Homework Chapter 19—Aldehydes and Ketones: Nucleophilic AdditionReactions Problems Considered for Exam #3 are Highlighted SHORT ANSWER Drawing Instructions: Draw structures corresponding to each of the given names. 1. Draw: 2,2,2-trichloroethanal (chloral) ANS: 2. Draw: benzophenone ANS: 3. Draw: trans-3-isopropylcyclohexanecarbaldehyde ANS: 4. Draw: 5,5-dimethyl-1,3-cyclohexanedione (dimedone) ANS: 1 Aldehydes and Ketones: Nucleophilic Addition Reactions 5. Draw: 2-cyclohexenone ANS: 6. What is the correct structure for 2-hydroxyacetophenone? a. b. c. d. ANS: c IUPAC Naming Instructions: Provide proper IUPAC names. 7. Name: ANS: m-nitrobenzaldehyde 8. Name: ANS: 4,8-dimethyl-7-nonen-2-one 2 ANS: 3 . Show all intermediate structures and all electron flow with arrows. Name: ANS: 1-phenyl-2-propanone 10. Write the complete stepwise mechanism for the reaction shown above.Chapter 19 9. Refer to Exhibit 19-1. Name: ANS: 5-oxoheptanal Exhibit 19-1 Consider the reaction below to answer the following question(s): 12. Name: ANS: cis-1.3-cyclopentanedicarbaldehyde 11. a much better nucleophile ANS: d 16. ANS: The carbonyl carbon in cyclopropane is highly strained because the preferred bond angle for an sp2-hybridized carbon is 120° but the real angle is 60°. c. This placeholder question is here to maintain the numbering system integrity between the printed copy and ExamView. b.Aldehydes and Ketones: Nucleophilic Addition Reactions 13. b. Explain this phenomenon based on the structures of cyclopropanone and its hydrate. d. This question was omitted on the printed copy. a. Refer to Exhibit 19-1. Refer to Exhibit 19-1. Going from sp2 to sp3 hybridization relieves angle strain by about 10°. 15. a. ANS: Answer not provided. it has been marked "do not use on test" in ExamView's question information dialog. The substance formed on addition of water to an aldehyde or ketone is called a hydrate or a/an: vicinal diol geminal diol acetal ketal ANS: b 14. The exact position of the equilibrium between ketones/aldehydes and their hydrates depends on the structure of the carbonyl compound. Many nucleophilic addition reactions of aldehydes and ketones are catalyzed by acid or base. c.5°. and the equilibrium lies to the right in this reaction. Refer to Exhibit 19-1. 4 . Therefore. This angle strain is somewhat relieved when cyclopropanone is hydrated⎯the preferred bond angle for an sp3-hybridized carbon is about 109. Although the equilibrium favors the carbonyl compound in most cases. Thus. d. cyclopropanone forms a stable hydrate. As a result. the hydrate of cyclopropane is more stable than the carbonyl form. Bases catalyze hydration by: making the carbonyl group more electrophilic shifting the equilibrium of the reaction making the carbonyl group less electrophilic converting the water to hydroxide ion. this placeholder question is automatically prevented from being chosen as a test question. 5-diketones. ANS: 5 . On the structures provided below. draw arrows showing electron flow for the reaction mechanism for the acetic acid-catalyzed formation of an enamine from cyclohexanone and pyrrolidine.Chapter 19 17. Enamines formed from the cyclic secondary amine pyrrolidine are important intermediates in the synthesis of 1. Refer to Exhibit 19-2. Nitriles can also be hydrolyzed to carboxylic acids using aqueous base. Identify the electrophile in the reaction of benzaldehyde with hydrogen cyanide. b. The reaction of benzaldehyde with hydrogen cyanide is catalyzed by the addition of a small amount of KCN. a nucleophilic substitution an electrophilic addition an electrophilic substitution a nucleophilic addition ANS: d 19. . d. Refer to Exhibit 19-2. 18. The nitrile functional group can be hydrolyzed by aqueous acid to yield a carboxylic acid. ANS: The benzaldehyde is the electrophile in this reaction.Aldehydes and Ketones: Nucleophilic Addition Reactions Exhibit 19-2 Consider the data below to answer the following question(s). c. 6 Refer to Exhibit 19-2. Cyanohydrins are important intermediates in the synthesis of α-hydroxycarboxylic acids from ketones and aldehydes. Unfortunately. when a cyanohydrin is treated with aqueous base the original carbonyl compound is isolated. Show all electron flow with arrows and show all intermediate structures. Write the complete reaction mechanism for the KCN-catalyzed reaction. 20. The reaction of an aldehyde with hydrogen cyanide is an example of _____ reaction. a. shown above. Write the complete stepwise mechanism for the Wittig reaction shown below. Refer to Exhibit 19-2.Chapter 19 ANS: 21. a phosphorus ylide adds to a ketone or aldehyde to yield an alkene. Formulate a reasonable mechanism for the reaction of the cyanohydrin of benzaldeyhe. In the Wittig reaction. ANS: 7 . Show all intermediate structures and all electron flow with arrows. Show all intermediate structures and all electron flow with arrows. with aqueous NaOH. ANS: 22. The product of this reaction is called: an ylide an acetal a gem diol a hydrate ANS: b 8 . Refer to Exhibit 19-3. Refer to Exhibit 19-3. a.Aldehydes and Ketones: Nucleophilic Addition Reactions Exhibit 19-3 Consider the reaction below to answer the following question(s). b. 23. d. The catalyst in this reaction is: ANS: C 25. c. The nucleophile in this reaction is: ANS: B 24. Refer to Exhibit 19-3. as shown below. ANS: 9 . Draw a resonance form for the unsaturated carbonyl that accounts for this reactivity.β-Unsaturated aldehydes and ketones can undergo reaction with nucleophiles at the β carbon. Write the complete stepwise mechanism for this reaction.Chapter 19 26. Refer to Exhibit 19-3. Refer to Exhibit 19-4. 27. ANS: Exhibit 19-4 α. Show all electron flow with arrows and show all intermediate structures. ANS: 10 . b. a 1.2-addition. a direct addition d. c. 29. ANS: a Exhibit 19-5 Give the major organic product(s) for each of the following reactions or sequences of reactions.Aldehydes and Ketones: Nucleophilic Addition Reactions 28. a 1. ANS: 30.2-conjugate addition. This reaction is called _____ reaction. Refer to Exhibit 19-4. Show all relevant stereochemistry. an electrophilic addition. a. ANS: 32.Chapter 19 31. ANS: 33. ANS: 11 . Aldehydes and Ketones: Nucleophilic Addition Reactions 34. ANS: 35. ANS: 36. ANS: 12 . ANS: 13 . ANS: 39. ANS: 38.Chapter 19 37. ANS: 40. b. H3O+ All of the above work well ANS: c 43. a. ANS: Exhibit 19-6 Choose the BEST reagent for carrying out each of the following conversions. LiAlH4. d. b. LiAlH4. c. d. ether NaBH4. THF NaBH4. ethanol 1. pyridine H2/Pd ANS: b 14 . 42. ethanol CrO3. c.Aldehydes and Ketones: Nucleophilic Addition Reactions 41. a. toluene 2. DIBAH. H2O All of the above ANS: a 15 . d. ether ANS: c 46. a. ether 2. H3O + (C6H5)3P=CHC 6H5. 1. ether 2. ether 2. ethanol CH2PPh3 NaOH. c. b. PhCH2MgBr. d. c. H3O+ (C6H5)3P=CHC6H5. a. H3O+ 1. NaBH4.Chapter 19 44. THF Li(C6H5)2Cu. 1. ether 2. PhMgBr. PhMgBr. THF Li(C6H5) 2Cu. b. d. PhCH2MgBr. H3O+ 1. a. ether ANS: d 45. b. c. ANS: 16 . Identify the alkyl halide and the carbonyl components that would be used in each synthesis. More than one step may be required. 49. ANS: 48. ANS: Exhibit 19-8 Show how the following conversions might be accomplished. Show all reagents and all intermediate structures.Aldehydes and Ketones: Nucleophilic Addition Reactions Exhibit 19-7 Show how the Wittig reaction might be used to prepare each of the following alkenes. 47. ANS: 51.Chapter 19 50. 17 . ANS: 52. Refer to Exhibit 19-9. triplet) Refer to Exhibit 19-9. 54. most probably a ketone. Interpret the mass spectral data. triplet). 2. or a propyl group. McLafferty rearrangement fragment at m/z = 86. Calculate the degree of unsaturation for this compound. so the compound has one degree of unsaturation. What functional group is indicated by the IR data? ANS: Absorption at 1715 cm 1 in the infrared spectrum indicates the presence of a carbonyl compound. 18 . C7H14O IR: MS: 1 − H NMR: 53.Aldehydes and Ketones: Nucleophilic Addition Reactions ANS: Exhibit 19-9 Consider the data below to answer the following question(s). 1. multiplet). 0. ANS: A fragment at m/z = 71 indicates a loss of 43. from α-cleavage. from McLafferty rearrangement (transfer of a hydrogen atom from the gamma carbon to the carbonyl oxygen with concomitant breaking of the bond between the alpha and beta carbon). ANS: The base formula for C7H14O is C7H14.59 δ (4H.36 δ (4H. 1715 cm 1 M+ at m/z = 114. α-cleavage fragment at m/z = 71.92 δ (6H. or ethylene. A fragment at m/z = 86 indicates a loss of 28. The formula for the saturated compound is C7H16. Refer to Exhibit 19-9. − 55. CH3CH2CH2COCH2CH2CH3 Exhibit 19-10 Consider the data below to answer the following question(s). α-cleavage fragment at m/z = 71. ANS: The 1H NMR indicates that there are only three different kinds of hydrogen in the molecule. C7H14O IR: MS: 1 1715 cm 1 M+ at m/z = 114.jp/RIODB/SDBS 19 .Chapter 19 56. ANS: 4-heptanone. and the 4H multiplet is two equivalent CH2 groups between a CH2 and a CH3.aist. Interpret the 1H NMR data. shifted by a C=O. 57. Refer to Exhibit 19-9. the 4H triplet is due to two equivalent CH2 groups next to two other equivalent CH2 groups. The 6H triplet is due to two equivalent CH3 groups next to two equivalent CH2 groups. Propose a structure consistent with the spectral data presented above.go. Refer to Exhibit 19-9. no McLafferty rearrangement fragment − H NMR: Spectrum obtained from: SDBSWeb: http://www. The 2H multiplet (many adjacent H) is consistent with two equivalent hydrogens of two isopropyl groups. too. Refer to Exhibit 19-10. The absence of a McLafferty rearrangement fragment means that there is no hydrogen atom on a gamma carbon. The 12H doublet (one adjacent H) is most likely four equivalent methyl groups of two equivalent isopropyl groups. ANS: 1-chloro-3-methyl-2-butanone 20 . The multiplet is shifted to about 2. Interpret the 1H NMR spectrum. (CH3)2CHCOCH(CH3)2 61.4-dimethyl-3-pentanone. Propose a structure for this compound. 60. and not n-propyl. Interpret the mass spectral data for this compound. from α-cleavage.Aldehydes and Ketones: Nucleophilic Addition Reactions 58. 59. ANS: A fragment at m/z = 71 indicates a loss of 43. or a propyl group. Atoms other than carbon and hydrogen are labeled. ANS: The 1H NMR spectrum indicates that there are only two kinds of hydrogen in this compound. Refer to Exhibit 19-10. Name the following compound.77 by the adjacent C=O. so the propyl group must be isopropyl. Refer to Exhibit 19-10. ANS: 2. a. Which of the labeled peaks would allow the distinction of an aldehyde from a ketone based on a this spectrum? 1 2 3 4 5 This is not the spectrum of an aldehyde. d. Which of the labeled peaks would allow the distinction of an aldehyde from a ketone based on this spectrum? a. 3 d. ANS: A 21 . f. 1 b. b. 2 c. c.Chapter 19 MULTIPLE CHOICE 1. e. 4 ANS: B 2. Atoms other than carbon and hydrogen are labeled. Based only on the spectrum below. b. what is inferred about the compound used to produce the spectrum? aromatic aldehyde para disubstituted ethyl substituent All of the above are evident from the spectrum. a. b. c. Consider the following structure. c. ANS: E 4.Aldehydes and Ketones: Nucleophilic Addition Reactions 3. 22 . d. Oxidation of this compound yields: a. e. O3 c. The product of the reaction is: a. a. 23 .Chapter 19 d. The following substance is heated in the presence of aqueous NaOH. CrO3 b. DIBAH d. Which of the following reagents could be used to convert 3-cyclopentyl-2-methylpropanal to the following substance? Atoms other than carbon and hydrogen are labeled. No reaction ANS: D 5. Atoms other than carbon and hydrogen are labeled. LiAlH4 ANS: A 6. Aldehydes and Ketones: Nucleophilic Addition Reactions b. d. both b and c e. all of the above ANS: D 7. 24 . If the following substance were treated with HCN followed by aqueous acid and heat. a. c. which of the following would be produced? Atoms other than carbon and hydrogen are labeled. a. Consider similar R groups in the following types of carbonyl compounds. ester c. d. f. b. c. Which of the following is not a characteristic of a carbonyl group? sp2 hybridized carbon atom planar geometry about the carbonyl bond carbonyl carbon atom is electrophilic carbonyl oxygen atom is nucleophilic weakly polarized carbon to oxygen bond All are characteristics of the carbonyl group ANS: E 10. c. e. d. e. In which type(s) of compound is a negative charge on the acyl group not stabilized to function as a leaving group in a nucleophilc substitution reactions? acid chloride acid anhydride ester aldehyde a and b 25 . all of the above ANS: C 8. carboxylic acid d. c. a. d. both b and c e. b.Chapter 19 b. ketone b. phenol ANS: D 9. Which of the following functional groups does not contain a carbonyl group? a. carbonyl condensation . nucleophilic addition b. nucleophilic acyl substitution ANS: C 26 c. α substitution d. b. how is the following reaction classified? a. a. c. a. Of the types of reactions that characterize carbonyl groups.Aldehydes and Ketones: Nucleophilic Addition Reactions f. and d ANS: D 11. b and c g.