12/25/2023 0 Comments Anomeric carbon meaning![]() ![]() And then we protonate, and we can form our hemiacetal. Of alcohol come along, and a lone pair of electrons takes this proton, leaves these electrons behind. And alcohols are amphoteric like water, so they can function as acids and donate protons as well. So we're obviously extremelyĬlose to our product, we only need one more acid-base reaction. Plus one formal charge from the oxygen, and we have this. All right, these elctrons in here, between the oxygen and the hydrogen are now on the oxygen, so that takes away the So on this oxygen right there, is now another lone pair of electrons which came from the deprotonation step. So we deprotonate, and now we have our oxygen bonded to our R double prime group, and then we still have this oxygen over here on the right, with a negative one formal charge. So let's go ahead and draw the results of that acid base reaction. All right, so we can think about lone pair of electrons on this alcohol taking this proton, and leaving these electrons behind on this oxygen. Molecule of alcohol, so let's go ahead and draw that in here, so another molecule of an alcohol, which in this case can function as a base. This intermediate here, so we could have another ![]() All right, next step would be to deprotonate Let's just say it's that one right there. And then our pi electrons in our carbonyl here, moved out onto our oxygen, so it doesn't really matter which lone pair we say it is. All right, so these elctrons right here in magenta on our alcohol formed a bond between the oxygen and the carbon, so these electrons right in there. And then we still had an R group and then a hydrogen. Lone pairs of electrons, it just picked up another lone pair, so it now has a negative one formal charge like that. This carbon was bonded to another oxygen, which used to have two And there was still one lone pair of electrons on our oxygen, giving our oxygen a And there was a hydrogen attached to our oxygen, and also an R double So here's our oxygen, it's formed a bond to our carbon. So the oxygen now is bonded to our carbon. So let's go ahead and show the result of that nucloephilic attack. So our oxygen already had two lone pairs of electrons like that. So lone pair of electrons on our oxygen is going to attack ourĬarbonyl carbon right here, and push these pi electrons in here off onto our oxygen. So our alcohol molecule, I'll go ahead and draw it out here, is going to function as our nucloephile in this reaction. So this carbonyl carbon right here is partially positive, So we have a partially negative oxygen and a partially positive carbonyl. So in terms of the mechanism for the formation of a hemiacetal, it's completely analagous to the formation of a hydrate, right? We have our carbonyl situation over here on the left, for our aldehyde or ketone, with the oxygen being more electronegative and withdrawing some electron density away from our carbonyl carbon. And then over here on the right, our product this time is a hemiacetal, so this is a hemiacetal right here. And so the difference is, instead of adding water, this time we're adding an alcohol and so this reaction is at equilibrium. Voiceover: In the previous video, we saw how to make hydrates from aldehydes and ketones, and this video will show how to form hemiacetals from either an aldehyde or a ketone. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |