 Write down the heading, differentiation between glucose and fructose. Differentiation between glucose and fructose. OK. So we know glucose are easily oxidized. With mild oxidizing agent also, it get oxidized by oxidizing agents like felling solution, felling solution, and tolerance reagent. Fructose, since it contains carbonyl, sorry, ketone as a major functional group, it is not oxidized by, oxidized by mild oxidizing agent. But should not, should not, you're right, should not. Why? Because fructose has ketone as major functional group, and this has aldehyde as major functional group. This should be the actual thing we have. But actually what happens, the fructose contains, fructose which contains ketone functional group, also gives positive tolerance and felling solution test. So write down the heading first. Fructose, fructose shows positive tolerance reagent and felling solution test. Now why it does so? That's the question. For to understand this, I'll go to the next page. You copy it down. OK, done? Yes, sir. The reason behind this, to understand this, we need to understand this. What is this? What is? It's Dobri D. Van Bryan-Ikistin rearrangement. Sir, this had better be summed up a little bit. The name is not important. You can ignore that. In this rearrangement, what happens? Dobri. You have glucose and the structure is this, CH2OH. This with basic medium dilute OH minus. It converts into mannose, mannose, which is this fructose. Sir, by any chance is there a more condensed way of writing down these formulae of T compounds? This, better if you write mannose. That's why this takes a bit time. Structure only we need to draw a lot of time. This is the reaction we get. Glucose and mannose, we know these are C2EP mers. Glucose and mannose are C2EP mers. Copy down this first. Can you tell me the mechanism of this? How this reaction is taking place? Anyone? How do we get fructose from glucose? Can you tell me the mechanism of this? Sir, is it similar to something? Is it similar to, like, alcohol condensation or something? No, it's not. Is there tautomerism involved? Yeah, it's tautomerism. It's tautomerism. Can you tell me how glucose converts into fructose through tautomerism? Sir, is it something like OH minus attacks the C double bond OH, then you'll have C... No, no, no, no, no, just one simple thing. How do you draw tautomeric structure? Mechanism, though, you know that we already... How do we draw a tautomeric structure? That is trial. Sir, we just shift the W bond and remove the H and... Yes, yes, yes. I'm not sure about that. See, actually, it is very simple here, you see. This one, one... So it extracts our H plus, right? Yeah, one, two, and three. This is what we have. H plus comes out from here, and it goes on to this oxygen. And this double bond comes over here, okay? So what we get? COH double bond. And here what we get? CO minus, okay. Yes, sir. So we get this, actually. I'll write down that this part of it. The whole structure I won't draw. In basic medium, this gives you COH H double bond COH. Is it clear? This H plus comes out, and it takes this O minus, we'll get this. Again, in this one, we'll draw the tautomeric structure again. One, two, and three. So from this, from this, H plus again comes out, leaving this electron pair behind, and this will attach onto this carbon, which converts into, the top one will be CH2OH, and here the second carbon will get C double bond O, and that is how we get this. All other things will be same. Yes, sir. Correct? So this is because of tautomerism, this glucose, fructose, and mannose. This three molecule exists in equilibrium, in basic medium, OH minus. And that is why when you take fructose, okay, some part of it through tautomerism, converts into glucose. If you take glucose, it converts into fructose and mannose, okay? And in the mixture, you started with glucose only, or fructose only, right? But after some time in the mixture, we have mannose also, we have glucose also along with fructose. And that is why, since mannose and fructose has aldehyde functional group, and that is why that particular mixture shows or gives positive tolerance test. Got it? So this is just keto in tautomerism? Yeah, it is. Keto in tautomerism. Right on this point, the reaction of tolerance reagent and failing solution. The reaction of tolerance reagent and failing solution, and failing solution, takes place in alkaline medium, takes place in alkaline medium, where fructose converts into mannose and glucose through tautomerism, where fructose converts into mannose and glucose through tautomerism, through tautomerism, and hence the mixture gives, the mixture gives positive tolerance and failing solution test. In the thing that you've given there, you've shown that glucose becomes mannose and fructose. Ha, the point is? Both happen the same way, right? Yeah, this is also happens the same way. Fructose also if you take, this converts into all these, that's what I wrote here, all these three are in equilibrium. Yes sir. That's how it is. Okay, that's why you see to differentiate glucose and fructose, we need a medium, we need a reagent whose medium is not alkaline. You understood this point. If alkaline medium is there, then there will be tautomerism, keep going on tautomerism. And it is difficult to differentiate both the molecule. Hence, right on the next line, to differentiate glucose and fructose, to differentiate glucose and fructose, we need an oxidizing agent whose medium is not alkaline. Whose medium is not alkaline. And that is bromine water that we use in the first step to, to understand that structure of glucose. And that's why we use bromine water for this process. Sir, in this, why doesn't tautomerism take place further? Like, why doesn't the third carbon form double bond over? What? So why doesn't tautomerism take place further? Why can't the third carbon form a ketone? In fructose. Second carbon is forming ketone. No, where is third carbon? This second carbon. This one. So it's asking where ketone form. From fructose. He's asking after that. You're talking about further, why it does not go? Yeah. That is also possible. If it goes also, then also you'll get ketone, correct? Yeah. Then also you'll get ketone. But the point is, see, you can, you can go after this also. This edge comes over here and you'll get double bond O here. So you'll get double bond O here. But the point is here that this basic medium reaction, this product will also have over there, but that is not in major in amount. It has very few. Otherwise the reaction goes on till here. Yes, sir. Point is that we have this carbon and here also you see, I have drawn this structure by two steps, two tautomeric structure I have written. After this we'll get this. This is one tautomeric compound and then we'll get this, another tautomeric compound. First, tautomers takes place between one, two and three here and then this, this and this, which is involved in tautomism. Two steps we have here. Further also it's possible, but the rate is very slow. We won't get major product into that. So we are not considering that. Right. And the thing is we are getting this because the question is see, I have written it other way. The question is why fructose shows tolerance test? So for that, this fructose, if you go reverse, you'll get glucose and mannose. And that is why it shows. If you go from here, if you go this side, then also you'll get fructose, you'll get ketone only as a major functional group. That won't explain why fructose shows positive tolerance test. Are you getting my point? Yes, sir. So I have explained this with the help of glucose. Reverse if you go, that explains the reason why fructose shows positive tolerance test because then only it gives healthy height as a major functional group. So this entire thing is called low brie, divan, brine, I can stand the arrangement. It can stand the arrangement. Yeah. Sir, in an alkaline medium in which form do they mostly exist in the Harvard projection, right? What, what? Srijan, come again? In an alkaline, in any medium, they mostly exist in the Harvard projection, right? Yes, that also we can write. That's another reason why it doesn't continue after fructose because it forms a four-member ring then and that's not stable. Yeah, that also you can say. If you draw the Harvard structure, obviously you'll get fourth-member ring, not a stable. That's why further reaction does not take place this side. That is also right Srijan, correct. Okay. Now we'll start with the reaction of glucose and fructose. We don't have time. I want to start this now because again we have to draw the structure again and again. So we'll start this glucose and fructose reaction in the next class and we'll finish this chapter next class.