4.2 Nitration

• The mechanism is similar to the one used for bromination.

• There is a mechanism for the aromatic substitution reaction when benzene is treated with a complex.
• The same mechanism is used to install a br on the ring.
• Don't look back at that mechanism to copy it.
• When you are done, compare your answer to the answer in the back of the book to make sure that all of your arrows were drawn correctly.

• When treated with a suitable source of I+, aromatic rings will also undergo iodination.
• If you are responsible for knowing how to iodinate benzene, you should look in your textbook and lecture notes.
• The mechanism is the same as what we have seen.
• The mechanism of how I+ is formed will be the only difference.

• There is a mechanism for the reaction between benzene and I+.

• The mechanism of an aromatic substitution reaction was shown in the previous section.
• The mechanism is the same if you are installing I+ on the ring.
• This same mechanism explains how an aromatic ring can be used to install an E+).

• We need NO+ to form nitrobenzene.

• This complex could be a source of NO+.

• We need to take a close look at how NO+ is formed.

• You can't do that because it would give five bonds to the central nitrogen atom.
• Nitrogen can't have five bonds because it only has four orbitals.
• Charge separation is needed to draw nitric acid.

• It's true that nitric acid and sulfuric acid are acidic.

• It might make us uncomfortable to use nitric acid as a base, but that is exactly what is happening.

• The acid removes a protons from the acid.

• This probably would make more sense.
• It is likely to happen a lot more often.
• The un charged oxygen atom is more difficult to remove than the negative charged oxygen atom.
• The transfers of protons are not always permanent.

• All of the time, particles are being transferred back and forth.
• The only thing that can happen when the oxygen atom is negatively charged is for the protons to be given back to nitric acid.

• The un charged oxygen atom can remove the protons.

• NO+ is generated when this happens.

• The same mechanism that we saw in the previous section is used once again: NO+ on and then H+ off.

• There is plenty of water because nitric and sulfuric acids are both aqueous solutions.
• The mechanism is very similar to what we have seen before.

• We have seen how to install a halogen on an aromatic ring and a nitro group.
• Make sure you are familiar with the reagents needed to perform these reactions before we move on.
• In order to achieve the desired transformation, identify the reagents that you would use.

• A piece of paper is needed to record your answer.

• We will learn how to install an alkyl group.

• A methyl group is the simplest of the alkyl groups.

• The logic we have developed in this chapter would allow us to use CH+.

• It would not be very stable.
• We don't use primary or methyl when drawing mechanisms.
• We are trying to make a carbocation.
• The answer is yes.
• We will use the same method that we used in the previous sections.

• We are not forming a free carbocation that can float off into solution.

• We must see this as a complex that can serve as a source of CH+.

• We have seen the same mechanism over and over again.

• A Friedel-Crafts alkylation is a process in which an alkyl group is put on an aromatic ring.
• It works well for installing groups on the ring.

• There is a simple reason for this.
• Since we are forming a complex with a carbocationic character, it is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 It is not possible to rearrange a carbocation.
• An ethyl carbocation cannot be rearranged to become more stable.

• A mixture of products is what we observe.
• If you use a Friedel-Crafts alkylation to look for carbocations, you need to be careful.

• We already know that we will get some rearrangement, and we will not get a good yield of the desired product.

• We will likely get a mixture of products if we just use 1-chlorohexane.

• We need a trick.
• There is a trick.
• We need to look at a similar reaction that bears the name Friedel-Crafts to see how it works.
• Let's compare an acyl group with an alkyl group.

• The first reagent is called an acyl chloride, and we are already familiar with its role.

• There is a positive charge.

• There are no side products that would result from a carbocation.

• Let's point out a very important feature when we take a close look at the acylation above.

• We will only focus on one method right now, but we will see two other methods in the future, one using basic conditions and the other using neutral conditions.

• In the presence of zinc that has been treated so that its surface is an alloy of zinc and mercury, the C--O bond is completely reduced and replaced with two C--H bonds.

• A Friedel-Crafts acylation can be followed up by a Clemmensen reduction, as a clever way of installing an alkyl group on an aromatic ring.
• When you want to install an acyl group on the ring, you won't want to do a Clemmensen reduction afterwards.

• You would just use Friedel-Crafts acylation to achieve this transformation.
• There is no need for a reduction in the bond because we don't want to reduce it.

• An alkyl group needs to be installed on a benzene ring.
• We want to see if we can do this in one step.
• We have to worry about a carbocation because we can't do it in one step.

• What reagents would you use to accomplish the transformation?
• Friedel-Crafts acylation is used in some situations, while Friedel-Crafts alkylation is used in other situations.

• All of the possible rearrangements can be considered.