 Monday, Wednesday, Friday, classes end up being 10 to 11, 11 to 12. I've kind of split the hour from 10.30 to 11.30. But honestly, if you want to catch me another time, come on by my office. You should net my doors usually open. There shouldn't be an excuse I can't make to office hours. In terms of getting in touch with me, this way, catch me after class or during my office hours, particularly for questions involving organic chemistry where there are structures involved, it's very hard to communicate about technical matters by email and just honestly not too good at checking my email. Let's see, the other thing, if you, the other people who are going to be very, very important to you in the class are teaching assistants, Johnny Pham and Kim Lee. And I picked two of the best graduate students from my laboratory to serve as teaching assistants. Johnny and Kim, do you want to stand up? So Johnny and Kim are going to be handling the discussion sections, and so you'll get to know them in the various discussion sections for the course. They've set office hours on Wednesday and Monday, and they meet right in the area outside of my office, so you'll be able to meet with them. And I've posted their email addresses here. So the textbook for the class is the Smith Text, which you've been using. I won't go a whole heck of a lot into it. I think it's a pretty good book. I'm going to put emphasis on various parts in the lecture to break up some of these. You'll get a feeling for what I think are some of the most important aspects of seminal material. I'll sort of follow directly out, but I think they have a really good way of explaining things, some of the things I'll pull from other notes of my own. You'll get a sense of what my perspective on them is. Ultimately, what I want to be doing with this is sharing my perspective on the Smith Text, which I really love and am passionate about. Organic chemistry is so central to life and to all of its functions. Johnny and Kim are both earning their PhD in organic chemistry and are working on health-related problems. Johnny is working on how to understand his research, how to understand and control protein aggregation and Alzheimer's disease using organic chemistry. Kim is working on protein interaction in cancer and in HIV transmission again using organic chemistry. And the thing that we're going to learn in this class is central to understanding all of life's processes and in terms of developing new medicines. All right, so the textbook for the class, as I said, is pretty good by now. Probably none of you are going to be doing this, but if you want to get the electron, if you're coming in, say, from having been in a different quarter elsewhere and you want to get the electronic version, that's available as well. Now, organic chemistry classes are really only a whole piece of the picture. The biggest picture for organic chemistry is not reading a textbook. It's not just coming to class. That's sort of the basis. But the real part is active learning. And organic chemistry, in particular, you learn by actively processing problems. One of my developments in this section is I can't do what I've done in the honors class. The honors class has students get rated feedback from the GAs. It's also a much smaller class. And it's really, it's just so incredibly valuable. When you're working and wrestling with a problem set in a deadline, you have to actually work with the problem set yourself. And the other thing, of course, that's wonderful, is day one. I hate them, but I love them for myself. I mean, it keeps me on focus. And this is, of course, one of the greatest quarters that I've ever been in in the past days. It's easy to fall behind in the class. And so, what I've done is the next best thing that happened with Johnny and him were homework assignments individually. And that is, you're going to have electronic homework through that little learning. How many of you have used this in previous quarters? So most of you are familiar with this. This has been the first year I've adopted this system. I consider it to still be a work in progress. This is the first time, there's a lot of junk out there, I've been watching for years with the textbook companies coming up with their fifth molecule, quick. This is the first point, I think it's getting close to thinking of life of any kind. It's not perfect. It's a little plumpier on the implementation than I'd like. But it's a baseline, it's a starting point. On top of that, we're going to have problems that you work and present in the discussion section. And there are homework problems, which, alas, are too adsorbed, have the answers key with them. So you can always check yourself. But I know, I know, I know there's this temptation when you're working problems to look at the problem, say, oh, I understand it, or I think I understand it, then look at the answer key. And that is such a broad circuiting to the learning process. And so I urge you, I beg you, if you want to master the material, don't do that. Actually write out the answer, come in, and then go ahead and look at the answer key. And I know it's hard to answer the question. So, all right. So you have the website for the course, and let's see. So we have discussion sections for the class. As I said, we're going to be working the problems, working problems in most of these. I've made them match up to the chapters in the course for running through chapters 19 through 25, and then we're jumping to carbohydrate in 27, and then the last week we'll do some special topics from amino acids and from some of the chemical chemistry. And so I've matched up the discussion sections to them. You need to be enrolled in a discussion section. It's best to go to the one you're enrolled in, but if you can't make it to the one you're enrolled in, there are other discussion sections you can go to. It's a little confusing how I've juggled things because we miss Monday discussion section. We're going to hit the ground running on Tuesday. Discussion sections in the first half of the course are going to run Tuesday to Monday, Tuesday to Monday each week. Then at the midterm, we're going to switch. We'll have a block of discussion sections from Wednesday to Friday right after the midterm, which will be going over the midterm. I urge you to come to it. It's a great way to learn about things that you didn't understand. And then for the course after the midterm, our discussion sections will be running one day to Friday, one day to Friday. And if you're in the Memorial Day one, you'll just pick up one of the others. If that sounds confusing, don't worry. I've put a link here. And you can go ahead and see the schedule for discussion sections so you never miss out. So that's just on the syllabus website. Friday had two discussion sections that had very low enrollment. And so we closed those discussion sections. I urge you to come to the, I think it's the 12 to 12.30 on Friday. Instead, 12 to 12.30. But if that doesn't work with your schedule, just pick another discussion section. This is the first time that I've taught this particular section. And so I've set up our schedule in advance. I think it's all going to work. But you should check the website just in case we make any changes in the scheduling. So I've set up all of our reading assignments for the year up here. And I've set up our first homework assignment and it's deadline. And then others, I've set the deadlines, but I'll be getting the problems up there. The problem should be up about a week in advance. If you're not seeing the email, I'll let you know if there's maybe something went wrong with the posting. Sorry, like for the homework assignment, some of them say not to be submitted. Ah, great question. So the question is, for the homework assignment, some of them say not to be submitted. So the sapling one is the course you submit online. I would love to be able to see your paper written out of homework. In fact, you would make me incredibly happy if you come to my office, if you ever don't understand something. And bring me a big sheet of sloppy, messy papers with pencil straws with all of your efforts on the homework. If you come to my office, bring your notes, I don't know if you don't understand, I want to be able to help you. I want to see your homework. But as much as I would love for Johnny and Kim to be able to actually bring their homework, they can. So the second best thing to having homework that's actually due to hand in is problems from those textbook homework assignments are going to come back to you on the quizzes. So the quizzes, you're going to have seen all of the problems before. The quizzes are going to have problems that are taken directly from the discussion sections and from the Smith homework problems. The discussion section problems won't have answers. You won't be able to get them along the line. So you've got to go and visit the discussion sections to see the problems and to discuss them. All right, homework's always a conundrum, particularly in the context of the issue of academic honesty and reading. And I've really thought before you about this issue for homework because I see it as different from the exams. My heartfelt feeling for you on the homework is I want you to learn by doing the problems. Some people like to work problems alone. Some people like to work problems alone. My primary feeling is learning. And so I've really set up the net. If you get a problem wrong, it coaches you. You get a chance to do it over. There's just a small penalty. So for working in groups, my philosophy is it's OK to have real peer learning to be learning every day. What's not OK is to just be approving a person's answers and then to be mindlessly typing them into the sample. And that's not learning. That's not teaching. If you're actually communicating and understanding something here, you're learning how to communicate. You're better reinforcing the ideas in your mind. And your peer, in turn, is actually learning. And it's the industry, industry, or individual working groups that I would see on the homework problems. All right. So I've got to come to the lecture section. You're going to miss things if you don't. I've set up this course on video. Videos for the course will be available if you have to miss the lecture or better still, if you want to miss the lecture. You can download them. We're going to get them on YouTube. The open course website produced the I. And I tuned you, so there'll be lots of ways to access the material for review. But come to the class. All right. So quizzes. We have six quizzes. As I've said, the quizzes are going to come directly from the homework assignments and from the discussion section problems. The quizzes are on the dates that I posted here. We don't have makeup quizzes. We drop the lowest quiz. Any quiz that's missed counts as a zero. And I think that we drop the lowest, lowest quizzes. Quizzes are returned through the electronic thingamajiggy here. I think you're all familiar with electronic exam return. Yeah. Yeah, so you'll get your quizzes back through that. Quizzes count for 20% of the grade. The midterm exam, which is on Tuesday, May 8th, and covers chapters 19 to 22, is on. Counts for 25% of the exam. The final exam is on June 12th. And the homeworks count for 10% of the course. There'll be a seating assignment chart for the midterm and for the final exam. I won't have seating assignments for the quizzes, so I appreciate it if you try to spread out and choose an empty seat without a neighbor, if possible. You do need to bring a picture ID. The UCI ID is the best thing. A driver's license would be the alternative. For the midterm and for the final exam, we'll be passing them down the aisle with DAs. We'll be matching your face with the ID in the exam, you know, the agency. And you're in the exams, you need to have that. All right, academic honesty. You all know a cheating is copying off your neighbor, getting material attention appropriate way. Don't do it. It is fatal. You will get a zero in the course, a note will go into your file, and you will not be able to go on with things that require this to progress. Two students in my previous class of 1051 received a failing rate for cheating. And one friend of them who wasn't an enrolled student but colluded received a note from this file. So don't do it. All right, cell phones. We all have them, we all love them, we check our email on them, we get text messages, take them away in class, away, off, no buzzing, we vibrate if it doesn't distract you. I find my own distracting if it vibrates because it means, oh, there's something in my pocket that I now need to need to know on. Just turn it off, don't test yourself for this. If you don't, if you're distracted by your telephone, they will send you out. By now, you probably know about enrollment in these large classes. The professors don't handle any of that. It's done online and through the undergraduate office and there's all the contact information. Tutoring, best place to get help. Me, Johnny, Cam, office hours, discussion section, their office hours coming by. If you want to get some help through tutoring, there's LARP. Chemistry also makes tutoring services available for free and they'll have information that's posted. And then, I already blessed you with an email. I thought this was actually pretty cool what the chemistry department was offering. Rather than focusing on this particular homework or that particular homework they were covering for all the topics, I feel like that's pretty good. That's important here, too. So anyway, let's see if there's anything else that I want to talk about. I think that pretty much covers it. Oh yeah, I'll be giving you some software. I paid about 700 bucks for this software. It's great for visualizing molecules and they said I could give it to all my students and they should be using it for research so it's really cool for looking at molecules. We'll use it later on to look at sugars and understand some of your theory of chemistry. And so during one of the discussion sections, the TAs will be working with you to help teach you how to set that software. Who has a laptop, computer or portable device in the class? Good number of you. Bring those to that discussion section. That will be the week of, they will help you set up on your computer. That will be the week of April 17th through April 23rd and we will remind you again. Alrighty, well, I think covers it. So, questions on the syllabus, of course. Our discussions are running. The question is, when does the discussion start? So it will start on a Tuesday and run through Monday. So Tuesday, Wednesday, Thursday, Friday, Monday will be the same for the first half, of course. Up through the midterm. And then after the midterm, we'll have three Wednesdays on the midterms on a Tuesday. So Wednesday, Thursday, Friday will be the use of the midterm and then you go on to make a Monday schedule. Oh, the quiz schedule, the quiz is, check the syllabus, I believe, there on Thursday, the first half of the quarter and Tuesday and the second half. All right, other questions? Well, I'm really enthusiastic about teaching this particular course. This is, in my opinion, the most exciting quarter of organic chemistry because you get to learn all the good stuff, all this groundwork in place. You've learned about stereochemistry. You've learned about alt-teens and alt-teens and alcohols and texting on our cell phone. So, you've learned about all of this incredibly, incredibly cool stuff. And now we come to what, in my opinion, is the richest, the most wonderful stuff in organic chemistry. And most of the class, seven weeks, is going to focus on carbonyl chemistry, broadly defined. We are going to start off with carboxylic acids, carboxylic acid family. We're then going to work on to aldehydes and ketones. Bites and ketones have just a fantastically rich chemistry, they have chemistry of reactivity at the carbonyl group, they have chemistry of reactivity at the adjacent carbon, alphabeta unsaturated carbonyl compound, they have chemistry of reactivity of the alkene part of the molecule, carboxylic acid, we're going to start off. Chapter 19 is kind of funny, it's sort of just a whole little throwaway chapter on carboxylic acid, just the taste of it. But carboxylic acids constitute a big and important family and so we're going to learn about members of the family, we're going to learn about esters and amids and so forth. And then we're going to move on in about the eighth week of the course to talk about amines, and then we're going to spend the ninth week of the course talking about carbohydrates, sugars, and finally, if everything goes according to schedule in the tenth week of the class, we'll have some selected topics, the eighth. Chapter 28 is on amino acids, and so it's sort of a refrain of carboxylic acid chemistry and amine chemistry, we'll talk a little bit about peptides and their synthesis. And if everything goes according to plan, we'll spend maybe our last lecture talking about chapter 26 and some really cool organometallic chemistry that I want to show you. We won't have too much emphasis on this material, but there'll be one homework assignment from Sapling, that's due to help reinforce that material. We won't throw in the people or things past the account because you won't get a discussion. It is to plunge right into chapter 19 carboxylic acids. Acids are really important compounds. You encounter them literally every day. One of the simplest carboxylic acids is acetic acid. You encounter that on your salad, the salad dressing from vinegar. You get to taste your chemicals. You know that carboxylic acids are kind of tart, kind of sour, that some of them have some strong aromas to them. They're volatile. You encounter them also perhaps in the morning in your orange juice through citric acid. Citric acid is actually a tri-carboxylic acid. Citric acid has three carboxylic acid groups. Two on the end of the five-carbon chain and one off of the middle, along with the hydroxy group. So before you follow the alpha-hydroxy acid, you might have heard of alpha-hydroxy acids. Anyone? Face cream, stuff that you put on your face to go ahead and maybe you will peel or something for your skin. I don't know if anyone uses that for garbage. But you see it advertised in the cosmetic product. Alpha-hydroxy acid, lactic acid and milk is another alpha-hydroxy acid. Due to the inductive effect, they're a little stronger than regular carboxylic acids. The amino acids are also carboxylic acids. Your chapter gives a nice coverage of them. And as I said, we'll be coming back to them in the chapter 28 in the last week. So I'll just draw one of these here. I will draw the simple amino acid alanine. I use the term alpha-hydroxy acid. Alpha means the position next to the carboxylic acid. You'll also hear amino acids referring to as alpha-amino acids. That's because the amino group is alpha. So carboxylic acids are important. And they're ubiquitous. And the defining feature of carboxylic acids is the carboxyl group. So we have a general structure. I'll kind of write out all of the lone pairs of electrons and all of the atoms here. In fact, let me be even more explicit. I have trouble getting in the habit. I'm so used to writing skeletal structures. But I will write all of the atoms here. So this is a carboxy group, the functional group that defines the carboxylic acid. The carboxy group is sometimes referred to as a carboxyl group. Probably, here, we're referred to it both ways in this class. Now, you've already seen that I can write carboxylic acids in a number of ways. I wrote it as CO2H over here. So in addition to seeing structures explicitly spelled out like this with or without the carbon, you'll see them written as RCO2H or RCOOH. These are all representations of the same thing. Compounds containing the carboxyl group fall into the broader family of carbonyl compounds, which ketones and aldehydes and so forth. So this is the broader family. Much of the reactivity that we see in the carbonyl group of the ketones and aldehydes, which we'll be talking about later, you get in the reactivity of carboxylic acids and in their family members. So one of the things that I think students get awfully caught up on is this whole issue. And it's really important to be able to understand the anatomy of something. In other words, to recognize when we look at a molecule like citric acid that I just added up. Oh, there's a hydroxy group in the molecule. There's a carboxy group in the molecule. It contains a hydroxy chain. It is that looking at a greater level of depth. And the way I will also point out chemistry is growing, which is why I said writing alcohol or active reward is so important. And yet it is so easy to lose the forest from the trees and naming molecules and just start to say, oh my god, I've got to remember do I alphabetize di-methyl under D for di or M for methyl? Do I put methyl before methyl because it has an ear after because it's bigger? It's so easy to get caught up on that. And the fact that once things go on for pages and pages of nomenclature, that it's difficult to see the forest from the trees. So I'm going to talk about what I see as the forest from the trees on the nomenclature of carboxylates. You name them the name of the alkane chopping off the E plus OIC acid. So very simple. If I have a carboxylic acid that has six carbons in it, 1, 2, 3, 4, 5, 6, the alkane that it would have been derived from is hexane. And so this molecule becomes hexanoic acid. The molecule that I drew on the blackboard before and said its common name is acetic acid, is formally known as ethanoic acid. Great question by email, Les. And the question was, how much do we have to know it? Now, some acids have names that are so widely used that you're going to never hear anyone referring to the binocysthmatic name. I doubt ethanoic acid would ever roll off of my tongue voluntarily or at least outside of the context of a benedictic situation. Because everybody calls it acetic acid. Another one that's a perfect example where just about nobody would refer to it by the common name is this guy. Now, on the underpact name, what's it? It's a one-carbon acid. One-carbon is nothing. So its systematic name is methanoic acid. And yet you will invariably hear it to refer to as formic acid. It gets its name from ants, because ants have formic acid in their pipes. And if you distill, and indeed the way it was first isolated, was to put it in a place much like UCI, which is loaded with ants. The first way that it isolated formic acid was to throw ants in water and steam to still out the formic acid. And since ants in Latin are formis, they ended up calling the acid formic acid. And of course, it's often the simplest compounds that have these historically driven common names because they weren't discovered so long ago. So the carboxylic acid is one of the highest ranking functional groups in naming. In other words, it ends up dictating the name of many compounds. So for example, if we have a carboxylic acid that also has a hydroxy group on it, we don't name it as the carboxylic, as the alcohol. We name it as the carboxylic acid. So this is for hydroxybutanoic acid. If you have a ketone group on the chain, we would call this three-oxobutanoic acid. Again, naming it after the 1, 2, 3, 4 carbon chain molecule before carbon chain acid. Like so many molecules, this has a common name. That common name happens to be acetoacetic acid. If you have two carboxylic acid groups at the ends of a chain, we call it a diyoic acid or two. So this six-carbon chain molecule is hexane diyoic acid. You're going to encounter it in the discussion section this week. Hexane diyoic acid is also referred to adipic acid. It's a component of nylon. Question? Yeah, sorry, is that diyoic acid or diyoic acid? Dioic, so it's H-E-X-A-N-E-D-I-O-C acid. Dioic, pardon me, thank you. D-I acid, thank you. Good catch. All right, the last sort of class that I'll just talk about in general is if you have benzene, then it's a benzoic acid. And so I'll just give you one last example if we put a chlorine off of our benzene. This would be P-chloro-taurobenzoic acid. Carboxylic acid makes really good hydrogen bonds. Carboxylic acid makes really good hydrogen bonds. I don't quite do a big class. Great, great question. They do indeed thank you so much for leading us into our next topic, which will be the physical properties of carboxylic acid. So carboxylic acids boil a little higher than you might expect for compounds of their size. Acetheic acid is a little molecule. It just has two carbon atoms and a couple of oxygen atoms. And yet it's got a high boiling point. It has a boiling point of 118 degrees. And I borrowed this example from your textbook because I thought they did a really nice job of explaining things. If you look at a comparison, so it's a liquid, if we would all expect something with a boiling point of 118 degrees to be a liquid, unless of course it were solid that might melt below 118. If you compare it to a molecule about the same size, let's say butane, butane is a gas. It boils at zero. Molecules have boiling points above absolute zero because there are forces that make them stay again. Don't know if you'll get it. Liquid helium boils pretty darn close to absolute zero. It's four degrees Kelvin. It's helium. It's just the tiniest thing you can imagine. And the old thing that helium has are Van der Waals interactions. Remember, spontaneous dipole-induced dipole interactions that make the molecule stay together. By the time you get up to hexane to butane, of course you've got a lot more molecule and a lot more polarizability that can give rise to interaction. So butane has Van der Waals interactions holding it together about the same size and yet the boil is a lot lower. If you go to a molecule like you know, or let's go to provenol, for example, again about the same size, about the same number of heavy atoms, about the same molecular weight as acetic acid. Butanol, propanol has a point of 97 degrees so it's lower, 97, of course these are all Celsius. So it's lower than acetic acid. You've got Van der Waals interactions. You've got dipole-dipole interactions. In other words, you've got a dipole in the CO bond and in the OH bond and that can make the molecule stay together. But I'm just bonding because the OH groups can bind into the bond of a molecule. And so, collectively, those interactions bring the boiling point of propanol way above almost 100 degrees above the boiling point of butanol. And yet, not as high as acetic acid. So nitrogen bonds are clearly worth something. How long do you think about separating them from, say, the dipole-dipole component? Well, we can look at an example of a similar molecule that doesn't have any nitrogen bonding. So we can look at propanol. Propanol, again, is about the same molecular weight. It's got the same basic number of heavy atoms for heavy atoms. It has a dipole in it. And again, it has an hydrogen bond. Its boiling point is 48. It's a liquid, just like propanol. Hydrogen bonding, its boiling point is about 50 degrees lower, so you have Van der Waals. So there's something really, really special about the hydrogen bonds in acetic acid and in carboxylic acids in general. Carboxylic acids love to hydrogen bond together because they can form a very nice hydrogen bonding dimer. In the hydrogen bonding dimer, you have one carboxylic acid facing another carboxylic acid. And the oxygen of one hydrogen bonds to the hydrogen of the other and vice versa. And this makes the molecules stick together extra well. If you, in your laboratory course, ever run thin layer chromatography, TLC, like carboxylic acid, you will see that typically they streak in the TLC. By streaking, I mean that they have a spot with a tail line like a comet. Because at the front of the band of the TLC is yourself that moves up the TLC. Your sample is really concentrated. And it's hydrogen bonded to itself, so it doesn't hydrogen bond to the silica of the TLC plate and moves quickly up the plate. But at the tail, as it gets more dilute, you have less hydrogen bonded dimer, less in the molecules sticking to itself, and more of it available to stick to the silica gel of the TLC plate. And so it lags. The more it lags, the more diluted it becomes. The more diluted it becomes, the more you have, the more longer you have, the more it lags. So TLC-wise, you see very characteristic behavior of this. You see some really interesting features spectroscopically for carboxylic acid. So for example, in the infrared spectrum, you have an OH stretch at a characteristic position. It's really, really unusual. You see this very, very characteristic band from about 3,500 to 2,500 wave numbers. It's one of the ugliest features that you'll ever see in the IR spectrum. It's very broad. And the best way I can sketch it out would look something like this. If your IR spectrum sort of starts at 4,000 wave numbers, by about 3,500, you start to see this band come up, and it's sort of misshapen. And then it kind of comes down at about 2,500. That's not hard part. And so it usually obscures the CH stretches at about 3,000. And then as you come along in the carbonyl region, at about 1,700 or 1,725, you'll also see the CO stretch, the carbonyl stretch. So let's say about 1,725 to 1,700 wave numbers. So really, really characteristic, just staring you in the face when you look at these. So NMR and IR spectra also have characteristic features of carboxylic acids. And a lot of us, the best way, you'll get to see some of these compounds in the lab class if you haven't already. The best way is to actually see spectra question. Still, it's still pretty ugly. And so the question that's being asked is about concentration. And if you want it, concentrated would be, say, the liquid sandwich between two salt points would be typical. Or if it's a solid in a potassium bromide pellet. And those tend to be really ugly in my experience. In solution, I haven't looked personally recently. I would think of anything you possibly very dilute, see a little more monomer, which would be more well-maintained. So I'm not sure if that's true, but if you see an example, I'd love to see what you're reading there. It's the other thing that's interesting in the IR spectrum. Some of it depends on how big the molecule is. After all, if you've got a small carboxylic acid like butanoic acid or acetic acid, that molecule has a ton of carboxyl compared to other stuff. So when you're sandwiching a drop of acetic acid between two salt points, there's a ton of carboxyl groups. If you had a molecule with 20 carbons in there and just one carboxyl group, you'd see a much smaller stretch for the carboxyl group. So what I'm saying here and for that spectrum is sort of characteristic of a smaller molecule. For like, I mean, do you like the molecule like a steroid, like a cholesterol molecule? The carboxylic acid will be smaller and a little bit less obvious, but there's still you to the obvious. Good question. Other questions? How can we differentiate a carboxylic acid from just an alcohol? Ah, great question. Carboxylic acid from just an alcohol peak. So typically, an alcohol peak, and again, I'll refer to one concentrated, kind of picks up at about 3,500 and kind of comes down by about 3,000. So this would be a typical alcohol. And you'd see it more sort of centered at 3,300. Whereas the carboxyl is pretty featureless. It may have some small features over here or over here. And it's just sort of this blob that encompasses the CH region of about 3,000. Questions like, so how can we see the CH peak? You may not. The question is, how do we see the CH peaks? And the answer is, you might not see them, but guess what? In these days, in organic chemistry, there are so many ways to tell if a molecule has CHs in it, for example, NMR spectroscopy, that in general is less important. And in the scientific journal called Journal of Organic Chemistry, back many years ago when IAR was the primary way of describing molecules, you were supposed to describe every band in the spectrum and list like 20 or 30 peaks. Nowadays, the instructions, since there are so many good ways of looking at a molecule, the instructions aren't list the main peaks instead of shooting the function groups. So these days, if Johnny or Kim prepared a carboxylic acid and described it in the Journal of Organic Chemistry or in a laboratory report, they would probably say 3,500 to 2,500 wave numbers of broad peaks and 17, let's say, 10 wave numbers of another peak. So you may not see them. But in the NMR spectrum, you, of course, get to see lots and lots of hydrogen. The carboxyl hydrogen, ironically, you don't always see. Generally, it's about at 10 to 13 ppm. Your textbook says 10 to 12. Neither of those is fine. Often, it's broad. Its position depends a little bit on the solvent, if you're looking at it in chloroform, if you're looking at it in dimethyl sulfoxide. And sometimes, you actually won't see it. Your textbook, I would never give you an example of an NMR spectrum where you didn't see the carboxylic acid OH. But if Johnny or Kim went into the laboratory and prepared the carboxylic acid, we're trying to determine if it were a carboxylic acid. And took an NMR spectrum in chloroform and said, I don't see the carboxylic OH. Even though it looks like a carboxylic acid in the infrared spectrum, I don't know if I have a carboxylic acid. I'd say, sometimes you don't see the OH because it can be very broad due to exchange with water. Why don't you go back and run the NMR in a different solid like dimethyl sulfoxide? You'd try to come back and say, ah, I see it. But your textbook would never give you that much reality, or I wouldn't, because it's way beyond the scope of this book. But that's the reality you really want to see. Now, the other thing is, okay, what do you think about when you think about the hydrogen is the carboxyl group is the electron withdrawing? Exactly. And so the CH that's next to a carboxylic acid generally appears at about two to three PPM. The textbook says two to 2.5, either is fine. If it's a methyl group, it'll be at about two. If it's a methylene, a CH, two group, it'll be about two and a half. If it's a methine group, a CH group, it'll be at about three. And if there are other electron withdrawing groups, it'll be further downfield. The NMR spectrum, the carbon-13 NMR of carboxylic acids, your carboxyl carbon generally appears at about 170 to 180 PPM. That general region of about 170 and further downfield is generally referred to as the carbonyl region. So generally, carbonyl compounds are generally about 170 to 220. Your textbook said for carboxylic acids, 170 to 210, but they were really trying to encompass all of the carbonyl region. Generally, it'd be about 170 or 180 PPM. I'm gonna write in general. So carboxylic acids, carboxyl groups of carboxylic acids is in a high oxidation state. In fact, they are the highest oxidation state of any organic compound with the exception of things that are in the carbon dioxide oxidation state. So if you in general have a carboxylic acid like acetic acid or hexanoic acid or benzoic acid, the oxidation state is plus three for the carbon. Informic acid, if you count your oxidation state, it's plus two. But what that immediately tells us is they're generally synthesized by oxidation reactions because in general, a lot of organic compounds you encounter have carbon in lower oxidation states. So alcohols, for example, depending on the substitution, will have oxidation state of if it's a primary alcohol, negative one, if it's secondary, it'll be one different. And so primary alcohols can be converted to carboxylic acids by oxidation, countered oxidation reactions in the 51B course. So for example, with chromium-6 reagents, say EG with chromium-V, I like. So what I mean is potassium dichromate and sulfuric acid or sodium dichromate and sulfuric acid or chromium trioxide and sulfuric acid, they're all about the same in their reactivity. There are other oxidizing agents. In general, chromium-6 is a really bad actor. It's personogenic, it's toxic. In general, organic chemists try to use safer oxidizing reagents these days, ones that are more environmentally friendly and don't generate waste. So other sorts of oxidation systems that get used involve things like bleach, sodium hydrochloride and various catalysts. Anyway, the general gist is there are many oxidation reactions that can make, can synthesize the carboxylic acid group. So for example, you're also familiar with oxidative cleavage. That's a little bit of an oddball in some way because alkynes aren't that commonly occurring. Alkenes are a lot more common. So I also included in the example in this week's discussion section, alkenes. And you'll see a reagent system for the oxidative cleavage of alkenes. Your textbook provides a nice review and so you'll also see in your textbook oxidation of aromatic compounds, the benzylic CH group. So these are all things that you've encountered in your previous course. And in that case, you'll see, for example, potassium permanganate KMNO4 as a reagent. Carboxylic acids are acidic. They're not strong acids like sulfuric acid, like battery acid or hydroporic acid. Those acids, if you dissolve them in water, completely ionize. One molar solution of sulfuric acid is pKa or one molar solution of hydroporic acid is pKa of zero, is pH, pardon me, zero. It's a very strong acid and if you splash it in your eye, it's going to cause real damage. Vinegar is a weak acid. Vinegar or acidic acids are weak acids, a 5% solution which is close to one molar. If you splash vinegar in your eye, it's going to hurt but you'll wash your eye out and you're not going to be blind or need to go to the emergency room. Weak acids and strong acids, of course, react with strong bases. So for example, acidic acid reacts with hydroxide aniline to give you acetate aniline and I've sort of focused here on the ions. You can't just buy or find a bottle of ions if you go to the stock room and you say, give me some hydroxide. They're going to say, well, I can't just give you any hydroxide. You've got to have a particular hydroxide. I can give you sodium hydroxide. I can give you calcium hydroxide. I can give you calcium hydroxide but you can't get hydroxide ions just to sit with each other without metal counter on these other parts. And so we could write a real balanced chemical equation for say, acidic acid plus sodium hydroxide goes to sodium acetate, CH3, CO2, all right, and minus NH plus. They're not good people or horrible about balancing equations but now I'll be a good person and balance my equation. Sodium acetate, water, yes. Oh, sorry, for the sodium acetate, shouldn't it be CH3CO2 minus CH3? CH3CO2 minus, thank you. I want you in the front row of every class. I don't know what else to help out with this. I haven't written an equilibrium there because that reaction just lies so bloody far to the right that for all intents and purposes, if I throw sodium hydroxide, one mole of sodium hydroxide, together in a mole of acidic acid, there's no acidic acid left. I've got the mole of sodium acetate. That equilibrium lies fantastically far. Acidic acid has a pKa, so away an indicator of acidity is pKa. The pKa of acidic acid is 4.76, that's typical of a weak acid. The strong acid, like sulfuric acid, is negative. Hydronium ion is negative, I believe, 1.7. In this equilibrium, water is acting as a base. In the, or rather hydroxide is acting as a base. Water is the conjugate acid. We often compare equilibria by comparing the conjugate acid on the two sides of the equation. Water has a pKa of 15.7 acting as an acid. In other words, it's a much, much weaker acid, much, much weaker acid than acetic acid. That equilibrium lies to the way, way, way to the right. So far to the right that we barely consider it. Organic chemists often think about water and alcohols together. They're kind of in the same family. They both have hydroxyl groups. They have many similar properties. The pKa of alcohols is very similar to the pKa of water. Alcohols are about, if you want to keep one number in your head, about 17. If you can't keep one number, just say, oh, they're about the same as water. We call them both 16. So these are weaker acids. Their conjugate acid, conjugate base, is RO minus or OH minus. And so if we think about why they're weaker acids, one way, one model in which to understand this is when we look at acetate anion, we spread that negative charge around. There isn't a negative charge on one oxygen and a neutral charge on the other. There isn't a double bond to one oxygen and a single bond to the other. It's sort of half and half. There are two resonance structures that are equivalent that together represent a more complete picture of the structure of the anion. We can say that the negative charge is stabilized by resonance. It's a little stabilization that doesn't occur and hydroxide anion or in alkoxide anion makes this a weaker base, makes acetic acid a stronger acid than water or then an alcohol. Chemists aren't big calculators. Organic chemists are big estimators. We tend to think about things in sweeping terms. So when you're taking general chemistry, you're typically focusing on calculating in detailed positions of equilibrium. When you're thinking about organic chemistry, often you're thinking about acid-base reactions and asking, where does this equilibrium lie? Does it lie in the middle? Does it lie to the right? Does it lie way to the right? Does it lie way to the left? Does it lie all the way? I've used EPAs in my thinking. So when I think about equilibrium, the reaction is mixed in terms of pKa. And I'm going to write an equation. I need to write equations because that's not how I think, but I'll show you how I get to my thinking. So equilibrium constant is 10 to the delta pKa. So what are we? I mean, if you have an acid or COA, and it's pKa is about five. See, I'm not even going to worry about extra digits here because basically I'm thinking in broad terms. Carboxylic acids have pKa in four or five. And I have a base like alkoxide or hydroxide. And I have an equilibrium. I've already said this equilibrium line is way, way, way to the right. And I'm so far to the right, I'm not even bothering to think about why it's where it is. So here's my equilibrium. And the pKa of my alcohol or my hydroxide is 17. My estimate, the thing that's going on in the back of my head is oh, kEq is equal to 10 to the 17 minus 5 is 10 to the 12. That equilibrium is so far to the right equilibrium. It's just there. It's just reactive. You know, 10 to the 10th is a big number, right? It's 10 to the 1, 10 to the 2, maybe even, you know, 10 to the 5, even maybe sort of up a little bit above that, like 10 to the 8. You can say, OK, there's kind of sort of an equilibrium. But this is way, way, way to the right, which is why I didn't even bother to think about it. So most carboxylic acids are pKa of four or five. We saw it with acetic acid 4.76. Benzoic acid is a little bit more acidic. But sometimes you have big effects. Sometimes you have big effects that lead to inductive stabilization if it comes to your face. And that's going to lead to a stronger acid. So as I said, a typical carboxylic acid is four to five. But if you take something like trifluoroacetic acid, trifluoroacetic acid has a pKa of 0.23. Joni and Kim work with trifluoroacetic acid all the time in the laboratory. They use it as a relatively strong acid, sort of right on that equilibrium between strong, meaning you pour it into water and all that. And leave me if it doesn't ionize a lot. Ionizing a lot, if you get it in your eyes, there, you should worry about it. You get it on your skin. There, you should worry about it. What's going on? Those fluorines are super, super electron of drawing, and we got three of them. And so they all have these night poles pulling negative charge away from the conjugate base, stabilizing the conjugate base. And so we get five orders of magnitude more acidic than a regular carboxylic acid. If you put fewer electron of drawing groups, like one or two fluorines, you get less acidity. If you go ahead and you move your halogens down the chain, like 4-chlorobutenoic acid versus 4-chlorobutenoic acid, out 2-chlorobutenoic acid, they're both more acidic than but 4-chlorobutenoic acid, but 4-chlorobutenoic acid, but 4-chlorobutenoic acid is a little more acidic, whereas 2-chlorobutenoic acid is a good big more acid. And you get the same effect. I'll give you one last example of a close here. You get the same type of effects with benzoic acid. And you can think of this in terms of the inductive effects that we've learned. So benzoic acid has a pKa of 4.19. If you take parenitrobenzoic acid, you can have inductive and resonance effects pulling electron density away from the carboxyl group. And it's pKa, it's pKa, so you get effects there. All right. I think that wraps it up for today.