 Good morning. Welcome back to Centrum Academy. Today here in this session we are going to discuss further about hyperconjugation, okay. Last class friends, hyperconjugation, we have discussed about how hyperconjugation is possible in alkene and we have also seen few, you know, application of hyperconjugation, right, like stability of alkene. We have also seen heat of hydrogenation, heat of combustion, okay. Like I have already discussed friends that hyperconjugation is possible in alkene, carbocation and free radical. It is not possible in the case of carb anion, okay. So the next part we are going to discuss here is hyperconjugation in carbocation, okay. So in case of carbocation, how hyperconjugation is possible that we are going to discuss today, okay. So you see here first hyperconjugation in carbocation, right. Hyperconjugation in carbocation, okay. For example you see, simplest example here which is CH3 CH2 plus, okay. Basically like I discussed alpha hydrogen is required for hyperconjugation, right. In case of alpha chlorine also it is possible. I have already discussed this. So the previous example that I have written, they are also hyperconjugation possible but we can take that example later on, okay. So here you see we have alpha hydrogen present, okay. So this molecule we can also write this as CH2, okay. When I draw the hyperconjugative structure here, this sigma converts into pi, right. Sigma and pi conjugation it is. So we can write CH2 H plus double bond CH2. And further we can draw two more hyperconjugating structure here. Total three hyperconjugating structure possible. Why? Because we have three alpha hydrogen. You see the number of alpha hydrogen is three. So total hyperconjugating structure is what? One, two and three, okay. So in this the number of hyperconjugating structure, number of HC structure, hyperconjugating structure is equals to the number of alpha hydrogen, right. Which is three in this case. If they ask you how many total structure we can draw, that will be equals to three hyperconjugative structure, one structure we already have, okay. So total it will be number of alpha hydrogen plus one. This is the answer, okay. So in this you see hyperconjugation, carbocation if it is present then also hyperconjugation is possible, okay. Remember friends one thing here that in this hyperconjugation sigma bond which is comparatively a stronger bond is converting into pi, right. So stronger bond is converting into pi which is a weaker bond, right. So when we compare the hyperconjugation in various compounds, bond strength also will have a role, okay. Like suppose if you have isotopes of hydrogen, the bond strength of CH, CD and CT according to that bond strength will compare the hyperconjugation, okay. Because we have to break sigma bond and that is converting into pi, okay. So this is how we draw hyperconjugative structure in carbocation, okay. Now the next thing is what? The stability of carbocation if you consider of carbocation it is directly proportional to the number of hyperconjugative structure, okay. And which is directly proportional to what? The number of alpha hydrogen, okay. So basically the molecule which has more number of alpha hydrogen gives more stability to the carbocation. When I say stability, this is stability of carbocation we are talking about in terms of alpha hydrogen due to what? Stability due to hyperconjugation, right. So if and only if hyperconjugation is possible then what we will check? We will just check the number of alpha hydrogen and if number of alpha hydrogen is more, more will be the stability of carbocation. Friends there are also possibilities that in the molecule we can have more than one type of electronic effects like for the given 3 and 4 molecules you can have inductive effect possible, you can have resonance possible and you can have hyperconjugation possible, okay. So whenever we have all the effects or more than one effects present in the molecule then the stability will define according to what? Resonance first then hyperconjugation and then inductive effect, okay. But if and only if we have hyperconjugation we will just check alpha hydrogen, okay. So next point I will write down here in case of, in case of more than one, more than one electronic effects, electronic effects the stability is defined following, okay. So stability due to resonance is maximum. So first factor will consider resonance then we will consider hyperconjugation and the last will see inductive effect, okay. So the order will follow here what? R and then H and then I, okay. So the point is when molecule has more than one electronic effects if resonance is there then the stability of carbocation is maximum then we consider hyperconjugation and then we will consider I effect, okay. Only hyperconjugation if you have then we will count only number of alpha hydrogen but when two molecules are given one is showing resonance other one is showing hyperconjugation then obviously the resonance molecule will give the more stable carbocation, right. So this is what the you know theory we have discussed. Now we will see few examples on this and we will apply these concepts to determine the stability of carbocation, okay. We see all this molecule here you see in all these molecule only hyperconjugation is possible, right. Only hyperconjugation is possible. We can also say I effect here, right. I effect and I effect with both will get the same answer but since hyperconjugation is also possible then we will consider what the stability due to hyperconjugation because hyperconjugation is more dominating effect then inductive effect, okay. So number of alpha hydrogen here it is what? 9, number of alpha hydrogen 6 and number of alpha hydrogen is 3. So more number of alpha hydrogen more will be the stability. So stability order is this A will have maximum then B and then C, okay. Now you see this has 3 alpha carbon, number of alpha hydrogen is what? 2, 4, 3, 7, number of alpha hydrogen 1, 2, 3, number of alpha hydrogen is only 1. So more alpha hydrogen more will be the stability order will be this. Here you see here we have resonance possible, right. Sigma pi vacant P and here we have hyperconjugation with alpha hydrogen is what? 2. So whenever we have 2 different electronic effects resonance and hyperconjugation resonance is more dominating stability of second is more than that of first, okay. Here you see again here we have resonance here we have hyperconjugation resonance is more stable, okay. Here we have hyperconjugation alpha hydrogen is 2, here the alpha hydrogen is alpha hydrogen is 3, right. So the second one is more stable than the first one. These structures you see, okay. Here you see we have both eye effect and hyperconjugation both possible. Alpha hydrogen if we calculate 2, alpha hydrogen if we calculate 2, right. So with respect to hyperconjugation we cannot decide which one is more stable. Why? Because both has equal number of alpha hydrogen, right. But we know the eye effect of this is lesser than the eye effect of this because it is a bigger alkyl group, right. So the stability order of this will be B is more stable than A and this is because of what? Alpha eye effect plus eye. This is because of plus eye effect not hyperconjugation, okay. Here you see here we have hyperconjugation, right resonance and here also we have resonance. So when you compare this is hyperconjugation so obviously this is the least stable third position, right. In this two if you compare hyperconjugation is not possible possible but resonance is a dominating effect here. Here we have greater resonance, right. Here we have greater resonance. So stability of this will be more and this will be less, okay. First second and third the order of stability. If you compare this, this has alpha hydrogen 9 and for this alpha hydrogen is 1. Stability of first is more than to that of second, okay. Here you see we have resonance. Here we have resonance and here we have hyperconjugation. So stability order if you see hyperconjugation is least lesser resonance here. Large conjugation we have here order will be this, okay. So like this you can easily compare the stability of carbocation with respect to hyperconjugation and if we have more than one electronic effects are present then we will compare the higher stability according to R H and I resonance, hyperconjugation and I effect, okay friends. So next we are going to discuss about hyperconjugation in free radical, hyperconjugation in free radical. For example you see CH3, CH2 radical, right. CH3, CH2 radical, right. This molecule if I write it as CH2H, CH2 radical, okay. So in free radical what happens homolysis takes place, okay because it is the unpaired electron to make a double bond to convert sigma into pi. Since we have already one electron, so here also one electron is required and that is only possible when homolysis takes place. So when homolysis takes place this bond alpha carbon, this bond one electron goes on to hydrogen and another electron comes on to this carbon atom, okay. So what happens here in this process the hyperconjugative structure here it will be hydrogen with one unpaired electron double bond CH2. This is what it is. Now in this also we can draw two more resonating sorry hyperconjugative structure here. Since we have three alpha hydrogen, so one, two and three hyperconjugative structure possible, okay. Here what happens this is homolysis, homolytic cleavage it is, okay. So again here also if you write number of hyperconjugative structure, hyperconjugative structure is equals to number of alpha hydrogen, right. Total structure if I ask you is equals to number of alpha hydrogen plus one, one structure already we have, okay. Next thing the stability of free radical. We can compare this as similar as carbocation because like carbocation also free radicals are electron deficient, okay. So stability is directly proportional to the number of alpha hydrogen, okay. Stability is also directly proportional to the number of alpha hydrogen. For example you see we have to compare the stability here, okay. Number of alpha hydrogen, nine, number of alpha hydrogen, six, here number of alpha hydrogen is zero. So stability order is this, right. More alpha hydrogen more will be the stability. Number of alpha hydrogen, eight, number of alpha hydrogen, three. Stability order is this. More alpha hydrogen more will be the stability. So friends so far we have discussed about hyperconjugation and in which of these molecules, what are the types of molecules in which hyperconjugation is possible, okay. So we have discussed about alkene, carbocation and free radical. Now we are going to see the types of hyperconjugation, okay.