Okay, gang, we've done A LOT of chemistry up to this point. We've seen many a reaction, countless mechanisms, and likely hundreds of cyclic structures. However, in all the rings we've seen, we haven't done a ton of chemistry with what are called heterocycles: rings with more than one type of atom in them. Well, that changes in this series. In this section, we'll be doing chemistry with cyclic structures that of course have carbon in them but also oxygen, nitrogen, and even sulfur. We'll even learn mechanistically how to make pyridine. The chemisty is cool and the rings are different--let's have ourselves a time.
https://joechem.io/videos/166 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). Alrighty, jOeCHEMists: In this video, we begin our descent in heterocycle land. This video is a light introduction to what heterocycles are (definition wise), and we'll look at some examples from our past, present, and future as far as molecules we'll work/have worked with. This is light and breezy, so kick back and relax.
https://joechem.io/videos/167 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, jOeCHEMists, we'll get better acquainted with pyrrole, furan, and thiophene. We'll discuss these molecules' aromaticities as well as why the N in pyrrole isn't electron rich (and is in fact, electron poor).
https://joechem.io/videos/168 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). After learning a bit about pyrroles/furans/thiophenes, in this video, we look at a reaction that enables us to synthesize these heterocycles. It looks scary at first, but I promise that it's really not that bad. Also, I misspelled the reaction name in the video (lol, wasn't using my noodle), so please ignore that.
https://joechem.io/videos/169 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we spend even more quality time with the pyrrole/furan/thiophene (aka heterocyclopentadienes), this time looking at how they behave in EAS reactions. We'll rely on our old knowledge of EAS to predict where substituents are added to rings.
https://joechem.io/videos/170 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). jOeCHEMists--I know this is a long one, but I'm very proud of this video. I think it does an excellent job of explaining the mechanism behind the Hantzsch Pyridine Synthesis, how to reliably and quickly predict the product, and how to easily deduce the reactants from a pyridine product.
https://joechem.io/videos/172 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). After being introduced to pyridine a bit in the Hantzsch Pyridine Synthesis (link below), we build on our knowledge of this new, aromatic friend of ours. Instead of producing pyridine, we're going to use it as a reactant. And, in fact, we're throwing it back yet again to EAS. We'll look at why pyridine adds electrons to C3 as well as how to make EAS reactions with pyridine more favorable by having EDGs attached beforehand. Hantzsch Pyridine Synthesis - https://joechem.io/videos/170
https://joechem.io/videos/173 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). After attaching electrophiles to pyridine, of course we're going to talk about adding nucleophiles to pyridine! Gang, in this video we further extend our pyridine abilities. First, we'll discuss the Chichibabin reaction, and after that, we'll talk about why nucleophilic attack on pyridine occurs on C2/C4 (when a good leaving group is present).