 Good morning friends, welcome back to Centrum Academy again. Today friends in this session, we are going to discuss various intermediates and their stability comparison, okay. Like if you remember previous classes, we have already seen what kind of different intermediates we have and how the stability of those intermediates get affected by different different electronics effect, electronics effect, right. Like for inductive effect, we have done the comparison of carbocation, free radical carbonyl, okay. Similarly with respect to resonance and hyper conjugation also, we have done the similar comparison. Now since we have already done all these various electronic effects, so now we are looking at the combined effect of all these effects to various intermediates. Like carbocation, last class we have discussed. Now in this session, we are going to discuss free radical and its stability with various electronic effects, okay. So the first intermediates here we are discussing is free radical, free radical. Remember carbocation we have already discussed in the last class, so this is the second comparison we have, okay. Now with this free radical, we have seen that it is electron deficient. Free property if I write down, free radicals are electron deficient, right. These are paramagnetic, paramagnetic, sp2 hybridized, okay. Example you see x, y and z and it has one electron, unpaired electron which is present in this p orbital, right. This is the unpaired electron we have, unpaired electron we have, right. So all these things actually we have discussed, okay. Paramagnetic, sp2 hybridized, trigonal planar geometry, once you see the previous lecture, you will get all this information. Why I am discussing this again here? Because we are going to discuss the stability of this free radical, okay. Since it is electron deficient, so to make this, you know, concept easy, carbocation is also electron deficient, okay. So you can consider this as carbocation whenever you have to compare the stability. Like the same way, like we have compared the stability of carbocation, similar way we can compare the stability of free radical also, okay. However there are not same, okay. Carbocation is what? Carbocation behaves as electron pair acceptor, right. It has vacant p orbital but this is not vacant p orbital. This cannot behave as an electron pair acceptor. So there are difference in free radical and carbocation but whenever you have to compare the stability of free radical, you can consider this as a carbocation, you will get the same answer, okay. So like in case of carbocation, stability order you see, stability order here also is directly proportional to plus M effect plus H effect and then plus I effect, okay for free radical and it is inversely proportional to minus I effect minus H effect and minus M effect, okay. So these are the three things you have to keep in mind, okay. So if we have to compare, so which order we will have to follow because suppose if the molecule has more than one type of effect present in the molecule then which effect is dominating on other that we have to keep in mind. So first we will see the plus M effect, right. Second we will see plus H effect and third we will see plus I effect. After this the fourth one is minus I, fifth one minus H and the sixth one is minus M, okay. This is the order we have to follow, right. Plus M provides maximum stability, okay. So stability decreases in this order. The point is what? Here these three are stabilizing factor and these three are destabilizing factor and among these three minus M will destabilize by a maximum, okay. Minus I will destabilize minimum, okay. So if you have two compounds in which minus I and minus H is minus I and minus M is present over there then the compound which shows minus I effect is more stable than the compound which shows minus M effect, right. If the compound shows plus M and plus H effect then the compound with plus M effect is more stable than the compound with plus H effect, okay. So this order you have to keep in mind. For example we see like you see if you compare the stability of these three, okay. This is 3 degree free radical, 2 degree and 1 degree. Stability order is maximum for 3 degree then 2 degree and then 1 degree, okay. So for this molecule stability order is maximum for A then we have B and then we have C, okay. Here you see A, B and C. It is also 3 radical 3 degree. So A will be maximum then B and then, okay. So like this we can compare the stability order of free radical. Few more examples we will see. You can try it on your own and then we will discuss, okay. All these examples you see. First of all this oxygen has two lone pair on it, okay and it shows plus M effect and this is plus H, right. Plus M and plus H. Both are stabilizing factor plus M and plus H. Plus M is dominating on plus H. So obviously the first one is more stable than the second one, okay. This lone pair, this sorry, this 3 radical is involved in resonance. Here also we have resonance, okay. So in both the molecule we have resonance possible. Like this when resonance is possible in all the molecules then we will try to find out the more conjugation. More conjugation more will be the resonating structure and more will be the stability. So obviously you see here the conjugation is more than this one. Stability in this compound will be more, okay. This is 3 degree. See here what happens. You can apply here I effect. You can apply here hyper conjugation in this question. But hyper conjugation if you see here we have 2, 2 and 1, okay. So we have alpha hydrogen 5 here and here the number of alpha hydrogen will be equals to 1 and 2, 3 alpha hydrogen we have here, okay. So more alpha hydrogen more will be the hyper conjugative structure and hence more will be the stability, okay. Here this molecule you see this shows this shows plus H. This one shows plus I, meta position cannot show hyper conjugation plus I or resonance. This shows also plus H, okay. So obviously we know this as H dominating dominates this plus I. So this one is the least stable third one. The middle one is the least stable, okay. Now these 2 shows plus H effect, okay. So now we cannot differentiate with respect to hyper conjugation here. But plus H as well as CS3 has tendency to show plus I also, right. Here also we have plus I tendency, right. But this tendency is very less. Generally we do not consider plus I effect at para position, okay. So apart from plus H we have plus I nature also here, right. And hence the stability of this is more than this one. So this is the order. First, second and then third, right. Few more examples we can write down, okay. Now these 3 question you see. This free radical has larger conjugation. 1, 2, 3, 4, 5, 6, 7, 8 carbon atoms. You see this free radical and this free radical is in resonance with 1, 2, 3, 4 atom here. But this radical is in resonance with 1, 2, 3, 4, 5, 6, 7, 8. So larger conjugation more will be the stability, okay. And now 2 shows what kind of effect? Minus M at ortho and para position. So here also we have minus M. But here we have minus I. We know para position is, sorry, meta position is unaffected. So meta position because of an electronegative difference between nitrogen and carbon will have minus I effect possible. And minus M will destabilize the free radical. You see minus M is the maximum destabilizing factor, okay. So obviously this one shows minus I will have maximum stability first, right. This 2 if you compare apart from minus M here minus I is also possible, right. So this will destabilize this molecule even more than this one. So first, second and third stability order, okay. Here you see we have hyper conjugation, right. Here we have resonance and here also we have resonance. But here the conjugation is more stability will be more, okay. So this is how we compare the stability of free radical with respect to the different, you know, electronic effects, right. We have to keep this order in mind and accordingly we will assign the stability of various molecule, okay. Next session friends will see the stability of carbon ion.