 Friends, good morning. Welcome back to Centrum Academy. Today in this session, we are again going to discuss the another electronic effects which is hyper conjugation, ok. Friends, last session or last lecture, we have already gone through the two most important electronic effects and those are what? I effect and resonance that is mesomeric effect. We have also seen the various different application of eye effect and resonance mesomeric effect also, ok. Now, this is the third type of electronic effects we have and that is hyper conjugation, ok. Hyper conjugation is what? It involves alpha hydrogen, ok. It involves alpha hydrogen mainly, but in some cases there are few exceptions also. At alpha position, if you have chlorine present, then also hyper conjugation is possible, ok. This is not the actual definition, but it is because for alpha chlorine also, this hyper conjugation is possible. We will see that examples also, but here in this case, mostly whenever we have alpha hydrogen present, then hyper conjugation is possible, ok. So, hyper conjugation actually exists or possible in three different cases, right. So, for hyper conjugation, for hyper conjugation and short hyper conjugation, I will write as h c, ok, h dot c, ok. So, whenever I write h c, you take it as hyper conjugation, ok. So, for hyper conjugation, there are three cases, three cases possible, three cases. First, hyper conjugation is possible in alkene. Hyper conjugation is possible in case of carbocation and hyper conjugation is also possible in case of carb free radical, free radical, ok. Here what happens? Homolysis takes place. We will see this later on. Homolysis takes place here, ok. So, the first example we are going to take here, that how in case of alkene, hyper conjugation possible and how do we draw the hyper conjugative structure, ok, in case of alkene. So, I will just try to make you understand with this example. And suppose the example I am taking is c h 3 c h double bond c h 2, ok. Now, this molecule if I write as this, this is the alpha carbon we have, ok. This is the alpha position adjacent to double bond alpha position, ok. So, if you see if I write down this structure as this c h 2, hydrogen, single bond c h, double bond c h 2, ok. So, how do we draw the hyper conjugating structure? Here it is, this sigma bond comes over here and this pi electron or pi bond goes on to this carbon atom. So, the hyper conjugative structure here will draw is c h 2 double bond c h single bond c h 2 lone pair on it. And here we have the hydrogen present as h plus, ok. So, like you see here, this hydrogen is present here only. It would not go away, right. It would not leave this place, ok. That is why we also call it as no bond resonance. Because there is no bond present between the carbon and hydrogen atom, still the h plus ion is available over there. So, we call it as no bond resonance, ok. So, hyper conjugation we also call it as no bond resonance. Now, the second point here you have to understand is this sigma converts into pi and pi bond comes over here, right. So, we also call it as what? Since sigma bond converts into pi, we also call it as sigma pi resonance, right. So, hyper conjugation is nothing but we call it as no bond resonance. We also call it as sigma pi resonance, ok. So, all these three names are same actually, hyper conjugation, no bond resonance and sigma pi resonance, ok. So, now you see the hyper conjugation is possible, like how this hyper conjugation takes place. This bond has to break, right. The sigma bond has to break. So, like this thing you have to keep in mind. Whenever the comparison we have to do, like in which of these molecules hyper conjugation is easier, then that comparison depends on the bond strength of the carbon and hydrogen or we can have any isotopes of hydrogen also, right. So, in those cases, we if you know the bond strength of this carbon, hydrogen or carbon isotopes of hydrogen bond, accordingly we can compare where the hyper conjugation is easier, ok. So, this you must keep in mind sigma bond has to break. This converts into pi bond and this pi electron comes over here, right. So, here you see this type of structure this is the only one structure, right. This is the only one structure from this molecule we got this. Similarly, we can draw two more structure because we have two more hydrogen present here, right. Then we will get one h plus we will get here and then one h plus we will get here, right. So, the point is if you have three alpha hydrogen, then we can draw three structure like this, ok. This structure we call it as hyper conjugative structure, ok. So, in this one if I write down number of hyper conjugative structure, number of hyper conjugative structure if I ask you the answer will be what? This will be equals to the number of alpha hydrogen, ok. Number of hyper conjugative structure is equals to the number of alpha hydrogen present. If they ask you how many total structure possible that will be equals to three hyper conjugative structure and one the given molecule, ok. Total structure will be what? Number of alpha hydrogen plus one, ok. This is the one molecule, ok. So, basically with this three hydrogen one and two hydrogen one two three, we can draw three hyper conjugative structure, but total structure will be what? This three plus the given structure one, ok. That is the number of total number of structure, ok. Now, here the stability of alkene we can also compare with this hyper conjugation, ok. That we will see few days few times later, ok. Now, few examples I will just write down because this all these you know structures or hyper conjugation depends on the number of alpha hydrogen present. You must know to how to calculate the alpha hydrogen, which is not that much difficult, ok. Just you have to keep in mind the double bonded carbon adjacent to that carbon, right. The carbon present adjacent to double bond is alpha carbon and all hydrogen associated with alpha carbon is alpha hydrogen, ok. So, for example, you see this molecule C H 3 C H double bond C H C H 3, ok. So, adjacent to double bonded carbon, these are the double bonded carbon atom. Adjacent to this carbon, we have this is alpha carbon and this is alpha carbon. Basically, it is alpha position, right. These two are alpha position. So, number of alpha hydrogen present here is nothing but 3 plus 3, 6, ok. Similarly, another molecule if I write down, you have to count the number of alpha hydrogen, ok. So, this is the alpha position and this is the alpha position, ok. So, alpha hydrogen will be what? 2 plus 2, 4. Here you see alpha position, alpha position. Number of alpha hydrogen will be 6, alpha position, alpha position, alpha position, alpha position. So, alpha hydrogen will be 12, alpha hydrogen. Here it will be, this is the alpha position and this is the alpha position, ok. 2 plus 2, 4, alpha hydrogen. Here it will be, this is the alpha hydrogen which is 2, ok. So, basically, more number of alpha hydrogen if you have more hyper conjugative structure, you can draw. And more will be the stability of alkene, ok. So, we will see that just now. You can see, you can go all through, go through this, ok. We will discuss the further things.