 Another quick sound check or five minutes from the hour. Alrighty, we have hit 9 p.m. Pacific Standard Time That may be a lot of different times in The world for the people here tonight for me, it's 11 p.m So I'm Hopefully going to match the energy that I had 12 hours ago And I give you a lively and non-threatening Chemistry so thank you all for coming this morning Morning, it's not even morning for me and for many of you it's not morning, but for me, it's always morning, I suppose Thank you for coming. I really appreciate it And I really appreciate folks who came to the first time I presented this And Have come back for it again I haven't made many many changes. I had I had planned to do a lot more updating but in the last two weeks we went from In-person classes to online classes and back again With like oh only a couple of days notice for each transition. So it's it's it's kind of been a Roller coaster here. So Anyway Let's get on with the show here. Let me delete my warning here may contain chemistry and cats and Drawings I've drawn myself We do that guy and There we go. Okay, I Always have to take a moment to figure out the the The screen so When the Nobel Prize was announced in Last fall, I thought it would be a good opportunity to talk a bit to this group about Some organic chemistry some of the basics of organic chemistry I'm gonna mention several Nobel Prizes that have contributed to like the current one so You know, basically I'm gonna Talk to you about some of the basics of organic chemistry, I'm gonna talk to you a lot about some of the jargon and what it means because You know the the field is just full of jargon So We go that works. Okay, so the 2021 Nobel Prize in chemistry was awarded to Benjamin List and David McMillan Listed some some some reactions. I'm gonna focus on McMillan's work Which was an actual deals elder Reaction and the Nobel Prize was given for quote the development of asymmetric Organic catalysis See if I can Copy that and put it in the local chat then you can actually see this I have given the PDF of this talk to Jess it's in your science circle email Jess. So this will be posted as as well Asymmetric organic catalysis it sounds like English, but is it really no it's more organic chemistries So so let's dissect these words and figure out what they actually mean There we go, so this comes from Chemistry and engineering news And it's a picture of the reaction that Was cited in Nobel Prize. This is from McMillan's work So it's it's this stuff and this stuff in the presence of this stuff and you get these two things Thank you very much. That's the end of my talk. We'll see you tomorrow. No, no, no, I need to explain a lot more than that So, yeah, how does this work? Well the Key part on this chemical is where the pointer is there's a double bond Then there's a double bond single bond double bond and These two key parts get together to form a ring and we end up getting this Structure here That's the basic deals Alder reaction. Okay, and there are some details details that we need to know about here Okay, so What are these details? Alright Well, the deals Alder reaction was discovered and discovery only has one s. I should have caught that before but It's discovered in 1928 by two guys auto deals and Kurt elder some of my Students make the mistake of thinking it's dr. Deals Alder just one guy, but it is two guys They got the Nobel Prize for this in 1950 and It forms six-membered rings six-membered rings. Why are those important? Do the previous slide There's a carbon there's a carbon I'll explain this a little more that's two There's one. There's another one. There's another one. There's another one. That's four So two plus four six and they end up one two three four five six So this reaction makes Two carbon-carbon bonds. That's actually pretty special It makes two carbon-carbon bonds at the same time Next it There's some more jargon it does so with a preferred direction for how the bonds are made. That's regio specificity or regio specifically and if there's a Handedness like left-handedness or right-handedness just that physical property Of not being superimposable on your mirror image If it's got a hand in this then These reactions prefer just one single hand this to the prod product Hey caveats there is that you have to actually start with a single handedness of the starting materials If that's a physically possible thing okay, so This is all about geometry figuring out how to Make new carbon-carbon bonds which has been a huge problem in organic chemistry Most of the 20th century was spent figuring out reactions That would make you new carbon-carbon bonds and have those bonds point in the directions that you really need them to right One of the beautiful things about this deals elder reaction is that once quantum theory came into Existence and we figured out how to do some Quantum mechanical calculations on the these compounds These reactions are completely explainable and You can make predictions about structure right so this this ends up being a Topic that is covered in detail in organic chemistry class so You know it's part of a larger class of reactions called pericyclic reactions But I'm just gonna focus on this one type of reaction that takes like a double bond and two adjacent double bonds It makes a six-member frame the deals Alder So yeah next so Asymmetric catalysis that was in the Nobel Prize blurb the quote I read Why is it important? Well, here's here's an example. So you may remember the movie awakenings with Robin Williams and That was based on the experiences of Oliver sacks awakenings was about patients that had extreme parkinsonianism and Giving them L. Dopa allowed for them to come out of their catatonia and Re-engage with Sadly was not a permanent fix Because you needed more and more L. Dopa to get to the same place and then there are side effects But L. Dopa is an important drug It's synthesis Well, I was first made possible Was first made possible in I believe the 70s 60s and 70s and you know, basically there was a catalyst involved. There is a There is a Rodeum Catalyst involved. I won't go into the details of this reaction. It's it's really really wonderful But here's the thing you have a double bond there and You add a hydrogen to this carbon and a hydrogen to that carbon And you get this molecule, right? Nothing else has changed. You just added a hydrogen here and a hydrogen here but the thing is Look at this carbon There are four different things attached to that carbon. There's a hydrogen which isn't drawn That's that's that's a thing in these structures and then there's like That carbon which has something attached to it this carbon has had something different attached to it and that NH2 a carbon with four different things attached is I'm gonna have this property of left-handedness or right-handedness It won't be super opposable on its mirror image So, let's see. I think that is the Well, it's L-dopa, so that is the left-handed version of it So The other hand in this I don't know if it's actually biochemically active that would be the best case scenario if it were biochemically active might even be poisonous, so You know, basically it is really important to have the hand at this right. Okay, so the 2001 Nobel Prize was awarded for this type of work and rhodium catalysis palladium catalysis that gives you This handedness to molecules in really really really really high priorities that has been that has been a huge area of developments in chemistry But here's the thing do you want traces of Heavy metals like rhodium or palladium in your pharmaceuticals Right There we go. Okay, so here's an example L-dopa's handedness. I got ahead of it ahead of myself It's a better picture of it. You can actually see the hydrogen there And you can see that if you go from nitrogen to this group to that group You're going in a counterclockwise Direction if you swapped the nitrogen in that group then you go in a clockwise Direction there and the two Forms just aren't the same that wouldn't interact the same biochemically and that's because most of the biochemicals in you have a handedness to and just as You know, it's easy for one person to shake the right hand of another person with their own right hand It's it's harder for someone to shake someone's left Right, they the hands just don't go together Let's see Shiloh's question handedness That well, here's the thing the L-dopa the handedness there is What the dopamine receptors will accept? The opposite handedness May just be ignored by the receptors or may just be toxic. So, yeah Let's see. Oh, yeah. Yeah You know, if you have the wrong handedness in the wrong place, it might get stuck And kill the receptor. I think there's some examples of that. No, all right Let's go on with the next slide So, yeah, basically no one wants traces of heavy metals in their pharmaceuticals Heavy metals bad traces of heavy metals You know in one dose might not be a problem But if it's a thing that you have to take for the rest of your life, then that is a Is a problem So, yeah, you know, L-dopa the other Dopa Is probably nerd, I don't know but for The general case where you have molecules that have handedness that are important for Pharmaceutical things you want to make sure the handedness is is correct. Thalidomide for example turns out Thalidomide was a Pharmaceutical that was given to pregnant women in Canada the US never Approved it And it was I think it's a relaxant, but it caused severe birth defects Yeah, you know basically deformed limbs. There's a whole generation of people just just my age who You know have Have deformed limbs because of this and it ended up that It ended up that One form was talked what well one form was mutagenic and the other form was not it wouldn't have mattered if they had given just the form that was You know Just the Relaxant because it turns out in the body the two forms actually inter-convert So so, yeah, the left-handedness and the right-handedness is is a really important thing So looking at McMillan's work again, let's dissect the jargon in this picture Starting with like how this bonding how how the carbons and stuff are all held together in the organic molecule So I'm gonna start with Lewis dot structures excuse my drawing program it's Mike draw very very quaint I I do like having a mixture of Technologies it from from from drawing to You know the 3d models, I'll show you later Let's start with just thinking about the periodic table. We've got elements And in the first row of the periodic table, we've got hydrogen and helium Notice how I've drawn a little number above excuse me the symbol for each element that number is the number of protons in the nucleus and periodic table is essentially broken down into rows and I'll tell you why and You know the rows start at the left they go to the right and Elements are You know in the sequence of how many protons they've got in a nucleus So hydrogen has one proton a neutral hydrogen since protons have a positive charge a neutral hydrogen atom will have one electron associated with it Helium has two protons in its nucleus and then neutral helium atom will have two electrons associated with it and Then for some reason we decide to start a new row Okay, I'll tell you about that So Lewis dot structures basically look at the outermost electrons the Electrons that actually do chemistry So while lithium has three electrons associated with it Two of them are in this first shell and they're associated so tightly with a nucleus that Yeah, you're never going to get them to participate in any chemistry So that means that only one electron on lithium is actually left over to do any chemistry with And that's why lithium sits under hydrogen because hydrogen just has one electron and it's outermost shell that Sees the world Okay, we look at lithium element three element four is beryllium Five is boron element six is carbon and while carbon does have six electrons again two of them are in that first shell They don't do anything. They don't associate with the outside world They're too far down close to the nucleus held too tightly for any chemistry to happen So that's why in a Lewis structure of just a carbon atom We have the element symbol surrounded by four little dots and each dot represents a carbon right same as for the hydrogen hydrogen just has one dot and what we can do is put these structures together so as to Satisfy the electronic requirements. That's the jargon of each each atom It turns out That each of these atoms is going to strive to get to eight electrons To fill the shell. There's enough room in the second shell for eight electrons. How does it do that? Well by sharing so One hydrogen can share its electron with a carbon That means this hydrogen Sharing a pair of electrons with a carbon Essentially means that has a bond but it has access to both of those electrons so it's electronically satisfied Carbon's gonna need some more friends. So there is more hydrogens invited to this party so With four hydrogens carbon can now Have access to eight electrons and that's a magic number. It makes carbon Carbon's electronic Requirements be be satisfied. It's basically all the space it's got around it is actually filled with something Pairs of electrons are usually just represented by lines if they're a bond Right. So What I've drawn here the CH4 is just methane Okay There we go. So, you know, basically if I'm gonna teach my teach my classes Show how to make these low structures. There's a little procedure. I'll run through that real quick These are my cats the little ones have grown a lot bigger That guy is eight years old. This one is three years old. She's she's she's quite large She hasn't grown anymore And in fact, they're running around in the basement with me and I'm trying to make sure that no one just kind of Diabombs the keyboard so Anyway, if if I'm if we're trying to figure out how to make a how to make a molecule just like predicted from a Formula for example CH2O That would be formaldehyde What we would do is count how many electrons are Carbon has four It's four from the left of the periodic table So basically give it four electrons two hydrogens each has one. So that's two times one Oxygen if you look at it Six from the left to the periodic table six electrons you add all of those up you get 12. Okay, you got 12 electrons to work Well, you're gonna use pairs of electrons to hold the atoms together So let's attach the hydrogens and the oxygen to the carbon and so One two three bonds three bonds. Ah, that's six electrons because there's two electrons per line So 12 that we had at the beginning minus six leaves you six and you have to do something with them Turns out that atoms attract electrons more strongly as you go towards the right hand side of the periodic table So we're just going to give all those electrons to the oxygen. So the oxygen can have It's eight electrons or at least access to eight electrons And you know, we don't have any left and that's sad because the carbon only has access to six electrons And it is very unhappy about this and essentially forces the oxygen to share one of those pairs of electrons and we get this thing called a double bond okay, and With the double bond the carbon now has access to Eight electrons a magic number Another piece of jargon are these stick diagrams. I've actually shown you some stick diagrams before but let's let's formally talk about this This would be a molecule called butadiene. This is one called ethylene and These guys are the simplest Molecules that can do the deal's alder reaction. So you got your double bond You got a single bond you got your double bond in one molecule and you got your double bond in the other Molecule and I've drawn each carbon with four bonds right double bond counts as four electrons CH's each count for two electrons. So each carbon has four electrons in our line notation, which I've given down here we Represent each vertex as a carbon atom and so there's four carbon atoms right there We show the double bonds between the carbon atoms the single bonds and the double bonds But we don't show hydrogen it is assumed that You know if a vertex doesn't have four lines The ones that aren't to draw on go to hydrogen. Okay, so this Structure means the same as this This structure the ethylene CH2 double bond CH2 means the same as this Okay, so you know it takes a little bit of practice in an organic chemistry course to Get to this point where you know it becomes second nature, but with practice it does You know people get there Let's see next So One of the nice things about these organic stick reactions It makes it a little bit easier for us to draw reactions What I've drawn with the red lines here is arrows and these arrows represent movements of electrons So double bonds actually are very electron rich because there's four electrons involved And one of these One of these pairs of electrons Can go to connect that carbon atom to that carbon atom So I've shown where the electrons come from by the tail end of the arrow and the head of the arrow shows where they go Same thing as this guy this pair of electrons can go over here This pair of electrons can go over there to join this carbon atom to that one And then we get The new bonds showing up in red And our six-membered ring Yeah, this is this is One of the hardest parts of the organic chemistry in the second year is Getting people to be careful of where the arrows start and where they end the Organic chemists are real strict about that And rightly so because this is a means of communication It is a way of telling other people that you know how our reaction happens So this upper one is just a Diels-Elder reaction this lower one. I've taken benzene Which is a six-membered ring. It's got three double bonds in it it alternates double bond single bond double bond single bond double bond and the thing is that these double bonds can move or can be represented as moving they don't actually and You know, I can have a double bond here or I can have a double bond there I've drawn what's called the two kekule structures after kekule basically first proposed these and it introduces Another piece of jargon. It's called resonance and Benzene these bonds don't actually move about the true structure is An average of these guys turns out this Lewis structures these line structures, they are so useful that You know We make them do things sometimes that they're not really designed to do You know the lines that connect the atoms They were they they imply that the electrons stay between those two atoms and are just connecting two atoms That's that's not really how Electrons work. It's not really how bonding works. There is the localization to bond So this idea of resonance where the bonds are a little bit more mobile and we say okay Well, the true structure is a hybrid of several structures. That is a patch on the theory Louis Louis structures, so I mentioned this eight electrons thing. Well Eight electrons electrons are particles and waves at the same time. It's a quantum thing so If they're particles and waves at the same time then the wave-like properties of Electrons can tell you something about where the electrons can be found The think of vibrations on a string the basic vibration on the string might have a Like a single up and the down you might have a harmonic that has a node in the middle and While the left half is up the right half would be down and vice versa, right? The 3d structure of where the electrons are allowed to go are very similar to how vibrations on a piece of string might be so the lowest energy of the lowest You know the lowest energy the one that is most close to the nucleus just has Just looks like a sphere In fact, if I stand up You stand up and There we go. I've got my orbital reser here This is Hey sometime that'll show up that is a Hydrogen One s orbital that's where a hydrogen might stash its electron. Okay, these represent these do temporary structures carbon has a Carbon has that and it's close to the nucleus, but it's got another one that's in its second shell and The second shell is bigger Because it has to be bigger because the electrons are a bit further away so Electrons that do Some bonding with other atoms and they happen to be the spherical type of electron Would be something that looks like that the thing is each shell so that hydrogen has just a one shell Carbon has two shells. It's got the interior shell, which is the same as hydrogens and then it's got The next shell second shell has something that looks like the hydrogen thing but bigger and then it has its own other set of Calling them or busy These guys are harmonics. They're like the vibration on the string that is the second order So think of it as a sphere There's essentially been cut in half right and the different colors Represent phases so that like the red may be have a positive Phase if you were to graph this on a piece of graph paper or something the blue might have a negative phase the phase itself has no physical meaning That it's not going to translate into anything macro stop if you This you know if one side is positive the other side is negative what translates to a Macroscopic property is the square So, you know if the one side is negative and you square it then it becomes positive and the macroscopic property is The probability of finding the electron so This is the shape of where the electron can be the colors phases They're kind of important in terms of bonding in terms of being able to put the Electrons So that they can connect different atoms to each other. So let's go back here So This is a bit of math and I'm gonna try not to scare you here. So there's here's a picture of a cat suiting each other As I talked to them about What we can do on an atom is Combine these or we can basically say Okay, let's take that spherical one. Let's take those dumb two of those dumbbell looking ones and mix them up and Well, if you take a spherical one If we take Oops Okay Well, there's a dumbbell inside the blue sphere Think of the blue areas adding together and inflating and where the blue and red Intersect they cancel each other out So that will end up giving us one lobe. That's big And one lobe that's small So like what I've drawn here with the blue Big lobe and then kind of a little nubby Blue lobe on the other side, right? The red represents a different one and the green represents a different one these things basically are Just going to be where your single bonds and organic molecules are made Hmm, I said there were Three of the dumbbell looking once x a one along the x-axis one along the y-axis one along the z-axis, right? We've left the one along the z-axis alone. So we just have its normal dumbbell thing This is important This is what gives us our double bonds because we get sideways overlap of these Dumbbell looking things that give us Give us where these double bonds can be Okay, if you want to do it Matthew, you can Say that I'm going to take the math for this orbital and then take the math for that orbital I'm either going to add them together or Subtract them from one another other in other words I'm going to make an interference pattern one where they combine and one where they destroy each other and on the next Slide I can show you what that looks like a little bit. So You know if you have The dumbbell on one atom Dumbbell on another atom you bring the atoms close together You're going to get a combination of those that's down here where the Atoms or where where the electrons actually pull the nuclei closer together That would be a stabilizing force. So the energy goes down y-axis on this little graph is a The Destructive interference Version of this where they subtract from one another makes the energy goes up and that shape corresponds to This Actually did Some low-level calculations on And then imploded the results into second life. So here you go. Okay, what I'm Pointing at right now moving my pointer. There you go Okay, so the thing that my pointer is pointing at right now is just just ethylene. It's just this CH2 double bond CH2 the upper the upper thing with the Four lobes on it corresponds to corresponds to a Oh a molecular Where the double bond So at this point you can't introduce that we've got Places where electrons can go some of these places occupied with electrons Okay, so If you only consider what the p-orbitals are doing the dumbbell-looking things are doing You can actually it's all back at the envelope Calculation at the very very lowest level Quantum theory and basically kind of figure out what they're gonna look like by Considering what the individual ones are going to do So in view to dying Which is one of the ingredients of a Diels Alder reaction. You've got four carbons each with one of these dumbbells The lowest energy one is going to be where the dumbbells have all the signs Align the same the next one up. Oh, you've got to the same and then there's a flip and then to the same Next one up There's two places where the signs flip And then the next one up There's three places the more flips the higher the energy And In this picture what we've got let me bring the 3d models out again Trying not to scare you by Getting them like right in your face. I've got the model of the molecule right in front of them as well so that's a beauty dying and I calculated the energies of these guys. I can see them as the labels um Beauty dying has Four electrons in these dumbbells so each of these or Two down there two down there two in there and then the top two are empty we're almost to Where the Diels Alder reaction actually occurs Considering Considering the shadings on how these Orbitals look Woodward and Hoffman came up for with a series of rules I'm not gonna I'm not gonna dwell on them because I don't want to I don't want to spend too much time on that We have to watch the energies. That's that's Margie. She's one of my kiddies. She's the big one and Sometimes she's very low-energy. She would be one of the lower but occupied So to make these reactions work What you have to do is take Electrons and figure out where they can go so that means something like Taking a highest occupied molecular orbital, which is on view the dying where my red 3d arrow is pointing to and Figuring out where on the ethylene which one of these orbitals on the ethylene It can overlap with Or it can match Can't really match with that one because The Shadings don't line up very well in here this one Okay, it can't for on ethylene. It can't do the lower one. It can do the upper one For the upper one The low bond the left and the low bond the right in the back of the in the back where of the what I'm pointing to can with Those those the colors line up Okay, I pop this in the back again You know, essentially the colors line up with the different sides of the molecule and That is where the bond formation starts because there's electrons Up in one of these orbitals and emptiness in the other one, but electrons are allowed to go And there's a nicer picture of it from Wikipedia you can see Whatever sign of orbital that Clear space corresponds to they match up as do the shaded spaces and normally you would get Let's see normally you would get the dying which has two double bonds in it Yielding it's electron over to the like dienophile is another Brita jargon that we don't really need to worry about But it would go into the unoccupied and basically you get the bond formation starting It is possible for it to go the other way Just depends on where you have electron richness and where you have electron poor So Show you one last This guy I've drawn the product over here I've drawn the product. There's my perfectionism kicking in. I need the arrow to point where I want it to point There we go. Um so You know, essentially we started with Um Two double bonds on the butadiene one double bond in the ethylene and we ended up making two new carbon carbon bonds And there's one double bond still still remaining and if you look at the if you look at the lobes Look at the lobes on that double bond You can see that's a double bond. It should look a lot like what the ethylene does But there's some participation from neighboring at right. It's not just exactly the same as the Ethylene structure in the middle I'm only mentioning this because uh, this helps to show that electrons aren't as localized as the Lewis structures might suggest they do roam around a little bit they can Um show a little ability then you would expand Okay, uh, especially in that that upper one. Um, those those electrons are kind of all over that molecule Right, uh, it's uh lowest unoccupied, but if you put an electron in there that electron would um have considerable mobility Pop this back Yeah, so I used um I used a program called games G-a-m-e-s-s Uh, that comes out of I think university of Okay, um, I'd have to I'd have to check that it is um Been made freely available, uh, you know one just has to register for a license and for academic use that is You know for non commercial use that is that is free Um, another um calculation program is called orca and uh, that's out of the max plank institute They give very very similar results So I did the calculations of all of those molecules at fairly low levels And then was able to import the calculation results into second Okay, so the Woodward Hoffman rules, um, the thing I love about it is that there's a mnemonic Um, George Scott endures Antarctic conditions and that's that's timely. Um, it's been Um, it's been cold here. Uh, sorry. I've been the U. S. Uh We've been seeing temperature about eight Fahrenheit or freedom height as uh, I've seen some people call it I think it's like mine's 10 Celsius Mine's infant Celsius But the g s e A c those actually have chemical meanings. Um, uh ground state Even that's a number of pairs of electrons Even number pair of electrons and Tara would be a um And Tara facial I'm gonna show you slides on this anyway. It's gonna it's a way of Defining how the molecules get together the form bonds. Um, so the geometry is what you want And the condition is either con rotatory dis rotatory. I've got slides on that becomes easy Let's see, um Deals alder reactions Uh, don't really occur in biofuels. No, uh They may occur when you burn biofuels just as a very minor minor thing, but then those products would get burnt as well. So um No deals alder is going to be more for making highly structured molecules Um with like pharmaceuticals being the prime example There we go. Uh, so yeah, I'm not going to worry about this Uh, Susan, I I think it is I do think it is So what do these guys mean? Um, well this entire facial essentially means that um, your second molecule has to Be twisted somehow so that on one end of your first molecule it attaches to the top and on the other end it attaches to the bottom Uh, that's kind of hard for a lot of reactions to do okay, uh Superfacial means that the second molecule has to come in and it makes uh bonds from uh, the same face From the from the same side so, um Having things make bonds from the same side versus opposite sides as much Is is much easier. So deals alder reactions do this super facial Type of thing. I think you can see if um, if we have um, if we have The ability to have molecules um react so that you form um new carbon carbon bonds And they both have to point in the same direction that actually starts to give you control over the reaction Um what products are made? oops here we go, um more jargon Exo versus endo all this means is Um, how does the second molecule this guy for example, how does that come in? relative to the first notice how it's Oh double bond c c double bond c And so in this case we've got the double bond is actually making The deals alder reaction happen and then there's this other thing Well here it's on the top there. It's on the bottom so Oh, thank you games. Yes, perfect um, so basically there's um, you know one this is one face that's um reacting with the thing on the top That's the other face uh How the faces react it kind of depends on what's attached Right, so endo versus exo endo is the one that usually happens It forms faster this that extra a little bit of interaction helps it to form faster and it makes the product faster Even though it's more congested overall to give them the products and I can show you an example of that over here uh Move this guy over here So, uh, this is See I meant to have the bonds in From uh pretty much the reaction shown on the slide very similar But one's an exo one's an endo The back of the molecules are in exactly the same orientation, but you can see the front One points, you know, if you look at them from the top one's a little more flattened out. One's a little more congested They're different molecules. They have the same connectivity Like each atom is connected to its neighbor in the same way But because of the left-handed stuff in the right-handed stuff the overall geometry So, uh, one of these is exo. It's the one on the right One of them is endo The exo one would be the one that would tend to form All of the things being equal Okay, so basically that's uh That's how how the visualization goes. So there's this molecule on the Um left plus the one on the middle. Um, I've made them parts of rings So that uh endo and exo actually Does matter in this particular case Okay, it's still a di-e because it's got two of these double bonds The e and e When it's part of a molecule mean there's a double bond in there somewhere Maybe I'll do a different talk on nomenclature and how to name things Yeah, okay. So, um There was also con rotatory and dis rotatory. I just mentioned that really really briefly This is a molecule with a double bond a single bond and a double bond and what you can do is shine light on it and um This carbon will rotate Clockwise this one will rotate counterclockwise I'm sorry. It's drawn so that this one rotates Clockwise that one rotates counterclockwise. Yes, I said that right No, they're both going clockwise duh that way you get the lobes of the same shading Coming towards each other forming a bond Uh, and then you have a bond But you know, if you had a methyl group there and a methyl group there You start with everything in the same plane But you end up with one methyl group up one methyl group down Okay If you have a different number of double bonds involved You can have a reaction Where these guys have to rotate in the opposite direction. So that's the dis rotatory to make that bond Okay, so, um these these rules these, um considerations of What colors the lobes are essentially? Um, give us control over structure So, so yeah, I mean, there's just a couple of points here Um, a lot of the times these things all happen at the same time But you could have one side connect Earlier than the and the other go click click um Lewis assets, I'm probably, um Going over with my time. So I think I'll um not Inflict that on you right now One nice point here is that these reactions are reversible. Um, you know, you can, um Heat these molecules up after the reals reals reactions and make them make them go back to their starting material That's particularly useful if you want the deals elder starting materials But uh, there's no real good way of making them. Maybe what you can do is get the particular like product That you would get from the deals elder reaction. Maybe you can make it a different way and if so heat the bejesus out of it and um, you know, basically get back to Starting materials that you want not a particularly efficient way of doing things, but uh, sometimes they are used Let's say I got one little model of a transition metal complex Which basically means transition metals the brown atom It's not the most efficient the brown Got it is an iron That the brown atom is an iron atom and it happens to be connected to Looks like a six-membered ring. That would be what's uh, up and down vertically on It's actually connected to four of those carbons. You can see four lines there um, it would be that would be a dyeing um The iron being connected in that way. So what we could do is Maybe a reaction that might Give you a deals elder reaction if the iron weren't around but uh, this ends up being a masked Reverse but again Having metals In your pharmaceuticals Is not good That brings me back to uh, macmillan's work basically found ways found a way to um Make this deals elder reaction. You see your double bonds. You see the pair of double bonds. He made this reaction go um faster And he made it go to One of these products I think about 97 yield maybe 3 yield of the other one um And he did it without a method Um, this catalyst This thing if you didn't have it there the reaction would probably not go very well And maybe give a 50 50 mixture or something like that I got it to go in a 90s I think with I've got it on the slide 97 to three years So Essentially this is from the original paper shamelessly stole the picture essentially This catalyst that nh group Can End up where that oxygen is Okay, so this isn't exactly this. This isn't exactly the same molecule as an intermediate. The only difference is um, this benzene ring over here Has been replaced by a hydrogen in the molecule they chose to draw but essentially This set of atoms corresponds to that starting material The rest of it Is where that nh is attached And the beautiful thing you can see is that there's this huge group on this side That's going to block the second molecule from coming in and make it so that only one face Of this guy can react And that's where That's where our like 97 yield comes in um This is this is how You would have to explain what's going on if you were to um, take an organic chemistry course and write an exam on it. Uh, essentially um You know, you could go through a step by step analysis and you see that c double bond O is a place where that nitrogen can interact and then there's a series of logical steps that uh You can spit out water And end up having that carbon, which is that carbon Those two are the same carbon Um, ending up being attached to that nitrogen. Let's see Shiloh is asking when this process is used to artificially produce something like vitamin d or vitamin like What occurs when the vitamin reaches passes its expiration dates? Uh, are the hydrogen bonds breaking down naturally or even in the medicine? Okay, so this is a great question because double bonds Uh, and vitamin d is a great example of that because it's got a lot of these double bonds It's got this arrangement double bond single bond double bond single bond double bond Those arrangements are subject to oxidation so essentially, um Very very slowly this happens. So it's got a shelf life but essentially, um, what can happen is that you get a Um, one of those double bonds reacting with oxygen to give you a peroxide and then that starts to Um make links with adjacent molecules double bonds it ends up being a chain process Um, and it's the process of going rancid essentially So, um, you know after its expiration date, uh, they're pretty conservative with the expiration date But you know after the expiration dates probably got a bit of rancidity happening. So, yeah, basically it's changing the structures So essentially, uh on this slide, I've just kind of shown how those, um, how the catalyst gets on the, um Species of interest and all of these reactions are reversible. So once the catalyst gets on and makes the thing that actually does the reaction it can come off again In the same way as it gone on just a reverse order so Let's see what I've circled there is, uh Carbon atom that's got four different things attached. It's got a handedness There's two starting materials did not have any handedness to them So that carbon I've circled is going to Imprint its handedness on The reaction product right because this end this side Um is blocked You might get the opposite reaction product if you swapped those two groups And that's how a lot of these reactions work. I guess you get 94 of the one product and then uh six percent of the other. That's still great for the very first reaction um published Um with this purely organic catalysis Let's go back for a second. I've got a thing to say though. Um This particular uh catalysis will only work Excuse me If you have that C double bondo in the starting material to begin with Here we go. So if you have this part of the molecule That catalyst will work if you don't if you have something else there instead That catalyst won't do the same thing so McMillan's work is Is Really nice in that it shows that this catalysis is possible but You have to tune your catalyst for the reaction that you want to do So it's not something where you can just have you know, like in the transition metal catalyst the ruthenium stuff You just have it on the shelf. You just throw it in see what happens and it's likely to work Uh, you actually have to do a lot more thought and design To make a particular reaction go Uh for for for these methods All right, so that's bringing me to the end. Sorry for going a little bit late here um You know, it's very flexible and we get metal free pathways to Good good chemicals flying chemical sister as they're called Thanks, thanks orange for coming And uh, you know, basically i'm wrapping up here uh each reaction I said you need to design its catalyst and this is uh Active topic of research. I mean very very uh, lots and lots of uh papers. This has been exponentially growing since its discovery um 20 years ago Okay, so with that Uh, thanks to everybody, uh, thanks to all of you for coming and for having patience with me while i'm talking about chemistry Sorry if i'm um scaring you with the organic stuff um, I really appreciate Coming, um, you know, basically also thanks to nsf that supports The science circle and supports my research My research students. I um, i'm happy with uh, they they help a lot behind the scenes for Different things that we've done. Uh, dr rick de radiou is my collaborator on the grant Yeah, I owe him so so much. Uh, and of course, um, you know my own school You know department college graduate school of those things and definitely you for your attention Thank you so much Let's see and i'm happy as answering some questions if anyone's got questions All right Well, thank you so much. Uh, have a great evening Everybody I'll wrap up on the catalyst. They settled down Kind of fending them off only during talks Do they I'll make sure my molecule pets when I go away doesn't