 Right on the heading, monosecarides. This is the most important. What are monosecarides? These are the single unit of carbohydrates, unit of carbohydrates, which cannot be broken down, which cannot be broken down into lower sugar on hydrolysis. Monosecarides are those compounds which contains 3 to 9 carbon atoms. It contains here only a write down, 3 to 9 carbon atoms. Minimum 3, maximum 9. There are actually two types of monosecarides also. The first one is aldose. The second one is ketose. Aldose are those monosecarides, which has aldehyde as primary functional group. Because we have seen monosecarides, the examples of monosecarides are what? And glucose, fructose we have. So fructose we have, ketone is a primary functional group. And glucose we have aldehyde is a primary functional group. That's why we have two types of monosecarides. Aldose, whose primary functional groups are aldehyde, ketose, whose primary functional groups are ketone. PFG is ketone here. Here the general formula of aldose is C-H-O-C-H-O-H-N. And we have C-H-2-O-H. This is the general formula. Can you tell me the possible values of N? What is the possible value of N, can you tell me? Like I said here that the maximum number of carbon atom is 9. And minimum number is 3. So possible value of N is what? N can be 1, 2, 7. This is the possible value of N. So wait, why is that restriction? What happens if it's more than 7? What is the carbon atom? It is monosecarides. It is monosecarides, right? See, it's just a fact, observation. Because the definition of monosecarides are what? Which cannot be broken down into smaller aldehyde or ketone, polyhydroxy. So for that we have a given set of compounds. If the number of carbon atom is more than 9, then it can be hydrolyzed because the size is too big. That is one of the reasons. So carbon bond gets hydrolyzed? Hydrolysis takes place over there. See actually what happens if the chain is, if the compound is too big, right? Because there is polarity in the molecule because we have oxygen-hydrogen bond, oxygen-carbon bond. So if the compound is too big, then the lone pair of the oxygen may attack the carbon atom, which is a slightly positive charge. That we will discuss in Sahar's tradition of this. So for monosecarides, the number of carbon atom is maximum 9. And less than 3 is not possible because it must be polyhydroxy. That's why the condition is. For monosecarides, more than 9 carbon atom is not stable. They dissociate into the smaller molecules. That's why they are not monosecarides. So here you see if n is equal to 1, if n is equal to 1, what is the formula we get here? C-H-O-H, C-H-O, C-H-O, C-H-O-H, right? So this molecule, the general name of this, we call it as aldotriose. Why triose? Because the number of carbon atom is 3 here. Aldotriose, which is nothing but glyceraldehyde. If you see the formula, it is glyceraldehyde only. So aldotriose is nothing but glyceraldehyde. This question also they have asked in the exam. Because the number of carbon atom is 3. If n is equal to 2, what is the general name of this compound? It is aldotetrose because the number of carbon atom is 4. If n is equal to 3, number of carbon atom is 5. It is aldo... Pentose. Pentose. n is equal to 4. It is aldohexose. Aldohexose is nothing but what? Nothing but glucose. That's why this name is also very important. Aldohexose. Another name of glucose. It's not only glucose. Different variations of it. Sorry? It's not only glucose. It can be different variations of it. Yes, that is possible. But the general thing is... Aldoes and all that. Yeah, that is also possible. There will be optical isomers. Optically activities. All these carbohydrates are optically active. Not just optical isomers. Optical isomers of? Nothing is nothing. Fine, fine, fine. Now, this is the... So glucose belongs to... Which family? Aldoes family. This you must remember. Glucose belongs to aldoes family. Practoes belongs to ketose family. Similarly, you see, for ketose, the general formula... For ketose in the next page, I'll write down... General formula is CH2OH. Then we have C double bond O. The primary functional group. And here we have CHOHN. And here we have CH2OH. The possible value of N here is 0, 2, 6. Minimum 0, maximum 6. Because again, the number of carbohydrates is minimum 3 and maximum 9. That's why 0 to 6 is possible. So if N is equals to 0, there are 3 carbon atoms. And we call it as keto... Keto triose. Triose. N is equals to 1. It is keto tetrose. N is equals to 2. It is keto hexose. And this is nothing but... Fuctose. Sir, why does the C double bond O need to be right after the CH2OH? Can it be in the middle of the chain? No. It is here only. For that region, we need to understand the structure elucidation of glucose. How do we come to know that there is only 5 hydroxy group? There is principal functional groups, aldehyde, not ketone and glucose. So for that, we need to understand the structure elucidation. For that again, we have to... We will discuss that. Keto pentose. Keto pentose. So there is a series of experiment to define the structure of glucose and fructose. So not all, but there are 3-4 things which is there in our neighbors that we will discuss. For example, you can also ask why only 5 hydroxy group is there? Why in glucose we have aldehyde, not ketone functional group? So for that, we have some reactions. We will discuss that later. Sir, you missed Keto pentose. Keto pentose. Keto pentose. If n is equals to 3, n is equals to what? So you missed Keto pentose. I missed Keto pentose. No. So it will be 0, 1, 2 is what? 2 is pentose. Sorry. 2 is Keto pentose. And 3 is Keto hexose. That is fructose. So correct it. So this one is Keto pentose. 5 carbon atom. And n is equals to 3. It is Keto hexose. And that is glucose. That is fructose. So fructose belongs to this time. Keto hexose. Okay. So these are two things that we need to understand. So in glucose, there are the most important part that we were discussing here is the structural elucidation of glucose. How do we come to know about the structure of glucose? So for that, we have a series of reactions. We'll see that. Okay. It is not that important to understand like for a school exam and all, but for a competitive exam two, three things you should know about this, you know, reaction. So that's what we are going to discuss here. The complete thing we are not going to see, it is not there in our syllabus. Okay. The first thing you write down, glucose, heading you write down glucose, which is also known as dextrose. Heading you write down the first thing, glucose. And the other name of glucose is dextrose also. Sir, the only the D form of glucose. Yeah, because naturally it occurs in this form only. That's why we are calling it as dextrose. All of these occur in D form only, right? Yeah, mainly. So why we are calling it as dextrose? Because it occurs in the nature as optically active optically active deisomer. That's why it is dextrose. Okay. Preparation is what? Preparation of this is not important. I'll just write down two reactions here. Like we know in laboratory it is prepared by the hydrolysis of cane sugar. It is nothing but sucrose. So in laboratory by hydrolysis of sucrose reaction is we have sucrose plus H2O acidic hydrolysis in alcoholic medium. It gives glucose one unit of glucose and fructose. Okay. In large scale it is prepared by large scale it is prepared by the hydrolysis of starch starch is C6H12 O6 and like this we have N units of this plus H2O H plus it gives glucose with N unit of C6H12 O6. This is the preparation method we have. Which is obviously not that important. But structure elucidation there are two, three things which is important here to understand and that we'll discuss next. All of you copy. Sir, how do we separate the fructose? What? How do we separate the fructose? From glucose mixture of fructose. It is very difficult to separate. But there is a method. So fractional distillation? That is also you can use. But we don't use fractional distillation for this separation. But we use like there is a equilibrium mixture we have. There's a method. See I'm not getting that name. Because mannose and fructose. Sir, is there any way by which we can exploit the fiber? Glucose has an aldehyde group and fructose has a keto. Glucose has an aldehyde group or ketose while fructose is a ketose. It only has a keto group. So we can exploit that fact. Yeah, you can. But the thing is like I said see fructose having ketone functional group. But it shows tolerance reagent because some part of it shows tautomerism and it converts into glucose also. That's why it is difficult to separate the two mixture of glucose and fructose. Even we have an equilibrium in glucose, mannose and fructose. So when you take fructose, automatically it converts into glucose also and mannose also. So it is difficult. Generally distillation thing and all we use where we have difference in boiling point where we are last difference in boiling point where we use distillation method. Okay, so for here we use some different method. I forgot the name. Okay, I will tell you that name later. But the point is since fructose converts into glucose and mannose and there is an equilibrium in three molecules glucose, mannose and fructose. That's why this mixture is difficult to separate. But we have methods, we can do that. Okay, distillation is you know, costly also. That's why we don't use distillation for this purpose. Method, I will tell you the name of that. I forgot the name. I will tell you. Okay.