Often, compounds can be synthesized by more than one method. S...

Question

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

(a) two different ketones

Accepted Answer

Hey everyone and welcome back in today's video. We are going to look at the following problem in organic synthesis. A compound can usually be prepared in more than one way, show how the following molecule can be synthesized using two different ketones. As the problem suggests, we are going to form an alcohol out of a ketone. And we noticed that the given alcohol is actually tertiary alcohol. The alfa position that is directly bonded to the alcohol group has three alcohol substations and this essentially implies that we may form a tertiary alcohol out of a key tone using the Greenert reaction, right Recall that whenever we are starting with a ketone, we can control a general form of a ketone with two alcohol substations. R one and R two. We may simply use our three some alcohol group bonded to magnesium bro. Might we call this our granular reagent. And according to the mechanism were essentially attacking attacking our electoral position, breaking the pi bon and forming the elk oxide. And I on. So this is our first step. We are just adding our three MGB R in the presence of ether. And this is where we are forming the elk oxide. But now we are also adding an additional alcohol substation. So this will be our three R one R two. And to get that tertiary alcohol, we need an additional step which is acidic work up during the aesthetic work up. We are forming our final alcohol. So we can say that B O. H With three L kill groups. So, using this logic, we can just look at the alcohol and we can think in reverse, let's look at our alcohol submissions and let's take the smallest ones. We have a metal group. So that's our possibility one. We can just break it off and make a graveyard region out of it. And we have an ethyl group. We can also break it off and make a green yard region out of it. So let's see how that looks like If we think about the first possibility and if we just break off that metal group which would be added later, we would get our key zone right? We are going to remove hydrogen. So essentially we want to form our elk oxide by removing hydrogen and then restoring the carbonell group by removing this metal meaning our substrate would essentially look like this. This will be our starting key zone. We would have our six member ring, then at position number one, we would form our carbonell group. We are getting rid of number one because this is our possibility number one. So we are getting rid of the metal group and we are just left with an ethyl group. So this is our first key tone that we can use. And according to the reaction scheme, we're only left with two alcohol substations. We need to add the third one, which is the metal group. So the metal group must be bounded to magnesium bromide, which implies that the first possibility is to use the following reaction sequence. Number one, add metal magnesium bromide in the presence of ether. And number two we went to hide relies our Alcock said, and I on that would be acidic work up to form the final alcohol. And if we notice this is indeed consistent with the mechanism were essentially adding the methyl group. Over here we get it. We perform an acidic work up on the elk oxide and I informed and we are forming our final alcohol. So this is our first way to form the given structure. We can just clearly indicate that we're getting that product. That would be our oh, age methyl group and then our ethyl group. So yes, that works for us. We can use that key zone using the given sequence of the reactions. However, what if we look at breaking off the second one, This is an ethyl group. What if we break it off? And what if we make a green yard reagent out of it? Then the keystone that we get would look differently. If we look at the second possibility possibility number two would involve the ring itself. And now when we are forming that carbonell group, we will only be left with a muscle group instead of an ethyl that we had previously meaning an ethyl group will now belong to the graveyard region itself. So let's show how that looks like reaction. Number one would be addition of ethyl magnesium bromide because the ethyl group is now our our three and number in the presence of ether And # two is acidic work up. So now, once again, if we look at our structure, we have two alcohol groups, we're going to add an ethyl group. So yes, we will get an ethyl group and then we protein ate the elk oxide and I want to get our alcohol meaning indeed this works for us too. We can show that we're getting our alcohol. So this would be our key ways getting the desire to tertiary alcohol. We can just outline these our final two reactions and just review what we did. So we started with the fact that this is a tertiary alcohol. And the problem suggests that we want to use our starting material as a key tone. We understand that one common way to form a tertiary alcohol out of a key zone is to use a granular reaction. So we outline the steps of a general granite reaction. And we said that we are going to look at two possible alcohol substations and add the third one to our chain to form Alcock side and then protein ate it to get our alcohol. So we started thinking in reverse and we said, okay, we are going to remove this hydrant to look at the elk oxide and iron and going back, we want to get rid of any of these three substations. And we said, let's just choose the method of submission And the ethyl for simplicity, even though we could have gone with Cyclo Hexcel substation. Right? So looking at this, we understood that, okay, let's look at the first possibility removing the metal group. If we remove the metal group, it will automatically belongs to the Green yard regions. We place it here and the result on keystone only had psycho heche cell and ethyl groups present on it because we're adding the methyl group. Possibility number two, we said, what if we make this part, our Green yard regions. We set another possibility is to use ethyl magnesium bromide, which means that the keystone will only have two substitutions psycho heche cell itself and a metal group. And we noticed that both of these reactions work for us, meaning we can simply conclude that the correct answer choice to this question is B However, if you have any questions, don't have states, leave your comment down below in the comment section and thank you for watching

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

(a) two different ketones

Key Concepts

Alcohol Functional Group

Ketone Reactivity

Synthetic Pathways

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