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- Solutions 63

Draw all constitutional isomers with molecular formula C_{5}H_{10} that possess one π bond.

Hey guys. So, in this problem we need to go ahead and figure out all the constitutional isomers for the formula C5H10, okay? And we know that we already have one PI bond in the compound, okay? So let's go ahead and use our IHD to figure out if we need a ring or anything, okay? So guys C5H10 we know that our IHD formula is 2 and plus 2 minus H all divided by 2, right? So guys our n is equal to the number of carbons and our H is equal to number of hydrogens in this molecule, right? So guys we're going to get 2 times 5 plus 2 minus, minus 10, right? All divided by 2, 2 times 5 is 10 plus 2 is 12, 12 minus 10, what we're going to get is 2 over 2 or 1, right? So we know that we can't have any ring since we already have that double bond, that PI bond included, okay? So let's just start off by drawing a carbon chain, right? I'll find a carbon chain, there we go, we have a 5 carbon chain and we need a double bond, done, right? What about anything else, can we draw something else? sure, right there, can we draw anything else with the straight chain? no, because if we were to draw it here or on the other side it's the same thing just a rotated version, right? The rotated version of this one is this, the rotated version of this one is this, right? These are equal, so we only have these two right now, but what about branching? sure, we can definitely go ahead and branch, what if we did this and on our fourth carbon? Well, really on our second, follow the IUPAC rules, we get another carbon, right? Well, what if we add our double bond here, okay? That one works, what if we do this? add our double bond here, that one also works, what if we did this, that one works just as well, that's a whole different thing, what if we drew something like this? guys, if you notice that's actually just the one right here, that's this one right here, it's the exact same thing, I just rotated it, right? How about something else? no, I'm just going to save some time and tell you that no, these are our complete ones right here, these five right here are all of our Constitution isomers. Alright guys, let's move on.