Show how you would accomplish the following syntheses.
...

Question

Show how you would accomplish the following syntheses.

(b) benzonitrile → propiophenone

Accepted Answer

Hey everyone and welcome back to another video in which we are going to show how the following conversion can be carried out using suitable regions when we look at a given reaction, we understand that the starting material is a night trial, there's a presence of carbonized and triple bond. That's very important to understand to classify it as a night trial and then we are forming a key tone out of it because there's a carbonell group, bonnets to l kill substitue ints. So now let's understand how to perform this conversion. It's important realize that within the nitrile we have one carbon atom bonded to the ring ketone has two carbon atoms. So this is the additional al kiel group that we have added to night trial. Of course we don't have night train anymore because it's not supposed to be in a key tone. Right? So let's start with the blue part. We understand that okay, we once had a metal group, we want to make our carbon carbon chain longer. And to do that we can use the graveyard reaction mechanism because if you think about the nitrile group, nitrogen is partially negative because it's more electro negative and carbon is partially positive right? Because electrons are withdrawn towards nitrogen. So reforming that dai po and we can say that because of that I poll the green jerk reaction will work and it is often used with night trials. So let's see how that happens if we draw our night trial. This is our carbon nitrogen triple bond. We want to make sure that we're adding that metal group. So which graveyard region can we use if we need a method group we are going to use method magnesium bromide. Recall that essentially electrons are significantly polarized towards that carbon atom because magnetism is electro positive. So he can show that there's an attack and that partially positive electra filic carbon atom and then the pi bond will be broken. Right? We're essentially going to transfer the pi electrons onto nitrogen to form a negative charge in nitrogen. So let's see how that looks like. So we're going to get Our five member ring. Now we are adding that metal group. So we can essentially say that there is that carbon number one and then carbon number two will be death metal group and also carbon number one is still bonded to that nitrogen. But now we only have a double bond because the pi bond was broken, right? We essentially use these electrons to form an additional loan pair of nitrogen, which initially had one lone pair. Now we will have to And according to the formal charge formally, you may understand that 5 -4 -2 gives us a formal negative charge of negative one on nitrogen. Now here it looks similar to the key Tony wants reform. But the problem is that there's the presence of nitrogen instead of oxygen, right? We first of all call this a sold of a mean right? The reason why it's the soul is because there's a negative charge and actually magnesium bromide as a positive charge. So we can think of it as a sold right now we want to hide relies that that would be our next step if we hide relies that the first equivalent of hydro sis would be used information of the mean itself rather than it sold. So if we add the first equivalent of our asset, which would also break the grainier creation, recall that a stick conditions mixed with the granule creation just break the region itself so it will not react further. We made for the resulting in me that would be and H. Right, so that's our IMing and now we are ready to form our final material by adding our final equivalent of hydro ni um in that case we're essentially replacing the HN with oxygen and we're getting our key tone which is indeed the material that we wanted to get. Right. So we may now state that the conditions for this reaction are the following ones. Let's just cleared a bit. And now we can say that the first step was the addition of method magnesium bromide. So we are saying C three mg B r. Recall that this reaction requires a solvent. So we're going to use an ether and number two we used acidic conditions we can say access but if we don't specify apparently we're not using a specified amount of Israel places, not one equivalent for sure it's basically implies access. Right? We need to hide relies completely and we're getting our kids own. So these are our reaction conditions number one. Once again addition of the gradient region method. Magnesium bromide in either full by acidic hydraulics is to make sure that we produce our key zone. So to summarize whenever we want to form a ketone out of a night trial, if the chain is longer, let's use the brainiac reaction to increase the length of the chain and let's hide relies it together ketone. Now the correct answer to this multiple choice question is a However, if you have any questions don't hesitate to leave your comment down below. Thank you for watching.

Show how you would accomplish the following syntheses.
(b) benzonitrile → propiophenone

Key Concepts

Nitrile Reactivity

Grignard Reagents

Hydrolysis of Nitriles

Watch next