For each of the statements in Column I, choose a substituent f...

Question

For each of the statements in Column I, choose a substituent from Column II that fits the description for the compound on the right:

Accepted Answer

Hello everyone. Let's do this problem. It says adding substituent to a benzene ring affects its reactivity in various ways. Classify the given substituent in the following ways. Choose one. For each part, the substituent are a myth group. Sulfonic acid, tt beutel and a chlorine atom. OK. So we are going to sub classify these substitutions in the following three ways. Part one, is it an electron withdrawing group or electron donating group? Two, does it participate in induction resonance or hyper conjugation? And three, is it an Ortho pera or meta director? So let's review what all of these types of classifications are? So part one electron withdrawing group or electron donating group. So electron withdrawing groups, as they suggest are going to withdraw that electron density away from the benzene ring outside of the ring. So if it is withdrawing electron density, it makes sense that electron withdrawing groups are partially positive or maybe explicitly positive, but they are just positive in nature. And electron donating groups are the opposite, they are negative in nature, partially negative or they maybe have a lone pair of electron, they don't have to. But it is likely that they will especially if they donate electrons to benzene in the form of resonance. So let's move on to part two. What are induction resonance and hyper conjugation. So induction is when there is a dipole induced usually by alcohol groups. OK. So think alcohol groups resonance can either be donating electrons to the benzene ring in the form of resonance or withdrawing electrons away from the ring and causing resonance resonance is the de localization of pi electrons in a conjugated system. And we know a conjugated system is alternating pi bonding orbitals and hyper conjugation is a phenomenon similar to resonance. But instead of pi electrons, it deals with sigma electrons. So de localization of electrons primarily of sigma character. So if we have a ch bond that is neighboring, let's say a positive carbon, the sigma electrons in this ch bond can migrate over to that neighboring empty p orbital delo de localizing that electron charge. So look for carbon hydrogen bonds or carbon carbon bonds, but we usually look at ch bonds. OK. So the more ch bonds you have in this case, directly next to that benzene ring, the more hyper conjugation you will have and lastly part three orha Pera or meta directors, let's say we have substituent x and we want to add another, another substituent Ortho that would be a 12 substitution meta would be a relationship. And Pera is a 14 relationship. And recall that electron withdrawing groups tend to be meta directors except for halogens. They are the only exception and electron donating groups tend to be Ortho para directors. OK. So let's go through our four substituent first, we have our metox group. So we see that the oxygen that would be directly attached to our benzene ring. Actually, let me draw this attached to a benzene ring. If we have our myth group attached to a benzene ring, we see that those electrons can be donated into the ring and would result in a resonance structure that is increasing the electron density in the benzene ring. So this metox group is going to be an electron donating group. It will participate in resonance and it will be an Ortho pera director since it is an electron donating group. All right, moving on to our second substituent sulfonic acid. Oops I'm also going to draw this on a benzene ring. Mhm OK. So oxygen we know is electron negative and sulfur has about the same electron negativity as carbon. So there's going to be a partial negative charge on that oxygen, partial positive charge on that sulfur atom. And the sulfur atom is the one directly connected to that benzene ring. So that is going to make this an electron withdrawing group, right, that partial positive sulfur is going to pull the electron density away from the ring. And looking at part two, how will it do that? Well, it can do that in the form of resonance, these pi electrons from benzene can form a double bond between the carbon and the sulfur and breaking this double bond between sulfur and oxygen. And then we will get a positive charge in the benzene ring that can then be de localized further by more resonance. So this will participate in resonance and since it is an electron withdrawing group, it will be a meta director. All right, moving on to tt beel, tt beutel would look like. So now alco groups, we know are weekly electron donating groups. And you can find all of these substituent groups summarized in Johnny's badass activity chart, the eas activity chart and it is an electron donating group through hyper conjugation. So as I mentioned before, we have those C AC C and CH bonds close to the benzene ring. But this will not be as strong as as strong of an electron donating group as let's say to you because the more carbon hydrogen bonds that are directly next to that benzene ring, the more hyper conjugation, but still, it will donate electron density towards benzene in the form of hyper conjugation. And since it is an electron donating group, this will be an Ortho pera director. And lastly, we have chlorine, which is a halogen and we mentioned that halogens are an exception to one of our rules. So we know they are electron negative. So it is going to pull that electron density away from the ring. So it will be an electron withdrawing group and it will do so in the form of induction. OK. So we, as I mentioned, electron negative, it will induce a dipole to withdraw that electron density away from benzene. And even though it is an electron withdrawing group, we said halogens are the only electron withdrawing groups that are Ortho pera directors. So chlorine is going to be an Ortho pera director. So those are the classifications for these four substituent groups. That's it for this one. I hope this was helpful and thanks for watching.

For each of the statements in Column I, choose a substituent from Column II that fits the description for the compound on the right:
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Key Concepts

Substituents in Organic Chemistry

Functional Groups

Structure-Activity Relationship (SAR)

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