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For (a) (iii), how do you get the second product listed in the answers manual? I just can't visualize it.

What about (c) (i), why are there three resonance structures? If a hydrogen is taken away from a specific carbon of the initial molecule to have a radical, there is no way you can have three resonance structures.

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The barrier to rotation in the allyl radical is low (~15-16 kcal/m) and it can undergo cis-trans isomerization.

enter image description here

As to question (c)(i), you're right, there are only two resonance structures.

enter image description here

What you show above with three resonance structures is the trimethylenemethane diradical, isobutene with 2 allylic hydrogens removed.

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  • $\begingroup$ ron, what are the dotted lines? Why is there a positive charge? $\endgroup$ – yolo123 Sep 27 '14 at 18:43
  • $\begingroup$ the delocalized allyl radical, a shorthand way of drawing the 2 resonance structures; no positive charge, it is a radical, so just 1 unpaired electron. $\endgroup$ – ron Sep 27 '14 at 18:44
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    $\begingroup$ The symbol that might look like a plus sign is just how my drawing software draws a radical. $\endgroup$ – ron Sep 27 '14 at 18:47
  • $\begingroup$ Oh, ok. I didn't know this barrier to rotation was so easy. It seems that Solomons' textbook does not discuss this. :O Thanks for the info. $\endgroup$ – yolo123 Sep 27 '14 at 19:21
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    $\begingroup$ @yolo123 I'll edit my answer to cover this. $\endgroup$ – ron Sep 27 '14 at 20:31

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