CHEM Chapter 21. Carboxylic Acid Derivatives_Nucleophilic Acyl Substitution Reactions (homework) W

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1 Short Answer IUPAC Naming Instructions: Provide proper IUPAC names. 1. Name: 2. Name: 3. Name: Drawing Instructions: Draw structures corresponding to each of the given names. 4. Draw: acetic formic anhydride 5. Draw: N,N-dimethylformamide 6. Draw: methyl cis-3-ethylcyclobutanecarboxylate 7. Draw: (E)-2,4-dimethyl-2-hexenoyl chloride Exhibit 21-1 What is the order of decreasing reactivity towards nucleophilic acyl substitution for the carboxylic acid derivatives? (most reactive first) pg. 1

2 8. a. I, III, II, IV b. II, III, I, IV c. III, II, I, IV d. IV, I, III, II 9. The ester ethyl p-nitrobenzoate is more reactive towards nucleophilic acyl substitution than ethyl p-methyoxybenzoate. Explain this reactivity difference using both words and structures. 10. Write the complete stepwise mechanism for the basic hydrolysis of acetamide, shown below. Show all electron flow with arrows and draw all intermediate structures. Exhibit 21-2 Consider the reaction below to answer the following question(s): Acid halides react with diazomethane to yield diazoketones. Excess diazomethane is used to prevent the HCl produced in the reaction from reacting with the diazoketone. 11. Refer to Exhibit Diazomethane is an example of a dipolar molecule; a molecule which is neutral overall but has charges on individual atoms. One resonance form of diazomethane is drawn below. Draw the Lewis structure of the other resonance form of diazomethane. Be sure to include all formal charges. 12. Refer to Exhibit The intermediate structures for the mechanism for the reaction of propanyl chloride with diazomethane are provide below. Show all electron flow with arrows on these structures. pg. 2

3 Exhibit 21-3 Consider the reaction below to answer the following question(s): 13. Refer to Exhibit Write the complete stepwise mechanism for this reaction. Show intermediate structures and all electron flow with arrows. 14. Refer to Exhibit This reaction is an example of: a. an intermolecular nucleophilic acyl substitution reaction b. an intramolecular nucleophilic acyl substitution reaction c. an intermolecular S N2 reaction d. an intramolecular S N2 reaction 15. Refer to Exhibit The product of this reaction is: a. a lactone b. an anhydride c. a lactam d. an ether 16. Methyl butanoate has been isolated from pineapple oil and can be prepared by the Fischer esterification reaction shown below. Write the complete stepwise mechanism for this reaction. Show all electron flow with arrows and include all intermediate structures. pg. 3

4 17. Write the complete stepwise mechanism for the acid-catalyzed hydrolysis of the following amide to yield mandelic acid. Show all electron flow with arrows and draw the structures of all intermediate species. Exhibit 21-4 Consider the information below to answer the following question(s). The reaction of a carboxylic acid with an alcohol in the presence of acid is termed Fischer esterification. 18. Refer to Exhibit The nucleophile in this reaction is. 19. Refer to Exhibit Fischer esterification is an example of: a. nucleophilic acyl addition b. nucleophilic acyl substitution c. nucleophilic acyl elimination d. nucleophilic acyl rearrangement 20. Refer to Exhibit Write the stepwise mechanism for the Fischer esterification reaction of benzoic acid and methanol given above. Show all electron flow by using curved arrows, and include all intermediate structures. Exhibit 21-5 Provide structure(s) for the starting material(s), reagent(s) or the major organic product(s) of each of the following reactions or sequences of reactions. Show all relevant stereochemistry. 21. pg. 4

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6 Exhibit 21-6 Choose the best reagent(s) from the list provided below for carrying out the following transformations. Place the letter corresponding to the best choice in the blank to the left of the transformation. pg. 6

7 a. (Ph) 2CuLi, ether f. 1. DIBAH, toluene b. NaBH 4, ethanol 2. H 3O + c. 1. CH 3MgBr, ether g. 1. (Ph) 2CHMgBr 2. H 3O + 2. H 3O + d. 1. LiAlH 4, THF h PhMgBr, ether 2. H 3O + 2. H 3O + e. (CH 3) 2CuLi, ether Exhibit 21-7 Show how you would accomplish each of the following transformations. More than one step may be required. Show all reagents and all intermediate structures. 40. pg. 7

8 Ethyl phenylacetate is a pleasant smelling compound used in perfumery. Draw structures for each of the intermediates in the synthesis of ethyl phenylacetate below. Exhibit 21-9 Refer to the data below to answer the following question(s): Kodel is a staple and filament fiber prepared from dimethyl terephthalate and 1,4-cyclohexanedimethanol. Fabric made from Kodel has good crease resistance. 44. Refer to Exhibit Draw the structure of the Kodel polymer. 45. Name the following substance. Atoms other than carbon and hydrogen are labeled. pg. 8

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10 Answer Section SHORT ANSWER 1. ANS: methyl phenylacetate 2. ANS: trans-2-butenoyl chloride 3. ANS: N-cyclopentyl-3-methylbutanamide 4. ANS: 5. ANS: 6. ANS: 7. ANS: pg. 10

11 8. ANS: d 9. ANS: In general, any factor that makes the carbonyl carbon more polarized will increase the reactivity of the carboxylic acid derivative. In these particular examples, both are aromatic ethyl esters. It is the substituent on the aromatic ring that is affecting the reactivity difference. The electron-withdrawing nitro group increases the polarization of the carbonyl by withdrawing electrons from it through the aromatic ring. The electron donating methoxy group decreases the polarization of the carbonyl by donating electrons to it through the aromatic ring. 10. ANS: 11. ANS: pg. 11

12 12. ANS: 13. ANS: 14. ANS: b 15. ANS: a 16. ANS: pg. 12

13 17. ANS: 18. ANS: B 19. ANS: b 20. ANS: pg. 13

14 21. ANS: 22. ANS: 23. ANS: 24. ANS: pg. 14

15 25. ANS: 26. ANS: 27. ANS: 28. ANS: 29. ANS: pg. 15

16 30. ANS: 31. ANS: 32. ANS: 33. ANS: 34. ANS: pg. 16

17 35. ANS: h 36. ANS: a 37. ANS: d 38. ANS: f 39. ANS: d 40. ANS: 41. ANS: pg. 17

18 42. ANS: 43. ANS: 44. ANS: 45. ANS: ethyl 1-chloropropanoate pg. 18