 One more question we'll discuss. Sir, is there any particular reason as to why both of them are same? The stability of carbonyl in the first one is a medium and here it is alkene. So we'll just try to get more stable alkene in the basic medium and more stable carbonyl in the basic medium. Sir, but does it rule that we can look at the initial compound and say that? No, no, no. We just have to, if medium is basic, write down the carbonyl in the forms. Acidic, write down the alkene and compare the stability. Okay, this way it will be OH minus and H plus. OH minus, write down the carbonyl in the forms, write down the alkene here and compare the stability. We'll get here dried in space, right? So both are same. Dried in space, both are the same. Major product same in both of these. So the two carbonyls that we get here is double pond scope. We'll get a carbonyl here and we'll get a carbonyl here, right? Basic mediums we'll write down the carbonyl. Two, this one is dried and this one is in space. Which negative charge is more stable? Large conjugation. Large conjugation, okay? This is in conjugation till this oxygen and here we have lesser conjugation, right? This is more stable, it means this gives you what? Major product. So major product we'll write according to the more stable carbonyl. This comes over here, this is what we get, right? And here the minor will be, in this way it's the cross conjugation, extended conjugation. This is the major product. In acidic medium we'll write down the alkene index. So we'll get a double pond here and double pond here, right? So two different alkene that we get here is double pond OH, double pond plus extended conjugation here. Alkene is more stable, this is the major product. You see in this also two different mediums we are getting same major product, right? So we cannot generalize. First we had to count the alpha hydrogens, we count them on both the double bonds? No, we count for this one only because it has to be hybridized. Please. What if there was like one more CHC group on the last one? That is six. When you count them? Both. What is the resonance in this case? Resonance, aromaticity, dominance over resonance. I'll say resonance to certain extent, dominance over resonance. Got it. So we cannot generalize that the major product in acidic medium becomes mild and invasive. We cannot generalize that. Sir, is it because there's a space and a trial? No, it's just because this camera is more stable than this. Sir, because even in the last example, space and trial is the first two ones before that where it was opposite, it was only two space, only two trials. See, you can say that but I haven't seen this anywhere. We cannot generalize that. So maybe you get one example here and there where the thing is not going correct. That's why it was not. Okay. Next we'll start stereo isomerism. Structural we have done. Stereo isomerism. Stereo isomerism. Sir, can you get a break after this? Yes. This will take two hours. The geometrical isomerism. I have to discuss the optical and then conformational isomers. No, no, no. We'll discuss this later. Right on to this. These are the isomers. These are the isomers which has the same molecular and structural formula. Geometrical isomers. These are the isomers which has the same molecular or structural formula. Molecular and structural formula. But the arrangement of atoms or groups in space is different. In space is different due to the restricted rotation across carbon-carbon double bond, across carbon-carbon double bond, or anything structure. So what is this? Carbon-carbon double bond, across carbon-carbon double bond, or anything structure. Of course. Triple bond is not possible. Across carbon-carbon double bond, or in... Oh yeah, because you can only go off. It's linear. Across carbon-carbon double bond, or ring structure. So, you see, the rotation is restricted across the carbon-carbon double bond. What does it mean? Suppose, what is the name of this compound? What is the name of this compound? Just H. U2E. U2E. U2E. What is the name of this compound? U2E. That's not what you're doing. These two are different compounds. Or the same compounds. The same or different? Same or different? Different, sir. Then why are you saying the same name? U2E. What is the name of this compound? U2E. What is the name of this compound? U2E. Okay, if I write down this example, then... U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. What about these two? U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. U2E. Okay, see, you wrote it as same compound. Okay, see, this is structure. These two structures are same structure. Equivalent structure of this. Is trans Z or Z? What is Z, what? Then, it's anguished. Trans and cis, this and Z and E. It can't be anything. E can be cis also and trans also. Z can be cis also and trans also. So, E and Z has nothing to do with cis. So, E and Z has nothing to do with cis. So, E and Z has nothing to do with cis and trans. And E and E have the same. What is E and what? Correct. And explain. Let me explain. Okay, stop talking. Okay, first of all, these two compounds. Right, these two compounds are different. Why different compounds? Because of the position of these two, this methyl group and this methyl group here. And this methyl group and this methyl group here is different. Okay? This distance. Suppose this distance is L1. Right? But this distance is not L1. It is different from the distance over here. It is L2. And it is observed that this distance L2 is more than L2. Okay? Because both are at opposite end. Right? So, this distance is more. Obviously, when the distance is more, L2, bulky group are a part. So, repulsion will be less comparatively here. And hence we can say this compound is relatively more stable than this. Okay? So, when stability is different, obviously the two compounds are also different compounds. Same compound over the stability we say Mogi. Right? If the two compounds are same, their stability, physical properties, chemical properties, everything will be same. Right? But their stability is different. Hence these two compounds are what? These two compounds are different compounds. And they are known as geometrical isomers of each other. They are GI, geometrical isomers of each other. Because same molecular formula, but the arrangement of atoms or groups across carbon-carbon-double bond is different. Right? Here they are at opposite end. So, arrangement is different. Different compounds, geometrical isomers. Here what happens? We do not have double bond here. So, we can rotate the carbon-carbon bond this way. Rotation is not hindered. So, when I say hindered rotation across carbon-carbon-double bond, it means what? Suppose this is carbon, we have carbon-carbon-double bond. Right? Now, when the pi bond is there, how this pi bond forms by lateral overlapping of the two orbital? This pi bond, right? Now, when you try to rotate this, suppose this carbon sticks and this carbon you try to rotate. If you rotate this carbon this way, you will get this molecule. So, if you want to rotate one of the carbon atom, you have to rotate this way. So, the pi bond you have to break, which is not possible. Bond you cannot break. That is why we say we have hindered rotation across carbon-carbon-double bond. But this rotation is not hindered here right? So, these two are same molecule but these two are different molecules. The carbon bond will not move but that won't show isomerism because it is linear. So, where do you want to rotate? Both are high. Yes, so it is like a linear molecule. Right? What do you want to rotate? The entire molecule will rotate. Right? So, these two compounds are different compounds because of the hindered rotation across carbon-carbon-double bond. Even with ring also it is possible. Right? So, this kind of compound we call it as what? Geometrical isomers of each other. So, what do you want to rotate? Geometrical isomers of each other. Now, in this we have two, three different representation. Because when you do the IOPSE nomenclature of this, let's say buted to in. This one is also buted to in. Right? So, if I ask you to draw the structure of buted to in, some of you will draw this one and some of you will draw this. And since both the compounds are different compounds, so we are not very sure that which structure we have to draw with buted to in if only I say. Right? So, to specify this whether we are talking about this molecule or this molecule, we will come over here. And that term is cis or trans, syn and T, E or C. Right? Three different types of you know representation we have. We can talk about cis and trans. We can talk about E and Z or we can talk about syn and N. Right? Suppose for this example, this is cis isomers. And this one is trans isomer. How do we say it is cis and trans? I will come to that. But suppose if I tell you draw the structure it is cis to butene. It means both cis and trans must be on the same side of double bond. So, you have to draw this structure. Trans to butene is opposite side. That is the significance of these terms. So, cis and trans isomer we define only when the double bonded carbon atom contains identical group on it. So, cis and trans So, we can define this cis and trans with respect to one of the identical group present on the double bonded carbon atom. And what is cis? When the identical group present on the same side of double bond carbon-carbon-double bond, then the compound is said to be cis isomer of that. When the identical group whether it is CS3 or H or on the opposite side of the carbon-carbon-double bond it is trans isomer. Is it clear? Right? Syn and NT or EZ we use for more substituted alkane. For example, suppose I write C and N here. So, this one is more substituted in the previous one where we have H hydrogen present here. So, this we can also define a cis and trans and we can also define as ENZ. This molecule is said to be cis with respect to what? CS3. It can be E or Z also and how do we find out ENZ? For that we have to assign the priority on the group. We will discuss that one by one. What about that? Name will be different but whether it is cis or trans it is cis with respect to CS3. ENZ also we can define because it is more substituted. Syn and NT we define when the molecule has this kind of bond N double bond N or C double bond N. This can also show geometrical isomer. Because we have double bonded so, syn and NT is mainly defined for nitrogen containing. ENZ is defined for more substituted. For example, if I write down this C double bond C and both the carbon atom contains halogen group. So, in this we cannot define cis and trans because identical group do have any of them. Both carbon atom does not contain same group all the four groups are what? Different. So, in this case we will define what? We will define ENZ. If any of the two groups are same suppose I have a BR with respect to brominitis cis but if we can also call it as ERZ isomer. We can choose what to call this and the other one will be the other letter. Preferably we will write this as ENZ and Z. ERZ not Z means whatever it comes if it comes E then E Z and Z. So, for this we like all these ERZs. We will see how to do that. We have to understand first the priority order and then we have the rule for that to assign ENZ and Z isomer. So, we are here instead of having two hydrogens and a methyl group instead of having like methyl hydrogen and chlorine and whether methyl chlorine and hydrogen. This is the same molecule. I don't know. Like no matter how I have a double bond. Here you can talk. CS3, chlorine and this? No, but if I had like three things attached to it in different order like one was because currently in SP3 so four coordinates of tetrahedral geometry is identical position. So whatever you know if you place just CS3 here H here and here chlorine that won't make any difference. Because SP3 hybridization tetrahedral geometry all the four atoms are represented and all four positions are what? Equivalent position. So that relative things will be same. Understood this thing. These three things we will define here. Now we will see some examples here. You should instruct your C double bond C COOH COOH Hydrogen and Hydrogen. Hydrogen and Hydrogen. And the other molecule is C double bond C COOH COOH Hydrogen and Hydrogen. The name of this compound is Malic Acid. M-A-L-E-I-C This is Malic Acid and this is Fumalic Acid. This name you must remember. Sir, if you give us common names and ask us. I forgot what question I have. I don't remember. One or two questions will be there for the moment. It's like common name. We normally don't need two questions. How many do you want? At least ten. No. Okay. The relation between this Malic Acid and Fumalic Acid is what? They are they are geometrical isomers of each other. So this question they have asked once. The relation between Malic and Fumalic Acid are they are geometrical isomers of each other. What is this? Can you tell me the name of this compound? Pute 1 for DIY gas. Pute 1? No. No, no, no. How is it 1? It's di-carb. It's ethyl. No, no, no. It's di-carb oxide. It's ethyl. It's ethyl. Sir, a school chem project is saying something. A school chem project is saying a school chem project is said to have a profile and if they are the same, we will include them. No, no, three. I don't know. I can't read. No, I don't know. 1, 4, 4, 4. 1, 4 is understood because we have to start the building. Di-ionic Acid. Di-ionic Acid. Di-ionic Acid. So we can also put the numbers in a link to 1, 4, 5. So 1, 4, 5. But if you write direct acid that is also fine. Because we are bound to give perspiration to this carbon atom. So 1 and 4. Now if it is both COH group present on the same side, it is cis form of this. Cis, but 2, E, 1, 4, dipoic acid. This one is what? Trans. Trans, but 2, E, 1, 4, 5. Not required. We write actually this way. Okay. Okay. So this you must remember malic acid is the cis form of but 2, E, 1, 4, dipoic acid. And thymalic acid is the trans form of this, right? The relation between malic acid and thymalic acid that they are geometrical isomers of each other. Okay. Sir, can you give us an example with three things so that we know when not to take the. You have done so much of questions on malic acid, no? Yes. I have done this thing in the class. So it is 1, 2, 3, propane, 1, 2, 3, tri-carbohydrate. Which is? Oh. Carbon-containing functional group directly attached to the unbranched LK.