Draw the important resonance forms of the following free radicals...

Question

Draw the important resonance forms of the following free radicals. b.

Accepted Answer

Hey everyone, let's solve this problem. It says provide the structures of significant resonance contributors for the given free radical. So to recall free radicals can be de localized when there are pi pi bonds present on neighboring atoms. Do you look lies with pi bonds on neighboring Adams. So looking at our compound here, we have a radical and then on the neighboring carbon we have this benzene ring or fennel ring and there are three pi bonds in there. So we can definitely de localize this radical throughout the pi bonds of the fennel ring to give the following structures. So I'm going to first quickly redraw this so that we can include it in our resonance brackets. Okay, so something important to remember when you're drawing the arrows for free radical resonance is that there are usually three arrows, one from the radical in two from the pi bond. And remember these are half headed arrows, right, so arrows that look like this. So we're going to draw one arrow from the pi bond into in between these carbons, one half arrow from the radical, into that same carbon and then the other half arrow from that pipe on is going to go away from that new charge center that's being formed. Okay, so this is sort of the pattern, how it always will be for radical resonant structures. So let's see what that looks like. So now we have ch double bonded to or fennel ring, our first two double bonds are still there. Oops, yes, sorry I meant this arrow is going to go onto that next carbon because that's where our free radical will be now. So we have a free radical right there on that carbon. Okay, so similarly we can take that free radical and one half arrow from this double bond to do the same thing, move that double bond in between these two carbons and then another half arrow from that double bond onto the next carbon. And that's where our free radical will go next. So you're just sort of repeating that pattern around the ring as many times as you can. So now we have our double bond right there across from the other one and are free radicals down here where that the carbon with a methyl group and we have another pi bond so we can do it again. So half arrow from the radical to the next carbon carbon bond, Half hour arrow from our pi bond and half arrow to the next carbon. So I'm gonna draw the substitution groups first because those are not changing. So that's always a good idea draw what's not changing first. So then you can put everything else on. So now we're forming a double bond right here and our new radical is up there. Can we have any more resonance structures? Yeah, because the the radical is now again next to this carbon carbon bond here, that is double bonded. So it will be similar to the original structure except all of the double bonds have rotated. So that will look like this. Half arrow here, half arrow here, and half arrow back up onto that carbon with the hydrogen. So again, like I said, it looks very similar to the first, the original structure, but we see that the double bonds have shifted 11 carbon over. Okay, that's it for this problem. I hope this video is helpful, and thanks for watching.

Draw the important resonance forms of the following free radicals. b.

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