Multiple choice questions

Try the following multiple choice questions to test your knowledge of this chapter. For each question there is one correct answer. The periodic table, physical constants and relative atomic masses needed for these problems are given on the inside covers of Chemistry, fourth edition by C.E. Housecroft and E.C. Constable. Once you have answered the questions, click on 'Submit Answers for Grading' to get your results.

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This activity contains 18 questions.

	Which compound is not a carbonyl compound?   Pentanal. Butanol. Hexanoic acid. Ethanoyl chloride.

	A compound A shows signals at δ 200 and 31 ppm in its 13C NMR spectrum; in the 1H NMR spectrum, there is a doublet at δ 2.2 ppm (J 2.9 Hz) and a quartet at δ 9.8 ppm (J 2.9 Hz). When X is shaken with D2O, no change is observed in the 1H NMR spectrum. Which of the following identities for X is consistent with these data?   Methyl acetate (methyl ethanoate). Acetyl chloride (ethanoyl chloride). Acetic acid (ethanoic acid). Acetaldehyde (ethanal).

	Which statement about butanone is incorrect?   The C=O bond in butanone is polar with O δ–. Butanone can be prepared by oxidation of butan-2-ol. The IR spectrum of butanone has a strong absorption at ≈1720 cm–1. Butanone forms dimers through hydrogen bonding.

	Which statement about pentanoic acid is incorrect?   Pentanoic acid can be prepared by reacting n-C5H11MgBr in Et2O with solid CO2, followed by treatment with acid. Treatment of pentanoic acid with ethanol yields ethyl pentanoate. Pentanoic acid reacts with KOH to give a salt. The reaction between pentanoic acid and PCl3 gives pentanoyl chloride.

	Which reaction is unlikely to lead to the stated products?   Hydrolysis of cyanopentane in the presence of acid or base to give hexanoic acid. Reaction of hexan-2-ol with KMnO4 and aqueous acid to give hexan-2-one. Reaction of benzene and butanoyl chloride in the presence of AlCl3 to give phenyl propyl ketone. Treatment of methyl butanoate with DIBAL (diisobutyl aluminium hydride) in hexane to give butan-1-ol.

	Which of the following is a dibasic, weak acid?   Oxalic acid. Benzoic acid. Pentanoic acid. Pentane-2,4-dione (acetylacetone).

	Alkylation of a ketone that contains α-H atoms (e.g. acetone) involves the formation of a lithium enolate which then reacts with a halogenoalkane. Which statement about this reaction is incorrect?   The reagent used to form the lithium enolate is LDA (lithium diisopropylamide). The alkylation reaction works best with tertiary (rather than primary or secondary) halogenoalkanes. Alkylation of the ketone is a C–C bond forming reaction. Formation of the lithium enolate means that the carbonyl compound is fully enolized.

	Which statement about an acyl chloride is incorrect?   Acyl chlorides react with carboxylic acids to give esters. Friedel-Crafts acylation of benzene involves the reaction of benzene with an acyl chloride in the presence of a Lewis acid catalyst. Acyl chlorides are easily hydrolysed, forming HCl and a carboxylic acid. Reduction of an acyl chloride by LiAlH4 yields an alcohol.

	Which statement about the reaction between pentan-3-one and NC– is incorrect?   In the presence of base, pentan-3-one is regenerated. NC– acts as a nucleophile. The reaction involves initial abstraction of an α-H atom in pentan-3-one. A cyanohydrin is formed.

	Which statement about the reaction between acetone and NH3 is incorrect?   In the absence of a reducing agent, the product is an imine. NH3 acts as a nucleophile. In the presence of a reducing agent (e.g. LiAlH4), the product is 1-propylamine. The first step in the reaction, NH3 attacks the C atom of the C=O bond in acetone.

	Which statement about an aldol reaction is incorrect?   The first step in an aldol reaction is deprotonation at the α-H position. An aldol reaction is a C–C bond-forming reaction. An aldol reaction may occur between two aldehydes, and one reactant (at least) must contain an α-H atom. The product of an aldol reaction between two aldehydes is a β-diketone.

	Which statement about a Claisen condensation is incorrect?   The reaction involves C–C bond formation. The product is a β-keto ester which resists deprotonation by the strong base in the reaction mixture. The reaction involves the condensation of two esters in the presence of strong base. A strong base is required to remove H+ from an α-H position in one of the starting esters.

	Which one of the following is the most likely pKa value of butanoic acid?   16.00 2.30 10.50 4.87

	When the reaction of Br2 with acetone is catalysed by hydroxide ion, which of the following are the likely products?   tribromoacetic acid. acetyl bromide. bromoacetic acid. CHBr3 and acetate ion.

	The acid catalysed reaction of Br2 with acetone will lead to which of the following products?   CHBr3 and acetic acid. tribromoacetic acid. acetyl bromide. 1-bromopropan-2-one.

	Which statement is incorrect about an enolate ion?   An enolate can function as a nucleophile. An enolate is the conjugate base of an enol. An enolate can accept a proton. An enolate is a good electrophile.

	Which reagent would you choose to convert pentan-1-ol to pentanal?   K2Cr2O7 with aqueous H2SO4 in acetone. PCC in CH2Cl2. DIBAL. KMnO4 with aqueous H2SO4 in acetone.

	Lithium diisopropylamide (LDA):   can be used to deprotonate butanone. is formed by reacting an amide with butyl lithium. is a good nucleophile. contains a CONH2 group.

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