Functional Groups

Alright guys, so in the next few videos I want to go over probably the most important concepts of this chapter which is recognizing functional groups. Now I know that you’ve all have heard of this before. You’re going to have to memorize some stuff, you’re going to memorize what molecules look like. Hopefully a few of you guys know some of these things from Gen Chem. But regardless, it’s going to be fine. I’m going to give you guys enough practice so that by the end of today you’re going to feel pretty confident with these groups. Alright? So let’s go ahead and get started.
So what is the entire concept of functional groups? It turns out that before functional groups were categorized, what was happening was that scientists were literally just finding out new molecules and naming them after what they wanted. So they named them after their cat, they named them after their girlfriend, they break up with their girlfriend, and then it doesn’t even make sense anymore. And it was terrible. Basically they had these books of just millions of molecules that just had these random names. And you can imagine that if you hate chemistry now or if you think it’s challenging, back then it’s even way worse. So they decided, “Okay,” early 1900’s, “Let’s actually like make groups out of this. Let’s figure out what these molecules do. Let’s figure out if they do similar things and then we can group them together into similar sets of molecules.” So now instead of me teaching you like a thousand different names I’m only going to teach you like 10 or 14, or something like that, depending on how many you need to know for your book, that’s how many I’m going to teach you. Alright? So isn’t that a lot better? Are you guys ready to start? Cool. What we group them into is groups of similar functionality. So go ahead and write that down. That just means we group them according to what they do. Okay? So there are different types of molecules that they all do the same thing or they all reaact in similar ways and that’s how we group them.

So let’s go ahead and start off with hydrocarbons, okay? We’ve talked about hydrocarbons before and these would be your single bonds, double bonds, and triple bonds. Okay? There’s actually more types of hydrocarbons than that but these are the ones I want to focus on right now. Okay? So we’ve been calling them single, double, triple. Now I want you guys to refer to them as alkanes, alkenes and alkynes. The reason is because a double bond can exist in lots of different atoms. It could be a nitrogen-nitrogen double bond. That’s not the same. So if you have a carbon-carbon double bond you should be more specific and you say that it’s an alkene. Okay? So you can tell that all that changes is one letter—A, E, Y. Okay? So as you get further in the alphabet you are adding more bonds. Not too bad.
So I just want to say a few things about carbon structures before we get into a lot of functional groups because if you understand the carbon structures really well they’re going to be easy. First of all, it turns out that all carbon groups, regardless of their size can be symbolized using what’s called an R-group. Okay? This is something we use every single day in Orgo. All it means is this: your R-group is—pardon my French—is I-don’t-give-a-shit-about-this-part group. Okay? I means that you have a particular part of the molecule that you are focusing on and everything else that you don’t really care about, especially if it’s a big molecule, here’s what I’m going to say, that’s an R. Okay? That just means it’s a carbon group that it could be a hundred molecules long. I don’t care about that part of the molecule so I’m just going to write an R instead. Cool? We use that literally every single day in Orgo. Alright?
When alkane—so this is a separate thing—when alkane is attached to a greater carbon chain it’s given a –yl suffix. Okay? So what that means is that an alkane, if it’s a branch off of a bigger chain it actually becomes an alkyl. Okay? So here I’ve shown you an example where I have a six-carbon chain with a one-carbon branch coming off of it. The biggest chain is going to be referred to as the alkane whereas the smaller branch is going to be referred to as the alkyl. Okay? So that’s something to keep in mind that you keep that –yl when it’s a branch.

So lastly we want to figure out giving degrees for carbons and hydrogens. Okay? And degrees just have to do with how many things are attached to my object or to my target. Okay? So the carbon here is given a degree based on how many other carbons they are attached to. Okay? So what I do here is I say that not all carbons are the same. I’m going to differentiate my carbons based on how many other carbons they are attached to. Okay? So I’m going to show you an example on that in a second. So basically the words we use for that are primary, secondary, tertiary, and quaternary, or these little degree symbols. All that means is that tells you how many carbons are directly attached to that carbon. Okay? Then hydrogens, because hydrogens always have one bond, remember that hydrogens are only happy with one whereas carbons can have a lot of different, they always have four bonds but they could be bonded to other things besides carbon. Okay? So hydrogens are just going to possess the same degree as the carbon that they are attached to. So that means if I have a tertiary carbon—that means it’s attached to three other carbons—the hydrogen that’s on that tertiary carbon would be called a tertiary hydrogen as well because it’s a hydrogen of a tertiary carbon. Does that make sense? So what I want us to do, I know it’s kind of a lot to take in, I have these five circles. I want you guys to identify one at a time what types, what degrees of hydrogens and carbons we are dealing with in this molecule. That’s going to help a lot for the next page of functional groups.

So our next functional group is the alkyl halide. And alkyl halide tells you what it is right in the beginning. Alkyl has to do with carbon. So that would be an R. Remember that I said that R can be used for any carbon group. And halide is a halogen. So remember that the letter we use for halogen is X. So the abbreviation for an alkyl halide is R-X. And if you see R-X, we’re talking about alkyl halide. Okay? So like I say right here it’s any R-group that’s directly attached to a halogen. Alkyl halide. This is a very important functional group for Orgo 1 especially. And the degree of the alkyl halide—because remember we’re talking about degrees here—is going to be determined the same way as a hydrogen. Okay? So remember, how do we determine degrees of hydrogen? We would look at the carbon it’s attached to and see how many carbons it is attached to. Okay? So here I have three different alkyl halides for you. You can tell these are all carbon groups. I’m going to call this one A, B and C. these are all halogens directly attached to R. And now what I want you guys to do is tell me if they are primary, secondary or tertiary. Okay? So go ahead and look at the first one and tell me what you guys think. 

So for the next six functional groups what I want to do is I want to kinda clarify something. Have you guys heard about carbonyl? Maybe your professor calls it carbonyl. Totally fine however you want to say it that’s fine. In fact you’re probably going to notice this semester that I’m going to say something different from the way your professor says it. Maybe because the professor speaks a different language mostly as the first language, or also just because, you know, people have different ways of saying these molecules. Okay? So I’m just going to say carbonyl. Carbonyl looks like this. It’s a C double bond O. okay? And a carbonyl is not a functional group. Okay? It is only a component of many functional groups. So if I say the word carbonyl that doesn’t mean that it’s a functional group. It just means it’s a part of a functional group. Okay?
So I’m going to go ahead and talk first about functional groups without carbonyls and then we’re going add carbonyls and see how that’s going to change them. Okay? So the first one, no, not first, sorry. The third one that we’re talking about today is alcohols. Alcohols are defined as ROH. Any carbon group that’s attached to an OH. And there’s lots of different alcohols but the important thing to know is that the way that you name the degree on them is the same as H’s once again. Okay? So now we know that alkyl halides and alcohols are both named exactly the same in terms of degrees. Okay? So here I have an alcohol for you. Please don’t try to drink this alcohol. This will probably kill you, okay? The only alcohol that’s safe for drinking is ethanol. Even if you just take off one carbon to make it methanol it’s toxic, like 50 grams of that and you’re dead. Okay? So they’re not all fun and games, okay? We actually use these in the lab a lot. So what type of alcohol would this be, though? What do you guys think? So it’s attached to one carbon, that’s fine. Remember that we say that you always look at the carbon that that carbon is attached to. That carbon is attached to only one carbon. Okay? It’s the same as hydrogen. So this one is going to be a primary alcohol. Okay? And that’s how we categorize it. Alright. I’m going to give you guys more practice with this later, okay?
Then let’s talk about the next functional group, amines. Okay? So amines, the way that they work is that they actually have carbon groups directly attached to N which means there’s a lot of types of amines that you could have. One of the most common would be just be having just NH3, okay, that’s a type of amine. But if you add R-groups to it that’s also an amine. So if I have RNH2 that is also an amine. If I switched out hydrogens for R’s, that would still be an amine. So let’s say that I had R2NH. That just means I’m taking one of the H’s and replacing with an R. And finally I can even have an R3N that’s also… all of these would be types of amines as long as basically it is a carbon group, carbons or hydrogens attached to a nitrogen that would be an amine. Okay? So what I want to do here is talk about degrees. Okay. So this is an example of an amine. Anytime you just see a nitrogen single bonded to carbons, you’re in good luck. That’s an amine. Alright?
The way that we, oh man, so I just realized that there are typos here. So I’m gonna go ahead and scratch those out, okay? So the degree of the amine and the degree of the amide. Sorry about that. Okay, so go ahead and scratch those out. Sorry, my bad. But the degree of the amine is actually determined the same way as carbon. Okay? So in this case that’s why I have a star next to it because I want you guys to remember this. This trips everyone up where they think that the amine is named like the alkyl halide or whatever so you get them mixed up. What that means is that the primary, secondary, tertiary is based on how many carbons are directly attached to the N, not the carbon that’s attached to the N. So in this case, what type of amine would this be right here, this ring structure? What kind of amine? This would be a secondary amine. Okay? And the reason is because the N is directly attached to one, two carbons. So this one is basically considered like a carbon instead of like the hydrogen. Alright? Keep that in mind and that’s a huge distinction. Okay?
Then finally we have ether. Okay. Ether is abbreviated as R-O-R. An easy way that I’ve always remembered it is “I’m an ether, roar!” That was awkward, right? So anyway, I’m an ether, you’re scary, blow up. Ethers actually do blow up. So maybe that helps you remember. All it is is an oxygen in between two carbon groups. Okay? And honestly we don’t need to name degrees on these because there’s only one type. So that’s it. Just remember R-O-R and you’re good to go.

So what I want to do is I want to add carbonyls next to all of these and see how that changes them. So I’m going to add a carbonyl to my alcohol. I’m going to add a carbonyl to my amine. And I’m going to add a carbonyl to my ether. And I’m going to show you guys how that changes the functional group. So if I add a carbonyl to my alcohol, that means how it’s going to look like is C double bond O with an –OH next to it. Did you guys see that? So basically I’m taking the –OH from here and I’m just adding it next to my carbonyl. Alright? Turns out it’s going to react way different from a regular alcohol because of that carbonyl—which you’re going to figure more about that in the acid and bases chapter. Okay? So what that means is that this is going to turn into what’s called a carboxylic acid and this is the main acid of Organic Chemistry. So most acids that we deal with, a lot of them are carboxylic acids. Then what I’m going to do for these is I’m going to show you guys the condensed form of writing because this is very common. So the way that it’s written is COOH. So if you see COOH that has to do with carboxylic acid. Another way that it’s written is CO2H. Okay? These are condensed abbreviations that confuse a lot of students so it’s important that you guys keep in your memory. This is the memorization part. It’s important that you guys memorize that COOH is a carboxylic acid. It makes sense just by looking at it, COOH. But still you have to make sure you know it. Then you’ve got, so basically alcohol plus carbonyl then you have a carboxylic acid.
Then let’s do an amine plus a carbonyl. In this case what I would get is I would get my carbonyl and then I would add NH2 next to it. Okay? So I’m just taking my amine from here and I’m adding it here. Alright? Well, the condensed formula for this is going to be CONH2 or whatever that, however many H’s that nitrogen has. And this is going to go from being an amine to what we call, either you can call it an amide or amide. Okay? I’ve heard both pronunciations several times from different professors and I say amide. But there will be some ways sometimes you can say amide. It depends on what’s in front of it. Sometimes if the name is really long it’s better to say amide. Alright? So whatever. So I’m just trying to say that don’t be so strict on the pronunciation. Just be strict on knowing what it is. Okay? So that’s kind of easy. Notice that I go from amine, I add a carbonyl and it goes to amide. Easy. Okay? The degree of the amide is determined the same way as a carbon. Okay? So if I gave you the following amide, okay, this is actually going to be… Okay, yeah, I’ll give you that amide. Okay, what type of amide would that be? So it’s actually called a cyclic amide. And later on in Orgo 2 we’re going to learn that these are very important and it gets the name of a lactam. So I’m totally jumping ahead just to make this interesting. Okay. So you do not need to know about lactams yet. But I just want you guys to know that a lactam is a type of amide and what’s the degree of it. What would be the degree of this amide? It would also be secondary amide. So you can call it a lactam or you can call it a secondary amide. Why? Because this nitrogen here is attached to two carbon groups. See how that works? So it’s just the same that we used for that amine and also the same as we were using for carbon.
Cool. So we have this last one. I’ll try to move out of the way a little bit. So we’ve got ester. Ester is what forms when you add a carbonyl and then you just take the –OR from the ether group. Okay? So isn’t that cool? When you take an amine, add a carbonyl turns to an amide. Ether plus a carbonyl turns into an ester. So these names are very similar and that’s one of the ways that helps to remember. You can say you add a carbonyl to it and it becomes one that sounds like it. So ester, the functional group is going to be or the condensed functional group is going to be COOR. Okay? Anytime you see COOR that is an ester. There’s nothing else you need to know about that. Oh, it can also be CO2R. Okay? But other than that I just want to recognize these.

So now let’s talk about strict carbonyl groups. These are gonna be groups, these are going to be carbonyls C=O’s that do not have oxygens next to them, hydrogens next to them, stuff like that. All they have are carbons, okay? In that case it’s still not appropriate to call them carbonyls. Instead we’re going to use the word or the names ketone and aldehyde. Okay? So what I’m going to do here is I’m going to give you guys the explanation of the difference between them because a lot of students get stuck on what’s a ketone, what’s an aldehyde. Alright? So I’m just going to show you guys really quick. A ketone is going to be a carbonyl that has two R-groups on both sides, okay? Whereas an aldehyde is going to have one or more H’s on one of the sides. Okay? So right there there’s the difference. An aldehyde is going to have an H whereas a ketone will never have an H directly coming off of the carbonyl. Okay? But another way that I like to think about these because I think that it helps, is if you’re looking at a structure just like I have right here—like a really big structure, another way that I think is that a ketone is an internal carbonyl group whereas the aldehyde is a terminal carbonyl group. Now what are these words “internal” and “terminal”? They are location words. They are actually words that we use a lot in Orgo. It means it’s something in the middle of the chain or of a ring, or something at the very end. Okay? And then you could guess that terminal would be the end. So here what I have is I have three carbonyls, okay? And instead of thinking of H’s and R’s, we can think about internal or terminal. So right away, how many of these carbonyls are terminal? Meaning that they are on the very last carbon of whatever chain they are on. And the answer is two of them are terminal. This one is terminal because it’s at the end of that long chain. And this one is actually also terminal because it’s at the end of that break. Does that make sense? Both of these also have an H that’s not drawn. Okay? If they both have an H that’s not drawn, what types of carbonyls are these? Aldehydes. Isn’t that cool? I don’t really care which definition you use. I’m just trying to give you guys multiple ways of thinking about it. Okay? But I, a lot of times, I get confused on which ones are which so I just start thinking that aldehydes are at the end. I would say that aldehydes are at the end and that would help me. Alright? So lastly, what about this carbonyl here? This one’s not terminal because it has more, it has an R-group right there so it has a carbon coming off of one of those sides. So basically this carbonyl would be internal because it’s surrounded by carbon on both sides so this would be my only ketone on this molecule. Alright? So I’ve have my hetone, I’ve got my aldehydes. Learn to recognize them. I’m going to give you guys practice on this. Notice that these are only ketones and aldehydes because they don’t have other types of atoms next to them. If they had an Oxygen or if they had a Nitrogen, then they would become the other functional groups that we talked about like amines and stuff like that.

So now I want to talk about the condensed structures so the condensed abbreviations for these can be a little bit confusing so for ketone it's actually just going to be and so this can get this can get confusing sometimes it's going to be COC, OK? And what that means is that sometimes your professor is going to be nice enough and give you C double bond O C, OK? That means that kind of helps you that this is a carbonyl, OK? But sometimes they're just going to say COC and they're going to expect you know that there's a double bond in between, OK? Now so you guys are probably wondering how is that that differ from an Ether then? Because an Ether is ROR so how COC different from ROR? Because remember that if it was an Ether, Ether would be CH2OCH2 and then the rest of the R group, R here and R here notice that both of those carbons would have 2Hs coming off of them, OK? Whereas for the carbon right here that carbon is never going to have Hs coming off of it so that means that the R group is going to be directly attached to a carbon that does not have any hydrogens on it so basically the carbon I'm looking at is right here, I tried to use different color that carbon right there is never going to have hydrogen so that's the difference instead of saying CH2O it's just going to say CO and when you see the CO that tells you this is a ketone and not out an ether, this would be ether down here by the way, not trying to confuse you that would be ROR would be an ether, OK? So, like I said I'm kind of going above and beyond here hopefully your professor gives it to you like this if they give it to you like that then we're fine because you have a double bond there it's very easy but if they give it to you like this then you need to look at the fact that it's CO meaning C double bond O, alright? Awesome so then finally Aldehydes kind of sucks too the abbreviation for Aldehydes is probably one of the worst ones in organic chemistry and it's CHO, OK? How does that make sense? I do not even know I think of it like a Choo Choo train like it's CHO, alright? So, there's really not a good way to remember it other than just memorize it I still have students in Orgo 2 that will forget that CHO is an Aldehydes so I would just say commit it to memory make sure you don't get confused, alright? Make sure that you just like give extra special attention to Aldehydes.

So nitrile, this is a functional group that I really never have problems teaching because it's so weird. Basically, it's so much different from the others. It's just going to be C triple bond N. It starts with N and it has an N in it, so it's a nitrile.
The abbreviation for this in condensed formula is just CN. So that makes it really easy. If you see CN, that just means C triple bond N. 

Then finally we have benzene. I’ve been avoiding benzene for a while now. I haven’t really talked about it but now I want to give it some attention. So benzene is a type of aromatic compound. Okay? We will not learn about aromatic compounds until Orgo 2. So I’m not going to explain on that means. I’m just gonna ask you to know that that exists. Okay? That’s when we get into the fun stuff in Orgo 2, right? But dor right now just be able to recognize it. And it actually has two different names when it’s a branch on a larger chain, okay? If it’s just by itself, like the Clutch logo, okay? If you just see it by itself, that’s benzene. Just say that it’s benzene or you can also call it aromatic. But when it’s part of a larger chain it gets its own types of branch names. For example, when it’s directly attached to an R-group, the name isn’t benzene anymore. It turns into phenyl, okay? And phenyl indicates that I have a benzene directly coming off of a chain. The way that we write it in condensed formula, a lot of times it’s as C6H6, okay? I’m sorry. I messed that one too. C6H5, okay? Because it has one Hydrogen missing because it’s directly attached to the next R-group. Okay? And then also it can be abbreviated as -ph, okay? But this is not the pH you saw in acid and bases where you have like a lowercase p and a big h. This is like both of them in lowercase. Okay? Cool. And then if there happens to be an extra CH2 group just like in between the benzene and the ring, and then it gets an even different name and that name is benzyl. Okay? Now this one to me is counter-intuitive because if I were writing organic chemistry from the very beginning and I saw a benzene group on a chain I would say, “Oh, that’s a benzyl group because alkyl, alkyl like alkane, alkyl. That makes sense.” But it turns out, for some reason they decide to name the one directly attached to it at phenyl and the one that’s one carbon away as benzyl. So it’s kinda flipped from what you would think and that’s why I want to point out that benzyl always has that CH¬2 in the middle. The way that would abbreviate it is as -CH2C6H5. So notice that there’s that CH2 in there. And then it’s also abbreviated as –bn. Okay? Not often, but I have seen that before. So I’ve got this long chain with two benzenes on it. And I want you to tell me which one is the phenyl and which one is the benzyl. So go ahead and look at it for a second and then let me know. So this one will be the phenyl because it’s directly attached right here. And then this one would be the benzyl because it has one carbon in the middle. It has an extra CH2. Does that make sense? So that’s a benzyl and a phenyl. And that’s the way we’re going to use them when we’re naming benzenes on rings.

So what I want to do is just a work example. Just between you and me, free response, go ahead and try to identify all the functional groups in this molecule. So first of all tell me how many functional groups are there? Is it three, is it five, is it seven? Go ahead and tell me. Then go ahead and try to identify each one. And if applicable, tell me what the degrees are. So tell me, if it’s an amine, tell me that it’s secondary or whatever. So go ahead and try to do that. Pause the video and then let’s go ahead and talk about how many functional groups and what they are.
Alright. So that was a little tricky. I think that it was even more tricky because I gave you some condensed formula in there so it kinda threw you off a little bit. Students typically hate to work with condensed formulas. So if you didn’t mind it then good. So the first of all, how many functional groups did you guys find? And the answer was three. Okay? Because I had this double bond. I had this oxygen over here. And then finally I had that iodine. Okay? now, so you guys might be wondering, what about alkane? We learned that alkanes, single bonds between carbons and carbons are functional groups. We talked about it. Actually it turns out that alkane—I should have mentioned earlier—is the only one we don’t consider as a functional group because alkanes are the backbones for all organic chemistry. So, and they happen to not be very functional. In fact they barely do anything. So when we’re talking about functional groups we are talking about things that are different from alkane. So that would be these three things.
So what was the name of this first one? This would be an alkene, okay? What was the name of this one right there? This one actually gets tricky because I wanted you to name the degrees too. So this would be an alkyl halide and particularly it would be a secondary alkyl halide. Why is that? Because it’s attached to two carbon groups. The carbon here, remember that iodine, it would be named as a hydrogen. So I would count one carbon, two carbons. Cool? And then finally what did you guys get for this last one? This would be ether. Okay? Because this falls into the R-O-R category where I have R-O-R and there’s no carbonyls around so this would not be like an ester or anything like that. Cool? So does that make sense to you guys so far? Hopefully this is helping you guys reinforce all of the groups that we just learned. So let’s go ahead and go to the next page.

So now we're going to work on some groups that not all books make you know, but your book does, so we're going to go ahead and go over them just to be safe.
Acyl chloride. Acyl chloride, you can think of it like an aldehyde, but instead of having an H, it has a Cl. The acyl chloride has a condensed structure of basically, RCOCl. If you ever see that, that's an acyl chloride. We're not going to work with these a lot in orgo 1. We're actually not going to see these again until orgo 2, we're going to work with them a lot. But it's cool. It's good that you guys know these ahead of time.
Then you've got another one that has to do with carbonyls and that's anhydride. An anhydride is a little bit tricky. Think of it almost like an ether, ROR, but instead of having just R-groups it has carbonyls on both sides.
It turns out that the way to name an anhydride through condensed structure is pretty tricky. Sometimes it's just listed out exactly the way it looks so that would be – let's just write that out, CH3COOCOCH3. So you can see that was a little bit tricky.
But sometimes it's also written with the O in the middle leading off and that's the one that I happen to see a little bit more. So that would just be that you take the O and then you have everything on both sides instead of the same, in this case, in parenthesis. So then that would just be CO and then R, whatever R group you have, that would be this R group right here and this R group right here times two. And that basically tells you that you have – we're splitting this thing down the middle and you've got one of these things and you've got the second one there and both of them are COR.
There you go acyl chloride, anhydride. You're not going to have to work with these too much, but maybe just recognize them for the test. 

Then finally we've got sulfur compounds, now why am I listing oxygen again? Because sulfur happens to be right below oxygen in the periodic table so it's going to make very similar structures to oxygen, OK? So, what I want you to think of is what would the structure be like if it was an oxygen what would be called? And then what is it called if it's a sulfur? So, let's start off with the oxygen ones because I know you guys can help me with these, what type of group do we make if it's terminal? Basically, if the O is it the end of a carbon chain what is it called? good job that's called an alcohol, you got this, how about if its internal? Meaning that the O is sandwiched between two carbons, hint we just talk about this. Ether ROR scary stuff, OK? So, there we go we have our terminal Alcohol, terminal O is an Alcohol, internal O is an Ether, OK? So now let's talk about the sulfur, sulfur like I said right underneath O so it's going to have 2 bonds so it's going to make very similar compounds, if the S is terminal it's going to instead be called instead of an alcohol it's going to called a Thiol, OK? So, Thiol instead of Alcohol and then instead of an ether if it's on inside meaning it has carbons on both sides it's going to call the sulfide, OK? So, these are just names that you literally need to memorize you don't necessarily need to know degrees for these but if you were asked the degree of a Thiol it would be the same way as an alcohol so this would be what we would actually call a primary Thiol because it has only one carbon attached to that carbon.