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CAIE A-Level Chemistry Organic Structure and Mechanism Conventions

Practise CAIE A-Level Chemistry organic drawing conventions through unambiguous three-dimensional structures, optical isomers and wedge-dash notation.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • draw optical isomer pairs with wedge-dash bonds and correct three-dimensional arrangement

Covered syllabus points

Reference—Structural, displayed and skeletal formula conventionsReference—Optical isomer drawing conventionReference—Organic reaction mechanism conventions

Organic structure and mechanism conventions question 1

[Maximum number: 1]

Propanoic acid, methanoic acid and ethanedioic acid are all weak acids.

Draw the displayed formula of ethanedioic acid.

Organic structure and mechanism conventions question 2

[Maximum number: 2]

Alanine, H2NCH(CH3)CO2H\mathrm{H}_{2} \mathrm{NCH}\left(\mathrm{CH}_{3}\right) \mathrm{CO}_{2} \mathrm{H}, and glutamic acid, H2NCH(CH2CH2CO2H)CO2H\mathrm{H}_{2} \mathrm{NCH}\left(\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) \mathrm{CO}_{2} \mathrm{H}, are two naturally occurring amino acids.

H2NCH(CH3)CO2H\mathrm{H}_{2} \mathrm{NCH}\left(\mathrm{CH}_{3}\right) \mathrm{CO}_{2} \mathrm{H} exists as two optical isomers.

Draw three-dimensional structures of these two optical isomers.

Figure for Question Organic structure and mechanism conventions question 2 — CAIE A-Level Chemistry A2
Figure for Question Organic structure and mechanism conventions question 2 — CAIE A-Level Chemistry A2

Organic structure and mechanism conventions question 3

[Maximum number: 1]

Some syntheses use Diels-Alder reactions, which normally involve a diene and an alkene reacting together to form a cyclohexene.

Draw three curly arrows in Fig. 9.4 to complete the mechanism for the Diels-Alder reaction between buta-1,3-diene and ethene.

Fig. 9.4

Fig. 9.4

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