 here, which is not actually related here, but we'll discuss it here only and finish. Anomers we discussed next right now, epimers, epimers and all these they ask question, okay. So this is important definitions and all epimers write down those carbohydrates, which differs in configuration, those carbohydrates, which differs in configuration. Those carbohydrates, which differs in configuration only at one carbon other than anomeric carbon. Right. Those carbohydrates, which differs in configuration only at one carbon other than anomeric carbon are called epimers. Anomeric carbon, the configuration is the same. Sorry, anomeric carbon, the configuration is the same, right? In this case, no, no, no, no. The thing is, we are not considering anomeric carbon here. Basically, you can also say in other way that we are not considering the configuration of carbonyl carbon, the first carbon C1 that we are not considering. So it can either be same or different. It doesn't matter, right? No, no, actually, see, see one thing. It is written in the book that anomeric carbon, but actually, if you write that the configuration of carbonyl carbon, we are not considering. Because when I write you, when I give you the examples, you'll see over there like mannose and glucose are epimers, okay? And there is no anomeric carbon present. So point is, you say anomeric carbon, it is written like this in the book, but just you ignore the configuration of the first carbon. Okay, understood. Okay, that is the only thing you have to consider. Anomers are epimers at the first carbon. Yes, yes, that you are not considering. So when you see this example, you will understand this. You see, this is also very important. They have asked this question many times, neat. Maybe also they have asked this question many times. They'll ask you, these two are epimers like this, they ask. Suppose we have this molecule and one more, let me draw this here. Here we have CHO, OH on the right, left and right and then right and then CH2. This is glucose, yes or no? D-glucose. This you let it be. You see, there is no anomeric carbon here. We have OH this side. Only one carbon configuration I am changing. OH as it is, OH and OH. So can you see the difference here? We have the configuration differs only at which carbon? Only at second carbon, 1, 2, 3, 4, 5 and 6. 1, 2, 3, 4, 5 and 6. So this is D-glucose. The name of this compound is D-manose. Why D? The same logic, OH on the right. The structure is the name of the compound is manose. Now D-glucose and D-manose, what is the relation in these two compounds? These two compounds are epimers of each other. Why epimers? Because they differ in configuration but not at the anomeric carbon. Yes or not on the first carbon. These two are the epimers of each other. And since the configuration differs at C2 carbon, C2 carbon, we also call it as C2 epimers. This question will give you the glucose and manose are what kind of epimers? C1, C2, C3, then C4. Understood this epimers thing. These are C2 epimers. One more example in this we have, D-glucose, D-galactose are C4 epimers. Both of these questions they have asked in the exam. C4 epimers. So if you know the structure of glucose, can you draw the structure of D-galactose? With this information? Yes? Yes sir. So for galactose what would be the structure? At C4 this OH will be on the left and H will be on the right. That will be galactose. Am I clear? Very clear sir. So you must remember these two points that glucose and manose are C2 epimers and glucose and galactose are C4 epimers. Right? Next. Next should I write down Havarth structure of glucose. The what structure? H-A-W-O-R-T-H. This structure is given by a scientist, scientist name R-D Havarth and they won't ask the name. Okay? Don't memorize this. Okay Havarth and this structure, this structure is based on the structure of a molecule called Pyrene. A structure of Pyrene is this. I missed here. Here in the ring we have oxygen present. This is Pyrene and if you look at the structure, the cyclic hemiacetyl structure, it is also a six-membered ring with oxygen in the ring. Yes? Okay. So when you draw the structure of glucose with the help of this Pyrene, because it also has five carbon and one oxygen, similarly we have in cyclic hemiacetyl, hemiacetyl structure of glucose. So with the reference of this structure only, the Havarth structure of glucose has been drawn. Okay? The Havarth structure of glucose is this. This is a six-membered ring. Okay? A six-membered ring. This is first carbon. This is second carbon, third, fourth and fifth. On the first carbon, because we have two structure possible here where OH on the left and where OH on the right. Okay? So all of you look at the structure of cyclic hemiacetyl, alpha and beta. That is structure you look first. In the alpha D plus glucose, the OH on the first and second carbon is on the right-hand side. Okay? On the same side basically. To draw the structure, what do you have to do? Whatever atom or group on the right, you have to draw it on the bottom of the carbon atom. You look at this structure. First of all, you see that cyclic hemiacetyl structure. I am drawing this at this carbon. I am starting this from the first second carbon, sorry, from the second carbon. So at second carbon, you see, at second carbon, what is there on the right hand side? In the hemiacetyl structure of glucose, what is there on the right hand side? You tell me on the second carbon. OH. OH. So this OH will write on the, on this side. Like this we have. I will write down OH down and H on the top. And after this, we have alternate. Here we have OH down. Why OH down? Because OH on the right side. I am just telling you how to draw this structure. You can memorize this your way also, but this actually helps you. Second carbon, OH on the right, on the bottom. Third carbon, OH on the left, on the top. Fourth carbon, OH on the right, on the bottom. Fifth carbon, we don't have OH, but we have CS2 OH and H. Okay? So we'll write down this CS2 OH on the top because OH on the bottom here. So here, we have CS2 OH on the top. And this is the structure. And everywhere, we have hydrogen. Hydrogen. Hydrogen. Clear? Did you understand this? Draw a six-member ring where oxygen is present in the ring and start with this second carbon. OH on the right in cyclic hemiacetyl structure, right down in the bottom. And then alternate. Fifth carbon, we have, we don't have OH, but instead of this, we have CS2 OH. So OH on the bottom here in the fourth carbon, so fifth carbon CS2 OH on the top. Clear? Are you able to understand this? So first carbon, is it both hydrogen attached? I am coming to that first carbon. So if you see, first carbon, OH on the right side, we have, means on the first and second carbon. If OH on the same side, it is alpha. Yes or no? Yes. First or second carbon? Yes, sir. OH on the same side, it is alpha? Yes, sir. So if I write down here, like this, if I write down OH here and H here, then this is the structure of what? Alpha D plus glucose. Did you understand this? Am I clear with this? Yes, sir. Okay. If you write this OH on the top, H on the bottom, then it will be? Beta. Beta D plus glucose. Draw that structure also. Did you understand this? Yes, sir. Tell me. Yes, sir. 3D, Arvind, Ariman. Yes, sir. Devdas. Devdas is there. Ares there, Shaanat, 3D, all of your industry. Lakshya also understood. Okay. What about, okay. What about this, sir? Paras. Likith is there. 3D understood, Paras. Shreya, Samyukta, Adra. Tell me. All of you understood this. So how do we, you know, write down this structure that draw six-member ring, oxygen in the ring at second carbon, OH on the bottom, then the top on the bottom, and then CH2OH. Sixth carbon is not a member of the ring. This is one thing you need to notice. Okay. OH on the first carbon, if it is in the bottom, then it is alpha. If it is in the top, it is beta. Okay. So what happens here, you see, like I said, why beta form is more stable. Let me draw that structure. I'll just draw it here. Six-member ring, we have, I'll write down first carbon, OH here, etch here, then OH on the bottom, etch on the top, OH on the top, etch on the bottom, OH on the bottom, etch on the top, and then we have CH2OH on the top, etch on the bottom. Right. Alpha form, why it is not stable? Because when you draw the chair form of this, which is not required, or you can also see, this OH and OH are very close to each other. Right. So here we have diaxial repulsion. Here we have diaxial repulsion. I have discussed this in isomerism also. You can revise diaxial repulsion. And hence this alpha form is less stable. That's why in solid state or solid form, glucose exists in this beta form. So this is beta D plus glucose. These are structures. We call it as alpha beta D, another form of this is alpha beta, alpha D plus glucose only we say. Since the structure of this glucose is derived with the reference of this molecule, pyrene, we also call it as the name of this compound. The other name is glucose, or glucose and pyranose. So this molecule, both of this molecule is glucopyrranose. Clear? Clear. Sir, what about even the beta structure is it also called glucopyrranose? Yes. Yes. That is also glucopyrranose. It's a general thing actually. Position of OH if you change, it becomes alpha and beta, but both of them known as glucopyrranose. Even we also call it as alpha glucopyrranose and beta glucopyrran. That is also correct. Okay.