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Bromine water and alkene

If we add bromine water to an alkene it is expected that the orange colour should disappear, why is that?

Thanks.
Reply 1
Avatar for Genocidal
Genocidal
19
Because the double bonds open up to create a dibromoalkane which is colourless. If it's added to an alkane then nothing happens therefore it remains in its original colour which is orange.
Reply 2
Avatar for chembob
chembob
10
The bromine is added across the double bond by electrophilic addition and creates a colourless dibromoalkane
Reply 3
Avatar for soup
soup
11
Original post by Genocidal
Because the double bonds open up to create a dibromoalkane which is colourless. If it's added to an alkane then nothing happens therefore it remains in its original colour which is orange.


It will still change colour... (unless in darkness)
Reply 4
Avatar for Bloodbath
Bloodbath
Bromine can add to the double bond to form a brominium ion and then water or a br- ion can attack one of the carbons bonded to the brominium ion in an sn2 fashion
Reply 5
Avatar for Genocidal
Genocidal
19
Original post by soup
It will still change colour... (unless in darkness)


What? Since when? My notes have always said that if Bromine is added to the alkane then the colour will remain the same.
Reply 6
Avatar for thurin
thurin
11
Original post by Genocidal
What? Since when? My notes have always said that if Bromine is added to the alkane then the colour will remain the same.


Bromine homolytically fisses in the presence of sunlight, forming free radicals which will replace hydrogen atoms.
Reply 7
Avatar for SWEngineer
SWEngineer
OP
3
Thanks for your replies.

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