First of all, I don't really need to draw resonance structures to know the answer to this question because all I'm looking for with an SNAR mechanism is I'm looking for WAPs. The one with more WAPs is going to win. Let's analyze the first one. The first one, I've got a heteroatom on the meta. That's not really going to help me. That doesn't really help. Then I've got a donating group on the ortho. I have heteroatom on meta, donating group on ortho. EDG on ortho. Does that help me? No. That's terrible. This one isn't very favored. Let's go to the next one.
The next one, I have a heteroatom on ortho. I have a heteroatom on meta, but that's not really going to help me, so I'm not going to write it down. And I have a withdrawing group on meta, which again isn't going to help me, so I'm not going to write it down. Overall, 2 of these groups don't really help. The nitrogen on the meta and the withdrawing group on the meta don't really help because notice that I'll draw the resonance structure in a second. The resonance structure isn't going to hit those carbons. But I do have this one atom here that's going to make it more favored than the other because the other didn't have anything going for it. In fact, it had a bad group.
Drawing resonance structures, what you'd find is that you'd get something like this where oops, I should have a sulfur. You've got chlorine. You've got OEt. You've got negative. That negative charge is going to resonate to where? Well, it's going to resonate. I'm just going to put here the double bond here. It's going to resonate to there. It's going to resonate to here and it's going to resonate to here. I've actually got a bad group in place, this is going to push electrons into my negative. That's terrible.
On this one, double bond, double bond, double bond. Well, actually, let me skip the double bonds actually. What I get for a reaction is this attacks here. I move the electrons down here, so I wind up getting a negative charge on the N. I have chlorine. I have OMe, methoxy. I've got my dotted line representing my anionic sigma complex and my negative charges, oops, I forgot there's a nitro group over here. My negative charges, 2 of them aren't stabilized, but one of them is. This one is stabilized because it's on a heteroatom. This one is going to be more favored. This one is going to be less favored.
In terms of favorability, you could actually relate that to temperature, meaning that this reaction could occur possibly at a lower temperature than 350. The one above may need more than 350 because it's got that donating group that's destabilizing it. Makes sense? Cool, guys. Let's move on to the next question.