Biphenyl is two benzene rings joined by a single bond. The sit...

Question

Biphenyl is two benzene rings joined by a single bond. The site of substitution for a biphenyl is determined by (1) which phenyl ring is more activated (or less deactivated), and (2) which position on that ring is most reactive, using the fact that a phenyl substituent is activating and ortho, para-directing.
b. Predict the mononitration products of the following compounds
(v)

b. Predict the mononitration products of the following compounds

(v)

Accepted Answer

Hey everyone and welcome back in the city of where we're going to solve another problem. Buy fennel is an aromatic compound having two benzene rings joined by a single bond. The side of an electro chromatic reaction is usually the one that is on the more activated ring. The other ring and other substances present also affect the reaction. Regional chemistry predict a major product of a monoplane nation reaction of the fulling compound. Okay, so basically, just as the problem suggests, you have two rings. Notice that we have events in the ring on the left, a benzene ring on the right and they're bonded by a single bond. Now everything else can be considered as substitutions, bonnets them. Right? So now we are going to analyze our substations on the left side, our left ring, our substitution is a carbon steel group and in particular that's our key tone group. Right? Because we have carbon, carbon, oxygen and carbon and rights, right? So that's our key tone group. We may essential state that over here we have our carbon you'll group. So you can say that on the left wing we have our carbonell and now on the white train over here we have an L. Kill substation. Now, how do we know that? Notice how first of all this is our bond connecting the two rings and have the remaining bond contains a ch two group. Rights, we can essentially state that this is our L kill substitution so that we can say that this is an L kill substitution. Now, knowing the two substitutions on each ring, we just have to understand which one of them is activating and which one is deactivating. So first of all, starting with the left ring because we have a carbon steel group, we call that the maturity of carbon groups are the activating groups and key tone is one of them. Right? Whenever we have a key tone group, that would be a deactivating group. And the reason why it's called the activating is essentially because it's withdrawing the electron density from the ring and therefore lower ring the reaction rate for the electrical aromatic substitution. Whenever you decrease the electron density within the ring, you have a slower rate for your reaction. And carbonell for a key zone is indeed electron withdrawing. So it's decreasing the electron density. And now on the right wing we have our alcohol substitution. And you may recall that it's activating because in contrast to the previous one, it's actually donating electrons to the benzene ring. And if you're increasing the electron density within the benzene ring, the reaction rate for an electro chromatic substitution increases. So between the two, just as the problem suggests, the reaction will take place at a more activated ring. And because an alcohol substitute is activating, we are going to choose the right ring for our substitution. Okay, so between the two rings, we already know which one will undergo the reaction. We just have to determine the mono chlorination product. Now you may recall that alcohol suppositions that are activating our directing to two positions. And those positions are Ortho and para. Because the electron density increases that these two positions due to the activating effects. So we have to determine these positions. First of all. Or though will be the first position. If we go from our alcohol substitue in towards our ring, we may notice that this carbon has two neighbors. So these two are Ortho positions and then the other one over here would be our power positions. We have three positions for a potential substitution. But you may notice that this position is already substituted. So we actually have two possibilities either this Ortho or this power position and we are going to choose our power position due to the fact that our position is less hysterically hindered. Notice how this position over here contains a CH two submission. And due to that slight stereo hindrance effect, we are going with Para as our major product. Notice how we need to get our major product even though an auto substituted product is really significant. We are going with Para as our major product. The ratio of the products is roughly 2 to if we essentially don't have any substitution at the other words, opposition in favor of a power position. So now we clearly know our product because we know all of the effects required to get our products. So the final position where we will produce our monarch chlorination product will be this para position that said let's draw the required regions. So we need to make sure that we're using chlorine in the presence of iron three chloride, which acts as a lewis acid in the mechanism. So if we use these regions and we know that mono chlorination requires us to add only one equivalent of chlorine. We know which position we are going to use for substitution. This hygiene will be replaced with chlorine and now we are ready to draw our product. So let's start by drawing our benzene rings connected by a single bond. So those would be our benzene rings. Now let's add our substitutes. So starting from here we are going to draw our ring, we are going to add our carbonell group. Okay. And now we we are essentially going to add our chlorine at this position, just as we discussed. So let's label this is our final answer because we were asked to determine the major product. This will be our major monaco chlorinated product and based on our answer, we can say that the correct answer to the multiple choice question would be a However, if you have any questions don't have States livia comment down below in the comments section and thank you for watching

Key Concepts

Electrophilic Aromatic Substitution (EAS)

Activating and Deactivating Groups

Ortho/Para-Directing Effects

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