Road maps, error or my lack of understanding? :P

[rejuvenatedsoul]

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2010 edition, page 110, first roadmap on that page (last row, second reagent):

it shows NBS w/ROOR and heat adding bromine to the more substituted carbon. i thought it was anti-mark....so shouldn't it add onto the methyl?

 

[CANgnome]

NBC roor makes a radical, which adds to most sub.

if NBS ROOR adds to an alkene, the Br adds to the allylic position. like Br2 hv, it does not have a hydrogen to donate to break a double bond.

 

[whathashizzyDDS]

i though NBS adds in the allylic position

 

[rejuvenatedsoul]

^that makes sense, i can't find a situation where that isn't the case.

 

[RING12]

whenever you have NBS or hv, on a benzen ring remember that the NBS loves to take the closet Hydrogen to the ring. it's always rake the Hydrogen from -CH2. not from methyl group. Hope that helps you!

 

[rejuvenatedsoul]

thanks 🙂 okay that makes sense.


edit: i found this: http://www.organic-chemistry.org/chemicals/oxidations/n-bromosuccinimide-nbs.shtm

so NBS is used for allylic/benzylic brominations

see this too: http://en.wikipedia.org/wiki/N-Bromosuccinimide

😛