Exam Problem Set 8

Select an answer for each of the 61 multiple-choice questions below, then press Check Answers. The answer key unlocks after a genuine attempt.

Aldehydes and Ketones

1. Which of the following is a correct name for (CH₃)₂C=CHCOCH₃?
A) 2-methyl-2-penten-4-one
B) 4-methyl-3-penten-2-one
C) 1,3-dimethyl-2-pentenal
D) isopentenone

2. Which of the following is 3,3-diphenylpropanal?
A) C₆H₅CH₂CH(C₆H₅)CHO
B) C₆H₅CH₂CH₂COC₆H₅
C) (C₆H₅)₂CHCH₂CHO
D) (C₆H₅)₂CHCH₂COC₆H₅

3. Which of the following compounds is not named correctly?

A) 2-methyl-3-heptanone (CH₃)₂CHCOCH₂CH₂CH₂CH₃

B) phenylacetaldehyde C₆H₅CH₂CHO

C) 4-hexyn-2-one CH₃COCH₂C≡CCH₃

D) para-bromoacetophenone p-BrC₆H₄CH₂COCH₃

4. Which of the following compounds is not named correctly?

5. Which of the following compounds is not named correctly?

6 Which of the following may be classified as an acetal?
Four candidate acetals I-IV: 2-methoxytetrahydrofuran, 5,5-dimethyl-1,3-dioxane, 2-methyl-1,4-dioxane, 2-hydroxy-1,4-dioxane
A) I & II
B) III & IV
C) only IV
D) all but IV

7 Which of the following reactions is a good method for preparing an aldehyde?
A) Jones' reagent and a 1°-alcohol
B) Jones' reagent and a 2°-alcohol
C) PCC and a 1°-alcohol
D) H₂SO₄ a 1°-alcohol and heat

8 Which of the following are enol tautomers of 3-methylcyclohexanone?
Four methylcyclohexenol enol structures I-IV, candidate enol tautomers of 3-methylcyclohexanone
A) I & II
B) I & IV
C) II & III
D) only I

9 Which of the following statements is not generally true?
A) C=O is stronger than an equivalent C=C
B) C=O has a larger bond dipole than C=C
C) aldehydes and ketones have higher boiling points than similarly sized alkenes
D) alkenes add nucleophiles more rapidly than aldehydes or ketones of similar structure

10 Which of the following compounds exchanges the largest number of hydrogens for deuterium when treated with KOD in D₂O?
A) 3-methyl-1,2-cycloheptanedione
B) 2-methyl-1,3-cycloheptanedione
C) 5-methyl-1,3-cycloheptanedione
D) 6-methyl-1,4-cycloheptanedione

11 Four C₈H₁₄O ketones are examined by ¹³Cnmr spectroscopy.
One of them has five distinct carbon signals. Which of the following fits this fact?
A) 4,4-dimethylcyclohexanone
B) 3,3-dimethylcyclohexanone
C) 2,2-dimethylcyclohexanone
D) 2,2,4,4-tetramethylcyclobutanone

12 Which of the following compounds could not be converted to pentanal in one or two steps?
A) 1-pentyne
B) trans-5-decene
C) 2-pentanone
D) 1-pentanol

13 Treatment of cyclohexanone with an excess of H₂¹⁸O produces ¹⁸O labeled cyclohexanone.
Which of the following is a likely intermediate in this isotope exchange? (the isotope is not named)
A) 1-cyclohexen-1-ol
B) 1,1-cyclohexanediol
C) 2-cyclohexen-1-one
D) 1,2-cyclohexanediol

14 Reaction of C₆H₅CHBr₂ with NaOH in aqueous THF is likely to produce which product?
A) C₆H₅CHBrOH
B) C₆H₅CH(OH)₂
C) C₆H₅CHO
D) C₆H₅CO₂H

15 Which of the following carbonyl compounds reacts most rapidly with nucleophilic reagents?
A) benzaldehyde
B) 3,3-dimethylbutanal
C) acetophenone
D) 2,2-dimethylcyclohexanone

16 Which of the following amines would be best chosen for preparing an enamine derivative from cyclohexanone?
A) dimethylamine
B) ethylamine
C) trimethylamine
D) hydroxylamine

17 Which reaction or sequence of reactions would best accomplish the following synthesis?
Reaction: cyclohexanone converted via unknown reagents to 1-(aminomethyl)cyclohexanol
A) CH₃NH₂, acid catalyst & heat
B) CH₂=NH, acid catalyst & heat
C) (i) NH₃ acid catalyst & heat; (ii) CH₂I₂ & Zn(Cu)
D) (i) HCN & NaCN; (ii) LiAlH₄ in ether

18 Heating cyclopentanone with either: I ethyl amine, or II diethylamine, together with an acid catalyst leads to different results.
Which of the following best describes this difference?
A) I gives an imine & II fails to react
B) I gives an enamine & II fails to react
C) I gives an imine & II gives an enamine
D) I gives an enamine & II gives an imine

19 Which reaction or sequence of reactions would be best used to convert cyclohexanone to cis-1,2-cyclohexanediol?
A) PCC in CH₂Cl₂ and base
B) (i) NaBH₄; (ii) H₃PO₄ & heat; (iii) OsO₄ in pyridine
C) (i) NaBH₄; (ii) H₃PO₄ & heat; (iii) C₆H₅CO₃H
D) (i) NaBH₄; (ii) OsO₄ in pyridine

20 A C₉H₁₀O compound has a strong absorption at 1686 ^-1cm in the infrared.
Which of the following compounds would be expected to display such an absorption band?

21 A C₉H₁₀O compound has a strong absorption at 1730 and two smaller but sharp absorption peaks at 2719 & 2818 ^-1cm in the infrared. The ¹Hnmr has a strong doublet at δ1.0 ppm.
Which of the following compounds would be expected to display these features?

22 The Wittig reaction takes place between a carbonyl compound and a phosphorus ylid.
Which of the following represents the dipolar contributor to such an ylide?
Four phosphorus ylide resonance forms I-IV: dipolar ylide structures of (C6H5)3P=CHCH3 type reagents
A) I & II
B) II only
C) III only
D) I & IV

23 Which of the following reaction sequences would be best for converting cyclohexanol to methylenecyclohexane, (CH₂)₅C=CH₂ ?
A) (i) H₃PO₄ & heat; (ii) CH₂I₂ + Zn(Cu)
B) (i) PCC in CH₂Cl₂; (ii) CH₃MgBr; (iii) H₃PO₄ & heat
C) PCC in CH₂Cl₂; (ii) (C₆H₅)₃P=CH₂
D) CH₂N₂ & heat

24 Which of the following Wittig reagents would be useful for converting R₂C=O into R₂CHCH=O?
A) (C₆H₅)₃P=CH-OCH₃
B) (C₆H₅)₃P=CH-CH₃
C) (C₆H₅)₃P=Cl₂
D) (C₆H₅)₃P=CH-CH=CH₂

25 Two equivalents of the Wittig reagent (CH₃)₂C=CH-CH=P(C₆H₅)₃ were allowed to react with a C₄H₄O₂ compound.
The chief product was 2,11-dimethyl-2,4,6,8,10-dodecapentaene, (CH₃)₂C=CH(CH=CH)₃CH=C(CH₃)₂.
What was the C₄H₄O₂ compound used in this reaction?
A) 2-butyne-1,4-diol
B) 1,2-cyclobutanedione
C) 1,3-butadien-2,3-diol
D) 2-butenedial

26 Which of the following reactions would not be a useful way of preparing 1-phenyl-2-butanol?
A) phenylacetaldehyde + ethylmagnesium bromide
B) butanal + phenylmagnesium bromine
C) propanal + benzylmagnesium bromine
D) 1-phenyl-2-butanone + NaBH₄

27 Which of the following reactions would not be a useful way of preparing 2-phenyl-2-butanol?
A) 2-butanone + phenylmagnesium bromine
B) acetophenone + ethylmagnesium bromide
C) cis-2,3-dimethyloxirane + phenylmagnesium bromide
D) ethylphenylketone + methylmagnesium iodide

28 In the reaction of (R)-3-phenyl-2-butanone with methylmagnesium iodide, what happens to the configuration of the stereogenic center?
A) nothing, it remains unchanged
B) inversion takes place
C) racemization occurs
D) the product is achiral

29 Which of the following reactions would not be useful for converting 4,4-diethylcyclohexanone into 1,1-diethylcyclohexane?
A) Wolff-Kishner reduction (N₂H₄, strong base & heat)
B) Clemmensen reduction (Zn/Hg, acid & heat)
C) thioacetal reduction (i HSCH₂CH₂SH & BF₃; ii H₂ + Raney Ni)
D) LiAlH₄ in THF & heat

30 Which of the following is a semicarbazone derivative of an aldehyde (RCHO)?
A) RCH=N-NHCONH₂
B) RCH=N-OH
C) RCH=N-NH₂
D) RCH=N-C(CH₃)₃

31 Which of the following isomers is most acidic ?
A) 3,4-hexanedione
B) 2,5-hexanedione
C) 2,4-hexanedione
D) hexanedial

32 You have two C₆H₁₀O ketones, I and II. Both are optically active, but I is racemized by treatment with base and II is not.
Wolff-Kishner reduction of both ketones gives the same achiral hydrocarbon, formula C₆H₁₂.
What reasonable structures may be assigned to I and II?
A) I is 3-methyl-4-penten-2-one; II is 4-methyl-1-penten-3-one
B) I is 2-methylcyclopentanone; II is 3-methylcyclopentanone
C) I is 3-methylcyclopentanone; II is 2-methylcyclopentanone
D) I is 2-ethylcyclobutanone; II is 3-ethylcyclobutanone

33 Jones' reagent oxidizes aldehydes to carboxylic acids but normally does not oxidize ketones.
What intermediate species is most likely responsible for the aldehyde oxidation?
A) a carbonyl hydrate
B) an enol tautomer
C) an oxonium conjugate acid of the aldehyde
D) an acylium cation

34 The lithium enolate base from cyclohexanone reacts with alkyl halides, often in different ways.
As shown here, methyl iodide and tert-butyl bromide react to give different organic products, I and II, together with lithium halides.
What are the products from these reactions?
Cyclohexanone lithium enolate reacting with tert-butyl bromide (gives II) and methyl iodide (gives I) in THF
A) I is 2-methylcyclohexanone; II is 2-t-butylcyclohexanone
B) I is 1-methoxycyclohexene; II is 1-t-butoxycyclohexene
C) I is 2-methylcyclohexanone; II is 1-t-butoxycyclohexene
D) I is 2-methylcyclohexanone; II is a mixture of cyclohexanone and 2-methylpropene

35 A C₅H₁₂O compound is optically active, and is oxidized by PCC in CH₂Cl₂ to an optically active C₅H_1OO product, which is racemized in acid or base.
Which of the following best fits these facts?
A) 2-pentanol
B) 2-methoxybutane
C) 2-methyl-1-butanol
D) 3-methyl-1-butanol

36 Which of the following aldehydes, used alone, will undergo an aldol reaction?
A) formaldehyde, CH₂O
B) butanal, CH₃(CH₂)₂CHO
C) benzaldehyde, C₆H₅CHO
D) 2-propenal, CH₂=CHCHO

37 Which of the following reaction sequences would be best for preparing 2,2-dimethyl-3-hexanone from butanal?
A) (i) addition of tert-butylmagnesium bromide in ether; (ii) hydrolysis workup; (iii) PCC in CH₂Cl₂
B) (i) NaBH₄; (ii) PBr₃; (iii) Mg in ether; (iv) 2,2-dimethylpropanal, followed by hydrolysis
C) (i) Wittig reaction with (C₆H₅)₃P=C(CH₃)₂; (ii) BH₃ in THF; (iii) H₂O₂ & base; (iv) PCC in CH₂Cl₂
D) (i) Wittig reaction with (C₆H₅)₃P=CHC(CH₃)₃; (ii) BH₃ in THF; (iii) H₂O₂ & base; (iv) PCC in CH₂Cl₂

38 How can 1,1,1,2,2-pentadeutero-3,3-dimethylpentane, C₂H₅C(CH₃)₂C₂D₅, be prepared from 3,3-dimethyl-2-pentanone?
A) (i) NaOD in D₂O (excess); (ii) LiAlD₄ in ether; (iii) D₂O workup
B) (i) Wolff-Kishner reduction with N₂D₄ in ROD; (ii) NaOD in D₂O (excess)
C) (i) Zn & DCl in CH₃CO₂D; (ii) LiAlD₄ in ether; (iii) D₂O workup
D) (i) NaOD in D₂O (excess); (ii) HSCH₂CH₂SH + BF₃; (iii) D₂ + Raney Ni catalyst

39 Acetaldehyde reacts with (R)-1,2-propanediol (acid catalyst) to give two isomeric acetals. What is their isomeric relationship?
A) they are constitutional isomers
B) 2 they are diastereomers
C) 3 they are enantiomers
D) they are conformers

40 What is the product of the following reaction?

41 What product or products are expected from acid-catalyzed hydrolysis of the following compound?
2-phenyl-5,5-dimethyl-1,3-dioxane, a benzaldehyde acetal of 2,2-dimethyl-1,3-propanediol
A) only the starting material itself (no reaction)
B) benzaldehyde and 2,2-dimethyl-1,3-propanediol
C) benzoic acid and 2,2-dimethyl-1,3-propanediol
D) 2-phenyl-1,3-propanediol and acetone

42 Base induced elimination of 3-chlorocyclohexanone I is much faster than elimination of cyclohexyl chloride II.
What is the major factor accounting for this difference?
A) the halogen in I is less hindered
B) the halogen in I is forced to be axial
C) elimination of I produces a more stable conjugated double bond
D) I rapidly forms an enolate anion, and this immediately eliminates a stable chloride ion

43 Which of the following optically active compounds will be racemized on treatment with warm alcoholic sodium ethoxide?

I	II	III	IV
(R)-2,2,6-trimethylcyclohexanone	(R)-2,2,5-trimethylcyclohexanone	(R)-2-methyl-2-phenylcyclohexanone	(R)-4-methyl-2-cyclohexen-1-one

A) I and II
B) I and III
C) I and IV
D) all compounds will be racemized

44 A C₅H₈ hydrocarbon is reacted with BH₃ in THF, followed by oxidation with alkaline hydrogen peroxide.
Treatment of the resulting product with PCC in CH₂Cl₂ produces a chiral ketone, formula C₅H₈O.
What hydrocarbon best fits these facts?
A) 1-methylcyclobutene
B) methylenecyclobutane
C) vinylcyclopropane
D) cyclopentene

45 Which of the following compounds would not be a possible product from the mixed aldol reaction of acetaldehyde and butanal?
A) 3-hydroxybutanal
B) 2-ethyl-3-hydroxybutanal
C) 3-ethyl-2-hydroxyhexanal
D) 3-hydroxyhexanal

46 A C₇H₁₂O₂ compound gives a positive Tollens' silver mirror test and a positive iodoform test.
Which of the following would satisfy these facts?
A) 2-hydroxy-3,3-dimethylcyclopentanone
B) 2,5-heptanedione
C) 2,2-dimethyl-3-oxopentanal
D) 2,2-dimethyl-4-oxopentanal

47 The iodoform test for methyl ketones is not widely used anymore.
Which of the following spectroscopic tools is best for providing equivalent information?
A) UV-Visible
B) ¹H nmr
C) ¹³C nmr
D) infrared

48 An aldol condensation is used to prepare 1,3-diphenyl-2-propenone, C₆H₅CH=CHCOC₆H₅.
Which combination of reactants will lead to this product?
A) enolate donor=acetaldehyde; carbonyl acceptor=benzaldehyde
B) enolate donor=phenylacetaldehyde; carbonyl acceptor=phenylacetaldehyde
C) enolate donor=acetophenone; carbonyl acceptor=benzaldehyde
D) enolate donor=propiophenone; carbonyl acceptor=benzaldehyde

49 Which of the following compounds would be the major product from aldol condensation of 6-oxoheptanal?

50 Which of the following procedures would not be suitable for preparing 3-methyl-1-phenyl-1-butanone, C₆H₅COCH₂CH(CH₃)₂?
A) (i) C₆H₅COCH=CHCH₃ + (CH₃)₂CuLi in ether; (ii) H₃O⁺ workup
B) (i) benzene + (CH₃)₂CHCH₂COCl & AlCl₃ (ii) H₃O⁺ workup
C) (i) C₆H₅MgBr + (CH₃)₂CHCH₂CHO in ether; (ii) H₃O⁺ workup; (iii) PCC in CH₂Cl₂
D) (i) (CH₃)₂CHMgBr + C₆H₅COCH₃ in ether; (ii) H₃O⁺ workup; (iii) PCC in CH₂Cl₂

51 Formulas for four ethyl ethers are drawn below. Two are cleaved by aqueous acid much more easily than the other two.
Which ethers are more easily hydrolyzed?
Four ethyl ethers I-IV: 4-ethoxytetrahydropyran, 2-ethoxytetrahydropyran, 1-ethoxycyclohexene, 4-ethoxycyclohexene
A) I and II
B) II and III
C) III and IV
D) I and IV

52 The Wieland-Miescher ketone is an important synthetic intermediate. Its formula is shown below.
What starting materials would be suitable for preparing this compound by a combination of Michael and aldol reactions?
Wieland-Miescher ketone, an angular methyl bicyclic octahydronaphthalenedione
A) 4-methyl-2-cyclohexen-1-one and 3-butenal
B) 2-methylcyclohexane-1,3-dione and 3-buten-2-one
C) 2-methyl-2-vinyl-3-cyclohexen-1-one and acetaldehyde
D) 2-methyl-2-cyclohexen-1-one and 1,4-dichlorobutan-2-one

53 2,2-Dimethyl-1,3-propanediol is coveniently prepared by heating 2-methylpropanal with excess formaldehyde and Ca(OH)₂.
What sequence of reactions takes place in this synthesis?
A) dehydrogenation to 2-methyl-2-propenal followed by addition of formaldehyde
B) dehydrogenation to dimethylketene followed by addition of formaldehyde
C) a crossed aldol reaction followed by a crossed Cannizzaro reaction
D) a crossed Cannizzaro reaction followed by a crossed aldol reaction

54 A bis-aldol dimerization of 1-phenyl-1,2-propanedione, C₆H₅COCOCH₃, gives which of the following?

55 What donor and acceptor reactants should be used to prepare the following compound by an aldol reaction?
2,2-bis(hydroxymethyl)propanal, 3-hydroxy-2-(hydroxymethyl)-2-methylpropanal target aldol product
A) acceptor = formaldehyde; donor = propanedial
B) acceptor = 1,3-propanediol; donor = ethanal
C) acceptor = propanal; donor = formaldehyde
D) acceptor = formaldehyde; donor = propanal

56 What donor and acceptor reactants should be used to prepare the following compound by an aldol condensation (or Claisen-Schmidt reaction)?
2-benzylidenecyclopentanone, the Claisen-Schmidt condensation product of cyclopentanone and benzaldehyde
A) acceptor = cyclopentanone; donor = benzaldehyde
B) acceptor = benzaldehyde; donor = cyclopentanone
C) acceptor = phenylacetaldehyde; donor = cyclopentanone
D) acceptor = cyclopentanecarbaldehyde; donor = toluene

57 The formula of brevicomin, a pheremone of the western pine beetle, is shown below.
What open chain ketodiol would close to this bicyclic acetal? (ignore stereoisomer issues)
Brevicomin, a bicyclic 6,8-dioxabicyclo acetal pheromone of the western pine beetle
A) 7,8-dihydroxynonan-3-one
B) 6,7-dihydroxynonan-3-one
C) 7,8-dihydroxynonan-2-one
D) 6,7-dihydroxynonan-2-one

58 The formula of multistriatin, a pheremone of the elm bark beetle, is shown below.
What open chain ketodiol would close to this bicyclic acetal? (ignore stereoisomer issues)
Multistriatin, a bicyclic dioxabicyclo acetal pheromone of the elm bark beetle
A) 3-ethyl-5-methyl-6,7-dihydroxyheptan-2-one
B) 4,6-dimethyl-7,8-dihydroxyoctan-3-one
C) 4-methyl-7,8-dihydroxynonan-3-one
D) 3-ethyl-6,7-dihydroxyoctan-2-one

59 A conversion of 2,5-dimethylfuran into 2,5-dimethylpyrrole (see equation) may be accomplished in two steps.
i) hydrolysis of the furan in aqueous acid; ii) heating the hydrolysis product with excess ammonium carbonate
What is the intermediate hydrolysis product used in the second step?
Reaction equation: 2,5-dimethylfuran converted to 2,5-dimethylpyrrole
A) 2,5-hexanedione
B) 3,4-hexanedione
C) hexanedial
D) 2,5-dimethylcyclopentanone

60 The reagent semicarbazide, NH₂CONHNH₂, reacts with simple aldehydes and ketones (R₂C=O) forming crystalline derivatives called semicarbazones.
Which of the following represents the structure of a semicarbazone?

61 Which of the following compounds (I through V) should not be classified as an acetal?
Five compounds I-V to classify as acetals: bicyclic, fused dioxane, spiro dioxolane, cyclic enol ether, acyclic dimethyl acetal
A) II & III
B) IV
C) I
D) none (they are all acetals)

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