Rank the compounds in each of the following groups in order of their reactivity to electrophilic

Rank the compounds in each of the following groups in order...

Key Concepts

Directing Effects

Substituents not only influence the overall reactivity of an aromatic ring but also affect the position where an electrophile is most likely to substitute. Electron-donating groups typically direct electrophiles to the ortho and para positions due to enhanced electron density at these sites, whereas electron-withdrawing groups tend to direct electrophiles to the meta position. This concept is critical in understanding the regioselectivity observed in electrophilic aromatic substitution reactions.

Electrophilic Aromatic Substitution (EAS)

This is a fundamental reaction mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. The process involves the formation of a positively charged intermediate known as the sigma complex, which then loses a proton to restore aromaticity. The stability of this intermediate is directly influenced by the substituents present on the ring, thus affecting the overall reaction rate.

Activating and Deactivating Groups

Substituents on an aromatic ring can either increase (activate) or decrease (deactivate) the electron density of the ring, thereby influencing its reactivity toward electrophilic aromatic substitution. Electron-donating groups typically make the ring more nucleophilic, speeding up the reaction, while electron-withdrawing groups reduce the electron density, thus slowing down the reaction. Understanding these effects is essential in predicting and ranking reactivity patterns in substituted aromatic compounds.

Resonance and Inductive Effects

These are the two primary electronic effects that substituents exert on an aromatic ring. Resonance effects involve the delocalization of electrons through pi bonds, often enhancing or diminishing electron density at specific positions on the ring. Inductive effects occur through sigma bonds and involve the transmission of electron-withdrawing or electron-donating properties. Both effects play a crucial role in determining the reactivity and orientation of electrophilic substitution on the aromatic ring.

Transcript

00:01 Okay, so you were just introduced to substitution effects and directing groups, right? so you're given three sets of compounds, and all of them have varying degrees of activation, deactivation.

00:22 So in each scheme, you basically just have to figure out which you're going to react or rank them in order.

00:31 Of rate of reaction, right? so deactivated rings are going to be first.

00:38 So number one will be the most deactivated.

00:41 And then we'll go up to four, which will be the most activated.

00:45 So basically you're ignoring the benzene ring.

00:47 You're just looking at the substituents, pretty much, right? so in the first scheme, we have, we have nitrobenzine, we have phenol, we have tonyene, and we have regular benzene.

00:57 So if you look at all of the groups, right? so in this case, we have one deactivating group.

01:06 That's the nitro group.

01:07 And we have two activating groups.

01:09 That's the hydroxyl group and the methyl group.

01:11 And then benzene has an h.

01:12 That's nothing, right? so the deactivated group is going to be number one.

01:18 This is the slowest.

01:19 And then essentially, you have, you have two activating groups and you have benzene.

01:25 So any type of activating group is going to give you a faster, a faster rate to electrophelic aromatic substantiated.

01:32 Then benzene will.

01:33 So by default, benzene's going to be two.

01:37 And then when you're stuck with all of your activated rings, which ring is more active? so you go to page 581 and you look at the classification of substitution effects figure and you look at where hydroxyl is in comparison to alcohol.

01:53 And hydroxyl is much more activating than the alcohol group.

01:56 So tonnuin is going to be jah slower than phenol.

02:00 So phenol is going to be the fastest here.

02:03 So you do the same thing in in b, right? so in this case, you have two deactivating groups.

02:09 You have the chlorine and you have this, this acyl group, this carboxylic acid.

02:14 It's not really an acyl group...

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