Exam Problem Set 9

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

Carboxylic Acids and Derivatives

1. Which of the following is a correct name for (C₂H₅)₂C=C(CH₃)CH₂CO₂H?
A) 4,4-diethyl-3-methyl-3-butenoic acid
B) 4-ethyl-3-methyl-3-hexenoic acid
C) 3-ethyl-4-methyl-3-hexenoic acid
D) 3-ethyl-4-methyl-3-hexen-6-oic acid

2. Which of the following is 2-ethyl-3-formyl-pentanoic acid?
A) C₂H₅CH(C₂H₅)CH(CO₂H)CHO
B) (C₂H₅)₂CHCH(CHO)CO₂H
C) C₂H₅CH₂CH(CHO)CO₂C₂H₅
D) C₂H₅CH(CHO)CH(C₂H₅)CO₂H

3 Which of the following compounds is not an anhydride?

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

A) isopropyl propanoate (CH₃)₂CHCO₂C₂H₅

B) tert-butyl acetate (CH₃)₃COCOCH₃

C) methyl 2,2-dimethylpropanoate (CH₃)₃CCO₂CH₃

D) 2,2-dimethylbutanedioic acid HO₂CC(CH₃)₂CH₂CO₂H

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

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

7 Which of the following compounds is not named correctly?

8 Which of the following common names does not represent a dicarboxylic acid?
A) lactic acid
B) succinic acid
C) phthalic acid
D) glutaric acid

9 Which of the following statements is not generally true?
A) the boiling point of a carboxylic acid is higher than that of its methyl ester.
B) methyl esters are more reactive acylating agents than their amide counterparts.
C) amide hydrolysis may be carried out with either strong acid or base catalysis.
D) Fischer esterification of acids with alcohols requires a strong base catalyst.

10 What is the order of increasing acidity for the following compounds? (weaker < stronger)

I 4-methylpentanoic acid

II 3-chloropentanoic acid

III 2-bromopentanoic acid

IV 2,2-dichloropentanoic acid

A) I < II < III < IV
B) IV < III < II < I
C) I < III < II < IV
D) II < III < I < IV

11 When comparing the acidity of propanoic acid and pyruvic acid, CH₃COCO₂H, which of the following statements is correct.
A) propanoic acid has a lower pK_a and a smaller K_a than pyruvic acid
B) propanoic acid has a lower pK_a and a larger K_a than pyruvic acid
C) propanoic acid has a higher pK_a and a larger K_a than pyruvic acid
D) propanoic acid has a higher pK_a and a smaller K_a than pyruvic acid

12 Consider the following dicarboxylic acids?

I adipic acid
HO₂C(CH₂)₄CO₂H

II malonic acid
CH₂(CO₂H)₂

III oxalic acid
(CO₂H)₂

IV succinic acid
HO₂C(CH₂)₂CO₂H

What is the order of increasing acid strength? (weaker < stronger)
A) I < II < III < IV
B) IV < III < II < I
C) I < IV < II < III
D) II < I < IV < III

13 Dicarboxylic acids have two pK_a's.
For maleic acid (cis-2-butenedioic acid) these are pK_a¹ = 2.0, and pK_a² = 6.3
For fumaric acid (trans-2-butenedioic acid) these are pK_a¹ = 3.0, and pK_a² = 4.5
Which factor best explains why the cis-isomer has a smaller pK_a¹ and a larger pK_a² than the trans-isomer?
A) intramolecular steric hindrance
B) intramolecular dipole repulsion
C) intramolecular hydrogen bonding
D) selective solvation in water

14 An equimolar mixture of benzoic acid and benzyl alcohol is dissolved in equal volumes of ether and 5% aqueous NaOH.
The resulting mixture separates into two immiscible liquid layers. Which of the following is approximately correct?
A) both organic solutes are largely in the ether layer
B) the benzyl alcohol is in the ether layer and the benzoic acid is in the water layer
C) both organic solutes are largely in the water layer
D) the benzyl alcohol is in the water layer and the benzoic acid is in the ether layer

15 Fischer esterification of phenylacetic acid with 1-propanol gave a mixture of 93% of the ester, propyl phenylacetate, contaminated with 7% unreacted acid.
Which of the following treatments would be best used to purify the ester?
A) reduce the unwanted acid with LiAlH₄ in ether.
B) wash an ether solution of the crude product with concentrated brine (aq. NaCl).
C) wash an ether solution of the crude product with 5% aqueous sulfuric acid.
D) wash an ether solution of the crude product with 5% aqueous sodium carbonate.

16 Which of the following would not be a useful reaction for preparing isobutyric acid, (CH₃)₂CHCO₂H?
A) 2-methyl-1-propanol + Jones' reagent
B) 2-bromopropane + CO₂; followed by hydrolysis
C) cis-2,5-dimethyl-3-hexene + O₃; followed by H₂O₂
D) 2-bromopropane + NaCN; followed by acid-catalyzed hydrolysis

17 Which of the following would not be a useful method for converting a carboxylic acid into an ester derivative?
A) RCO₂H + CH₂N₂ in ether
B) RCO₂H + (CH₃)₂C=CH₂ & acid catalyst
C) RCO₂H + C₂H₅OH & acid catalyst + heat (-H₂O)
D) RCO₂^(-) Na⁽⁺⁾ + (CH₃)₃CBr

18 Which of the following is an intermediate in the Fischer esterification of propanoic acid with ethanol?
A) 1-propoxy-1,1-dihydroxyethane
B) 2-propoxy-1,1-dihydroxyethane
C) 1-ethoxy-1,1-dihydroxypropane
D) 2-ethoxy-1,1-dihydroxypropane

19 Which of the following reagents does not react with benzoic acid, converting it into a different compound?
A) NaI in acetone
B) SOCl₂
C) LiAlH₄ in ether
D) excess CH₃Li in pentane

20 Which statement regarding isotope exchange of ¹⁸OH₂ with the oxygen of a carboxyl group is correct?
no exchange occurs under any circumstances
base-catalyzed exchange is more effective than acid-catalyzed exchange
acid-catalyzed exchange is more effective than base-catalyzed exchange
acids and bases are equally effective in catalyzing an exchange

21 Which of the following compounds could not be converted into pivalic acid ( 2,2-dimethylpropanoic acid ) in three or fewer steps?
A) 3,3-dimethyl-1-butene
B) 2,3-dimethyl-2-butene
C) 2,2-dimethyl-1-propanol
D) 2-bromo-2-methylpropane

22 Treatment of benzoic acid with excess ¹⁸OH₂ and a strong acid catalyst results in what change?
A) both oxygens of the carboxyl group exchange with the 18O of the water
B) only the carbonyl oxygen exchanges with the 18O of the water
C) only the OH oxygen exchanges with the 18O of the water
D) no change takes place

23 Two C₈H₉Br isomers form Grignard reagents which on carboxylation give isomeric carboxylic acids.
Oxidation of each isomeric acid with hot KMnO₄ produces the same C₉H₆O₆ tricarboxylic acid.
Which of the following compounds are the original isomeric bromides?
Four bromotoluene/xylyl bromide isomers I-IV showing different methyl and bromine ring positions
A) I & II
B) III & IV
C) I & IV
D) II & III

24 Which of the following reagents will reduce a carboxylic acid to a 1 °-alcohol under mild conditions?

I BH₃ in ether

II NaBH₄ in ethanol

III H₂ & Pt catalyst

IV LiAlH₄ in ether

A) I & IV
B) II & III
C) only III
D) all of them

25 What is the order of increasing base strength for the following salts? (weaker < stronger)

I sodium ethoxide

II potassium formate

III sodium benzoate

IV sodium dichloroacetate

A) I < II < III < IV
B) IV < II < III < I
C) II < III < IV < I
D) IV < I < II < III

26 Reduction of 4-oxobutyric acid, also called succinic semialdehyde, by sodium borohydride followed by aqueous acid gives a C₄H₆O₂ product.
This product is which of the following compounds?

27 Which compound does not react with ammonia to form propanamide under mild conditions?
A) propanoic acid
B) propanoyl chloride
C) ethyl propanoate
D) propanoic anhydride

28 Which sequence of reactions would be best for the conversion of toluene into para-bromophenylacetic acid.? ( NBS = N-bromosuccinimide )
A) i) Br₂ & FeBr₃; ii) KMnO₄ & heat; iii) NaCN in ethanol; iv) H₃O⁽⁺⁾ & heat
B) i) Br₂ & FeBr₃; ii) NBS in CCl₄; iii) Mg in ether followed by CO₂; iv) H₃O⁽⁺⁾
C) i) Br₂ & FeBr₃; ii) NBS in CCl₄; iii) NaCN in ethanol; iv) H₃O⁽⁺⁾ & heat
D) i) Br₂ & FeBr₃; ii) KMnO₄ & heat; iii) Mg in ether followed by CO₂; iv) H₃O⁽⁺⁾

29 On heating in the presence of bromine, 2,2-dimethyl-3-oxobutyric acid produces 3-bromo-3-methyl-2-butanone.
What unstable intermediate is involved in this reaction?
A) 1,2,2-trimethylcyclopropanol
B) 2,2-dimethyl β butyrolactone
C) 2-hydroxy-3-methylbutene
D) dimethylketene

30 Fischer esterification of mesitoic acid ( 2,4,6-trimethylbenzoic acid ) is extremely slow compared with benzoic acid itself.
What is the major factor accounting for this difference in reactivity?
A) steric hindrance by the ortho methyl groups.
B) the electron donating inductive effect of the methyl substituents.
C) acid-catalyzed rearrangement of the methyl substituents.
D) rapid acid-catalyzed decarboxylation of mesitoic acid.

31 Which of the following reagents would be best for reducing an ester to an aldehyde?
A) LiAlH₄ in ether
B) B₂H₆ in ether
C) NaBH₄ in aqueous ethanol
D) diisobutylaluminum hydride (DIBAH) in toluene at -78 °C

32 Which of the following reagents are suitable for reducing an amide to an aldehyde?

I LiAlH₄ in ether		II diisobutylaluminum hydride (DIBAH) in toluene at -78 °C
III LiAlH(t-C₄H₉O)₃ in ether at -78 °C		IV NaBH₄ in aqueous ethanol

A) I & IV
B) II & III
C) only I
D) all but III are suitable

33 Which of the following reagents are suitable for reducing an acyl chloride to an aldehyde?

I LiAlH₄ in ether		II NaBH₄ in tert-butanol
III LiAlH(t-C₄H₉O)₃ in ether at -78 °C		IV H₂ and Pd/BaSO₄ catalyst

A) III & IV
B) I & IV
C) only I
D) all are suitable

34 Which of the following methods would not be useful for preparing ketones?

I Friedel-Crafts reaction of an acyl chloride with benzene (AlCl₃ catalysis)

II reaction of R₂CuLi with an acyl chloride in ether at low temperature.

III reaction of Grignard reagents with nitriles, followed by hydrolysis

IV reaction of methyllithium with the lithium salt of a carboxylic acid, followed by hydrolysis

A) II & IV
B) II & III
C) only III
D) none (all are useful)

35 What is the expected product from the double reaction drawn below?

36 Which of the following reactions is most likely to produce ethyl propanoate?
A) sodium ethoxide + propanoic acid
B) propanol + acetyl chloride
C) sodium propanoate + acetic anhydride
D) potassium propanoate + ethyl iodide

37 If diethyl amine is treated separately with the following derivatives of isobutyric acid, what order of reactivity is expected?
greater reactivity > lesser reactivity

I isobutyronitrile
( 2-methylpropanenitrile )

II isobutyryl chloride
( 2-methylpropanoly chloride )

III ethyl isobutyrate

IV isobutyric anhydride
( 2-methylpropanoic anhydride )

A) I > II > III > IV
B) II > IV > III > I
C) IV > II > III > I.
D) IV > III > II > I

38 Methyl esters of carboxylic acids, RCO₂CH₃, have somewhat higher molecular masses than 1 °-amide, RCONH₂, derivatives of the same acid.
However, the amides have much higher boiling points. What is responsible for this difference?
A) hydrogen bonding molecular association.
B) resonance conjugation of N with C=O
C) the lower electronegativity of N versus O
D) rapid pyramidal inversion of the nitrogen

39 What is the expected product from the reaction sequence drawn below?

40 Ethyl acetate undergoes the following sequence of reactions:
1. treatment with excess phenylmagnesium bromide in ether
2. heating with conc. H₃PO₄
3. treatment B₂H₆ in ether, followed by alkaline H₂O₂
4. treatment with Jones' reagent (CrO₃ in aqueous acid + acetone)
Which of the following is the expected product? note that C₆H₅ = phenyl

41 The C–NH₂ bond in acetamide is 0.1 Å shorter than the C–NH₂ bond in ethylamine. Why?
A) N:H repulsion in ethylamine
B) hyperconjugation in ethylamine
C) dipole interactions in acetamide
D) p-π resonance in acetamide

42 Which of the following is not named correctly?

43 Methyl butyrate is reacted with excess ammonia, and the product is then treated with bromine in aqueous NaOH. What is the expected product?
A) butylamine
B) pentylamine
C) propylamine
D) N-bromobutyramide

44 Which reactions would best accomplish the following transformation?
Transformation of 3-oxocyclohexanecarboxylic acid (ester) to 3-oxocyclohexanecarbaldehyde
A) 1. LiAlH₄; 2. Jones' reagent
B) 1. LiAlH₄; 2. PCC in CH₂Cl₂
C) 1. NaBH₄; 2. Jones' reagent
D) 1. NaBH₄; 2. PCC in CH₂Cl₂

45 Ethyl propanoate is added to an ethanol soution of sodium ethoxide and heated to reflux for several hours.
The product was then refluxed in 5% HCl for several more hours, and extracted with ether
What compound has been prepared by this procedure?

46 Adipic acid is converted to its diacid chloride by reaction with SOCl₂, and this then reacts with 2 equivalents of sodium azide in ether solution.
Addition of conc. HCl, followed by heating, results in considerable gas evolution and the formation of a crystalline water soluble solid.
What is this product? Hint: addition of aq. NaOH to the solid produces a foul smelling liquid.
A) 1,4-diaminobutane, dihydrochloride salt
B) 1,5-diaminopentane, dihydrochloride salt
C) 1,6-diaminohexane, dihydrochloride salt
D) diammonium adipate

47 What donor and acceptor reactants should be used to prepare the following compound by a Claisen condensation?
1,3-diphenyl-2-(ethoxycarbonyl) propan-1-one, a beta-keto ester Claisen product
A) acceptor = ethyl benzoate; donor = ethyl phenylacetate
B) acceptor = ethyl phenylacetate; donor = ethyl benzoate
C) acceptor = ethyl benzoate; donor = ethyl benzoate
D) acceptor = ethyl phenylacetate; donor = ethyl phenylacetate

48 What donor and acceptor reactants should be used to prepare the following compound by a Claisen condensation?
Ethyl benzoylacetate (ethyl 3-oxo-3-phenylpropanoate), a beta-keto ester
A) acceptor = ethyl benzoate; donor = ethyl acetate
B) acceptor = ethyl acetate; donor = ethyl benzoate
C) acceptor = ethyl benzoate; donor = ethyl benzoate
D) acceptor = ethyl acetate; donor = ethyl acetate

49 What donor and acceptor reactants should be used to prepare the following compound by a Claisen condensation?
Diethyl 2-methyl-3-oxosuccinate (diethyl oxomethylsuccinate), a Claisen condensation product
A) acceptor = ethyl propanoate; donor = diethyl oxylate
B) acceptor = diethyl oxylate; donor = ethyl propanoate
C) acceptor = diethyl carbonate; donor = ethyl propanoate
D) acceptor = ethyl propanoate; donor = diethyl carbonate

50 A Dieckmann condensation of diethyl adipate was carried out by heating with sodium ethoxide.
One equivalent of benzyl bromide was added, and the resulting mixture was then refluxed in 5% HCl for several hours, and extracted with ether.
What compound has been prepared by this procedure?

51 2,2-Dimethyl-1,3-cyclohexanedione is refluxed several hours in an aqueous dioxane solution of sodium hydroxide (10%).
The resulting solution is adjusted to pH=5 by addition of dilute HCl and then extracted with ether.
What compound has been prepared by this procedure?
A) 2-cyclohexenone
B) 5-oxohexanoic acid
C) 6-methylheptanoic acid
D) 5-oxo-6-methylheptanoic acid

52 The malonic ester synthesis is useful for preparing substituted acetic acids.
Which of the following would not be easily prepared by this method?

I phenylacetic acid

II 3-phenylpropanoic acid

III 2,2-dimethylpropanoic acid

IV 4-pentenoic acid

A) IV
B) II & IV
C) I & III
D) all but I

53 Which set of reaction conditions is best suited for the preparation of 2,2-dimethylpropanoic acid from 2-bromo-2-methylpropane?
A) 1. NaCN in ethanol; 2. H₃O⁽⁺⁾ & heat
B) 1. NaC≡CH in ether; 2. aqueous KMnO₄ & heat
C) 1. Mg in ether; 2. CO₂, then H₃O⁽⁺⁾
D) 1. Mg in ether; 2. CH₃CHO; 3. Jones' reagent

54 Which set of reaction conditions is best suited for the preparation of 5-oxo-hexanoic acid from 5-bromo-2-pentanone?
A) 1. NaCN in ethanol; 2. H₃O⁽⁺⁾ & heat
B) 1. NaC≡CH in ether; 2. aqueous KMnO₄ & heat
C) 1. Mg in ether; 2. CO₂, then H₃O⁽⁺⁾
D) 1. NaOH in ethanol; 2. Jones' reagent

55 Which of the following is most readily decarboxylated on heating?
A) sodium 4-oxopentanoate
B) succinic acid
C) phthalic acid
D) 4-methyl-3-pentenoic acid

56 Which one of the following compounds would react with C₂H₅MgBr to make 3-pentanol ?
A) ethanal
B) ethyl formate
C) acetic acid
D) acetone

57 The acetoacetic ester synthesis is useful for preparing methyl ketones.
Which of the following would not be easily prepared by this method?

I acetylcyclopentane

II acetophenone

III 3-ethyl-2-pentanone

IV 3-methyl-4-phenyl-2-butanone

A) I & II
B) III & IV
C) only I
D) only II

58 Devise a series of reactions to convert ethyl 3-oxobutyrate to ethyl 4-oxopentanoate.
Select reagents and conditions from the following table, listing them in the order of use.

1 sodium ethoxide in ethanol	2 ethanol + acid catalyst & heat	3 H₃O⁽⁺⁾ heat	4 CO₂ then H₃O⁽⁺⁾	5 Mg in ether
6 PBr₃	7 NaBH₄ in alcohol	8 CH₂I₂ in ether Zn(Cu)	9 BrCH₂CO₂C₂H₅	10 (CH₃CO)₂O + pyridine

A) 1 then 9 then 3 then 2
B) 7 then 6 then 5 then 10 then 2
C) 3 then 7 then 6 then 5 then 10 then 2
D) 8 then 3 then 2

59 A C₇H₉N base reacts with sodium nitrite and hydrochloric acid at 0 °C, giving a clear solution.
On heating with KCN and Cu₂(CN)₂ a gas evolves, and continued heating with conc. HCl yields a C₈H₈O₂ crystalline acid.
Heating this acid with aqueous KMnO₄ produces a C₈H₆O₄ product, which dehydrates on strong heating to give a crystalline C₈H₄O₃ compound.
What is the C₇H₉N base?
A) benzylamine
B) N-methylaniline
C) para-toluidine (the toluidines are aminotoluenes)
D) ortho-toluidine

60 Heating diethyl malonate with 2 equivalents of ethyl acrylate and 1.2 equivalents of sodium ethoxide,
followed by neutralization of the base, produces a C₁₅H₂₂O₇ compound.
Heating this compound in 10%H₄SO₄ yields a C₇H₁₀O₃ crystalline carboxylic acid.
What is this product?
A) 2-oxocyclohexane-1-carboxylic acid
B) 3-oxocyclohexane-1-carboxylic acid
C) 4-oxocyclohexane-1-carboxylic acid
D) 3-(2-oxocyclobutyl)propanoic acid

61 Which of the following acids does not decarboxylate on heating?

Close this tab to return to the textbook.