For each of the following compounds, indicate the ring carbon(...

Question

For each of the following compounds, indicate the ring carbon(s) that is/are nitrated when the compound is treated with HNO₃/H₂SO₄:

e.

f.

Accepted Answer

Welcome back, everyone. For each compound indicate the benzene carbon where bromine is added during the electro pyo aromatic bro. The first structure that we are given is four methyl benz aldehyde. And the second structure is three bromo starting with four bansal. The hide, we essentially want to take into account the given substituent benzene is di substituted. And one of our substitutions is a metal group which is an alki group. And we know that all kill groups are electron donors and they are weekly activating. So we're going to say a for activating, OK. And alky groups because they're activating, they are directing to Ortho and Parra physicians well done. In addition to that, we have an aldehyde group. So you can say cho, right. So the carbon group is directly attached to the ring. So the most important part is the carbonyl group which is electron withdrawing. So it decreases the electron density within the ring. And that means it is deactivating in addition to that it is me directing. So let's go ahead and identify our Ortho and power positions relative to the metal group. So we have two Ortho positions relative to the metal group, then we have two meta positions relative to the metal group and the power position is already substituted. So because the metal group is Ortho Power director, we have two positions in green, which are Ortho relative to the metal group where the substitution will take place. Now, similarly, we know that the aldehyde group is meir directing. So we are going to identify our metas positions with respect to the aldehyde group. So we have orthos positions with respect to the aldehyde. And then we have two metas positions with respect to the aldehyde. And those metas positions coincide with the Ortho positions relative to the metal group. So that means both substitutions are directing to the same carbon atoms within the benzene wing. Well done, we have identified the two carbon atoms where the electrolytic aromatic bro nation will take place. Those are two orthos positions relative to the metal group and two meta positions relative to the aldehyde. Now, we are ready to perform a similar analysis for the second structure which is three bromo pheno and we have once again a di substituted benzene, one of the substitutions is an oh group, we know that whenever oxygen is directly bonded to the benzene ring, such as ether or an alcohol group, it is activating because it's donating electrons through resonance. And that means once again, we have an Ortho Parra director. Similarly, we have a bromo substituent. We have to recall that halogens including chlorine bromine and iodine are weekly deactivating. Yeah, of course, we can include fluorine as well, but fluorine is much more electron negative. So it is withdrawing electrons inductively much more. Hm. Now, because the bromo group is weakly deactivating, even though that's the case, we have to remember that it is still an Ortho Parra director. So this is a very important concept. Not all of the deactivating groups are meir directing. Whenever we consider halogens halogens chlorine, Bromine, chlorine and iodine, they are orha and para directing even though they are deactivating. So first of all, let's consider our Ortho and power positions relative to the oh group have two oral positions. Then of course, we have our metas positions and we have our power position. So let's leave Ortho and power positions. Those are the sites where the age group is directing to and now the BROMO group is directing to Ortho and power positions. So we have two Ortho positions which coincide with the Ortho and power position relative to the o age group. And similarly, we have a power position relative to the BROMO group, right? So we have two Ortho and Parra, meaning once again, all of the three positions are equivalent. In other words, it would be more accurate to say that the two substitutions are directing to the same carbon atoms within the benzene ring, right? So that means we can have we car we carbon atoms undergoing electro pyro Matic bro. However, it is important to take into account that there will be one minor product due to the star kind, right? If you, if we want to form a product, adding bromine between the age group and the BROMO group, due to the fact that it, it is hysterically hindered, it will be much harder to perform the electro Electromatic substitution. The BROMO substituent is significantly large. And in addition to that, we have an a wage group nearby, right. So due to the the product at the oral position, relative to both the age group and the bromo substituent will be a minor product. And for the remaining two positions, we will have two more products well done. So we have labeled the carbon atoms to which bromine is added during the electro filic amata substitution for each structure. Thank you for watching and I hope to see you in the next video.

For each of the following compounds, indicate the ring carbon(s) that is/are nitrated when the compound is treated with HNO₃/H₂SO₄:
e.
f.

Key Concepts

Electrophilic Aromatic Substitution

Aromaticity

Regioselectivity in Nitration

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