The reaction of a nitrile with an alcohol in the presence of a...

Question

The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as the Ritter reaction, does not work with primary alcohols.

Chemical equation illustrating the Ritter reaction: nitrile and alcohol react with HCl to form an N-substituted amide.

a. Propose a mechanism for the Ritter reaction.

Accepted Answer

All right. Hi, everyone. So this question says that the Ritter reaction occurs when nitrile and alcohol react in the presence of an acid to form an N substituted aite, provide an appropriate mechanism for the rider reaction depicted below. And here we have propion nitrile with prop tool combining with in the presence of HCL to create an isopropyl propion amide. So recall that when it comes to the rider reaction, our first step involves the formation of a Carbocaine intermediate and that carbo CAD ion is going to form via the acid catalyzed dehydration of our alcohol. So first, I'm going to go ahead and redraw our alcohol. So we can begin our mechanism with its dehydration, right. So here HCL is our acid and recall that in order to generate a carbo CAD ion from this alcohol, the hydroxy group has to leave, right. It has to detach itself, but hydroxy groups by themselves aren't good lead groups, right? So we have to modify it somehow and one way in which we can do so is by proton it. So here our hydroxy oxygen is going to take that proton from HCL and that's going to create chloride, but also this pronated hydroxy group, right? This 02 plus. So now this is a fantastic leading group, right. So now it can go ahead and detach itself and once it detaches itself, it simply becomes water. So after we lose water, we generate a secondary carbo ion. So now we have our secondary carbo CAD ion, our night trial, which I'm going to go ahead and draw in blue can go ahead and attack. Right. So here the loan pair of electrons on nitrogen in our night trial is going to go ahead and attack our carbo. So during this process, we've gone ahead and combined together the our group of our alcohol with our nitrite. So here, here is our night trial and now we have an isopropyl group attached to the nitrogen in our nitrile, but this connection has given nitrogen a formal charge of plus one. So in order to, to mediate, right, this positive charge on nitrogen, let's go ahead and bring back our water molecule because water is actually going to go ahead and attack the sp hybridized carbon in our nitrite because that donates a pair of electrons towards nitrogen to make it neutral once again. So, as a result, right, as a result, we're going to have an intermediate in which there is now a double bond in between the carbon and nitrogen of r starting night trap, right? And here's our isopro group. But this time, right, we've also introduced a new substituent because now water has attached itself and that's resulted in a new positive charge on oxygen. And that's not ideal, right? So here, chloride, which formed in the first step is going to actually come in and save the day because chloride can go ahead and take a proton from our protend hydroxy group here and that will restore the neutral charge on oxygen. So now, now we have a hydroxy group on our intermediate. And right now, I just want to make sure that I'm keeping track of all my carpets. So now here's my oh group, like I said before. So now it's important to recognize that once chloride has taken that proton from oxygen, it has regenerated HCO, right? So now I'm going to redraw HCL because now nitrogen is going to get pronated because nitrogen is going to take a hydrogen from HCL. So now it's going to have a positive church. So here's my hydroxy group, here's my isopropyl group and like I said before, nitrogen is now pronated, which results in a formal charge of positive one, right. So in here here, we're going to start seeing the formation of the carbonnel because in order to mitigate that positive charge on our nitrogen, our hydroxy group is going to donate a pair of electrons between itself and the carbon it is bound to because that double bond in between our carbon and our nitrogen is going to break and its pi electrons are going to go towards the nitrogen because as you can see here, just keeping track of my colors here, our nitrogen is now neutral and now we have not quite a car bottle, right? We're almost there because notice how there is now a double bond in between carbon and oxygen, but there's a hydrogen attached to oxygen, right? So that creates a formal charge of plus one. So something has to deproteinate our oxygen and chloride once again is going to go ahead and help us out on that front. So, chloride is going to take this hydrogen from oxygen. And at long last, we've gotten two, our and substituted amide because now we have a neutral car bottle and also HCL as a byproduct. So this is going to be your final answer. And I know it was a lot. But our first step involved acid catalyzed dehydration of our alcohol to create a Carbocaine intermediate. That carbo CAD ion was then attacked by our night trial. And that nitrile soon became a double bond between carbon and nitrogen after water attached itself to the nitrile carbon. Then from there right after the protonation of our nitrogen, our carbonyl was formed and I know it was a lot. But if you stuck around to the end, thank you so much for watching. And I hope you found this helpful

The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as the Ritter reaction, does not work with primary alcohols.

a. Propose a mechanism for the Ritter reaction.

Key Concepts

Nitriles

Ritter Reaction Mechanism

Role of Strong Acid

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