[tobeever]

Predict the major Br monosubstituion product of this reaction.

http://img242.imageshack.us/img242/6717/image001kp7.gif


http://img230.imageshack.us/img230/3385/image002uj1.gif

can someone draw them for me plz or give me their SMILES

[macman104]

This process operates on a radical mechanism, where are the most stable positions to form a radical?

[tobeever]

I don't know

is it something like that

i know this is wrong

http://img339.imageshack.us/img339/136/hohoba1.png

This process operates on a radical mechanism, where are the most stable positions to form a radical?

[macman104]

Try again, what is the most stable radical out of these three:  primary, secondary or tertiary?  (Are you familiar with those terms?)

[tobeever]

tertiary?

Try again, what is the most stable radical out of these three:  primary, secondary or tertiary?  (Are you familiar with those terms?)

[nj_bartel]

Tertiary is right.  Can you think of why that might be?

[tobeever]

plz can someone draw it and explain it plzzzz
this is due in 2 hours
I really need help

[macman104]

You need to post on these forums to give us enough time to help you, we don't just hand out answers. 

But you identified tertiary is the most stable.  Do you see a tertiary carbon in the cyclohexane system?  For the ethylbenzene, your second picture, do you have any ideas for that one?  Do you know about resonance?

[nj_bartel]

Hint: Radicals are electron deficient.

[carboneel]

i think, on the ethyl benzene, that you would form a radical on the carbon attached to the ring. if i remember correctly, you can;t have a + charge on an sp2 carbon (all 6 in the ring)

i find myself on the right track most of the time but i havent been around organic chem as long as some of these other fellows.



---also i haven't come across these reactions with hv

[nj_bartel]

You picked the right carbon for the bromine to attach to, but not really by the right reasoning.  You don't form one carbocation because another is unstable - you form it because it itself is moderately stable.  The benzylic carbon (the carbon of the ethyl group attached to the benzene) can form a carbocation that is resonance stabilized through the ring.

[macman104]

Benzylic radicals, not carbocations.

[nj_bartel]

Oh sorry, what he said.