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Solution: Draw resonance structures for each of the following:...

Question

Draw resonance structures for each of the following:

Video Transcript

Alright guys, let's take a look at our compound it wants us to draw the resonance structures for this compound here now we need to include where our bonds are. So, really quick, let's just indicate them right here, here, here and we know there's going to be a bond here to our oxygen as well, this oxygen is going to have two sets of lone pairs on it, right? So it has a total of six valence electrons such that we have a lot of conjugation here a lot of resonance possible because we have alternating double and single bonds throughout our molecule, so what we can do is we're going to show that we're not going to have this lone pair come down and make a triple bond, right? We're going to show this pi bond kicking electrons up to our O and as a result of that we're going to get a compound that looks like this. Notice that nothing on our ring has changed but we originally had two sets of lone pairs here, but after doing our first arrow, right? after draw our first arrow and showing the flow of electrons we know that this oxygen is going to have a negative charge because it has seven valence electrons and as a result, remember, we have one hydrogen here, right? Now, there is no hydrogens there and here notice that we're not going to make a new hydrogen, we're going to have it a positive charge, right? So now we have a charge adjacent to a PI bond, so what's going to happen here is we're going to show that, show it in red, that this bond is going to break and move over, over here as a result or we're going to get is something like this and what I'm going to do is just show that these electrons up here aren't going to change, so I'm going to copy the structure, so we can continue on with this throughout our molecule. Notice that we're going to have a new PI bond right here, these are not going to change. Now, something's missing on this structure, right? Doesn't it look a little bit off, re we had alternating double and single bonds, so we had a conjugated molecule, here that's still going to be the case. Now, we have our positive charge moving over here and throughout all these resonance structures we're going to see this same pattern throughout this ring, right? Where if I just keep going here, we're going to have the same pattern occurred. So, feel free to go and try and jump ahead and see if you can draw, what these runnin structures look like and then we'll check our answers, so what's going to happen here is this charge is going to move over, that's going to give us a PI bond right here and this one's not going to change on top but when we do so we're going to get a positive charge here, okay? Next we're going to make a bond here, right? So we're going to have a PI bond here, a PI bond here and our positive charge is going to move up top. Now remember, we can keep going one more time, right? So what we can show is that when we get to here we're going to use this bond, right? And make a new bond there, so we now have again a six membered ring with alternating single and double bonds, so we're going to show our new bond here, we're going to have a bond here, and a bond here, so notice that our bonds actually changed from our original structure, so now what we can do and lastly we have a positive charge here. So, in our last compound, let's draw it right here, we're going to show, let's just do that an angle, we're going to show that we're going to get back to something very similar to our original compound where what can happen is this lone pair is going to reform that double bond, we're not going to get any charges in our final structure, right? And finally we're going to have a double bond, I'm going to redraw in this oxygen, we're going to have a double bond for right here, okay? Guys and this is actually our last resonance structure that we can draw, let's indicate all this in brackets, okay? So, just pay attention to the flow of electrons, we had a PI bond becoming a lone pair and then we had our double bonds moving around our ring. Alright guys, hopefully that made sense.