 Hemi-acetyl is structure? So it had ether with hydroxy. Carbon with ether and hydroxy, right? Yes, sir. OK. Next to write down, Hemi-acetyl is structure of glucose. Hemi-acetyl is structure of glucose. So hemicyclic Hemi-acetyl is structure of, better we write here, cyclic Hemi-acetyl. Cyclic Hemi-acetyl is structure. So Hemi-acetyl structure is the structure in which the carbon contains OH and OR group. If I give you a quick recap here that we did, the reaction of aldehyde, RC double bond OH, because glucose contains aldehyde functional group. So that's why it's very similar reaction we have here. And when this is allowed to react with an alcohol which is R1OH, the product here we get is RCOH, OR1 and H, if you remember this. We get this structure in acidic medium, obviously, H plus. So this we call it as Hemi-acetyl structure, where the carbon contains both OR ethyl bond and alcoholic bond. How do we get Hemi-acetyl structure in glucose? That is the question, correct? So now you look at this reaction, first of all, because glucose contains hydroxy group also, because you see, glucose has this OH and C double bond O, both present. That's why this kind of structure is possible. You see, if I draw the structure of glucose here, we have C double bond O, H, and OH, H, OH, H, OH, OH, H, CH2OH. This is structure. It is D or L glucose. First of all, tell me that. D is D, right? Yeah. So this is D plus glucose. And this information, I am giving you. How do we know plus or minus? Sir, isn't this experimental? Is the information we get from polarimeter, right? So this is factual, actually. For this, it is plus or minus. We have to do that experiment. Rotation of plane polarized light clockwise or anti-clockwise. That we only get from polarimeter. So this is the information I am giving you. I am telling you that this is the plus glucose, fine? So if you want, you can write down here this information, whether it is plus or minus info through polarimeter. You don't have to put brain over here. You cannot do it or anything into this. Now, what happens here, you see, like I said, that aldehyde and alcohol reacts forms hemiacetam. Why it is D? Because this OH on the right-hand side, that is one thing. That's why it is D. Now, the next thing what happens here is this lone pair, oxygen-vala lone pair, this lone pair, this has the tendency to attack onto this carbonyl carbon, OK? Now, when it attacks, this pi-electron shifts onto this oxygen. What is the hybridization of this carbon? SP2P2 to SP2. And when this attack takes place, what happens then? We'll get the structure like this. So this is, here we get carbon. With one side, we have OH. And this is H. This is oxygen. And this is same, OH, H, OH, H, OH, H here. And here we get CH2, OH, and here we have H. So basically, this hydrogen rearranged itself onto this oxygen. We get this. Is it clear? Yes, sir. OK. This carbon becomes SP3. OK. Now, the point is what? This oxygen can be this side also, means the attack takes place from this side or from opposite side also. Why? Because the carbon is SP2 hybridized. So this attack may be from the top or from the bottom. Both sides is possible. Equi, the probability is equal for that. OK. So we can also draw one more structure here, which is this carbon, H, OH on the opposite side. And here we have OH on the right, H on the left, OH on the left, H on the right, OH on the right, H on the left, H on the left, and CH2, OH. So can you tell me the configuration of this carbon and this carbon is opposite? If it is R, this one is S. OK. So when these two structures are di-stereomers of each other, first of all. And why it is hemiacetyl structure? Because the carbon contains OH and OR group. That's why this is the hemiacetyl structure of glucose. Cyclic structure we have, so it is cyclic hemiacetyl. Is it clear? So why does any other of the OH not take part in the reaction? So he asked why doesn't the OH take part in the reaction? Ashutosh? The Ariyaman asked, sir. I am not getting you. So he asked why only that OH, why not the other OH? It is almost six members. Why, why this, yes. I mean, coming to that. Coming to that, wait, wait. See, advantage of this oxen is what? Because you'll get a cyclic compound. Bhavar, can you answer this? It takes it from carbon number five because you get a six-membered ring. A six-membered ring is particularly stable. You'll get a six-membered ring here. One, two, three, four, five, six. Six-membered ring, including the oxygen in the ring. That's why it is. So under what condition does this transformation take place or is it spontaneous? This is actually, a condition is acidic medium we take generally. But this kind of reaction is possible. Okay, sir. Okay. Now, the thing is this structure, we call it a cyclic hemiacetyl structure. The carbon here is sp3 hybridized. This carbon is sp3 hybridized. Both of these structures are called di-stereomers. And this hemiacetyl structure forms when hydroxy group attacks onto the carbonyl carbon. Second point is this. Now this molecule where OH on the right side, right side of this carbon, we call it as alpha D glucose. So it is D plus glucose. This form is alpha when OH on the right. So we call it as alpha D plus glucose when OH on the right. If OH on the left, it is beta D plus glucose. Okay, alpha why? Because hydroxy group OH on the right. Because hydroxy group OH on the left. So is this only for D plus glucose or even minus sugar? See, alpha and beta is only for, this is again, I don't know why I'm doing this. Okay, Arima understood, right? Okay. What did you say for beta also it's fine. For minus also it's fine. Alpha has nothing to do with D plus or minus. It is only concerned with alpha is only related with hydroxy group, whether it is present on the right or on the left. Yes, sir. Okay. So that is possible with D minus even also. And why do we get these two structure? You understood this because this carbon is what? This carbon is planar. It is sp2 hybridized. So attack of this lone pair can be from the top and from the bottom also both side attack is possible. So if it attacks from the bottom, OH group will be this side and the attack from the top, OH group on opposite side. So both structure is possible. Okay. Yes, sir. Write down one note here, all of you, in solid state glucose found in these cyclic hemiacetyl structure in solid state. Sir, if it is on the left hand side, so if it's L plus glucose, then shouldn't the first carbon be opposite in nature? So shouldn't it be an anomer? Either rotation should happen for the OH or it should be anomer, right? What is anomer? What is anomeric carbon? Sir, anomeric carbon is a configuration in which it differs in the alpha carbon. No. Anomeric carbon is that carbon which contains OH group and ether linkage. Like this carbon is anomeric carbon. Yeah, but it should differ. Yeah, you are, I think you are trying to say something else. I'm coming to that point. Can you give me two, three more minutes? Yeah, yeah, okay. Okay. So first of all, what I said, this is very important in solid state. Glucose found in these cyclic hemiacetyl structure and this beta form is more stable. You write down this. Means this glucose exists in this form. Beta form is more stable. You'll ask me why? Yes. Yes, sir, why? We'll discuss that later. A reason I'll tell you, but we need to understand a few things. So we'll come to that. So our solution we'll discuss. There we'll see. Is it because OH should be on same side? I'll tell you the reason over there. So here only you write down, beta form is more stable reason. I'll tell you in some time. Let's wait for some time. You see, alpha and beta form are di-stereomers of each other and they're also known as anomers of each other. You'll ask me what is anomer? So that I'll explain here. Write down. Alpha and beta forms are di-stereomers of each other and they are also known as anomers, A-N-O-M-E-R-S. To understand why they are anomers, first of all, you write down the definition of anomers. Definition of anomer, you write down. Write down, these are the carbohydrates. These are the carbohydrates which differs in configuration, which differs in configuration only at anomeric carbon. Which differs in configuration only at anomeric carbon. Next line. The carbon which contains, the carbon which contains both hydroxy group, OH group, the carbon which contains both hydroxy group and ether linkage are called anomeric carbon. Are called anomeric carbon. Understood? So in this structure, the previous structure, which one is anomeric carbon? C1, right? First carbon. First carbon. This is the anomeric carbon, correct? Now the configuration of anomeric carbon is different in one of the molecule, O-H-E on the right and in the other one, O-H is on the left. That's why the configuration of this carbon is different in these two compounds and hence these are anomers of each other, okay? So this question also they ask that in glucose or alpha D glucose, which one is anomeric carbon? They'll give you the option C1, C2, C3, C4. Answer will be what? C1. So in glucose, alpha D glucose, C1 is the anomeric carbon. And when the configuration differs at anomeric carbon, the compounds are said to be anomers of each other. Am I clear? Okay. So here, that's what my doubt was. Yeah, tell me. So here the O-H on the opposite side can't take place, right? It can't form a hemiacetam. Why it can form? How? No, your doubt is what if O-H on this side, that's what you're saying. Right. O-H on this side. That will also form, so you'll get this first. Means if top side attack, suppose O-H is on the left. Top side attack. But it won't be glucose anymore, right? Sorry? It won't be glucose anymore. It will be L form of glucose. That will be L form, that is glucose only, but it is the L form of glucose. Okay, understood. So you will get this structure, but the point is here the top side attack, if it gives alpha, there the top side attack gives you beta. That's the only difference you get. Yeah, okay, got it. Okay. Now, see one more thing. This enomer thing is defined only in cyclic structure. You must keep in mind. This is a cyclic structure, guys. Don't, you know, keep this in mind. It is a cyclic structure, six-member ring. Anomeric thing or enomers are defined only for cyclic compound.