Chemistry — AS

Organic Synthesis — Multiple-Choice Questions (Cambridge International AS Chemistry): Exam Questions

19 questions · 19 marks · ≈ 19 min

Guided practice

11 markeasy

Lactic acid occurs naturally, for example in sour milk.

Displayed formula of lactic acid (CH₃CH(OH)COOH) showing the hydroxyl group on the central carbon and the carboxylic acid group

Which property does lactic acid have?

Choose your answer

It decolourises aqueous bromine rapidly.

It is insoluble in water.

It reacts with sodium carbonate.

It reduces Fehling’s reagent.

21 markeasy

Which reagent can be used to convert CH₃CH₂CO₂CH₃ into CH₃CH₂CO₂CH₂Cl?

Choose your answer

Chlorine in bright sunlight at 100 °C

Concentrated hydrochloric acid at 100 °C

Phosphorus pentachloride at room temperature

Sulphur dichloride oxide (thionyl chloride, SOCl₂) at 50 °C

31 markeasy

Which reaction produces a coloured organic compound?

Choose your answer

CH₂=CH₂ + cold dilute acidified KMnO₄

CH₃CH₂OH + acidified K₂Cr₂O₇

CH₃CHO + 2,4-dinitrophenylhydrazine reagent

CH₃COCH₃ + Fehling's solution

41 markeasy

A compound X has the following properties:

liquid at room temperature
soluble in water
reacts with cold aqueous sodium hydroxide

Which of the following could be compound X?

Choose your answer

Propanoic acid

Propanol

Propene

Propyl propanoate

51 markeasy

Tartaric acid (HO₂CCH(OH)CH(OH)CO₂H) can occur naturally, for example in wine, and may be synthesised in the laboratory.

The laboratory synthesis occurs in 2 steps:

OHCCHO $\overset{\mathrm{step}1}{\rightarrow}$ intermediate $\overset{\mathrm{step}2}{\rightarrow}$ HO₂CCH(OH)CH(OH)CO₂H

Which reagents could be used for this synthesis?

	Step 1	Step 2
A	HCl (aq)	HCN (g)
B	H₂SO₄ (aq)	K₂Cr₂O₇ / H₂SO₄ (aq)
C	KCN (aq/alcoholic)	K₂Cr₂O₇ / H₂SO₄ (aq)
D	HCN, NaCN (aq/alcoholic)	H₂SO₄ (aq)

Choose your answer

61 markeasy

This molecule is responsible for the flavour of spearmint chewing gum.

Structural formula of carvone (spearmint flavour molecule) with arrow 1 pointing to the C=C alkene double bond in the cyclohexene ring and arrow 2 pointing to the C=O ketone carbonyl group

Which statement about functional groups 1 and 2 is correct?

Choose your answer

1 will undergo electrophilic substitution

1 will undergo nucleophilic addition

2 will undergo electrophilic substitution

2 will undergo nucleophilic addition

71 markmedium

Sorbic acid is a natural organic compound which is used as a food preservative because it kills fungi. Sorbic acid reacts with bromine in an organic solvent and hydrogen in the presence of a nickel catalyst.

Displayed formula of sorbic acid showing H₃C group connected through two conjugated C=C double bonds to a carboxylic acid (COOH) group, with all hydrogen atoms shown

How many moles of bromine (in an organic solvent) and of hydrogen (in the presence of a Pt / Ni catalyst) will be incorporated into one mole of sorbic acid by these reactions?

	Moles of bromine	Moles of hydrogen
A	2	2
B	2	3
C	$\frac{1}{2}$	2
D	2 $\frac{1}{2}$	3

Choose your answer

81 markmedium

The naturally-occurring molecule civetone was one of the first known ingredients used in perfumery.

Structural formula of civetone: a 17-membered cyclic ketone containing a C=O group and one C=C double bond (HC=CH), with the remaining ring positions occupied by CH₂ groups

Which reagent will not react with civetone?

Choose your answer

2,4-dinitrophenylhydrazine reagent

Fehling’s reagent

Hydrogen bromide

Sodium tetrahydridoborate (III), NaBH₄

91 markmedium

An alkene is reacted with acidified manganate (VII) ions, MnO₄^-. The organic product has a relative molecular mass greater than that of the alkene by 34.

Which of the following are the correct conditions for this reaction?

Choose your answer

Cold, concentrated MnO₄^-

Cold, dilute MnO₄^-

Hot, concentrated MnO₄^-

Hot, dilute MnO₄^-

101 markmedium

Pentanoic acid can be produced from 1-bromobutane using reagents Y and Z as shown below.

1-bromobutane $\overset{\mathrm{reagent}Y}{\rightarrow}$ compound X $\overset{\mathrm{reagent}Z}{\rightarrow}$ pentanoic acid

Which of the following could be reagents Y and Z?

	Y	Z
A	KCN in ethanol	HCl (aq)
B	KCN in ethanol	NaOH (aq)
C	NaOH (aq)	HCl (aq)
D	NH₃ in ethanol	H⁺/Cr₂O₇^2- (aq)

Choose your answer

111 markmedium

In which reaction does a carbocation intermediate form?

Choose your answer

CH₂=CH₂ + Br₂ → CH₂BrCH₂Br

CH₃CH₂Br + NaOH → CH₃CH₂OH + NaBr

CH₃CH₃ + Cl₂ → CH₃CH₂Cl + HCl

CH₃CHO + HCN $\overset{\mathrm{CN}^{-}}{\rightarrow}$ CH₃CH(OH)CN

121 markmedium

Hept-4-enal, shown below, naturally occurs in cow's milk.

CH₃CH₂CH=CHCH₂CH₂CHO

Which organic product is formed when hept-4-enal is reduced with either hydrogen with a nickel catalyst or sodium borohydride?

Choose your answer

CH₃(CH₂)₅CH₃ when hept-4-enal is reduced by H₂ / Ni

CH₃(CH₂)₅CHO when hept-4-enal is reduced by NaBH₄

CH₃CH₂CH=CHCH₂CH₂CH₂OH when hept-4-enal is reduced by H₂ / Ni

CH₃CH₂CH=CHCH₂CH₂CH₂OH when hept-4-enal is reduced by NaBH₄

131 markhard

The diagram shows the structure of the naturally-occurring molecule cholesterol.

Skeletal structure of cholesterol: a steroid with four fused rings, a hydroxyl (-OH) group on ring A, a C=C double bond in ring B, and an isooctyl side chain attached to ring D

Two separate test tubes of cholesterol are used in an experiment. One test tube of cholesterol is treated with cold, dilute acidified KMnO₄, and the other is treated with hot, concentrated acidified KMnO₄.

Which row correctly describes the change in the number of chiral carbon atoms in the molecule during each reaction and the structure of the product in each test tube?

	Cold, dilute acidified KMnO₄	Hot, concentrated acidified KMnO₄
	Change in the number of chiral carbons	Number of hydroxy groups in product	Change in the number of chiral carbons	Number of 6-membered rings remaining in product
A	+1	1	-1	3
B	+1	1	0	2
C	+2	3	-1	2
D	+2	3	0	3

Choose your answer

141 markhard

The cyclic compound G is heated with dilute hydrochloric acid.

Skeletal formula of compound G (morpholine-2,5-dione): a 6-membered ring containing an NH amide group, an ester linkage (C=O bonded to ring oxygen), and two CH₂ groups

Which of the following are the products of the reaction?

Choose your answer

H₂NCOCH₂OH and HOCH₂CHO

HO₂CCH₂NH₃⁺ and HO₂CCH₂OH

HOCH₂CO₂H and H₂NCH₂CO₂H

HOCH₂CONH₃⁺ and HOCH₂CHO

151 markhard

Santonin is a drug that has been used to treat a worm infection.

Skeletal formula of santonin: a bicyclic sesquiterpene lactone with a 6-membered ring containing a conjugated C=C–C=O enone system and two CH₃ groups, fused to a 5-membered γ-lactone ring containing a C=O ester group, ring oxygen, and CH₃

When santonin is first treated with warm dilute H₂SO₄, product X is formed. If X is treated with cold acidified KMnO₄, the final product Y is obtained.

How many atoms of hydrogen in each molecule of product Y could be displaced in a reaction with sodium metal?

Choose your answer

161 markhard

Compound M is used in leather processing.

Skeletal formula of compound M (glycolide/1,4-dioxane-2,5-dione): a 6-membered cyclic diester ring containing two C=O groups and two ring oxygen atoms, with two CH₂ groups completing the ring

Compound M is synthesised in the presence of concentrated sulfuric acid and heat.

Which other starting materials are required to synthesise compound M?

Choose your answer

CH₃COOCH₂COOH only

CH₃COOH mixed with HOCH₂COOH

CH₃COOH only

HOCH₂COOH only

171 markhard

Mixture F is produced upon refluxing compound G with aqueous sodium hydroxide.

Upon distillation of mixture F with acidified potassium dichromate (VI), propanone is produced. Mixing compound G with aqueous silver nitrate and dilute nitric acid gives a cream precipitate.

Which of the following could be compound G?

Choose your answer

CH₃CH₂CH₂Br

CH₃CH₂CH₂I

CH₃CHBrCH₃

CH₃CHICH₃

181 markhard

Antipyrine is a drug used to reduce fever. The initial step of its synthesis is the reaction of phenylhydrazine with compound X.

Reaction equation showing phenylhydrazine (C₆H₅-NHNH₂) reacting with compound X (ethyl acetoacetate: CH₃COCH₂CO₂CH₂CH₃, containing both a ketone and an ester group) to give product Y

Which of the following is product Y?

Choose your answer

191 markhard

Ibuprofen is an anti-inflammatory drug, the structure of which is shown below.

Skeletal formula of ibuprofen: a para-substituted benzene ring with an isobutyl group at one position and a methylcarboxylic acid group (-CH(CH₃)CO₂H) at the para position

Which reaction leads to the formation of ibuprofen?

Choose your answer

Step 1

Step 2

HCl (aq)

HCN (g)

H₂SO₄ (aq)

K₂Cr₂O₇ / H₂SO₄ (aq)

KCN (aq/alcoholic)

K₂Cr₂O₇ / H₂SO₄ (aq)

HCN, NaCN (aq/alcoholic)

H₂SO₄ (aq)

Moles of bromine

Moles of hydrogen

\frac{1}{2}

\frac{1}{2}

KCN in ethanol

HCl (aq)

KCN in ethanol

NaOH (aq)

HCl (aq)

NH₃ in ethanol

H⁺/Cr₂O₇^2- (aq)

Cold, dilute acidified KMnO₄

Hot, concentrated acidified KMnO₄

Change in the number of chiral carbons

Number of hydroxy groups in product

Change in the number of chiral carbons

Number of 6-membered rings remaining in product

-1