Identify each of the following as the α or ß isomer:
a.

Question

Identify each of the following as the α or ß isomer:

a. Cyclic structure of a monosaccharide showing hydroxyl groups, with labels for α and ß isomers.

Accepted Answer

Hi, everybody. Our next question set determine whether the compound shown below is an alpha or beta isomer. And we're given a five membered ring that, that oxygen in there. But it looks like we have a 123456 carbon sugar. So we have a sugar that was a ketose here and it's straight chain form. So let's look to evaluate, are we looking at an alpha or beta isomer? So the first step in this is to look for the anomic carbon. So first we want to find that oxygen that's within the ring, look at its neighboring carbons and find the carbon that has two oxygens bound to it. So if we go to the right, we see that the carbon to the right of that oxygen has the ring oxygen and then the extra cyclic oxygen, which is in the form of a hydroxyl group going down below the plane of the rent. So our anomic carbon is the farthest one to the right, which is usually the way this is drawn often in, you know, in Aldo sugars al doses, the anomic carbon is carbon one, but this is a ketose. And So there's another carbon on the other opposite the hydroxyl group, there's AC h2o H. So that would be carbon one, the C H2O H group sticking up. And then the anat carbon will actually be carbon two in this case. So then we just go around the ring numbering our carbons. So carbon five is the last one in the ring. And then we have another extra cyclic carbon group as carbon six CH two H sticking up. So when we look for alpha beta isomer, first, we look to see the direction that our hydroxyl group on our anomic carbon is pointing. So we'll highlight that in pink there it is, it's going down. Now, what do we compare it to? Well, of course, it's going to be opposite the carbon one there, we compare it to the reference carbon, which is the C H2O H group sticking up out of the last chiral carbon in the ring. So go around the ring. The last chiral carbon is carbon five. So the group we're interested in is carbon six. That's C H2O H group. So we compare or you know, another way to think of it is look at the carbon group sticking up on the other side of the oxygen from the anomic carbon. So in this case, it's that group with carbon six and then our hydroxyl group on carbon two. So we see that these groups are on opposite sides of the ring. Carbon six being above the hydroxyl group being below. So the way I remember it is that we have the word opposite, which starts with a vowel like the letter A, which starts with a vowel. So opposite sides of the ring means this is an alpha animal. If it were on the same side of the ring, the same starting with a consonant B starting with a consonant, it would be the beta anima. So there we go. Since it's on the opposite side of the ring, our molecule here is the alpha isomer. See you in the next video.

Identify each of the following as the α or ß isomer:
a.

Verified video answer for a similar problem:

Key Concepts

Alpha (α) and Beta (β) Isomers

Anomeric Carbon

Cyclic Sugar Structures

Identify each of the following as the α or ß isomer:a.

Verified video answer for a similar problem:

Key Concepts

Alpha (α) and Beta (β) Isomers

Anomeric Carbon

Cyclic Sugar Structures

Identify each of the following as the α or ß isomer:
a.