2006-11-04 09:55:59 · 4 answers · asked by Kiya 2 in Science & Mathematics ➔ Chemistry
The Bromine test for alkenes works because bromine is electron deficient and alkenes have pi electrons forming a double bond that are open for attack.
The exact mechanism is shown here:
http://en.wikipedia.org/wiki/Halogen_addition_reaction
Alkanes can be brominated but the reaction is a lot slower and it requires a UV light catalyst (it's a radical bromination)
2006-11-04 15:54:52 · answer #1 · answered by niuchemist 6 · 0⤊ 0⤋
The reaction is:
H2C=CH2 + Br2 ---> BrH2C-CH2Br
Due to their C=C double bonds which can be broken, alkenes react readily with bromine to produce saturated dibromoalkanes. When an alkene is reacted with bromine, the red-brown color of the bromine is immediately lost due to the reaction of the bromine.
2006-11-04 10:05:55 · answer #2 · answered by Dr. J. 6 · 0⤊ 0⤋
an alkene has 1 or more double bonds between carbon atoms C=C. in the presence of Br2 or Br-Br( which is red/brown), the Br-Br bond attacks the double bond forming C-Br new bonds. thus the red/brown colour dissappears. Alkanes do not have C=C, but have C-C which Br-Br can not attach to.
2006-11-04 10:08:26 · answer #3 · answered by toasteddeer 2 · 1⤊ 0⤋
triple bond.
2016-03-17 06:24:47 · answer #4 · answered by ? 4 · 0⤊ 0⤋