Chapter 18 Ketones and Aldehydes

1) Which of the following correctly describes the bond angle and hybridizations present in formaldehyde? A) C, sp2; O, sp3; HCO, ~120° B) C, sp2; O, sp2; HCO, ~120° C) C, sp2; O, sp2; HCO, ~109.5° D) C, sp3; O, sp2; HCO, ~109.5° E) C, sp3; O, sp3; HCO, ~109.5°

2) The positively polarized carbon atom of a carbonyl group acts as: A) an electrophile and a Lewis base. B) a nucleophile and a Lewis base. C) an electrophile and a Lewis acid. D) a nucleophile and a Lewis acid. E) both a Lewis acid and a Lewis base.

3) Would you expect the carbonyl carbon of benzaldehyde to be more or less electrophilic than that of acetaldehyde? Explain using resonance structures.

4) The double bond between carbon and oxygen is similar to an alkene CC, except that C=O is: A) shorter and weaker. B) shorter and stronger. C) longer and weaker. D) longer and stronger. E) longer.

5) Another name for β-methoxybutyraldehyde is: A) 2-methoxypropanal. B) 3-methoxypropanal. C) 2-methoxybutanal. D) 3-methoxybutanal. E) 2-methoxypentanal.

6) Provide the structure of cyclohexanecarbaldehyde.

7) Provide the structure of 4-oxohexanoic acid.

8) Provide the proper IUPAC name for PhCH2CH(CH3)CH2CH2CHO.

9) Provide the proper IUPAC name for CH3CHOHCH2COCH2C(CH3)2CH2CH3.

10) Provide the proper IUPAC name for CH3OCH2CH2CH(CH3)CHO.

11) Provide the structure of benzophenone.

14) Give an IUPAC name to the following compound. Be sure to include configurational information in the name.

15) Draw the ethylene acetal of benzaldehyde.

16) Provide the proper IUPAC name for (CH3)2CHCH2CH2COCHCH2.

17) Provide the proper IUPAC name for CH3CHBrCH2COCH2CHO.

18) What is the correct IUPAC name for the following compound?

A) 2-oxocyclohex-3-ene carbaldehyde B) 5-formylcyclohex-2-enone C) 2-formylcyclohex-5-enone D) 3-oxocyclohex-4-enal

19) Name the following compound.

20) Name the following compound.

22) Which of the following represents the correct ranking in terms of increasing boiling point? A) n-butane < 1-butanol < diethyl ether < 2-butanone B) n-butane < 2-butanone < diethyl ether < 1-butanol C) 2-butanone < n-butane < diethyl ether < 1-butanol D) n-butane < diethyl ether < 1-butanol < 2-butanone E) n-butane < diethyl ether < 2-butanone < 1-butanol

23) Which of the following compounds is most soluble in water? A) acetone B) cyclohexanone C) 2-butanone D) 3-butanone E) benzophenone

24) Which is more soluble in water, 2-butanone or n-hexane? Explain.

25) In carbon NMR, the carbon atom of the carbonyl group in aldehydes and ketones has a chemical shift of about: A) 20 ppm. B) 40 ppm. C) 60 ppm. D) 120 ppm. E) 200 ppm.

26) Which compound will show an intense peak in the mass spectrum at m/z 58? A) CH3COCH2CH2CH3 B) (CH3)2CHCOCH3 C) CH3CH2COCH2CH3 D) (CH3)3CCHO E) (CH3)3CCOCH3

27) In the mass spectrum of 3,3-dimethyl-2-butanone, the base peak will occur at m/z ______. A) 43 B) 58 C) 84 D) 85 E) 100

28) When a carbonyl is part of a conjugated π-network, the CO stretch: A) has a higher frequency than in a nonconjugated system. B) has a lower frequency than in a nonconjugated system.

29) In the proton NMR spectra of aldehydes and ketones, the protons bonded to carbons adjacent to the carbonyl group typically fall into which of the chemical shift ranges below? A) 1.0-2.0 ppm B) 2.0-3.0 ppm C) 4.0-4.5 ppm D) 7.0-8.0 ppm E) 9.0-10.0 ppm

30) The proton NMR spectrum of an unknown compound contains a triplet at 9.8 ppm. Which of the following could be this unknown? A) (CH3)3CCHO B) CH3CH2CH2CO2H C) CH3CH2CH2CHO D) CH3CO CH2Ph E) PhCHO

31) Which of the following compounds would show only one triplet in its off resonance decoupled 13C NMR spectrum? A) acetone B) butanal C) pentanal D) 2-pentanone E) 3-pentanone

32) Which of the following transitions is usually observed in the UV spectra of ketones? A) n to π* B) n to π C) σ to n D) σ to σ* E) n to σ*

33) How might one distinguish an aldehyde from a ketone using IR data alone?

4 Copyright © 2013 Pearson Education, Inc. 34) The strongest absorptions in the UV spectra of aldehydes and ketones are ones which result from ______electronic transitions. A) σ to σ* B) σ to π* C) n to π* D) π to π* E) π to σ*

35) Trioxane is a cyclic trimer of formaldehyde that can be converted to formaldehyde upon heating. Show this reaction.

36) What name is given to the linear polymer which contains many formaldehyde units? A) trioxane B) formalin C) paraformaldehyde D) polyacetaldehyde E) polyalal

37) What reagent can be used to convert 2-methylbutan-1-ol into 2-methylbutanal? A) LiAlH4 B) Na2Cr2O7 C) O3 D) KMnO4 E) PCC

39) Provide the major organic product which results when PhCHOHCH3 is treated with PCC.

40) What reagents can be used to convert 1-hexyne into 2-hexanone? A) 1. Sia2BH; 2. H2O2, NaOH B) Hg2+, H2SO4, H2O C) 1. O3; 2. (CH3)2S D) 1. CH3MgBr; 2. CO2 E) 1. H2, Ni; 2. Na2Cr2O7, H2SO4

41) Oxidation of a 1° alcohol with chromic acid results in the production of ______. A) an ester B) a ketone C) an aldehyde D) an ether E) none of the above

42) Oxidation of a 2° alcohol with chromic acid results in the production of ______. A) an ester B) a ketone C) an aldehyde D) an ether E) none of the above

43) Oxidation of a 1° alcohol with pyridinium chlorochromate results in the production of ______. A) an ester B) a ketone C) an aldehyde D) an ether E) none of the above Answer: C Diff: 2 Section: 18.7

44) Which of the following reactions will not yield a ketone product? A)

45) Propose a synthesis of 3-heptanone from propanal.

46) By which single reaction can benzene be readily converted into acetophenone?

47) Provide the major organic product which results when pentanal is subjected to the following sequence of steps:

48) Name the compound generated when ethylbenzene is treated with CO, HCl, AlCl3, and CuCl.

49) Complete the following reaction by filling in the correct reagents.

50) Oxidation of a 3° alcohol with chromic acid results in the production of ______. A) an ester B) a ketone C) an aldehyde D) an ether E) none of the above

51) Beginning with sodium acetylide (NaCCH), propose a three-step synthesis of hexanal.

52) Name the compound generated when 1-methylcyclohexene is subjected to O3 followed by dimethyl sulfide. 53) Provide the major organic product which results when PhCH2CH2CO2H is treated with excess butyllithium followed by H3O+.

55) How might one prepare 4-heptanone from CH3CH2CH2CN in two steps?

56) Provide the major organic product of the reaction shown below.

57) Treatment of a nitrile with a Grignard reagent followed by hydrolysis results in ______. A) an ester B) a ketone C) an aldehyde D) an ether E) an alcohol

58) Complete the following reaction by filling in the necessary reagents.

59) Which of the following describes a synthesis of an aldehyde? A) hydrogenation of an acid chloride using Pd/BaSO4/S as a poisoned catalyst B) reaction of a primary alcohol with Na2Cr2O7 C) reaction of a ketone with ozone D) treatment of an alkene with Sia2BH E) none of the above

60) Which series of reactions described below, if any, will result in the formation of 2-methylpentan-3- one starting with 1-propanol? A) 1. (CH3)2CHMgBr/ diethyl ether 2. dilute H3O+ 3. PCC B) 1. Na2Cr2O7/H2SO4 and heat 2. SOCl2 3. 2 (CH3)2CHMgBr/ diethyl ether 4. H3O+ C) 1. Na2Cr2O7/H2SO4 and heat 2. (CH3)2CHMgBr/ diethyl ether

61) Provide the major organic product which results when (CH3)2CHCH2CH2COCl is treated with LiAlH[OC(CH3)3]3.

62) What organic compound is generated when PhCOCl is treated with (CH3CH2CH2)2CuLi?

63) When the carbonyl group of a neutral ketone is protonated,: A) the resulting species becomes more electrophilic. B) the resulting species is activated toward nucleophilic attack. C) subsequent nucleophilic attack on the resulting species is said to occur under acid-catalyzed conditions. D) the resulting species has a positive charge. E) all of the above

64) What reagent can be used to convert benzophenone into triphenylmethanol?

65) Provide the structure of the hydrate of cyclopentanone.

66) Consider the equilibrium of each of the carbonyl compounds with HCN to produce cyanohydrins. Which is the correct ranking of compounds in order of increasing Keq for this equilibrium? A) H2CO < cyclohexanone < CH3CHO < 2-methylcyclohexanone B) CH3CHO < 2-methylcyclohexanone < cyclohexanone < H2CO C) cyclohexanone < 2-methylcyclohexanone < H2CO < CH3CHO D) cyclohexanone < 2-methylcyclohexanone < CH3CHO < H2CO E) 2-methylcyclohexanone < cyclohexanone < CH3CHO < H2CO

9 Copyright © 2013 Pearson Education, Inc. 67) The following compound has been found effective in treating pain and inflammation (J. Med. Chem. 2007, 4222). Which sequence correctly ranks each carbonyl group in order of increasing reactivity toward nucleophilic addition?

A) 1 < 2 < 3 B) 2 < 3 < 1 C) 3 < 1 < 2 D) 1 < 3 < 2

68) Draw two major resonance forms of the cation which results when cyclohexanone's carbonyl group is protonated.

69) Rank the following compounds in order of their propensity to become a hydrate in water (i.e., start with the least easy to hydrate: CH3COCH2CH3, H2CO, Cl3CCHO, and CH3CH2CHO.

70) Provide the major organic product of the reaction shown below.

72) Provide the major organic product of the reaction shown below.

73) Propose a synthesis of 4-phenylbutan-2-ol from 3-phenylpropanal.

74) Provide a detailed, stepwise mechanism for the base-catalyzed hydration of 2-butanone.

75) Which sequence ranks the following carbonyl compounds in order of increasing rate of nucleophilic addition?

A) 2 < 3 < 1 B) 3 < 2 < 1 C) 2 < 1 < 3 D) 1 < 3 < 2

76) Why are the equilibrium constants for hydration of aldehydes typically greater than those of ketones?

77) Propose a synthesis of 3-methylhept-4-yn-3-ol from but-1-yne.

78) An ylide is a molecule that can be described as a: A) carbanion bound to a negatively charged heteroatom. B) carbocation bound to a positively charged heteroatom. C) carbocation bound to a carbon radical. D) carbocation bound to a diazonium ion. E) carbanion bound to a positively charged heteroatom.

80) Through what sequence of steps can toluene be converted into PhCH2PPh3+Br-?

81) Provide the structure of the major organic product which results when CH3CH2I is treated with PPh3 and the resulting salt is reacted with one equivalent of butyllithium.

82) Provide the major organic product of the reaction shown below.

83) Provide the major organic product of the reaction shown below.

84) Provide the preferred reagent pair to synthesize 3-ethylpent-2-ene via a Wittig reaction.

85) Show how the following reaction may be accomplished by filling in the correct reagents.

87) Propose a Wittig reaction-based synthesis of hex-3-ene using propene as the only carbon source and any other reagents necessary.

88) Provide the structure of the compound which results when HCN adds to pentanal.

89) Provide the major organic product of the reaction shown below.

90) Which of the following is also known as a Schiff base? A) an imine B) a cyanohydrin C) a hydrate D) sodium hydroxide E) an aldehyde

91) Give the structure of the acyclic compound from which the following imine was formed.

92) Provide the major organic product of the following reaction.

93) Provide the major organic product of the reaction shown below.

94) Provide the major organic product of the reaction of aniline with 3-pentanone.

96) What product will result from the reaction shown?

A) imine B) amino acid C) amino alcohol D) hydrazine E) hydroxylamine

97) Provide a detailed, stepwise mechanism for the acid-catalyzed condensation reaction between benzaldehyde and methylamine.

98) Conversion of aldehydes and ketones to imines is an acid-catalyzed process. Explain why this conversion is actually hindered by the presence of too much acid.

99) When H2NCH2CH2CH2CH2COCH3 is heated in the process of an acid catalyst, a reaction occurs. The product has the formula C6H11N. Provide the structure of this product.

100) Provide the structure of the compound which reacts with a ketone to form its hydrazone derivative.

101) Provide the major organic product of the following reaction.

103) Provide the structure of cyclohexanone oxime.

104) Provide the structure of the major organic product which results when benzaldehyde reacts with hydroxylamine in the presence of acid.

105) Provide the major organic product of the reaction shown below.

106) What product will result from the reaction shown?

A) acetal B) hydrazine C) ester D) ylide E) ketone

107) Provide the structure of the semicarbazone derivative of 3-pentanone. Answer:

108) Provide a detailed, stepwise mechanism for the acid-catalyzed condensation reaction between cyclohexanone and H2NOH.

110) What would be the product of the following reaction?

112) Provide the structure of the diethyl acetal of butanal.

113) Provide the major organic product of the reaction shown below.

114) Why do acetal-forming reactions that use ethylene glycol have more favorable equilibrium constants than those using methanol? A) Ethylene glycol reacts more rapidly. B) They are more favorable on entropy grounds. C) They are more favorable on enthalpy grounds. D) Ethylene glycol is acidic and catalyzes the reaction. E) The ethylene acetal can serve as a protecting group.

115) When HOCH2CH2CH2CH2COCH2CH2CH2CH2OH is heated in the presence of an acid catalyst, a reaction occurs. This product has the formula C9H16O2. Provide the structure of this product.

116) Predict the product of the following reaction.

A) 1. HO-(CH2)2-OH /trace H3O+ 2. DMSO (COCl2)/Et3N, CH2Cl2 3. MgBr-(CH2)2-CH3/diethyl ether 4. work-up with H3O+ B) 1. PCC 2. SOCl2 3. LiCu-((CH2)2-CH3)2 4. work-up with H3O+ C) 1. Na2Cr2O7/H2SO4 2. SOCl2 3. 2 MgBr-(CH2)2-CH3/diethyl ether 4. work-up with H3O+ D) both A and B E) both B and C

118) Propose a sequence of steps to carry out the following conversion.

120) Propose a sequence of steps to carry out the following conversion.

121) Which would be more appropriate as the reduction in the following sequence, a Clemmensen or a Wolff-Kishner? Explain.

122) Millad NX8000, shown below, is a clarifying additive for polypropylene ( C & En News, Sept. 2010, 34). Predict the products of the following reaction.

123) What intermediate occurs when a ketone undergoes a Wolff-Kishner reduction? A) a cyanohydrin B) a hydrated aldehyde C) a carboxylate D) a semicarbazone E) a hydrazone

19 Copyright © 2013 Pearson Education, Inc. 124) The reagent which converts a carbonyl group of a ketone into a methylene group is ______. A) Na, NH3, CH3CH2OH B) LiAlH4 C) NaBH4, CH3CH2OH D) Zn(Hg), conc. HCl E) LiAlH[OC(CH3)3]3

125) Provide the major organic product of the following reaction.

126) (S)-Carvone is the main component of spearmint oil. What product would result from treating (S)-carvone with DIBAL-H?

128) Which of the following carbonyl compounds may be made from 1,3-dithiane?

1) methyl vinyl ketone 2) 2-pentanone 3) 3,3-dimethyl-2-butanone 4) 2-phenylethanal A) 1 & 4 B) 2 only C) 2 & 3 D) 2 & 4

129) Beginning with 1,3-dithiane, propose a synthesis of 4-heptanone.

131) What compound is produced when 1,3-dithiane is subjected to the following sequence of reagents: 1. n-BuLi 2. CH3CH2Br 3. n-BuLi 4. (CH3)2CHCH2CH2I 5. HgCl2, H3O+?

132) Why is (CH3)3CCHO not available via a 1,3-dithiane based synthesis?

133) What compound is produced when 1,3-dithiane is subjected to the following sequence of reagents: 1. n-BuLi 2. (CH3)3CCH2CH2CH2I 3. HgCl2, H3O+?