when br2/H2O is using on double bond!!!

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atlanta213

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I know product should include Br and OH. Does Br always have to bond with least sub while OH bond with most sub?
 
Yes, if the alcohol is located on the most substituted part of the molecule then Bromine is the one that formed the bridge. If you have Br on the most substituted part of the molecule and -OH on the least, then it came through an epoxide. The reason -OH goes to the most substituted part of the double bond is because when Br forms the bromonium ion, the Br on the bridge is actually leaving slightly ahead of the incoming nucleophile (H20). This leaves partial positives on the carbons attached to the bridge. The largest delta positive is located on the most substituted part of the bridge because it is best accomodated there by the extra alkly groups donating their e- density. Therefore, H20 will attack the larger delta plus, swinging the Br to the least substitued part of the bridge.

I know product should include Br and OH. Does Br always have to bond with least sub while OH bond with most sub?
 
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