AQA A-LEVEL CHEMISTRY EXAMINATION 2026|ORGANIC CHEMISTRY: REACTION MECHANISMS CHEMISTRY (7405) |ADVANCED LEVEL EXAMINATION – 2026 PAPER 2: ORGANIC CHEMISTRY — REACTION MECHANISMS AND SYNTHESIS Qualification: A-Level Chemistry (AQA Specification)

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AQA A-LEVEL CHEMISTRY EXAMINATION 2026|ORGANIC
CHEMISTRY: REACTION MECHANISMS CHEMISTRY (7405)
|ADVANCED LEVEL EXAMINATION – 2026
PAPER 2: ORGANIC CHEMISTRY — REACTION MECHANISMS AND SYNTHESIS
Qualification: A-Level Chemistry (AQA Specification)
Paper Code: 7405/2
ACADEMIC YEAR: 2025/2026




Name and outline the mechanism, reagents and conditions, for the reaction of an alkane to a
haloalkane.

[Free-radical substitution]



E.G.

1. Initiation, essential: UV light

Cl₂ --> 2Cl•



2. Propagation

CH₃CH₃ + Cl• --> HCl + CH₃CH₂•

CH₃CH₂• + Cl₂ --> CH₃CH₂Cl + Cl•



3. Termination

CH₃CH₂• + Cl• --> CH₃CH₂Cl




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Name and outline the mechanism, reagents and conditions, for the reaction of a haloalkane to
an alkene.

[Elimination]



NaOH, ethanol, reflux




Name and outline the mechanism, reagents and conditions, for the reaction of a haloalkane to
an alcohol.

[Nucleophilic substitution]



Warm NaOH(aq), reflux




Name and outline the mechanism, reagents and conditions, for the reaction of an alkene to a
haloalkane.

[Electrophilic addition]



HBr, 20°C




Name and outline the mechanism, reagents and conditions, for the reaction of an alkene to an
alcohol. (1) (H+)

i.e. Hydration of an alkene

[Acid catalysed addition]



H₃PO₄ catalyst, steam, 300°C, 60atm


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