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CAIE A-Level Chemistry A2 29.2 Characteristic Organic Reactions Questions

Practise classifying electrophilic substitution and addition–elimination mechanisms from complete reaction evidence.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • name the mechanism from the bond changes and sequence rather than from the reagent or product alone
  • form the required electrophile with a Lewis acid and retain the corresponding negatively charged species
  • use curly arrows from an electron pair or bond and include charges, intermediates and regenerated species

Covered syllabus points

29.2.1—Terminology associated with types

Question 1

[Maximum number: 3]

The reaction of phenylethanone with 1,4-dibromobutane, BrCH2CH2CH2CH2Br\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}, in the presence of FeBr3\mathrm{FeBr}_{3} is shown in Fig. 6.2.
phenylethanone

Fig. 6.2

Fig. 6.2

The mechanism of this reaction is similar to that of the alkylation of benzene.

Complete the mechanism in Fig. 6.3 for the reaction of phenylethanone with BrCH2CH2CH2CH2+\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}^{+}ions.

Include all relevant curly arrows and charges.
Draw the structure of the organic intermediate.

Fig. 6.3

Fig. 6.3

Question 2

[Maximum number: 1]

The structure of cyclohexylamine is shown in Fig. 9.1.
cyclohexylamine

Fig. 9.1

Fig. 9.1

Cyclohexylamine reacts with ethanoyl chloride to form the corresponding amide, L.

Fig. 9.2

Fig. 9.2

Name the mechanism for the reaction shown in Fig. 9.2.

Question 3

[Maximum number: 4]

The structure of benzene-1,3-dicarboxylic acid is shown.

benzene-1,3-dicarboxylic acid

benzene-1,3-dicarboxylic acid

Question (a)

(a)

Benzene-1,3-dicarboxylic acid can be made by the two-step synthesis shown below.
benzene-1,3-dicarboxylic acid
compound P

Figure for Question (a) — CAIE A-Level Chemistry A2
compound Q

compound Q

[ 4 ]

Question (i)

(i)

The reagents used for step 1 are CH3COCl\mathrm{CH}_{3} \mathrm{COCl} and AlCl3\mathrm{AlCl}_{3}. These reagents give rise to CH3C+=O\mathrm{CH}_{3} \stackrel{+}{\mathrm{C}}=\mathrm{O} ions which react with compound P.

Name the mechanism of this reaction.

[ 1 ]

Question (ii)

(ii)

Draw the mechanism of the reaction of CH3C+=O\mathrm{CH}_{3} \stackrel{+}{\mathrm{C}}=\mathrm{O} ions with compound P. Include all relevant curly arrows and charges, the structure of the intermediate and the structure of compound Q.
intermediate

CH3C+=O\mathrm{CH}_{3} \stackrel{+}{\mathrm{C}}=\mathrm{O}

compound Q

Figure for Question (ii) — CAIE A-Level Chemistry A2
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Figure for Question (ii) — CAIE A-Level Chemistry A2
[ 3 ]
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