In light of your answer to Problem 9.82, would you expect p -methylphenol to be more acidic or l

step 1 Okay, this problem, last problem in the chapter. Paramethylphenol, is it going to be more acidic

In light of your answer to Problem 9.82, would you expect p...

Key Concepts

Acidity of Phenols

This concept involves understanding that the acidity of phenols is determined by the stability of the phenoxide ion that forms when a proton is lost. The more stabilized the negative charge is in the conjugate base, the greater the acidity of the phenol.

Substituent Effects

Substituent effects refer to how different groups attached to the aromatic ring can influence the electron density of the system. These groups can either withdraw or donate electrons, thereby stabilizing or destabilizing the phenoxide ion and affecting the overall acidity.

Electron Donating vs Electron Withdrawing Groups

Electron donating groups, such as a methyl group, add electron density to the aromatic ring, which can destabilize the negative charge on the conjugate base and reduce acidity. In contrast, electron withdrawing groups, such as a bromine atom, pull electron density away from the ring through inductive effects, stabilizing the negative charge and increasing acidity.

Resonance and Inductive Effects

Resonance effects involve the delocalization of electrons across the aromatic ring, which can help stabilize the conjugate base. Inductive effects work through sigma bonds to either donate or withdraw electron density. Together, these effects explain how substituents alter the acidity of phenolic compounds.

Transcript

00:01 Okay, this problem, last problem in the chapter.

00:06 Paramethylphenol, is it going to be more acidic or less acidic than regular phenol? so i would actually encourage you to go back and watch my video for, i mean, i would encourage you to watch all my videos, but for problem 16 .73.

00:19 So i just walked, i just talked about what is needed to stabilize negative charge and the relationship between how stable.

00:30 A negative charge is versus how basic something is.

00:35 And i demonstrated that through residence with the paronitriotphenol in that example.

00:41 So by extension of that, right? so that question would tell you that paronitriphenol is more acidic than regular phenol.

00:48 Nitro is an electron with strong group.

00:51 So therefore, if you replace that with an electron donating group like the methyl group, you should, you could imply that the acid is going to be weaker.

01:00 You're going to have a higher pca.

01:03 And why is that? right? so this is a radio extension.

01:06 So i had left up some of my drawings from that example.

01:11 So here is how through residents you're able to stabilize the negative charge of phenol on the benzene ring.

01:19 Right.

01:20 So you can push that charge around the ring.

01:22 And it's stabilized in basically with three different resident structures that are of similar energies, right? there's nothing really destabilizing the phenol too too too badly.

01:42 So how do you do that with with methyl, right? so what does that methyl group do? so i'm going to draw my phenoxide here and i'm going to do what i did before.

01:54 I'll take that lone pair.

01:56 I'll draw the ortho loan pair here double bonds loan pair will be on the ortho position um right so this is where um the discussion comes in right so if you went back and watched this video from 16 .3 i'm going to push that electron down make the bonds here um now you have a negative charge that is on the same carbon as an electron donating group so in that last video i had discussed that um more states basis will have a more stabilized negative charge, which means that through residence, you can show that the more resident structure is something has, the more stable that it, as long as those resident structures aren't incredibly high in energy, the more stable the form of that, the more stable that base is through residence.

02:55 So with nitro, you're able to push the negative charge onto the nitro group.

03:00 Stabilize it using the no2 and stabilizing it using the oxygen atoms on the nitro group...

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