All mechanisms

Electrophilic addition — bromine

Year 1
AQA 3.3.4

Electrophilic addition · Br2 (bromine water or in an organic solvent) · room temperature

Reagents: Br2 (bromine water or in an organic solvent) · Conditions: room temperature

Step 1 of 2

CCHHHHδ+δ−BrBr
  1. 1.The π electrons attack the induced δ+ bromine (the end nearer the alkene).
  2. 2.The Br–Br bond breaks heterolytically towards the δ− bromine, releasing Br⁻.

A carbocation forms with Br on the adjacent carbon; Br⁻ is released.

Step 2 of 2

BrCHHC+HHBr−
  1. 1.Bromide's lone pair attacks the positive carbon.

1,2-dibromoethane forms.

Product: 1,2-dibromoethane

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