jOeCHEMists, welcome to Organic Chemistry II. If you're here, that means you've taken on OChem I and came out the other side a stronger warrior than when you entered. Now, with one semester of chemistry in the books, we look forward to the second half of our carbon conquest, and we begin with Conjugation. In this series, we'll explore the stabilizing effect of lining up many carbons in a row that have p orbitals parallel to each other. After we understand conjugation, we'll see how that affects reaction we've done in the past, and then we'll round out the series with a brand new reaction--the Diels Alder reaction. So, gang: OChem II. Let's get after it.
https://joechem.io/videos/21 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we talk about the concept of Conjugation--how to identify it, why its a stabilizing force, and much more. In addition, we talk about the allylic position, and how conjugation helps in stabilizing charges when they occur at an allylic position (hint, our friend resonance is back :D).
https://joechem.io/videos/22 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we'll take our knowledge of Conjugation and see how Conjugated Systems behave in reactions that we've used in the past, such as Markovnikov Additions, Halogenation of a double bond, etc.
https://joechem.io/videos/190 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we discuss why the Free Radical Halogenation reaction comes up short (and doesn't work) in terms of halogenating an allylic carbon. Instead, we talk about how to leverage NBS (N-bromo succinimide) in order to brominate the allylic position, opening up a world of possibilities. Related videos: https://joechem.io/videos/15 - Free Radical Halogenation - Part 1 - The Mechanism https://joechem.io/videos/61 - Halogenation of a Double Bond with Bromine and Chlorine
https://joechem.io/videos/122 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we'll take a look at how we can get a mixture of products when doing reactions with conjugated systems that involve carbocation intermediates. We'll dig into how reaction conditions can push a reaction to be under thermodynamic or kinetic control and what that means for predicting products correctly.
https://joechem.io/videos/23 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we introduce a new reaction: the Diels Alder reaction. We talk about VERY simple Diels Alder reactions, and, before moving on to more involved examples (https://joechem.io/videos/24), we thoroughly discuss Electron Donating Groups (EDGs) and Electron Withdrawing Groups (EWGs). We need to talk about them because they can change how Diels Alder products form (altering how reactants connect, aka where the chemistry happens, aka regiochemistry, right?).
https://joechem.io/videos/24 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we continue to work with the Diels Alder reaction. Now that we've tackled EWGs/EDGs (https://joechem.io/videos/23), we look at how we can quickly and accurately predict the products of Diels Alder reactions in Complete the Reaction type problems. To do this, we'll use a little ochem life hack called the "In and Out" Rule, and if you're wondering how it works, then check out https://joechem.io/videos/25 :)
https://joechem.io/videos/25 for video on jOeCHEM and attached worksheet + solution (below video on jOeCHEM aka the link). In this video, we take an inside look at the Diels Alder Reaction, dissecting its transition state. With a concept known as The Endo Effect (which stabilizes the transition state through conjugation) we can better understand why Diels Alder products exhibit the regiochemistry (where the chemistry actually happens) that they do and how it allows us to use the "In and Out" Rule approach to predict products.