Pyrrolopyridines are a group of fused heterocycles where a pyrrole ring is fused with a pyridine ring. Nitration of the following pyrrolopyridine produces the 7-nitro product while the 5-nitro product is not seen. Draw resonance structures to show why the 5-nitro product is not formed. (Hint: Draw 5 resonance structures).

Everyone. So in this practice question, it says that pyrrolopyridines are a group of fused heterocycles where a pyrrol ring is fused with a pyridine ring. Nitration of the following pyrrolopyridine produces the 7 nitro product, while the 5 nitrile product is not seen. Draw resonance structures to show why the 5 nitrile product is not formed. Hint. Draw 5 resonance structures. Right. So we see that the position 5 is here. And we're gonna show all the different types of resonance structures that can be created and explain why c 5 oh, no. 5 nitrile products are not favored. Alright. So what we're gonna have here is we're gonna have our ring here. Let's draw that out first. Alright. And we're gonna show the nitro group attaching to that position 5. So we have this and this. Now there's an h that was here, and then we have an n o two group being attached. And this position here would be positive. All we're going to do now is resonate around, so this can resonate here. So that gives us our this is going to give us our next resonance structure. Alright. So this is gonna be a good amount of drawing because we have to draw 5 resonance structures. But through it, we're gonna see the different types of resonance structures that do appear, and which one is not favored. So we have h here, and this is still an n o two here. Heap resonating, this resonates here. And in this one, we're gonna see why this is not favored because once we draw it out, we're gonna see we just formed something that is not good. What did we just form? We formed a positively charged nitrogen. We don't want a positive charge on that more electronegative nitrogen. Wouldn't make sense. So this is a key reason why the phi nitro product is not observed. Alright. Let's let's keep going. We gotta still resonate. So let me draw this nitrogen here. Alright. So we're on our 4th resonance structure now. Alright. We wanted to get rid of this positive here, so I'm gonna just resonate this oops. Resonate this here to try to get rid of the positive. Okay. And that's gonna make this one here positive. And now that's positive, but remember this nitrogen here has a lone pair that it can resonate down to try to get rid of that positive. Okay. So we have this. So this is gonna resonate down here, making a double bond right here. Nitrogen's making, 4 bonds, so now it's positive. Now, this nitrogen is not as bad as this nitrogen in yellow because when nitrogen is making 4 bonds, it's positively charged. It's following the octet rule. This one here is electron deficient. It doesn't follow the octet rule. That's why it's positively charged. Right. So this this third resonance structure is the key factor in showing why the 5 Nitro product is not observed. We'd rather go with the 7 Nitro product because we're not gonna form a positively electron deficient nitrogen atom.

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