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CAIE A-Level Chemistry AS 21.1 Organic Synthesis Questions

Practise identifying functional groups and planning or analysing multi-step conversions using syllabus reactions.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • compare start and target structures to identify the functional-group change required at each step
  • choose a syllabus reagent, solvent, temperature and apparatus condition for every conversion
  • check carbon-count changes, intermediate structures and plausible inorganic or organic by-products

Covered syllabus points

21.1.1—For an organic molecule containing several21.1.2—Devise multi-step synthetic routes21.1.3—Analyse

Question 1

[Maximum number: 1]

31 X is an organic compound containing the elements carbon, hydrogen and oxygen only.
The table shows the observations made from three chemical tests carried out on X .

Table for Question 1 — CAIE A-Level Chemistry AS

What is a possible structure of X ?

A
Figure for Question 1 — CAIE A-Level Chemistry AS — Option A
B
Figure for Question 1 — CAIE A-Level Chemistry AS — Option B
C
Figure for Question 1 — CAIE A-Level Chemistry AS — Option C
D
Figure for Question 1 — CAIE A-Level Chemistry AS — Option D

Question 2

[Maximum number: 1]

2-bromopropane is converted to 1,2-dibromopropane in a pathway involving two reactions.

 2-bromopropane → reaction 1 compound X→ reaction 2 1,2-dibromopropane \text { 2-bromopropane } \xrightarrow{\text { reaction } 1} \text { compound } X \xrightarrow{\text { reaction } 2} \text { 1,2-dibromopropane }

What are the reagents and conditions for the two reactions?

reaction 1

reaction 2

heat under reflux with aqueous NaOH

HBr(g)\mathrm{HBr}(\mathrm{g}) at room temperature

heat under reflux with aqueous NaOH

Br2(l)\mathrm{Br}_{2}(\mathrm{l}) at room temperature

heat under reflux with ethanolic NaOH

HBr(g)\mathrm{HBr}(\mathrm{g}) at room temperature

heat under reflux with ethanolic NaOH

Br2(l)\mathrm{Br}_{2}(\mathrm{l}) at room temperature

Question 3

[Maximum number: 1]

Each of the compounds below is treated separately with an excess of NaBH4\mathrm{NaBH}_{4}.
The product of each reaction is then heated with an excess of concentrated H2SO4\mathrm{H}_{2} \mathrm{SO}_{4}.
Which compounds give only one final product with the molecular formula C7H10\mathrm{C}_{7} \mathrm{H}_{10} ?

1

1

2

2

3

3

A

1, 2 and 3 are correct

B

1 and 2 only are correct

C

2 and 3 only are correct

D

1 only is correct

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