The major product of the reaction of methylenecyclohexane with N -bromosuccinimide is 1 -(bromom

The major product of the reaction of methylenecyclohexane...

Key Concepts

Radical Reaction Mechanism

The reaction proceeds via a radical chain mechanism. An initiator (such as heat or light) generates bromine radicals that can abstract an allylic hydrogen from the substrate, forming an allylic radical. This radical quickly reacts with another bromine molecule, leading to the formation of the brominated product and regenerating a bromine radical to continue the chain reaction.

Resonance Stabilization of Allylic Radicals

The intermediate allylic radical formed after hydrogen abstraction is resonance stabilized because the unpaired electron is delocalized over the adjacent carbon atoms of the double bond. This delocalization lowers the energy of the intermediate, making the allylic position particularly favorable for radical formation and subsequent reaction with bromine.

Allylic Bromination

Allylic bromination is a process where a bromine atom is introduced at the carbon adjacent to a double bond (the allylic position). This is because the hydrogen at this position is more easily abstracted due to the stability that the resulting allylic radical gains from resonance stabilization with the nearby ? bond.

N-Bromosuccinimide (NBS)

NBS is a reagent specifically used in allylic and benzylic bromination reactions. It generates a low, controlled concentration of bromine radicals under the reaction conditions, which minimizes side reactions and ensures that bromination occurs selectively at the allylic position rather than leading to over-bromination.

Transcript

00:01 Okay, so now you have to take the substitution effect information that you just got from reading the last few sections and apply that system chemistry.

00:10 So the first question here is talking about the nitration of bromobenzene and it appears that i forgot the bromine on the ring.

00:18 Okay, so identify the group.

00:20 In this case, we have a halogen, right? so halogens are slightly deactivating, but they are orthoparad directors.

00:27 So just based off the logic here, you're going to get a mixture of the ortho and the para product to nitration.

00:37 Now, remember that the group you're adding doesn't have any effect on the electronics.

00:44 It's the groups that are already on the ring.

00:48 Sorry, that's n .o2, n03.

00:50 I'm thinking about sulfination here.

00:55 So in this case, you know, bromine is pretty big.

00:59 So you might actually favor the power addition here just ever so slightly between the two, just because bromide is a big atom and hysterically speaking.

01:09 It might play a role while the power position is completely unhindered.

01:13 But you'll probably still get some degree of a mixture, but it won't be 50 -50, for example.

01:18 Okay, so now it's bromination of nitro benzene.

01:22 So nitro is one of the more deactivating.

01:25 It's one of the most deactivating groups that you will learn about.

01:29 So it's also meta -directing, right? so it's pretty classical in that sense...

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