in this video, we're going to begin our lesson on piranhas confirmations. So recall from our previous lesson videos that a pirate nose is literally just a cyclic sugar or a cyclic mono sacha ride with a six member rain. And so these cyclic mono sack rides can actually exist in a variety of confirmations, which recall confirmations are just potentially flexible. Three D arrangements now also recall that way back in some of our previous lesson videos, we had distinguished between confirmations and configurations and so recall that unlike configurations, which arm or permanent and mawr fixed confirmations, on the other hand, because they are flexible, they can actually change without breaking or reforming bonds. Whereas configurations, on the other hand, the only way that they can change is by breaking and reforming bonds. And so this is important to keep in mind about confirmations as we move forward and talk about the piranhas confirmations in our next lesson video. So I'll see you guys there

so, really, the most common piranhas confirmations are the chair and the boat confirmations, which might actually sound familiar to you guys, because these are the same exact confirmations that cyclo hexane has. And you might recall from way back in your previous organic chemistry courses that you guys covered the chair in the boat confirmations of cyclo hexane and so also recall from your previous organic chemistry courses that the substitute, ooh INTs on the chair and boat confirmations can either occupy aim or crowded axial position that will encounter Mawr Starik Hindrance. Or the substitutes could occupy a less crowded equatorial position that are going to branch away from the ring and encounter less Starik. Hindrance. Now, you might also recall from your previous organic chemistry courses that the chair confirmation is actually mawr stable than the boat confirmation. And so for that reason, the chair confirmation predominates and is more common than the boat confirmation. And so if we take a look down below at our image over here, notice on the left were showing you guys a Hayworth projection off. A pirate knows that has a six member ring. And then over here, we're showing you the chair confirmation of that same exact PIRA nose. And over here we're showing you the boat confirmation of that same exact PIRA knows. And so if you were wondering the chair confirmation is called the chair confirmation because it literally looks like a chair. And so you can see this guy chillin watching TV in his chair and you can see this lady over here is just sunbathing in this really nice reclining chair. And of course, the boat confirmation is called the boat confirmation because it literally looks like a boat. And so you can see this guy rowing his boat down the river and you can see this guy rowing his boat as well. Now also, recall that again, the substitute Wint's of both the chair and the boat confirmation can either take the axial or equatorial position. And so down here in this corner, we're reminding you of that concept and so notice that each of these carbons will have substitue INTs that take on either in axial position. Uh, that is going straight up and down, so the a represents the axial. And again they're going straight up and down and these air going to encounter, uh, Mawr stare Kendricks. And they're going to beam or crowded just because they're going straight up and down above and below the ring. So they're not going away from the ring, whereas, uh, noticed that each of these ease that you see here are the equatorial positions that are going slanted and diagonally, and so they're going away from the ring. So they're going to be less crowded and they're going to encounter lest Eric hindrance. So the the equatorial positions are going to be mawr stable positions. Now, over here on the far right, notice that we have an energy diagram with the free energy on the Y axis and the reaction coordinate on the X axis. And what you'll notice is that the chair confirmation is lower and energy lower and free energy in comparison to the boat confirmation, which is much higher and free energy. And so again, what this means is that the chair confirmation because it's lower and energy, it's more stable. And the boat confirmation because it's hired energy, it's gonna be less stable. And so, of course, the more stable chair is going to predominate. Now you'll also notice that there are actually two chair confirmation in this diagram. And so, in our next lesson video, we're going to talk about how we can enter convert between the two different chairs with a chair flip, so I'll see you guys in our next video.

in this video, we're going to refresh your guys memories of the chair flip. And so you might recall, from our last lesson video that PIRA nose rings can actually assume two different chair confirmations. And so the chair flip is literally just the process of converting one chair confirmation into the other chair confirmation. And so if we take a look at our image down below, over here on the left hand side, notice that we have the same exact ladies sunbathing in our pirate knows chair confirmation. And so imagine that are piranhas Chair confirmation in this image is actually a reversible reclining chair. And so imagine our lady right here standing up and grabbing this end of the chair and pulling it downwards and then grabbing this end of the chair over here and pulling it upwards. And then when she does that, she can go and sit right back down in the chair. And really, this is the process of the chair flip. And so what we see occurring here in this image is really the same thing that occurs with our PIRA knows Chair flip. Now it's important to note is that during the process of a chair flip. All of the substitue INTs of the chair are going to change their axial and their equatorial positions. However, the upwards and the downwards positions of the substitutes are going to remain unchanged during a chair flip and we'll be able to visualize this down below in this part of our image. And the best way to analyze this is by looking at one carbon atom at a time. And so we're gonna focus in on carbon number four. But really everything that applies the carbon number four is also going to apply to the other ring carbons. And so notice that carbon number four has both an axial position and an equatorial position and notice that in this chair the actual position is going upwards. So we have an upwards axial position and notice that the equatorial position is going downwards for this chair. And so if we take a look at an actual PIRA notes right here, which corresponds with this one up above again focusing in on carbon number four, it has an actual position going straight up and down with a hydrogen atom, and then it has an equatorial position going downwards here with an alcohol group. And, of course, during the process of a chair flip, as we already noted, its carbon number four that's going to be pulled downwards and carbon number one that's going to be pulled upwards, just like this lady foot the chair over here previously. And so notice that carbon number four is now in this position over here after the chair flip And what you can see is that going upwards. This time we have an equatorial position, whereas previously going upward, we had an axial position and going downwards this time notice that we have an actual position, whereas previously we had an equatorial position. And so if we take a look at the actual PIRA knows, notice that going above the chain we still have the same hydrogen atom. However, the hydrogen atom is now in an equatorial position, whereas before it was in an actual position and then notice going below the ring. We still have the same hydroxyl group as before, but the hydroxyl group is now in an actual position over here, whereas previously it was in an equatorial position. And so what we're seeing here is that the substitue int are changing their actual equatorial positions. But again the upwards downwards positions remain unchanged. Now, the last thing that's important to note here is that equatorial preference can sometimes help us determine the most stable chair confirmation. And so equatorial preference tells us that the most stable chair confirmation is going to have its bulky groups in a less crowded equatorial position. And so when we take a look at the actual piranhas confirmations on the bottom, notice that this structure over here on the right, if we highlight all of the equatorial positions if we circle all the equatorial positions here, notice that they are all bulky groups. So all of the bulky groups are in equatorial position over here. However, when we take a look at this structure over here, notice that all of its bulky groups in its hydroxyl groups are in axial positions and axial is not going to be the preference. The preference is going to be equatorial on DSO equatorial preference tells us that this equilibrium is going to favor the one that forms mawr equatorial positions with bulky groups and so we can have ah larger equilibrium arrow going towards the one that's favored and a smaller equilibrium arrow going to the one that's not as favored. And so we'll be able to touch up again on this idea of equatorial preference in our next video. But for now, this concludes our lesson on the chair flip, and I'll see you guys in our next video.

in this video, we're going to talk about how the beta animal of glucose predominates, and so glucose exists predominantly in its cyclic beta d glue cope. IRA knows an imer, and if we were to analyze glucose is composition in a biological solution, we would find that about 64% or about two thirds of all of the glucose molecules, would be in the beta animal form. Then about 35% or about one third of all of the glucose molecules, would be in the Alfa Animal form. And then, of course, that leaves about less than 1% of all of the glucose molecules in other forms, such as the linear chain. But why is it that the beta and reform of glucose is so predominant? Well, it turns out it's because it's the most stable due to its equatorial preference, which you might recall from our previous lesson. Video just means that it has. It's bulky groups and equatorial positions, allowing them to minimize, stare Kendricks and be more stable Now. The last thing that's important to note here is that the chair flip is not to be confused with Muda rotation. Recall that the chair flip on, Lee changes the confirmation, whereas Muda rotation, on the other hand, changes configuration. And so we'll be sure to distinguish between these two down below and our image now focusing over here in this image with the black box notice that we're showing you one of the chair confirmations of glucose. And if we take a look at it's an American Carbon here, notice that it's alcohol group is going downwards in the opposite direction of the highest number carbon. And so the alcohol group here is reaching down for the ants. And so that reminds us that this is the Alfa animal. So this is Alfa D glucose piranhas, which we already said up above makes up about 35% of glucose is composition at equilibrium. Now notice that most of the bulky groups here in this chair confirmation are actually taking the equatorial position. And we do have one bulky group in this alcohol group here that is taking the axial position. And so through the chair flip, we know that all of the actual equatorial positions change and the upwards and downwards positions do not change. And so if we take a look at this and Americ Carbon over here notice that it's alcohol group is still going downwards in the opposite direction of the highest number carbon. So it's still reaching down for the ants and still gonna be the Alfa animal. And so we haven't changed the configuration. So it's Alfa and Alfa on both sides. And since there's no configuration, this is not mute a rotation. This is going to be a chair flip and again noticed that over here in this chair confirmation that there's only one bulky group in the equatorial position, which is this one right here. All of the other ones are in the axial position, which are going to be less stable. And so equatorial preference tells us that this chair confirmation over here on the left hand side, which has more bulky groups and equatorial positions, is going to be favored over the other chair confirmation so we can draw a larger equilibrium arrow going to the left. Now, if we move on to the bottom box that we have down below notice that we're showing you another chair confirmation of glucose. And so if we take a look at its and America Carbon noticed that the alcohol group is going upwards in the same direction as the highest number carbon. And so the bumps of the beta being on the same side reminds us that this is gonna be the beta and, um er and so this is beta d glucose. PIRA knows which again we set up above makes up about 64%. The vast majority of glucose is composition had equilibrium. Now, notice that this chair confirmation of body glucose piranhas actually has all of its bulky groups in the equatorial position. And the equatorial position through equatorial preference, tells us that this is gonna be the most stable chair confirmation. And so if we were to do a chair flip and get this other chair confirmation over here again, looking at it's in America Carbon. The alcohol group is going upwards still in the same direction as the highest number of carbon. So the bumps of the beta being on the same side tells us that this is also gonna be a beta and, um er and so we have beta and beta, so the configuration hasn't changed. So, uh, this is not going to be muted rotation. Instead this is going to be a chair flip and notice that again that all of the axial equatorial positions change, but upwards downwards positions don't change. And so this time we have all of the bulky groups in axial positions. What, you're gonna be less stable and again, equatorial preference tells us that it's this chair confirmation over here on the left hand side. Uh, that's going to be more stable and so we can draw equilibrium, arrows, larger equilibrium, arrow going toe left, showing that this will be the most stable form. And then, of course, what we have here in the middle eyes going to show the change in configuration from the Alfa configuration that we have at the top down to the beta configuration what we have in the bottom box. And so this is going to be representing Muda rotation a change in the configuration of the numeric carbon. And of course, because this one here has all of its bulky groups in equatorial preference positions, equatorial preference tells us that it's this bulky group down below that's going to be more stable and so we can draw a smaller equilibrium arrow going backwards. And so really. This is the conclusion to our lesson on how the beta anima of glucose predominates, and that's important to keep in mind as we move along. And so that concludes this video and I'll see you guys in our next one.