Lecture 21: Diels-Alder Reaction

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Lecture 21: Diels-Alder Reaction
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This is the second quarter of the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: 00:49 - The Diels-Alder Reactions 01:32 - Characteristics of the Diels-Alder Reaction: Mechanism 02:10 - Substituent Effects 09:37 - Stereochemistry 18:41 - The Diels-Alder Reaction is Stereospecific 24:22 - The Endo Rule
Ionenbindung Sunscreen Complication (medicine) Steel Wursthülle Methylgruppe Chemistry Reactivity (chemistry) Diet food Molecule Lead Electron Fire Human body temperature Atom Periodate Process (computing) Chemical reactor Hydrocarboxylierung Setzen <Verfahrenstechnik> Area Stress management Alkane Tuberculosis Asset Ice front Pressure Wine tasting descriptors Electronic cigarette Gesundheitsstörung Computer animation Yield (engineering) By-product Chemical structure Wasserwelle <Haarbehandlung>
Ionenbindung Hydrogen bond Walking Diamond Carbon (fiber) Electronic cigarette Wine tasting descriptors Steric effects Chemistry Optische Aktivität Atomic orbital Molecule Sample (material) Computer animation Tiermodell Fire Essenz <Lebensmittel> Covalent bond Suspension (chemistry) Cobaltoxide Pipette
Sense District Substituent Metal Substitutionsreaktion Growth medium Chemistry Electronic cigarette Systemic therapy Diet food Hydrogen Stream gauge Computer animation Fire Colourant Covalent bond Chemical structure Thermoforming Process (computing)
Area Ionenbindung Terrasse <Geologie> Alp (name) Stockfish Electronic cigarette Wine tasting descriptors Klinisches Experiment Systemic therapy Reducing agent Hydrogen Ice Computer animation Curing (food preservation) Fire
Übergangszustand Ionenbindung Bearing (mechanical) Left-wing politics Watt Chemistry Methylgruppe Diet food Dairy product Kalben <Geographie> Tidal race Electron Lactitol Common land Spring (hydrology) Radiology Waterfall Area Metal Molekulardynamik Carbon (fiber) Addition reaction Fiber Electronic cigarette Systemic therapy Hydrogen Computer animation Gasoline Azo coupling Covalent bond Cobaltoxide
Suture (geology) Substituent Hydrogen Ionenbindung Computer animation Elektrolytische Dissoziation Octane rating Colourant Saline (medicine) Watt Medical history Wursthülle
Substituent Diet food Hydrogen Computer animation Electron Elektrolytische Dissoziation Active site Medical history Periodate Process (computing)
apparently left out last time talking about deal is all the more exotic or about deals or come close to finishing Chapter 16 today and there and injected 17 isn't very fast chapter and there will be on the final chapter Chapter 18 so why open up Chapter 16 saplings Chapter 17 Japanese and really for designing and all of the matter as soon as we start that would've been Wednesday questions anybody before we get started are still deals sorry actually very simple mechanistic but it
is difficult to draw the includes structures even drawing either way on the like that like to drive that way because of would later on when we talk about it going and so far it's it's a little bit more clear than having this wave so this is sort of a sideways views so this could be be waged cereals sometimes see this waged in that way so it's really you know perpendicular to the page was kind of floating above the page or you can look at it from the top and then this would be and always coming up and you can drive this way it's a lot easier for allowed students to drop are excellent certain characteristics and we will really spend almost the whole time this time talking about characteristics of the deals all reaction so reacting bonds are broken product was recorded at the same time so and that's what a concerted reactions OK so reacted bonds are appropriate curveballs of is simultaneously so we had another concerted reaction which 1 was I heard some to the 2 also concern reaction so this is our 3rd concern reaction mechanism does not involve radical ionic intermediates firing so I'm going to talk about the factors fueling talk 1st about substituent effects was reacting Danny involves an electron electron poor In the most reactive Deininger electron which so when this reactive in this reaction that the of violent acts as an electrifying In some ways and so electron selection for and then the undying is is electron rich so acts as a nuclear bomb but it is a completely different reaction as you can see so the best of the best deals all reactions have a electron rich dying only 24 hours a day in file there are some examples where people have switched the 2 and made in view of the dining of viable electron rich and the dining electron quarter there's a few examples of those they don't work very well and you will see them in this class of cases it's it's best to have be this way so the DG is stands for electron doin Inge EWG stands for Elektrowatt touring group Oregon also use those abbreviations in Chapter 18 so that's going to be important certainly gives examples of some electron donating groups and also he will get Chapter 18 pretty quickly from now I worries the same terminology so far there are a means also Ch alkyl groups are slightly electron donating so hear some examples and these are all electron rich these are not the only examples but the common examples and it has elected only groups that have alone hair on the atom attached to that the dying are going to be more star stronger than going at once with art attached so the 2nd the strongest here the strongest ones have grown pears Our Elektrowatt during which the aura and you can't have both the kind with electron during the group is on the end or on both ends and these are the types you will see we give you some electron withdrawing 3 examples carbonyl conference teachers on master and the squiggly line is where it's attached to the dying of fire that I should do that over here to list squiggly lines here things like scientists I hadn't heard that Elektrowatt during the nature of very powerful electoral these are all electoral if you doing deals reaction and you don't have an electron which dying and you don't have an electron of poor dying file then I'm going to have to use a very very high temperature in order to get the reaction to go OK if you have a good diet which is of electrons rich and I could electron deficient data file the reaction was readily at room temperature so you can see example here and I don't want you to remember memorize these conditions but I just want you to be aware of what's happening here this 1 here this is a I'm dying in just technically have this methyl groups CH 2 not enough about methylene group attacked so it's somewhat electron donating but as you can see the dying a fire almost no electoral triumph and so in order to get this
reaction to go if you need to have a run at 200 degrees Centigrade at 800 2 900 pounds per square inch for 7 hours In what we call a OK so it's a it's a steal thick walled steel reaction vessel you put your reagents in their use screw it up screwed on with it bolted on and it has a pressure relief valve the pressure gets up above a certain pressure it will come out this will shoot up the side case it's called upon ideas from the forest cover the blast area so that was it's a thick-walled steel reaction vessel so I call discoursing conditions recalled still reaction vessel Air and if you do that you get about 60 per cent of the deals older again a to drop this way you can draw the flat where he was like this all dropped both ways this is a bird's-eye view as if you were sitting on top of this molecule looking down at it that would that would be what it would look like if you are going to what this way where it looks like the roof of a house you want to make sure that you break this back line here if you draw that line is crossed then that means there's a contrary view that junctures remember whenever we have overlapping and we're doing skeletal structures it this straight and fast then I means that there's a career here you've added that per cent want break that line if you have trouble doing that and then you can drop this way you don't wanna break the frontline because the back line is that this is in front of the backline if you break the frontlines it's looks a little strange will and Sciascia thing going on there you know and so yeah I want you the lines in 4 years this way and this line is broken off again can do it alright I'm still here sigh example where we have electron rich and single Richard this by putting good electron donated groups that have long periods but we can make this more electron rich of stood electron poor and again it is even more electrons but including tumult like part of the directive said on that type of file and if you do it this way this is 30 degrees centigrade atmosphere pressure you can only time for this 1 but as you can see it was much more readily and he did a very good 100 per cent yield of this call no side products whatsoever I'm deliberately not gonna show Sterry chemistry on this 1 because later we are going to talk about serious consuming on today will talk about certain so whenever set for that alright questions so far that deals the anybody are obsolete today means the very next thing stereo chemistry political lot aspects to steer country makes this makers of more complicated reaction but I'm going to show you an easy way to draw the correct staring chemistry that should make it you're able to do it more quickly than you normally would so 1st things 1st the dying must be in the years since confirmation for this reaction to take place so as we talked about already most offerings like to be in the as strands there were some exceptions but most like to be in the strands of an equilibrium this view dying we have about 95 per cent that's in the past trends and then of course that single bond always retain very rapidly and so some of the time we have assets so if we if we took a snapshot of a of a flask containing you dying would see that 95 per cent which took a picture of a 95 per cent will be a strengthened by persons will be in the process and I'm so even so even as transit is favored lead you have compilation every time that rotates and that's what's going to react so the dying we must rotate To the SS confirmation to undergo deals or reactions if you have a dying that doesn't readily wrote a consistory clearances can have a very slow jails or reaction if you have a dying and that is likes to be in this as confirmation of going to have a basket deals on solar adjacent examples we
have this 1 here and you can see especially if you were to draw out each of those carbon hydrogen bonds would see that you're cottages with jutting right into each other and so on for this particular 1 there steric hindrance and that is the inverse the SS Corporation so when this when this diamond rotates its chemical 1 being that confirmation had a very small percentage of of the molecules in their confirmation that's going to slow the reaction down so this is how much slower then we are in this 1 it wasn't really obvious to see whether the public will continue to look at a model for this 1 8 but this 1 has austerity entrance in the ass Trans confirmation so for this particular example the essence more favored than the strands I don't have numbers for the amount of each very anencephaly most molecules he took a picture of this a sample of the city's most of organ in in the ashtray status and so that means it's going to be back after the died next example but by the CIA has been considered suspense strands here's our double bonds and you can see that we have this double bond futures on 1 side of that single bond this 1 hears on the other side so this is a strange cannot rotate and SS impossible yeah so this 1 can to U.S. and because of that there is no deals alter so there's no deals although this can do other reactions that can do deals overreaction and then the last example here is is actually something that's fixed in the SS confirmation it can rotate into the transit you look a sample of this small it will all be assessed so this is going to be a much faster than you it that's because it's fixed in the asterisk corporations the step oxygen do the deals although we have to have dining rotated into the SS and then they have to collide in the correct orientation With the dying of file and others has been much more likely here that it will collide with is already in the correct orientation and pets that's that's a big deal what is the going to be in the answers confirmation this is about how the reaction takes place so this reaction you're reacting on the P orbitals of the firearms so here is unit dying years 1 "quotation mark hears the other double bond and that heroes are dying of file right here so there's the leader of his there the what's actually reacting is that fewer rules of the pipe bombs and if you see here we had overlap on top I understand overlap so that did the 2 airlines needs is overlap simultaneously so this is your opponent the book that in on so when the euro was overlap sideways make when the overlap and on like this then they make up a new single bonds were making 2 new signal once simultaneously so that fewer rules overlap and on to make 2 narrow Sigma bonds and they must overlap simultaneously so why simultaneously this is a concerted reactions so it's not a stepwise reaction so they have to overlap simultaneously if they aren't even if the John cleaning is in there as strands here's 1 double bond here's another global bond as you can see these guys are too far away from each other because for me that is the that's not end on we can overlap and 1 of them and we just like this guy over here with its like this over the here so this funeral was right on top of that 1 but then this would be even further away so we can make those 2 bombs simultaneously and therefore the reaction doesn't occur so past Trans if you but also are too far apart To overlaps With the on the ends of the dying of fire simultaneously so therefore no reaction of deals or action all right so more about
steering chemistry that deals all registers as an exception to on the same side of the dying on a diet of all the pieces on the newly formed brain so if you look at this look at this dying of fire here this room right here in this for system each other alive that that in the party will also use this to each other so there may be blocked the train and against the Jets have trouble seeing this or drama hijacked and will you see that this success so this is a B or C S and a thriving arrows for that process I connected she wants and then I just I start arrows going around in a circle does it matter where I started using it announced they start from a pylon I can go clockwise or counterclockwise so where those dotted lines are is that going to be a newborn and so moving electrons around in a circle and so when I do that I can have these bills going up I'm going to have both going up here I could have them both going down so there's a sense of urgency In in the dying a final and so they are also on the same side in the product so the media circle the groups that I'm talking about here and talking about the scrupulous and back here since I Isidro on same site foreign and here's another example here Argentina vows enough time so that's going to be a little bit different here but what struck areas around in a circle so when we use in our client is a dying of get a 2nd double bond in the rain 2 0 CH 3 most 6 that and what about the necklace there at the end of the dying to OK this month is going to be out this metals also going to be and so on the dying itself we also have groups and those are also with the Bulls were what we call we can label the use of my colleagues outside substituent a call these outside substituent and unless trying the hydrogen is view that a different color recycled inside and so the outside substituent starting to be on the same side in the ring and the inside substituent also then be on the same side of the ring in the product so outside substitutions on the same side in the ring hindering the reforms in the ring form so there's the outsides of judgments on the same side the Insider also are on the same side so if we drew them and we don't have to draw them in for a chance to do up to draw them in the saplings but he dropped them in here the insights of stations are also on the same side now your book doesn't really have any examples where they have outside constituents they actually just go wild goal by substituent there on the dining here and so I've I've added extra funds will be doing a lot of problems with the deals over this week I'm and there's also extra ones on Sakhalin Samye match the ones we're going to do in discussions so that you'll get practice to and assure you achieved the weighted Faldo's accurately pretty easily questions on Christians so far and staring chemistry Our writes that leads us to the end rule will pay so this is 1 more further complication and and this is why I draw all the ones with the system so known is that if you have a dying integrated into the Windows weird by cyclic working structures but it actually turns out that of the bicycle looking structure that is does a better job of conveying what I mean by and so what was that strongest you ways you can actually do all the product for this reaction but strong both ways and just in and I think he should just try to drop as wages so we can you can see the illustration here so so we have this group here hydrogen is off the 2 just draw that when or we can have this group actually coming up this point down and all that kind of little weird-looking let's fix them
instruments on each other we think we deftly Orin S. here but I know enough about the double 1 was thrown out on the side of that now you can answer the question of idols in inches insurers of each other while they're not mirror images announced that there would be if the Nanshan has announced a proposal Mary missiles or not and insurers even only have the opposite configuration at this corner right here what we can draw this when we draw this 1 that this is actually jotting down under any so this is a little houses jetting down into the house underneath his forms like a little cabin here and this is jetting down into the cavity over here it's got away from from back cavities so imagine if we continue our little house here this continual house and red here just on seeking custody or a few meters into
a house right that's going to jutting into the house right and if we bring this into a house here and that's again why I draw this way because it's easier to see and the rule that's Alps that's coming out of the house that's coming out from the roof there so we could use other that we call this 1 and only end over inside now of course it is in the house under strong lines the imaginary lines over to see you can have a little visual here that is chatting up under into that cavities I'm so that's end of this is so an answer from the outside so XO skeleton like you learn and bio that's outside of the body right so and XO staring which is better start the excellence better but it turns out that you don't get excelled you get so even if that's so it must mean that it can be 1st Terrace reason the reason that we get as the major and basically what we're going to do is we're going to ignore excellent Tyrese say we don't get for you actually do get a little bit with a small amount of work occurring so it turns out that at the end of it does happen in Traverse City get in and out of this 1 plus its intention this is what you get what is in instrument look like dropping their images that and then will still have been that's in the article .period then that driving their images that and that will be your announced so you do get me not to get into a life because we have to get a restraining nature because this is a marvelous is a trial there's no Cairo influence right so we have to get major scenic areas in which you don't get any are still out of my way explain this to you the dying functional range
in 2 different ways so we know that this reduction happened at the of the ice system so managers draw in office here so we have to worry and so that the dying fires right underneath here and this is a little hard to draw but we again we want these bonds to be forming simultaneously Mike whitecaps not trying perfectly well but Jeffrey drew it nicely and you would see that those bonds would you right underneath each other ready to overlap simultaneously and so noticed that this group is away from the supply system so let's stronger arm but strong product here if that's the orientation of the dying file the end of this probably going to be up in this hydrogen is going to be down but that's the orientation so this is XO outside steering earlier looks better now but Endo the lectern during group is tucked under the dying so let's try that but I do I miss on line 1 don't do that to an adjusted it there's no cure so this guy is right underneath these guys are overlapping simultaneously nature it's so small that it looks terrible so let's fix that so here's here's this 1 here's this 1 and these are overlapping simultaneously characters like that if they overlap this way then you have Oh product in starkly definitely could see when we dried out this way it's much worse start In spite of that tho this is the major product so now the hydrogen is outside so definitely on XM products are not favorite let's crosses that we don't get this overlap definitely that's how you get so it must not be stocks that are the reason why this
happens and the reason why this happens is that as it's called secondary overlap you will not need to describe this an exam I just want you to give you a picture here overlap of the appearance of Elektrowatt trying to put the evils of seats you would see 3 of the dining this stabilizes the transition state what happens when we stabilize the transition state chronological can contracted for me here the WGA so whenever you drawing canned rights which is at a relatively on the left-hand side so that is not a G W E that the you can that is a nice little data to so change that fact EWG I mean you know second-half OK so what happens is that this is our primary overlap right here that's were going to make a new single bonds in the secondary overlap happens with the electron which growing group on the only dying file so if you can imagine here and this is really hard to draw also to it's always is you have a chance here here's a carbon this is a commonly owned to carbon-oxygen double bonds so there's a carbon the carbon-oxygen double bonds In and were exaggerating this a little bit there's the oxygen and it turns out that this is going overlap not to make a new bond I happen to close together not to make a new bond but to lower the energy of the transition state so so the secondary overlap is right here this is secondary overlap you will not have to just drop out as will not have to describe this but it doesn't give you a reason why this electron which I believe even those steered clear its worst electoral withdrawing the talks under the dying like this 1 area doesn't go away it's under the diet under the object of a driving test under the time the tucked under the dining not so that the 2 detect doesn't have very many examples of being able to draw the products like I said we put someone unsettling and we have some a lot of women discussion this week so when we go through them main discussion this week stick that said that recent papers society and no studying for the final printout that try to do it yourself cancel that and then you'll be ready for any deals all reactions that I might ask that I will last until some reaction forests and there's examples using animal major product in the following cycle addition reactions so that once the yearbook calves are these ones were the dying is in a race that's the only time they have to display of those 4 4 practice the use of are the ones that they're missing so we went through a couple of examples to pirates cyclic dying again with strong our heroes here connected to Ansar the prices down just like the ones and so when his notices to Commons in between the 2 ends of the dying so that means that our house is going to have a squared off group here so there's a double bond that's a little during and the square everyone is a little more difficult to draw the flat I'm not going to interact no but this group the this is down this is odd dying file this is a fantastic fall because it has a double electoral during groups hydrogen hydrogen so looks like that those the 2 hydrogen is a out I'm drawing them straight up the usually the Little Al a little bit more than that but it's hard to kind of hard to draw but if the dynamism of fiber bearing that we have a roof so let's try that also volunteers around the circle I'm starting at different points in the spring when I do that I tend looks like that tend to go counterclockwise could again you have to do it that way so now we have our peaked roof here double bond over on the left hand side easy root forget that some make sure you keep an eye on the couch and of the electron join group is going to be
down now here we have on this on this diet you finally have an electoral during the family of electron donating group on this and it's the electron withdrawing the it's going to be and so that's really important so when the draw that went down hydrogen up here and then the Mosul is going to be In the hydrogen down so so no 1 in this he's trans here this metal and there's probably a lot France to each other so they're on opposite sides in the rain this one's down mountainsides so we have to maintain its dairy chemistry but the 1 that's down tapped into this cavity is the carbon electron withdrawing so the WGA His Endo not the methyl group now because the regions are a kind will we always wanna ride policy unless there is no easy unless there is no 1 inch or so on this 1 here does not Connecticut a cemetery that would cut us in half lengthwise here With slices like full a microphone laying radiology that has appointed senators so that they can I really don't to see this is Kiran so we will we will want to write a story here question anybody yes we're OK all I can I so so as it is is the bond making here that is voluntary here I will make a monster this guy right here so that dotted line is in the hands of the system so here's the enterprise system here that's his that's the sponsoring here this which of the in pondering that's right here the gasoline dropped 1 highlight that that's a really good question because I see a lot of mistakes on this on the exam because I think it's really difficult to see so this right here it is right here and just so you have an easier time its strongest flats so metal is going to be coming off this group here is going to be going back to feel free to drop this way only examined Sapp when you will need to draw hydrogen is on both of those problems and then let's change the colors and show you where bridges bridges right here Mike OK so clear yeah OK all right so that's it cited examples you look past let's talk about Issaquah died because a 2nd time is there they do also follow their role so it's important that we know not all are excellent overall by the cyclic dying to know there's 2 ways to draw audiences when he beat ways and I'm in the 1st line is going to be kind of paralleling the way I did it up here and probably nobody's going to do it this way but I want to show you where this is coming from OK so assure you this way and I think anybody is going to drop this way so what do is I'm going to imagine replacing them this needs to hydrogen is with the CH 2 as is just a temporary measure so I could make it easier to draw off of replaces 2 hydrogen with a C H 2 if that makes it more like this creates example works will be easier to see how you get allergy that temporarily and then I'm going to I'm due at the end so this isn't cheap pages you have it all and PAC could just go ahead and you work with the space that you you have you've got more space than are excellent major artists and purple animal keep an eye on the guys felonies bluefin that were sticking with blue for the for the Everybody was
think for the other groups and then here is my son died file OK we're going to need a new bond here between the 2 companies with color fired so there's the Arab pushing let's let's try being product I was in the same way that I have been doing it this hydrogen is on Saturday you'll want to draw these flat because they don't think sapling can read these guys will see what I have to take another look at this to see what with the cases but I'm so this is this 0 suturing must be down and because the bridges are out so let's coloring the bridge in light blue this is
our that's a temporary bridge we replace the 2 hydrogen is with that and then I cost I'm missing my double what the rate is easy to forget that so that we would get but that's not our product because we we don't have a siege to bridge in a product so now I'm going to remove the CH June and this is going to look a little weird I'm going to try exactly the way it is and I'm going to drive a little better dry flat Kansas is looking very strange I just want you to follow what I'm doing here so if I'm going to take that CH 2 out again and replacing it with 2 hydrogen so let's put the 2 hydrogen stand this hydrogen is up this hydrogen is up Everything else is going down 0 Ch trees going down here those siege the impact is going down in history right here the like Charlie Jernigan of course is always also going down because that's our lecture lecturing so that's what it looks like that a little strange to another query that OK that's a little better Everybody that withdrawn that flat Astana flat salinity to your arrow pages the your one-page Estrada flat notice that the O C H 3 is going down this associates 3 is going down this group here is also going down so we want to draw a product that certain products and since all of our regions or at Cairo we will get the unions where is this Cairo resisted a common products it's kind we've got 3 serious centers and no planes of cemeteries will write plus an issue here think so that's a long way to do this anomaly shorter waiting you it's that the outside substituent and that's all this is going to be a mnemonic for a meeting of the
jobless those are an outside what is the relationship between outside substituent Aaron the Elektrowatt during her from dying before our I think site so there's a online outside substituent and electron during the on the same side so this is the easy way to determine staring straight outsides of Tudjman's Annadiane electoral drinkers but diet violence inside the ring in the of the new not to go through this all prospects I'd Susan going back but you can draw them coming forward as long as they're all coming forward it's correct what would that be the Jordan all coming forward what is that that would be the mansion that I drove them all going back to the job of all coming forward you're going natural and there are too many insurers so both ways work so as to here's an example right here here's outside and back so the user outside and this is our electoral returning group they're all going back there all going on the same side I'm going to draw them going back isn't going
back this was told that this was going and as you can see we knew we were very quickly performing very elaborate rings here so but the nostrils this going back here but it's not enough to let's say history right no it is 1 of the 2 of them that's an OCS train now this is an OCA this is a the hydrogen is going back on an association is also going back and this 1 is also going to they will have that close an injured right .period there and we will finish this next time