CAIE A Level Chemistry 9701 · An introduction to organic chemistry

An introduction to organic chemistry: explain question

Explain4 marksStandard

Two organic reactions are described below.

Reaction 1: Benzene reacts with bromine in the presence of $\ce{FeBr3}$ catalyst to form bromobenzene. The $\ce{Br+}$ ion is generated as the electrophile, which is attacked by the $\pi$ electrons of the benzene ring.

Reaction 2: Ethyl ethanoate is heated under reflux with dilute hydrochloric acid. The reaction involves nucleophilic attack by water on the carbonyl carbon, followed by loss of ethanol.

Explain why Reaction 1 is classified as an electrophilic substitution reaction and why Reaction 2 is classified as an addition-elimination reaction.

How this question is marked

4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.

Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.

An introduction to organic chemistry: explain question

How this question is marked

More An introduction to organic chemistry questions