 Next slide down. We use a catalyst to get the ordered structure of any polymer. And that catalyst, we call it as Ziegler-Natta catalyst. What is this Ziegler-Natta catalyst? First of all, the formula you should remember. It is titanium chloride, the mixture of TiCl4 with trialkyl aluminium, AlR3, trialkyl aluminium. R group is the alkyl group. Generally, we take ethyl, but it can be anything actually. So if I draw a polymeric structure of polypropylene, so propylene, the structure is this CH2 double bond. CHCH3. This is propylene. And the polymerization of this gives this structure CH2, CCH3, HCH2, CCH3, H. And this side we have it. Do we have any carol carbon in this molecule? This is polypropylene. Do we have any carol carbon in this? No. I think we have the first one. How many, at least in this structure where two molecules have joined? How many carol carbon we have? I think except for that middle CH2, the carol. But then aren't the same groups repeated? Sir, after in the left side, CH2 is attached to... After this CH2, again we have CCH3H. See, this carbon... Yeah, then won't it be same on both the sides? Yeah, this side also we have CH2 and then the same thing. This is a repeating unit actually. This. This carbon is not a carol carbon because it has two hydrogen on it. What about this carbon? We have one molecule, this hydrogen. One molecule is this and another molecule is this. Symmetrical arrangement we are not considering. Got it. We are considering what? We are considering if the number of carbon on this side and this side is different. Then this carbon is the carol carbon we have. Okay. Or for this molecule you see when we have dimer this, then this carbon for at least this one is carol carbon because this group is this and this we have this side. Similarly, this carbon is also a carol carbon. Okay. Yes. No. All the alternate carbon which has four different group attached with it are the carol carbon. So now when it is carol carbon, so the CS3 and H which is attached to this carol carbon, their arrangement can be anything. Okay. So that arrangement we are trying to understand here. So what is the arrangement we have here? You see one possible arrangement is this. Okay. One possibility is what all CS3 present on the same side like this. And one arrangement is what one CS3 coming out of the plane. The other one is going into the plane then out of the plane into the alternate. And here we do not have any fixed arrangement. It is randomly arranged like this. Okay. There's no fixed arrangement here. Okay. Because we do not have any control in such reaction like I discussed about this radical mechanism we have. We do not have control on these reactions. So we can get any one of these possibilities. Okay. When possible arrangement is what? All CS3 on the same side then alternate and then random arrangement. Overall point I'm trying to make is what? That the possibility is to get either ordered arrangement or disordered arrangement. Both possibilities are there. Okay. So when all the CS3 group present on the same side. Okay. This arrangement we call it as isotactic arrangement. Isotactic arrangement. When all CS3 on the same side. When it is alternate like this, it is syndiotactic. Syndiotactic. And when there is no arrangement, random arrangement if it is there. It is random arrangement. So this random arrangement, we call it as a tactic. A tactic. So these two are actually a regular arrangement. Right. But that is ISO or syndiotactic. The arrangement there is a pattern. Regular arrangement we have. Okay. So this regular arrangement. Arrangement. They have good physical properties because ordered arrangement we have so their physical property is better. Good. And useful also. Since the physical property is good. High density we have. So if this one is useful also. Both isotactic and syndiotactic. Both are useful. They have good physical properties because they have. Ordered arrangement. Arrangement will have a fixed pattern here. This one also and this one also. But random arrangement. Their physical property is not good. Not. Good physical properties. That's why we'll try to and this is not useful also. Since the physical property is not good. That's why we try to avoid this particular arrangement. A tactic arrangement. Okay. And to avoid this arrangement. We use a catalyst and that catalyst. We call it as Jigler data. Got it. So this point you write down. The structure of the. The structure of polymers. Depends upon the type of. Mechanism. The structure of. The polymer. Depends upon. The type of mechanism. Next line. In free radical mechanism. In free radical mechanism. There is no control. Over the reaction. And the possibility to get. The random arrangement of. Molecules. Is high. The possibility to get. Random arrangement. Irregular arrangement of molecule is high. This is structure is known as a tactic structure. This is structure is known as. A tactic structure. And their physical property is not good. And hence they are not useful. Okay. This is structure is known as. A tactic structure. Their physical property is not good. Hence they are not useful. Next line to get regular arrangement. To get regular arrangement. We use a catalyst called. Jigler. Nutta. Catalyst. To get regular arrangement. We use a catalyst called. Jigler Nutta. Catalyst. To get regular arrangement. We use a catalyst called. Catalyst. Done. Can you move on. Yeah. The last thing here we have to discuss. In this chapter is. Write down reasons. What are reasons. Anything you know about reasons what are reasons. Some plant product. Plant product you must have seen on the tree. There's some yellowish orange color semi liquid substance. It's not completely solid. It's not completely liquid. Not completely solid. You can, you know. Change the shape also easily by applying some pressure on it. That's not a big deal. Okay. So that yellowish or orange color liquid that you have. Opt in from the tree. Those things. We call it as. Resins. Okay. The example. The example. Those things. We call it as. Resins. Okay. The examples of reasons. Are. The first example is. Beccalite. Okay. Beccalite is an example of reasons. You see this. It is actually. The product of. Or the monomer of Beccalite. Is phenol. And formaldehyde. And hence the. We also call it as phenol formaldehyde polymer. Okay. Or phenol formaldehyde resins. Beccalite is nothing but phenol. Formaldehyde resins. Okay. So this reaction actually reaction between phenol and formaldehyde. It takes place at. In both acidic and basic medium. Mechanism like I said. It is not required. So we just. Discuss little bit here. H plus. Oh minus. And it forms or the para substituted product. Which is OH. And here we have CH2. Or to substitute a product. And para substituted product is this. OH. And CH2. Which. Now the reaction takes place at both. Position ortho and para. These two reacts. OH. CH2 OH. Reacts with. Reacts with CH2 OH. OH. So this actually. And in acidic medium this goes out at H2O. It combines and gives. This product. OH. Ring. Here we have. Here we have CH2. OH. CH2. This also goes this way. Like this we'll get a long chain compounds. This kind of reaction is possible at this position also. So overall you'll get this product. So very complex reaction. I'm not writing down the. Entire reaction here. You get something like this. OH. We'll have here. And you get CH2. This also attached with CH2. OH. And this CH2 attached with this. Is an open bond here. CH2 this site. This is structure the entire complex structure. Is nothing but. Beccalite. Structure is not at all important. This is used for the production of. Pressure cooker handle. And it is. A cross linked. Thermosetting polymer. It is a cross linked. Thermosetting polymers. Thermosetting polymers means what. When we heat this. Cross linking takes place. Which does not break down on cooling. That's why it does not become soft again. The other examples of. Residence are. Phenol formaldehyde. We have seen already. The other one is. Melamine formaldehyde polymer. Just name you write down. Melamine formaldehyde. I'll write down the names. Other examples of. Residence are. Melamine. Plus formaldehyde. And one more we have. Urea plus formaldehyde. All these are examples of. Residence. Melamine structure you must remember. This has been asked in J exam. The structure based question of. Melamine. Here we have an S2. An S2. Here we have an S2. And double bond like this. This is a structure of melamine. Question that they ask how many lone pairs are present in melamine. Can you tell me the number of lone pair in melamine. Number of lone pairs in melamine. Is it six. Yes. Six. Six lone pairs. One lone pair on each nitrogen atom. The exact question they have asked in J exam. But they haven't given the structure of melamine. The name they have written. The question is count the number of lone pair present in. Melamine. Okay. So structure you must know because when the structure is given, there's nothing to do. In this. Okay. Okay. Okay. So this is it for polymers. Okay. Polymers is done. Okay. This is it for polymers. Okay.