactions? a. The leaving group b. Nucleophile c. Carbocation structure d. The solvent 3. The pKa of a terminal alkyne is: a. 15 b. 5 c. 25 d. 35 4. Carrying out dehydrohalogenation with sodium ethoxide (small, unhindered base) favors formation of the: a. More substituted alkene b. Less substituted alkene c. Less stable alkene d. Both a and c 5. E1 elimination requires a(n): a. Syn periplanar (or coplanar) transition state b. Anti periplanar (or coplanar) transition state c. Trigonal planar intermediate d. None of the above 6. SN1 reactions result in: a. Retention of configuration b. Inversion of configuration c. Racemic mixture of enantiomers d. None of the above 7. The only pathway not possible with a tertiary alkyl halide is: a. SN2 reaction b. SN1 reaction c. E1 reaction d. E2 reaction 8. Of the following, which is the worst leaving group? a. Iodide ion b. Bromide ion c. Chloride ion d. Fluoride ion 9. Which is a poor solvent for SN2 reactions? a. DMF b. DMSO c. water d. all of the above 10. Which is a poor solvent for SN1 reactions? a. DMF b. Ethanol c. Water d. Methanol 11. How many intermediates are formed in a SN2 reaction? a. 0 b. 1 c. 2 d. 3 12. SN2 reactions result in: a. Retention of configuration b. Inversion of configuration c. Racemic mixture d. None of the above 13. As discussed in class, planning an organic synthesis from simpler starting materials is called: a. An organic synthesis outline b. A retrosynthetic analysis c. An organic transformation plan d. None of the above 14. Which of the following reactions gives the anti-Markovnikov product? a. Hydroboration-oxidation of alkenes b. Electrophilic addition of hydrogen halides to alkenes c. Oxymercuration-demercuration of alkenes d. Hydration of alkenes 15. If electrophilic addition of an alkene to HBr results in a chiral compound, the result of the reaction is: a. inversion b. retention c. racemic mixture d. none of the above 16. If two groups of higher priority are on the same side of a double bond, the alkene is designated: a. R b. Z c. Trans d. E 17. Which of the following is the best leaving group? a. TsOb. H2O c. Id. Br18. A carbocation has what type of hybridization? a. Sp3 b. Sp2 c. sp d. None of the above 19. Which of the following has the most steric hindrance? a. Ethyl Bromide b. Methyl chloride c. Ethyl chloride d. Isopropyl chloride 20. The E2 reaction occurs by elimination of alpha-hydrogens a. True b. False 21. Zaitsev’s rule predicts that: a. The most stable carbocation will form in an elimination b. The most substituted alkene will form in an elimination c. The hydrogen atom adds to the carbon atom of the double bond that has the greater number of hydrogen atoms d. The hydrogen atom adds to the carbon atom of the double bond that has the lesser number of hydrogen atoms 22. The first intermediate formed during a dissolving metal reduction of an alkyne is called a: a. Vinylic anion b. Vinylic radical c. Radical anion d. Radical cation 23. If the concentration of both the substrate and base in a E2 reaction is doubled, the rate of the overall reaction: a. Stays the same b. Increases by a factor of two c. Increases by a factor of four d. Increases by a factor of eight 24. If the concentration of both the substrate and nucleophile in an SN1 reaction is doubled, the rate of the overall reaction: a. b. c. d. Stays the same Increases by a factor of two Increases by a factor of four Increases by a factor of eight 25. Hydroboration-oxidation occurs via a. Syn addition/Markovnikov b. Anti addition/Anti-Markovnikov c. Syn addition/Anti-Markovnikov d. Anti addition/Markovnikov Fill in the answer. 26. 10 pts Predict the major product and draw the mechanism of the reaction. 27. 2 pts each (total 14 pts) Predict the major product(s) for each reaction. Show stereochemistry where necessary using wedges and dashes. If there is no reaction, write NR. 28. 4 pts Predict the product and draw the mechanism of the following reaction. Pay special attention to which stereoisomer is formed. Is the product E or Z? 29. 4 pts Draw the full mechanism for the following SN1 reaction. Use arrows to show movement of electrons. 30. 8 pts What two elimination products can result from this reaction? Which is favored? 31. 3 pts Fully explain why polar aprotic solvents such as DMSO will increase the rate of reaction for SN2 reactions. 32. 3 pts Fully explain why polar protic solvents such as methanol will increase the rate of reaction for SN1 reactions. 33. 2 pts Predict the major organic product(s) for the following SN2 reaction. Show stereochemistry using wedges and dashes. 34. 2 pts Predict the major organic product(s) for the following SN1 reaction. Show stereochemistry using wedges and dashes.