Chapter 22: Carboxylic Acids and Their Derivatives

Chapter 22 1. Which of the following is a lactam? O O O O NH N H A. B. A) A Ans: A B) B C) C O N H C. NH D. D) D 2. Why is an amide less reactive to nucleophilic acyl substitution than an acid chloride? A) Chloride is a better leaving group. B) Nitrogen is better at donating electron density into the carbonyl with added resonance stablity. C) Chloride is a better leaving group and Nitrogen is better at donating electron density into the carbonyl with added resonance stability. D) The amide anion is less basic. Ans: C 3. What is the IUPAC name for the following compound? O g 932 NH I 4 methyl A) Methyl 3-methylbutanamide B) 5-methylhexanamide Ans: D C) D) N-methyl 3-methylhexanamide N-methyl 3-methylbutanamide 4. What is the IUPAC name for the following compound? CO2H F A) 4-fluoro-3-methylbenzoate B) 4-fluoro-3-methylbenzoic acid Ans: B C) D) I Page 1 3-methyl-4-fluorobenzoic acid 4-fluoro-5-methylbenzoic acid 5. Select the correct structure for acetic propanoic anhydride. Reiser O O O O A. A) A Ans: A B) B O O O O O O O O B. C. D. C) C D) D 6. Select the correct structure for ethyl 4-chlorobenzoate. O O t Cl t O O OH OH Cl D) x D A. C) C y x B. B) B O Cl Cl A) A Ans: D O C. D. 7. Select the correct structure for 3-cyanocyclopentanone. HO O CN O O CN CN A. A) A Ans: B NC B. B) B C) C C. D. D) D i 8. What is the IUPAC name for the following compound? y 2F I CN A) 2-fluorobutanonitrile B) 2-fluoropentanonitrile Ans: C C) D) 3-fluoropentanonitrile 2-fluorobutylcyanide 9. What is the approximate wavenumber for the IR absorption of the carbonyl group of a simple ester? A) 2.5 ppm B) 2250 cm–1 C) 3800 cm–1 D) 1740 cm–1 Ans: D Page 2 10. Which of the following would appear in the IR spectrum of a carboxylic acid? A) A flat line (carboxylic acids are not IR active) B) A sharp line at 2250 cm–1 C) A broad peak from 3800–2800 cm–1 D) A broad peak from 800–600 cm–1 Ans: C 11. Which of the functional groups below might give rise to an absorption at 2250 cm-1 in the IR spectrum of a compound? A) A ketone B) An aldehyde C) An ester D) A nitrile Ans: D 12. Where do the carbonyl signals appear in the 13C NMR spectra of carboxylic acid derivatives? A) 1700 cm–1 B) 180–160 ppm C) 2.5–3.0 ppm D) 100–80 ppm Ans: B e 13. Which structure is consistent with the following simulated 1H NMR spectrum? A) Ethyl acetate B) Propanone Ans: D C) D) 3,3-dimethyl-2-pentanone Ethyl 2,2-dimethylpropionate 14. What is the first step in the general mechanism for nucleophilic acyl substitution? A) Protonation of the carbonyl B) Removal of an α-proton C) Addition of the nucleophile to the carbonyl D) Loss of the leaving group Ans: C Page 3 15. Why doesn't nucleophilic acyl substitution stop at the tetrahedral intermediate? A) The nucleophile is too basic. B) Reforming the carbonyl is energetically favorable. C) The leaving group is unstable and prefers to be negatively charged. D) There is no tetrahedral intermediate. Ans: B 16. Will the following reaction occur as written? O O HCl O O O + Cl OH A) Yes, anhydrides are easily cleaved with strong acid to yield the acid chloride and carboxylic acid. B) No, anhydrides are cleaved with strong acid to give 2 equivalents of acid chloride. C) Yes, anhydrides undergo nucleophilic attack by HCl to form the acid chloride and carboxylic acid. D) No, although anhydrides can be used to make carboxylic acids, they cannot form acid chlorides directly since the leaving group is too strong a base. Ans: or B 17. Will the following reaction occur as written? O O CH3NH2 O O N H O A) + OH Yes, anhydrides can be converted into amides and carboxylic acids since the leaving group is a weaker base than CH3NH2. B) No, anhydrides cannot be converted into amides and carboxylic acids since the leaving group is a stronger base than CH3NH2. C) Yes, anhydrides can be converted into amides and carboxylic acids since the products have a greater amount of hydrogen-bonding. D) No, anhydrides cannot by converted into amides and carboxylic acids since the products are too polar. Ans: A Page 4 18. Will the following reaction occur as written? O OH NH cat. H2SO4 O H2 N O A) Yes, after initial protonation of the carbonyl oxygen, ethanol is added to open the lactam. B) No, the lactam would dimerize under these conditions. C) Yes, cyclic amides can easily be converted to esters due to the ring strain. D) No, ring opening of the lactam does not occur since the protonation of the nitrogen occurs more readily than protonation of the carbonyl oxygen. Ans: D 19. Why is pyridine included as a reagent in the reaction of an acid chloride and an amine or alcohol? A) Pyridine will deprotonate the amine or alcohol, making it a better nucleophile. B) Pyridine will neutralize the acid by-product of the reaction. C) Pyridine will protonate the carbonyl of the acid chloride, making it more reactive. D) Pyridine will absorb the heat of the reaction. Ans: B 20. Select the structure of the product of the following reaction. O NH2 O cat. H2SO4 O O N NH H N HO O A. A) A Ans: C C. B. B) B C) C D) D Page 5 OH N H O D. 21. Select the structure of the product of the following reaction. O O O Na Cl O O O Na O O O O O O O A. A) A Ans: B B. B) B C) C C. D. D) D 22. Which of the following reaction pathways could be used to convert a carboxylic acid into an ester? 1. Heat the acid with an alcohol and catalytic acid 2. Deprotonate the acid with a base and react with an alcohol 3. Deprotonate the acid with a base and react with an alkyl halide A) 1 only B) 2 only C) 3 only D) 1 and 2 E) 1 and 3 Ans: D 23. Which of the following reaction pathways could be used to convert a carboxylic acid into an acid chloride? A) Heat the acid with hydrochloric acid B) React the acid with thionyl chloride (SOCl2) C) React the acid with sodium chloride D) Fuse the acid with sodium chloride Ans: B 24. Select the structure of the product of the following reaction. NH2 CO2H DCC O H N A. A) A Ans: C B) B C) C O N H N H N H B. C. D. D) D Page 6 No 25. Which of the following is the direct product of the base-promoted hydrolysis of an ester? A) A nitrile B) A carboxylic acid C) An amide D) A carboxylate salt Ans: D 26. Which of the following two amides will react more readily with a nucleophile? O N H NH O 1 Why? A) 1, because it is less hindered B) 2, because it is less hindered Ans: C 2 1, because it is more strained 2, because it is more strained C) D) I 27. Select the product of the following reaction. 1. LiAlH4 CN 2. H2O A) hexanoic acid Ans: D B) hexanamide C) hexanal D) hexylamine 28. Select the structure of the product of the following reaction (after acidic work-up). CN CH3MgBr O CN NH2 NH2 A. B. A) A Ans: B B) B C) C C. D) D 29. Which reagent(s) would you use to effect the following transformation? CN A) LiAlH4 Ans: B CHO B) DIBAL-H C) NaBH4 t Page 7 D) H2, Pd/C D. 5 4 9 SHG 30. Select the structure for the compound whose IUPAC name is pentyl 2-methylbutanoate. O A. 1 B. 234 56789 O O O O C. D. O O O A) A Ans: A B) B C) C D) D 31. What is the IUPAC name for the following compound? 432 O O I A) Propionyl phenol B) Phenyl propanoate Ans: B C) D) I x Phenol propanoate Phenyl acetate 32. Select the structure of the product of the following reaction. O NH2 O O O NH2 N NH O NH O O O A. A) A Ans: C B. B) B C) C C. D) D Page 8 D. 33. Select the structure of the product of the following reaction. aq. HCl CN CO2 K CO2H A. B. A) A Ans: A B) B C) C CO2H NH2 C. D. D) D 34. Select the structure of the product of the following reaction. O O O O OH O O O OH O OH O O O O OH OH OH O O A. A) A Ans: A B. B) B C. C) C D. D) D D 35. Select the structure of the product of the following reaction. O SOCl2 OH O O H NH2 A. A) A Ans: D O OSOCl B. B) B C) C O C. D) D e Page 9 Cl D. 36. Select the structure of the product of the following reaction. O ∆ OH HO O O O Cl Cl O O O OH H2N O B. B) B H N O O A. A) A Ans: B O C) C C. D. D) D 37. Select the structure of the product of the following reaction. O 1. SOCl2 OH 2. CH3OH O O Cl OSOCl A. A) A Ans: D O OH B. B) B C) C O C. O D. D) D 38. Which of the following reagent choices would successfully bring about the reaction shown below? Cl CO2H O A) Acetic acid Ans: C B) NaOMe C) SOCl2, pyridine Page 10 D) Pyridine 39. Which of the following reaction conditions can be used to synthesize an ester (RCOOR')? A) RCOCl + R'OH + pyridine B) RCOOH + R'OH + H+ C) RCOOH + R'OH +Ribe OH– a D) RCONH2 + R'OH E) Both RCOCl + R'OH + pyridine and RCOOH + R'OH + H+ are acceptable methods. Ans: E 40. Rank the following compounds in order of increasing reactivity in nucleophilic acyl substitution. O O Cl CN O 1 2 E A) 1; 2; 3 Ans: B B) 3; 2; 1 X C) 2; 3; 1 3 D) 3; 1; 2 41. Select the structure of N-phenyl acetamide. O NH2 H N NH2 O O A. A) A Ans: t C O B. B) B C) C C. N H D. D) D 42. Which of the following substrates cannot be used as an immediate precursor to synthesize an ester? O O R Cl R A. A) A Ans: B O NH2 B. B) B R O O O R C. C) C D) D R OH E. All of these can be used. D. E) E 43. From the list below, pick the compound that does not react with acetyl chloride. A) Isopropyl alcohol B) Benzoic acid C) Ammonia D) Triethyl amine Ans:0D Page 11 44. Which of the following statements about amides is true? A) Amides react with methyl alcohol in the presence of an acid catalyst to form an ester. B) Amides are hydrolyzed in acid or base to form carboxylic acids or carboxylate anions. C) Amides react with thionyl chloride to form the acid chloride. D) Amides do not react under any conditions. They are inert compounds. Ans: B t 45. n-Butanenitrile will undergo all of the following listed reactions except one. Which of the reactions listed will not occur? A) n-Butane nitrile will react with ethylmagnesium bromide to form an alcohol. B) n-Butanenitrile with be reduced to butylamine in the presence of LiAlH4 with a water work-up. C) n-Butanenitrile is hydrolyzed in the presence of acid to form butanoic acid. D) n-Butanenitrile is reduced with DIBAL–H to form n-butanal. Ans: A 46. The IR spectrum of an unknown compound has a sharp, medium intensity peak at 2250 cm–1. The compound is probably: A) an alkane. B) an aldehyde. C) an alkene. D) a nitrile compound. Ans: D t 47. All of the following contain an sp2 hybridized functional group, except: A) a carboxylic acid. B) a nitrile. C) an aldehyde. D) an anhydride. Ans: B Page 12 Challenge Questions 48. Imidazole has been shown to increase the rate of ester hydrolysis. Based on the following mechanism, what is the best explanation for the increased rate of hydrolysis? O O + N NH O N N O O NH + O + OH NH H 2O O O + HN NH A) Imidazole protonates the leaving group, thus causing the rate of hydrolysis to increase. B) Imidazole increases ester hydrolysis by increasing the pH of the reaction mixture. C) Imidazole is a stronger nucleophile than water and provides a better leaving group than the alkoxide ion. D) Imidazole provides a stronger bond to the carbonyl carbon than water, thus increasing the rate of hydrolysis. Ans: C 49. Select the proper sequence of reagents used to accomplish the following conversion. O CN O A) B) C) D) Ans: [1] LiAlH4; [2] H2O; [3] CH2=CHCO2CH3 [1] DIBAL-H; [2] H2O; [3] Ph3P=CHCO2CH3 [1] BrMgCH2=CHCO2CH3; [2] H2O; [3] H2, Pd/C [1] H3O+; [2] CH2=CHCO2CH3; [3] KOtBu B Page 13 50. A class of compounds referred to as tyramides has been isolated from male ants. The synthesis of such compounds can be done in 4 steps starting from p-methylphenol. Based on the following reaction sequence what is the structure of tyramide A? 1. Br2, hν 2. NaCN HO Tyramide A 3. a) LiAlH4; b) H2O 4. ClCOCH2CH2CH3 O A. O O B. O HO O C. N H HO O O D. O A) A Ans: D B) B C) C N H D) D 51. What is the structure of a compound whose 1H NMR data is given below? 1 H NMR data: 0.97 (triplet, 3 H), 1.33 (doublet, 3 H), 1.68 (multiplet, 2 H), 5.08 (multiplet, 1 H), 6.92 (doublet, 2 H), 7.50 (singlet, 1 H) and 7.95 (doublet, 2 H) ppm. O HO HO A. B. O O O O O O O D. C. O A) A Ans: A B) B C) C D) D Page 14 52. Vegetable oil can be used to synthesize Biodiesel according to the reaction below. What is the general structure of Biodiesel? O O R R O O O O + R OH catalyst 3 CH3OH + Biodiesel (KOH) HO OH Glycerin Vegetable Oil O O O O O O O O A) A Ans: tD B) B O O O A. O O B. C) C R O O O C. D) D Page 15 O R O R D.