Classify structures A, B, and C in the figure as being either an enantiomer or a diastereomer of d-galactose.

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Video transcript

Welcome back, everyone consider the following structures and identify whether each of the structures A B and C is a dimer or an in an tumor of the glucose. We're given the structure of the glucose and to simplify this problem, what we're going to do is essentially focus on the chiral positions. We have four of them. So the first chiral position or basically carbon number two has hydroxyl on the right. So we're going to state R, the next chiral position has hydroxyl on the left. So we're going to state L, then we have hydroxyl on the right. We're going to write R and then we have hydroxyl on the right. We're going to state R now to, to identify a possible in an tumor. We want to flip all of those right. We want to draw a mirror image of the structure or basically reverse the configurations of the four chiral positions. So if we first of all, look at structure A, we notice that hydroxyl is on the left, then right, then left and left again, notice that R becomes LL, becomes RR becomes L and R becomes L again. So we have essentially reversed the configurations of all chiral positions. And we can visually see that those are non super imposable mirror images of each other. So this means that structure A is an in an tumor. Now for disaster, we want to flip some of the chiral positions, right. Essentially, we want to reverse several configurations but not all of them, at least one of them, right. So if we look at structure B, we have hydroxyl on the left left, right and right. So the first position has a reverse configuration, the second one has the same configuration and then we have two more which are the same. So we are only reversing one of them. And if we're only reversing one of the configurations or several of them, but not all of them, such a structure would be called a ditherer considering structure C, we have hydroxyl on the right, followed by left left and right again. So if we compare our carol carbon atoms, the first one corresponds to right, right. That's the same. The next one is left and left, that's the same. The next sc position is right versus left. So that's reversed and the final one is right versus right. So once again, we are reversing only one configuration, meaning structure C is also A, the, the and therefore we have solved this problem A is the Inan tumor B and C are di ester marks of the glucose. Thank you for watching.