Organic Chemistry Reactions - Video Tutorials & Practice Problems
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What you need to know about types of chemical reactions.
Video duration:
29s
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Video transcript
in this chapter, we're gonna be talking about reactions, and what that means is that your professor is gonna want you to be able to recognize basic types of reactions. So you're not going to need to understand all the reactions that happen in organic chemistry yet. But there are four major types of reactions that your professor is going to expect you to be able to recognize. So maybe you don't fully understand it. But you say, Hey, based on these general features, this must be this type of reaction, all right? And this could be a multiple choice type of question for you on your exam. Let's go ahead and get started.
We’re gonna learn about 4 different types of chemical reactions. You don’t actually need to understand these! Just be able to recognize them for now.
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Recognizing Acid-Base Reactions.
Video duration:
2m
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Video transcript
So, as I said, there's four major types and the first one is the easiest one. This is gonna be what we call an acid base reaction. And in most textbooks, this will have its own chapter, so usually will have spent an entire chapter just talking about acid base reactions. Now the general features of this that you should be aware of our that molecules of opposite charges are going to react together to exchange a proton. Okay, now I use the word proton. Earlier in the first chapter, when I was explaining just electrons and protons and stuff and what I said, a proton was is just a h plus. Okay, because remember that it's a hydrogen, that it doesn't have a new electron and it doesn't have a neutron. So it's just it's just a proton, and that's what we call it a proton. All right, now notice that I did put the word usually next to it because it turns out that there's gonna be some special types of acid base reactions that don't exchange the protons. Alright, but we'll get there. Okay, I'll let you guys know what those are, so I just want to show you guys this example. There's a very common example where I have basically a negative charge. Okay, so that would be one of the charges. And then I'm looking at the other molecule, and I see Well, there's no positive charge. So is this really gonna be acid base? Well, if you think about it, we've already wanted about election negativity, right? And remember that we learned how to draw dipole moments. So if I were to look at this H o Bond right there, is there a die poll on that bond? And the answer is yes. There's actually a very strong DYP whole pulling towards the oxygen. So what that means is that more electrons are at the oxygen and less electrons are at the hydrogen. Are you guys comfortable with that? That just has to do with the partial charges that we assigned. Imagine that the O is like the sumo wrestler pulling on that rope and pulling all the electrons towards itself. And the H is like the puny guy that can't even keep up. All right, So what that means is that we are going to get in exchange the opposite charge that I'm talking about is this opposite? Lee charged hydrogen. So I have a negative interacting with a positive. And what's gonna happen at the end is remember that I said you get exchange. So what that means is that I'm going to redraw this first compound and what I'm going to draw is that now this Oh, gets a negative because before the other oh, had the negative. And now this O H over here is now attached to the H that came from the other compound. All right, so basically what happened was that I switched a negative charge and in h see how that happened. That's what we call an acid based reaction when we're exchanging charges and protons alright and we'll get more into the into depth later.
In this reaction, two molecules of opposite charges react to exchange a proton. (There are some exceptions that don’t, but we’ll get to this later)
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Recognizing Substitution Reactions.
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1m
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So now what I want to do is talk about another type of reaction that's actually very similar. And that's the substitution reaction. The substitution reaction is essentially an acid based reaction. Really, It's the same thing, except that the atom or group of atoms that is exchanged is something other than hydrogen. Okay, so remember that in asset base, we're always moving a hydrogen from one compound to another in a substitution. It might be the same thing. We have the same charges. Negative, positive. But instead of moving an H, I'm gonna move another atom. So in this case, we would apply the same exact thing. I would say. Okay, I have my negative charge here, but do I have a positive on the other side? Well, if I draw my die pull moment, what I would see is that I have a very strong typo Mormon pulling towards the Florida. Do you see that? So what that means is that there would be a partial negative here, and there'll be a partial positive here. And what's gonna wind up happening is that we're going to wind up switching places of whatever's here and whatever's out here. Okay, so basically the two things that have negative charges are gonna wind up switching places. So, like I said, you don't need to know this yet because this is going to give get an entire chapter to itself. Substitution reactions always have their own chapter. But I'm just trying to explain that what's gonna happen is that now the O. H would be appear, and now the f negative would be over here. So see, what happened in a substitution reaction is that we still got things exchanging, but they weren't hydrogen. It was actually two different molecules, okay?
This is an acid-base reaction where an atom (or group of atoms) other than protons are exchanged.
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Recognizing Elimination Reactions.
Video duration:
40s
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Video transcript
I just want to talk about elimination. Really quick. Elimination is also ah, chapter that e mean a type of reaction that we dedicate an entire chapter two. And elimination is really easy. All you need to know for right now is that you're gonna take to single bonds or what we call Sigma Bonds. Right. And we're going to create one double bond or what we call a pie bond. Okay, So as you can see, the Z groups don't even worry about it. That just means it could be pretty much anything. Okay. And after the elimination reaction takes place, I'm gonna wind up getting a double bond. So I turn to Sigma's into a pie and the reason that we call it elimination. You're going from two bonds toe one. So think that you're eliminating a bond pretty easy, right?
Here, two single bonds (σ) are removed to create one double bond (π).
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Recognizing Addition Reactions.
Video duration:
38s
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Video transcript
addition is the opposite of elimination. The same way that you would say, like multiplication and division are opposites addition and elimination or opposites Addition also always gets its own chapter. So these are things that we're going to spend a lot of time on later in the semester. I'm just giving you a glimpse right now. And what we do for addition is we take one pie bond and you guessed it. We just do the opposite. So we make two Sigma Bonds. Okay, So all you need to feel to do for the sake of this chapter is just recognize these. Just look at it and say, Oh, that's in addition, reaction. That's a substitution. Okay, later on, we'll spend an entire chapter on each of these reactions, and you guys will actually be able to understand what's going on.
In these reactions, one double bond generates two new single bonds.
Addition and Elimination are inverse reactions! In some cases they can perfectly cancel each other out.