Question Re: Achiever Test1: Ochem 77

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Which of the following sets of hydrocarbons correctly displays free radicals in descending order of stability?



A. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
B. CH2=CHĊH2 > (CH3)3C. > (CH3)2HC. > CH3H2C.
C. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
D. (CH3)2HC. > CH3H2C. > CH2=CHĊH2 > (CH3)3C.
E. (CH3)3C. > CH2=CHĊH2 > (CH3)2HC. > CH3H2C.


I'm not sure if this question has been posted on the forum before, but i was wondering.. how a conjugated system affects a radical.

Is it the same as a carbocation? I picked E, but the answer says B

Thanks for the Help!

-building

 

[Dr. juju]

Which of the following sets of hydrocarbons correctly displays free radicals in descending order of stability?



A. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
B. CH2=CHĊH2 > (CH3)3C. > (CH3)2HC. > CH3H2C.
C. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
D. (CH3)2HC. > CH3H2C. > CH2=CHĊH2 > (CH3)3C.
E. (CH3)3C. > CH2=CHĊH2 > (CH3)2HC. > CH3H2C.


I'm not sure if this question has been posted on the forum before, but i was wondering.. how a conjugated system affects a radical.

Is it the same as a carbocation? I picked E, but the answer says B

Thanks for the Help!

-building

conjugated system affects radicals by donating electrons. and yes, it's the same trends for carbo cation. I believe a question similar to that was in one of kaplan's subject tests. conjugated system> 3`>2`>1`.
pay attention if you have a benzene group, that makes it very stable as well🙂

 

[_veo_]

Which of the following sets of hydrocarbons correctly displays free radicals in descending order of stability?



A. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
B. CH2=CHĊH2 > (CH3)3C. > (CH3)2HC. > CH3H2C.
C. CH3H2C. > CH2=CHĊH2 > (CH3)3C. > (CH3)2HC.
D. (CH3)2HC. > CH3H2C. > CH2=CHĊH2 > (CH3)3C.
E. (CH3)3C. > CH2=CHĊH2 > (CH3)2HC. > CH3H2C.


I'm not sure if this question has been posted on the forum before, but i was wondering.. how a conjugated system affects a radical.

Is it the same as a carbocation? I picked E, but the answer says B

Thanks for the Help!

-building

yep, a conjucated system is more stable because the electrons can jump around (resonance).
Same with a carbocation

 

[building]

what about level of stability?

from the question. it seems that primary w/resonance beats out tertiary.

but in carbocation stability. it goes:

secondary w/resonance> tertiary> primary w/ resonance > secondary etc.

thanks!

 

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