Dumb Organic Question

[rpatel8]

Advertisement - Members don't see this ad

If you react HBr/ROOR with cis-2-butene, what is the product? Would there be some sort of shift?

 

[flin5845]

If you react HBr/ROOR with cis-2-butene, what is the product? Would there be some sort of shift?

When reacting Br2 with a peroxide you will get anti-mark addition...it only works with Bromine though..

If you saw Cl2 with a peroxide it would be mark addition.

 

[rpatel8]

Well, with cis-2-butene, wouldn't either side be the same since there is one H on both carbons. The reason I posted this was I am looking at a road map from my organic class and it says the product is 1-bromo-2-methylpropane but that doesn't make sense to me

 

[rah08e]

Well, with cis-2-butene, wouldn't either side be the same since there is one H on both carbons. The reason I posted this was I am looking at a road map from my organic class and it says the product is 1-bromo-2-methylpropane but that doesn't make sense to me

someone plz post an answer... this is bugging me lol

 

[ugination87]

wouldn't it just be 2-bromobutane? i really dont think a methyl shift occurs with radicals.. i never read about it in my text book. hope that helps 😕

 

[rpatel8]

Thats what I thought as well. I don't know how correct this roadmap is but I found it in my stack of coursework from the past few years. It also says the reaction of the same alkene with B2H6/H2O2 forms 2-methylpropanol. This is confusing to me. I'm hoping that this is just wrong as my DAT is on wednesday

 

[Hope30]

I want to confirm ugination87. It is 2-bromobutane.

 

[Troyvdg]

to your original question, you would get the same product if the Br was added to the second or third carbon, it would be the same compound, 2 bromobutane; not sure what you meant, but there isn't any shift in radical mechanisms

Thats what I thought as well. I don't know how correct this roadmap is but I found it in my stack of coursework from the past few years. It also says the reaction of the same alkene with B2H6/H2O2 forms 2-methylpropanol. This is confusing to me. I'm hoping that this is just wrong as my DAT is on wednesday

this however is a different reaction. BH3 THF/H202, OH gives an anti-markovnikov syn addition of an OH over a double bond. So it should be 2-butanol, not 2-methylpropanol, maybe you just accidentally missnamed the compound while taking notes

 

[ugination87]

i guess the ultimate question is.. how did the text get their answer? it seems like something completely different than what we were taught

 

[flin5845]

It would be 2-bromobutane. The bromine would add across the double bond first in a radical fashion, leaving a radical on the C3 carbon. There no possible way to have any type of shift to give a more stable radical.