hey everybody welcome to Joe cam for my season vets that were with me all the way through oh come one welcome back for anyone that might be a little new welcome to Joe Kapp so obviously I'm Joe and basically I made this website because I love organic chemistry but what I love more than organic chemistry is helping other people understand it so the way this website works or at least the way I want it to work is that we're going to talk about everything under the Sun for the ochem 1 & 2 and basically we're going to kind of break it up in ways I think might be a little easier better way to understand them and then I have worksheets to kind of reinforce those concepts and I have the answers for you guys so because what's what's doing problems without having the answers to check yourself ok that's kind of a little introduction for those who are new but today I want to kind of introduce the topic of conjugation because we're going to kind of dive into the bigger kind of arena of conjugated systems but I just want to talk about conjugation in this video so nothing too overwhelming in the first one first video in O chem - ok so I want to review kind of what a PI bond is really quickly so I'm just going to throw up F beam on the board revenue F teen is just an alkene - carbon alkane alright so if I'm going to look at this carbon right here in this carbon right here if we are going to assign hybridization to both hydros Asians to both of those carbons right we have one two three bonding areas so that would be sp2 hybridize because I have three bonding areas that means I need three orbitals to make hybrid orbitals which leaves us one unhybridized p orbital to help make the PI bond right here and honestly same deal over here this guy's sp2 hybridized because he is one two three bonding areas that means we use just to make it clear s P P and we know that we have three P sub shells so he's on hybridized because we only need sp2 so he also has an unhybridized p orbital and if I was going to kind of draw a little molecular diagram of how that works right I have the carbon bonded to hydrogen's we know that in this double bond there's a sigma bond right sigma bond being the head-to-head overlap connection between these two carbons and then that unhybridized p orbital is manifested right here we have two P orbitals that are parallel to each other and that makes up the PI bond that is in this double bond okay so why did I cover that well here's why the conjugation is basically the concept that if you have a bunch of P orbitals strung together in a row that kind of is a stabilizing effect for a molecule and let me show you why so if I drew 1/3 of butadiene right here so just four carbon chain with two double bonds you can see that this card right here he's sp2 this carbon let me draw two up there this carbon right here he's sp2 carbon down there sp2 and you can see where this is going this carbon right here also sp2 so on hybrid SP orbital on hybrid SP orbital unhybridized p orbital on hybridized p orbital so let me just draw on these orbitals basically when you have these networks of continuous P orbitals I'll draw the residence in a second but these electrons right here in the this pi electron system they kind of get smeared and shared across the network of P orbitals and remember just like we've talked about resonance in the past whenever you can kind of distribute charge over a whole structure as as opposed to just keeping it in one place in a static situation that's a stabilizing effect right so let me draw some resonance really quickly so remember when those residents that's a stabilizing effect for an molecule so if I were to move this double bond over here I could kick this double bond up as a lone pair and that would look like this now I'm not saying that this is a great resonance structure but there's resonance apparent right so that's a stabilizing effect so what I'm trying to say is that conjugation whenever you have these lengths of continuous and sp2 hybridized carbons or sp2 hybridized atoms with P orbitals there's this delocalization of electrons right there aren't just electrons in this double bond here and electrons in this double bond here there are electrons you know kind of I'm going to draw another structure it's almost like they're kind of shared across all the atoms as you can see by this resonance form right because we know the overall structure the overall resonance hybrid of this structure is a mixture of this double bond representation here and this resonance form here it's kind of somewhere in between all right cool so let me just kind of throw up some examples of what does a conjugated chunk shirt wasn't what is not a conjugated structure so if I were to draw up this structure for you and I asked you is this conjugated or is it not conjugated it's conjugated because if you can see this carbon right here he has a p orbital he's sp2 hybridized this carbon part of the double bond sp2 hybridized so does this carbon and so is that carbon you need at least three carbons in a row to the sp2 hybridized okay so they all participate in this network of P orbitals they help support the delocalization of electrons conjugation stabilizing effect lowers the overall energy of a molecule okay now there's kind of a so we can have them all be a part of double bond or we can have a situation where there's they're not exactly part of a double bond but there's still sp2 hybridized so let's think of some other ways we can have carbons be sp2 hybridized let me just draw a simple three carbon structure for you here okay so here's a carbo cation and remember if I drink these hydrogen's right here since he's lacking the bond he only has one two three bonding areas aka he's sp2 hybridized and remember carbo cations they are sp2 hybridized they have you know that trigonal planar structure well because he's sp2 hybridized he has an empty unhybridized p orbital and this guy has an sp2 orbital or sorry an unhybridized p orbital and so T so carbo cations can also help participa can help link together these you know systems of P orbitals to support conjugation and also let me erase this real quick I just want to kind of give a name to that type of charge right here actually let's go up here so again let's just say I have a negative charge right here right so you're saying okay but you know if we drew in the implied hydrogen's that lone pair counts as bonding here yeah so you know he's 1 2 3 4 he's sp3 hybridized and I'm not going to disagree with you but one thing that can happen though is one of those sp3 orbitals because the structure knows how energetically favorable it is to be conjugated he'll put this lone pair and an orbital vacuum ally itself parallel to the P orbitals of the rest of the structure so if you can have a lone pair kind of orient itself to support conjugation it will on the other hand last cottage type of a way you can be conjugated without being part of them to bond if we have a radical throwback to the free radical chain reaction all the way back into a chem 1 we know that radicals are sp2 hybridized these radical electrons the one rack electron he's thrown in unhybridized p orbital again that helps support a link the linkage the system of conjugated unhybridized p orbitals so positive charges can support conjugation if they're all in a row with the rest of the P orbitals negative charges can align themselves to do the same so can radical electrons and also this charge I've continued to draw if you have something like a charge whether it be positive negative or a radical electron and it's next door to a bond like this this is called the allylic position this would be an allylic carbo cation or if I drew this for you guys this would be an allylic carbon ion or if I drew this this would be an allylic radical and you can see that this is stable obviously there's conjugation so we know it's stabilized but the stabilization comes through resonance right the charge is distributed or it's delocalized right because if I drew some residence for you guys here I could move him there that don't want over here and the charge is now moved to the far left or same concept if I move this electron pair over here and kicked him this double bond is a lone pair up there the charge is moved over there if I were to put the rack electron down there and move to one electron over here to form a double bond and moved the other radical electron over there I would have a new radical on the left terminal carbon so a look a little the allylic position is any position directly next to a double bond that is not a public apart of a double bond there has to be some type of charge right there has to be you know positive negative radical okay so you can see that it's conjugation is a pretty powerful thing it's a very powerful stabilizing effect because through through resonance we can kind of rearrange charge and every time we rearrange the localized spread charge out around a whole structure that's always a very stabilizing effect okay so this is just the first video just interested introduction to conjugation and the allylic appended position I have a worksheet for you guys so go ahead and hit the worksheet I'm pretty sure it's just identifying our structures conjugated because if I gave you guys something like this versus something like whoops like that see how one-two-three four-five-six sp2 carbons in a row and then there's a break because of these two carbons right the link is broken there's no continuous network of P orbitals so this would be conjugated and this would be not conjugated the worksheet it helps evaluate do you know how to identify a conjugation or did you know how to identify the lack of conjugation so go ahead mess around with some conjugation and then we'll talk about how this can affect reactions that we've done before and gives us a different mixture of products see in the next video