The hydroboration–oxidation of internal alkynes produces keton...

Question

The hydroboration–oxidation of internal alkynes produces ketones.

a. When hydroboration–oxidation is applied to but-2-yne, a single pure product is obtained. Determine the structure of this product, and show the intermediates in its formation.

Accepted Answer

Hey everyone and welcome back in today's video, we are going to solve the following problem. Hydro abrasion, oxidation of internal AL kinds produces key tones While the same reaction for terminal al kinds produces Aldo hides draw the final product when ethanol cycle vaccine as subjected to hydro operation oxidation. Additionally show any intermediate. As the problem suggests, the starting material is ethanol cycle vaccine. So we made through a six member ring that would be our parents, cyclo hexane and the group attached to it as ethanol. In other words, this is two carbon atoms with a triple bond. Right? So ETH means to and ethnic essentially Y. L. Over here at the ready and essential itself says that it must be a triple bond. So between carbon number one and carbon number two, there's a triple bond and the world. First thing that we notice about that structure is that ethanol cycle vaccine is a terminal AL kind. Keep in mind that terminal means that across that triple bond we only have one alcohol substation. And the remaining suspicion here is hygiene is not a carbon atom or any alcohol substation. So this is a terminal AL kind g to the presence of dad hydrogen. Now, according to the problem, there's a high preparation oxidation reaction taking place. And in general, whenever we want to perform a hydro operation oxidation reaction, we have to make use of two different reactions. Number one is the addition of boring in the presence of tetra hydro ferrin And recall that reaction. # two is the addition of hydrogen peroxide in the presence of hydroxide. This reaction in particular follows the Auntie Markov Markov radio chemistry. In other words, when you you're thinking about your pi bond, we have two different pi bonds, Right? Because there's a triple bond, there's one sigma bond and two pi bonds. We're going to consider just one pi bond. When we're thinking about our pi bond, we're going to add hydrogen and the alcohol group across it. So we're going to use one of the pi bonds. And the way we are using it is the following ante Markovic of radio chemistry implies that hydrogen is added to a more substituted position. So hydrogen is added to a more substituted position and the alcohol group of rage is added to a less substituted position, which is the opposite to the more comical rule. Right? And if we perform that, we notice that the left side is more substituted. It has an alcohol substitute print while the right side is not substituted, It has hydrogen, meaning hydrogen will be added on the left side and the alcohol group will be added on the right. We're only using one of the pi bonds, so the remaining pi bond will remain. This is exactly what the problem suggests. Right. It says that terminal al kinds produce algae hides. So we are going to draw our intermediate first because the problem also asks us to join their immediate Let's draw the six member ring. Now there are two carbon atoms over here and because we have the loss of one of the pi bonds. Now we have sp two hybridized carbon atoms, so we don't need to draw it as a linear chain. As we previously said, the alcohol group is added at position number two. So we simply need to add an a wage group over here. And this is an email if you recall, because there's a double bond with an adjacent alcohol group and this is our intermediate. So let's label this is our intermediate. This email would be our intermediate. Now the last thing to predict the final product is to recall the keto Enel totem tourism because animals are generally unstable. The equilibrium favors the formation of a ketone or an AL to hide. Just as the problem suggests, we make hold this as keto ino talk to more asthma, simply speaking. When you're thinking about this reaction, you may just visualize it as a proton transfer over here. So let's just expand that oxygen hydrogen bond. Right, let's show oxygen hydrogen essentially what's happening is that the lone pair on oxygen would prefer forming that carbon will bond. Carbon auction double bond will be formed. But if we're forming a bond over here, we have to break this bond, which will essentially get protein ated and then we will transfer these oxygen hydrogen bonding electrons in the form of a lone pair on oxygen to form a carbon ill group. And indeed, because there's hydrogen over here, it would be an AL to hide. So let's label our intermediate once again because I accidentally deleted it. And now we can clearly see that our found product is an AL to hide. So we can now proceed and throw our AL to hide. We are drawing our sixth member dring two Carbon atoms in the chain position. Number two now has an AL to hide groups. So we're going to show O H ch Oh, that's an AL to hide. Right? So we now clearly see that according to the problem, this makes sense. A terminal AL kind has produced an album hide. This is consistent with the problem. And we may simply label this is our final product. This Al to hide is are found product. Now we have everything that we needed. We have our in all intermediate. We have our found product Al to hide. We understand that the reaction for the anti narcotic of regional chemistry. We may just conclude that the correct answer choice to the small cultures question is C However, if you have any questions, don't have states, leave a comment down below in the comment section and thank you for watching

The hydroboration–oxidation of internal alkynes produces ketones.
a. When hydroboration–oxidation is applied to but-2-yne, a single pure product is obtained. Determine the structure of this product, and show the intermediates in its formation.

Key Concepts

Hydroboration-Oxidation Reaction

Alkyne Reactivity

Ketone Formation

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