Chapter 14 — Quiz
Twenty-five questions on synthesis design.
1. Retrosynthesis works: (a) forward, from starting material to product (b) backward, from target to precursors (c) randomly (d) only for simple targets
2. A "synthon" is: (a) a synthetic equivalent (a real reagent that plays the role) (b) an idealized fragment representing a disconnection (often charged or highly reactive) (c) a transition state (d) a final product
3. "FGI" stands for: (a) free-growth identity (b) functional group interconversion (c) fuel grade international (d) free group identity
4. Aspirin is synthesized from: (a) salicylic acid + acetic anhydride (one step) (b) sodium bicarbonate + acetic acid (c) phenol + ethanoic acid (d) benzaldehyde + acetate
5. The Williamson ether synthesis is: (a) alcohol + alkyl halide via SN2 (b) alkene + water (acid) (c) carbonyl + amine (d) ester + amine
6. Tosylation converts: (a) alcohol to a good leaving group (b) alkene to alkane (c) ester to amide (d) ester to alcohol
7. The progressive project of the book synthesizes: (a) aspirin first, then ibuprofen, then more complex drugs (b) only aspirin (c) randomly chosen drugs (d) only natural products
8. A retrosynthetic arrow (⟹) means: (a) "the target was formed by combining the precursor(s)" (b) "equilibrium between target and precursor" (c) "the forward reaction" (d) "exclusively reversible"
9. Protecting groups are used to: (a) mask reactive functionality during synthesis (b) speed reactions (c) reduce yield (d) visualize stereochemistry
10. The Synthesis Toolkit starts with: (a) ~10 reactions in Ch 14 (b) ~80 reactions by Ch 40 (c) Both (a) and (b) — it grows (d) ~5 reactions only
11. Why is the Williamson ether synthesis preferred over "alcohol + alcohol with acid"? (a) The Williamson is SN2 on a primary halide; clean, high yield (b) The acid-catalyzed approach gives a mixture of ether + alkene + alcohol (c) Both (a) and (b) (d) The acid approach doesn't work at all
12. A target alcohol can come from: (a) Reducing the corresponding aldehyde (b) SN2 on an alkyl halide with hydroxide (c) Markovnikov hydration of an alkene (d) All of the above
13. Why might a chemist convert an alcohol to a tosylate before doing SN2? (a) Tosylate is a much better leaving group than HO⁻ (b) Tosylates can be made in high yield with retention of configuration (c) Both (a) and (b) (d) Tosylates make the substrate more nucleophilic
14. A primary alcohol + HBr at moderate T: (a) SN2 gives primary alkyl bromide (b) SN1 on a primary substrate (impossible) (c) E2 elimination (d) Doesn't react
15. Aspirin's mechanism is: (a) SN2 (b) SN1 (c) Nucleophilic acyl substitution (d) Radical
16. A multi-step synthesis is "convergent" when: (a) two halves of the target are made separately and combined later (b) it's a long linear sequence (c) it converges on one product (d) all reagents are added simultaneously
17. Why is convergent synthesis better than linear (for the same number of steps)? (a) Higher overall yield (yields are not multiplicative across separate branches) (b) More fun (c) Faster (d) Cheaper reagents
18. A target has both an aldehyde and a primary alcohol. You want to do a Grignard addition on the aldehyde without touching the alcohol. What do you do? (a) Use a different reagent (b) Protect the alcohol first (e.g., as TMS ether) (c) Both (a) and (b) work (d) Run at low T
19. Strategic disconnection means breaking: (a) a random bond (b) a bond that, when broken, gives a simpler precursor with a known forward reaction (c) a C-H bond (d) the most stable bond
20. When designing a synthesis, you should: (a) Try forward synthesis only (b) Combine retrosynthetic analysis with forward planning (c) Memorize all reactions (d) Work randomly
21. Aspirin synthesis: which atom of salicylic acid attacks the acetic anhydride? (a) The carboxylic acid OH (b) The phenol OH (specifically, the lone pair on the oxygen) (c) The aromatic ring (d) None of the above
22. The Williamson ether synthesis works best when: (a) Alkyl halide is primary; alkoxide is the nucleophile (b) Alkyl halide is tertiary (c) Both halide and alkoxide are tertiary (d) Either component is bulky
23. A chemist wants to convert butan-1-ol to butan-1-amine. What's the issue and how to solve it? (a) Direct SN2 of HO⁻ → amine doesn't work; activate alcohol to tosylate, then SN2 with NaN₃, then reduce (b) Direct SN2 with NH₃ works (c) Use HCl (d) Use dehydration
24. Activating an alcohol via tosylation has the advantage that: (a) Stereochemistry is preserved (the tosylate has the same configuration as the alcohol) (b) Tosylate is a much better leaving group than HO⁻ (c) Both (a) and (b) (d) It's expensive
25. What is the key insight of Chapter 14 that you should leave with? (a) Multi-step syntheses are designed by working backward from the target. (b) The decision framework (Ch 13) applies at every step. (c) Both (a) and (b). (d) Forward synthesis only.
Answer key
- b. 2. b. 3. b. 4. a. 5. a. 6. a. 7. a. 8. a. 9. a. 10. c. 11. c. 12. d. 13. c. 14. a. 15. c. 16. a. 17. a. 18. c. 19. b. 20. b. 21. b. 22. a. 23. a. 24. c. 25. c.