Chemistry 9701 · AS & A Level · Organic synthesis

Organic synthesis — practice question

Organic reactions can involve substances that are atoms, molecules, ions or free radicals. The terms electrophilic, nucleophilic, addition, elimination and substitution are also used for organic reactions. Study the reactions below. Reaction 1: $\text{CH}_4 + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{HCl}$ Reaction 2: $\text{CH}_3\text{CH}_2\text{OH} \rightarrow \text{CH}_2{=}\text{CH}_2 + \text{H}_2\text{O}$ Reaction 3: $\text{CH}_3\text{I} + \text{OH}^- \rightarrow \text{CH}_3\text{OH} + \text{I}^-$ Reaction 4: $\text{CH}_3\text{COCH}_3 + \text{HCN} \rightarrow \text{CH}_3\text{C(OH)(CN)CH}_3$
(a)[2]

Using the terms given above, State as clearly as you can the type of each of the following reactions: reaction 1 reaction 2

(b(i))[1]

Using the four reactions above, suggest the formula of one substance that is an addition product. In each case, state which reaction you are considering.

(b(ii))[1]

Using the four reactions above, suggest the formula of one substance that is a leaving group. In each case, state which reaction you are considering.

(b(iii))[1]

Using the four reactions above, suggest the formula of one substance that behaves as an electrophile. In each case, state which reaction you are considering.

(c)[1]

State the meaning of the term nucleophile.

(d)[2]

Reactions 3 and 4 both involve nucleophiles. For each reaction, give the formula of the nucleophile. reaction 3 reaction 4

(e)[1]

A characteristic reaction of ethene is that it decolourises bromine. $\text{CH}_2{=}\text{CH}_2 + \text{Br}_2 \rightarrow \text{BrCH}_2\text{CH}_2\text{Br}$ In this reaction, ethene acts as a nucleophile. Suggest an explanation for why ethene can behave like this.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “reaction 1 is a free radical substitution” …

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