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Lecture 22. Conjugation, Resonance, Diels-Alder Reactions, Part 2


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so I just saw this news article From about tennis doing some
sort of work related to the oil industry was looks like some kind of picture from the 1960's with some old dude working alone in the lab most labs aren't like that anymore How could and say might wonder what is organic chemistry have to do it with underground rocks oilfield industry and so let's talk about that wire to wire the showing this picture of some chemist trend of some sort of an impact on the oil and gas field in history
and it has to do with fracking This term may have you heard of before this is revolutionizing energy production in the United States itself for my entire lifetime the United States has been an importer a net importer of oil and gas and that could change it could reverse to the point where we have so much boiling mainly natural gas were were able to export that other countries and it's based on this concept of fracking you take of an oil drilling rig trying to access natural gas where there isn't much if you drill into shale deposits but you can get it to go sideways and you initiate small explosions here and then you can use pressurized fluids to break up this this shale rock so that the gasses can escape and come back out there that's racking so breaking up the shale rock using high-pressure liquid but in order to allow natural gas to seep through it and escape you can collect it now so what is it take to take fluids that you can pressurize so much that they can break up shale rock while you need needed special chemical additives to that and those recipes a secret no chemical ,comma no oil company wants to tell you what secret recipe here they're using that allows them to pressurize I'm basically aqueous solutions so much that they will break up shale rock on but here's 1 of the additives it's now well known within the industry that 1 of the secret additives it's no longer sequence is a compound called wall are gone and this is changed the economics was certainly on a blog on production 75 per cent of the quantum this produced no world comes from India it's going to be it's used as a thickener and ice creams in food you can buy on the Internet but of course the oil and gas industry uses lots of this in fact Halliburton last year issued a profit warning is a 30 billion dollar company they said of working out problems of their profits next year because the cover price of war on has shot up so much so these Indian farmers a I guess there in the money because they're producing something that everybody wants is the structure of what on it's an old sack arriving and later on in can 51 C probably the last chapter did you cover you're going to cover glycol biology and although sack rides like this 1 this is go alright Gloriane it still goes said Greg defined in why gone and it's similar number of the sugar man knows so well because there's kind of a polymer era with the sugar minnows and attached to every other sugar there's a different sugar called galacticos so that's the structure of Warrenton Oregon and it's changing oil production in the United States and around the world but giving us access to the gas deposits that previously couldn't extracted out of the ground so the remind you that there's to new assignments there now up and running on the sapling of onwards said this Chapter 16 at the diamonds chapter that we're doing right now and Chapter 17 which we're going to start today and I'm making an assignment due on Sunday because I don't want you to fall behind it but this sort of the last chapter Chapter 18 is huge and I want you to have a clean slate by Monday when we started Chapter 18 I want to be done with the problems for Chapter 16 and 17 so I'm not letting you fall behind that's not going to be a choice for you so our goal today is to finish after 16 dying and resonance and something called the deal older reaction and then will have just a little bit of time to start Chapter 17 and uncle of benzene rings OK so 1 of the problems that you've been doing in discussion sections this week but you've been introduced to something called the deals older reaction and let me show you the deals the reaction and operates by saying I guarantee you I will have deals all the reaction on the final who knows I'm not at 20 deals all the reactions that every organic chemist loves deals all the reactions professor King loves steals all the reactions Professor Guan Professor Freeman and it's because it makes to carbon-carbon bond simultaneously someone of the reactants in a deal the reaction is a dying that's whites in this chapter sorry there's a question you can't see anything hard about that and fix that rise again so I'm talking about the
deal's older reaction and again here's the reaction that I love so much and it's a reaction that uses dying so here I'm showing a dying as a reactant and then there's some sort of a another reactant in here an keen on and we call that the dying know file I'm not a Latin expert but I think you can get what that means is it just loves doing deals all the reactions with diamonds and a 90 per cent of cases there's a carbon wheel attached to the dying of file that makes the reactions work faster so you have to keep them to a thousand degrees so here's my recipe for a deal reaction and there's no extra reagent that you had on typically even with the cardinal repair there you do have to heed these so if you just see a dying in our unity that's usually a sign that you're going to undergo a deals all the reaction and the product of the steals all the reaction is a six-member ordering and specifically a cycle hex you will generate a
cyclo hexane reign with a double bond somewhere in there every single time I see a six-member ring with a double bond in it I'm thinking I can't make that studios all reaction and I would like you to think the same thing I'd like you every time you see a six-member rain but with a double bond and had like you think you could make that through deals the reaction OK let me drop the Arab pushing this is a concerted process I don't know if you can see this but you form to new bonds here is 1 of those new bonds here's the other new bond so this right knew he formed to new bonds C bonds in this reaction had spectacular and slipped push the heroes but to understand as you can imagine that this pipelines down here could be a nucleophile and attack this double bond means had to break this Bonderman died 1805 and make that attacked this carbon and I don't have to monster carbon source swing bonds down here so the streaking arrows in the correct era pushing for deals all the reaction you make to know carbon-carbon bonds and it's very powerful that's very powerful to be able to make 2 bonds on it in a single OK so let me just remind you of these names because I'm going to refer to these now .period out why hate the name so much so this fragment recall the dying I hope that's obvious why it's called the damn thing because it's always entitles them to double bonds conjugated to each other this other fragment that reacts in a deals all the reaction if I want to describe the other partner any deals or the reaction I would call this the dying 1805 0 5 and the reason I always hated this is because I felt like the smaller component had the longer name that always seemed opposite of logic to me but I didn't invent the system that's that's the naming system so the dying but the 1 with 2 double bonds that's the
dying and the dying or file where just 1 double CCW 1 react on that's the smaller fragments that tends to get the larger now I expect you to practice this reaction there are lots of problems in the back of the chapter and I expect you do users problems sapling homework and I expect you to be good with this reaction backward and forward I expect you if I give you 2 components and to recognize that deals overreaction can happen incorrect control the product and the finish this productivity the missing the cardinal group the carbonyl group would be attached great there here we go so it looks kind of small but I forgot to draw that I was so excited about the psycho Heck OK so we need to practice the the deals all reaction backwards and forwards if I give you 2 starting materials I expect you to be a little the product if I give you the product I expect you to be able to draw the 2 starting materials this is a very important reaction in organic synthesis on and in those kinds of problems that on the last page of my exams I say here since starting materials here's the product show me what really agency reduced it to 2 that to convert all starting materials into products and steps so the key thing for from here if I want to figure out what my starting rituals would look like would be too we recognize that cycle hexane rain and recognize the 2 new bonds that would form a ideologue reaction is 1 of the new bonds there is the other new bond so by seeing those 2 new bonds that would form a deals all the reaction by recognizing this pattern you can back out with the 2 starting materials will be the 2 starting materials will be a dying maybe I'd enjoy straight as they could and then the others during Mitchell will be the dying and I just have to figure out what the substituent start on there sometimes the diagonal file could be an al-Qaida which would be the 2nd double bond that makes it very confusing on OK so if I look at this there's H attached to this position and then there is this he told a group so I'm not going to draw the age but I'm going to draw Hitomi group with an Ethel hanging off the other side and there I go I'm done with the unified and I have to look at what attached over here on the dining and like there's a methyl grouping offer for this carbon and others to other muscle groups and that's it that's how easy it is these are the 2 components and dying and denying all file that will lead to the six-member rang through this concerted bond forming reaction were 2 new carbon-carbon bonds form simultaneously and so sodium this that this is also the kind of question the last UN standardized exams if you're applying for a medical school or the deity they expect you to know this reaction very powerful stuff but it's never a requirement for the dying you can just take any old diaries and have engaging deals all the reactions and in the last lecture on Monday I introduced you this this nomenclature called decison as trains to describe 2 different flat confirmations of a dying so let me draw out a dying here here's a molecule that has to but inside the order conjugated dying and there's 2 different flat confirmation of this I would refer to this flight confirmation is the S confirmation you may recall that had drawn at flat in the plane of the of the and acting equilibrate This is not a resident structure because I knew Adams I have to move swings double bond around I have to rotate around this bond 1 way or the other and if you move Adams it's not a resonant structure as soon as you start moving Adams ,comma so when I draw this this dying in the alternative flat confirmation the S confirmation now I can more readily see how these 2 carbons on the right-hand side and can position themselves so that they are close to a potential die you know files and so let me draw this die you know file here I'm just to be different under draw the carbonyl group pointing downward you get stuck always drawing in in the same maybe you put I try not to get stuck driving the same confirmation I'm not going to draw the euro pushing I'm just going to try to show you here that way and that when a dying conjugated diners Iniesta's confirmation these 2 carbons over here are positioned and ready to form a six-member grade she can see which carbons will be attached there is OK so you can only engage deals all reaction are through the SS confirmation it's take a look at these 4 dining on the bottom they're all conjugated Dynes which ones of those what we expect to be able to engage in a deals the reaction and if I look at this dying over here on the bottom of this isn't as Trans but dying and unfortunately cannot all this user -dash I here it cannot rotate about that bond because this bond double bond on the bottom is locked into a six-member grain and so because this is cannot change to the SS confirmation that cannot engage in a reaction but there's no way for me to flip around is bond position this double bonds so so that its the ministers confirmation when I look at is dying down below here's the dining and there's a signal bonding between the 2 moieties here and this could rotate around the bond so I've drawn in the Trans confirmation but it's capable of rotating to put his double bonds into an SS confirmations so that could act in deals all the reaction Over here here's of cycle Hecht said dying and it's already got the 2 double bonds in its assist confirmation in fact the spends 100 per cent of its time and the US is confirmation that would be a marvelous dying for doing deals older reaction so it'll always and can be no way to rotate around respond here due to become the strains out and then this 4th example is another example where you can't really rotate around the central signal bond between the 2 out and so that's locked as TransCanada ever do anything different moments so that could never be engaging in deals reactions you need to be able to distinguish from dines there either locked Unisys confirmations that create as CIS is great for reactions for or rent contrast those with diamonds they can never adopt on confirmations things they're stuck in industry confirmation those are no good for deals older OK so to different conformations Osasuna strains on national media systems good 1 of the reasons why the deal all the reaction is so powerful it's a shame we don't have more time to to spend on the deal's overreaction on because there are lots of added new ones to this reaction make powerful but were also require you to learn some new stuff OK so here's an example of 2 deals all the reactions and I've got the same dying due to In this reaction what I've done as a change the diner file all I've done is a change the stereo chemistry of 2 substituent these are Esther functional groups so the case it's not obvious to you that C O 2 CH 3 year on year has a Kerviel responded In 90 per cent of cases the dying off I'll have some sort of a carbonyl substituent 1 2 carbonyl substitute you get 3 more carbon you have on the
al-Qaeda on the lower the temperature you can use and if he had no carbonyl groups you have to really these high temperature so again showing Delta and there's no reagents sometimes the book will be so polite to you it's really nice to them their ideals Alder so that you know it's going to be a deal's alder and I'm not going to do that for you I expect you when you see heat to say Gee it's heat and there's no reagents there may and I see a cycle Eckstein ring in the product may be that a deal all the reaction I expect you to do that kind of an analysis OK so the deals reaction is stereo specific and stereo specific means that if I start with 1 eye summer 1 on geometric ice rubber starting material like Tranz I'll get 1 product reserve start up with the other geometric isomers like albeit a different product that's what stereo specific means but payee isomer gives 1 type of product is the gives another product so the stirred up by drawing the product of this deal overreaction it's going to be a cycle had seen rain maybe it will help you if you sometimes you know you can do Aero pushing to help yourself see the new bonds that forms sometimes I like to destroy -dash lines to help me see what's going to be connected In the products little -dash lines helped me see and if you are at all worried that you're going to mess up on the positions of the substituent then do something as simple as numbering the carbon atoms oftentimes that will save you so that you can see where things are going to be attached so here firefight number the substitutes 1 2 3 or number the carbon atoms in it that are going to end up in my 6 grand it'll help me keep track so here's the 4 carbons and my dying and here's 5 and 6 and just by looking at those numbers like Intel will G I'm going to form a bond between carbons 4 1 5 and carbons 1 6 and let me try to number those over here the product lines 2 3 4 5 6 but just a little trick that can help you sometimes keep track and what I know now from looking at this as I need to have those 2 Esther groups attached to carbons violence now the key thing to note here was that there were hydrogen atoms attached this helps me to see stereo chemistry when I see hydrogen atoms silly point out to you that there were 2 hydrogen atoms on Commons 5 and 6 and they were trains to each other just like the esters were trained to each other and so the rule here is if you have to substituent your dining file their trains to each other they will end up trans to each other In the product let me draw those trains to each other so here draw the Esther functional groups not many Adrovel functional groups we can see Esther in all its glory there here's 1 asterisk sticking up None of the other esters truly trains in the product it needs to be going downward there we go and the hydrogen atoms are going the opposite direction so there was a hydrogen atom also attach this carbon sometimes and saplings they ask you to draw Osteria chemistry and the online sampling problems it's if you draw serious and you have to draw both the Bolden the -dash constituents others and there's no reason why this particular tumor would be favored over the other you get the other an antenna out of this there's a mirror image that's non superimpose wall and you get equal amounts of those but both in antennas In both civilian and tumors those 2 groups trains OK so so this is part of being mysterious Pacific the trans isomer of the diner filed gives you a Trans relationship between those 2 between the product and maybe this is not going to be such a big surprise if we have a sister relationship between the substituent in the starting material those groups will end up 6 In the product what and just admitted I feel like it makes it more clearly draw the H. Adams they Chatham substituent on their casinos oftentimes helps me resolved confusing looking relationships OK so that's what scares specific means trains 1 product Sisk is a different product annually those relationships to preserve excuse me again I notice and drawing here but it just so happens to pure chance that this product is Meza and so the mirror images identical not direct Plessey so that means meso means that the here and there is no In different mirror image the mirror images the same molecule that's true for me so compounds OK but but look for that issue that's not the typical case the typical cases you get mixtures of tumors and the deals Alder reaction because you generate usually in most cases new sterigenics centers and always look for that OK so that's scarier specificity and very powerful means if I wanted to make 1 or the other I would know exactly which dying both violation be choosing and in order to get those relationships so in more than half of cases with the deals all the reaction we used Diogenes the site click and the prototype all cycling cycling diamonds that are used in in the deal reaction is cyclo painted dying so the cycle pentane ring with 2 Elkington and I'm sure if you can get smaller than what you can get smaller than that will address that in the next chapter you can have a four-member during 0 2 double bonds has a special property calling two-year intercity but you'll often see five-member brings with to conjugated out teams in 6 Member brings to conjugated outings so in other words cycling isn't a little bridge here joins 2 ends of that dying so in engages in a deals reaction the complex that structure looks it's not always easy for you to tell I know exactly what was going on in this reaction I could use a little -dash lines but our use the aero pushing helped me see what it's connected with what OK I'll use this pipe bomb to attack that carbon means I have to break the CC pie bond so I'll use that CC pipe bombs to attack this carbon and lookup precise I am withdrawing my heroes His 1st year ends on a carbon atom this 2nd Euro starts with a pipe bomb in fact all 3 of these zeros on Monday to start at the pylon ministered Aerostar to the pipeline and swings over and makes the CC double bond that you see in the product so that's the criteria are pushing buffeted the deals all the reaction and I've highlighted these 2 new bonds in red here I hope you can see those and I've arbitrarily drawn that drawn the Sobhraj had flipped up there to new sterigenics centers in this molecule lets this over here and this down at the bottom some on the right policy on just to note that yes there there .period sterigenics centers on there where you have sp 3 carbons therefore different substituent so if you generate history Janet centers have to watch 4 whether you're going to have federer mirror image of the far less usual case you're going Lebanese compound OK so open because it's so common to use cycling dying means you have to practice drawing these types of structures and what's important is that you can draw them in a conformational drawings and somebody dropping the most common conformational drawing on
therefore for this type of system this type of bridge system and so 1st abroad for and then I'll explain what I'm doing to draw this this is called in Norborne system which I don't see any reason future to know that so I hope you can see when I draw this kind of conformational drawing of a dog born ring system there's a bond back that I've joining in a broken form and then there's there's this bond upfront yearly charitable the bond up front just so it's more clear in the bond up front is passing in front of the bond that's vertical and in back so that the relationship were conveying and we've got to Barnes crossing over each other and the bonnets and back astronomer broken fashion than you may not realize this but I was being super-duper careful when I drew this what I was doing as I was drawing basically a chair With 2 axial substituent that's how I do this he didn't notice what I was doing there but I drew this by drawing a chair with 2 two-axle substituent and then turn this into this type of bicycle system I simply do a bond here here and I the race for never really drew that stuff funny and wise it's so important to drawl so carefully these types of farm Norborne always likely going systems is because when you do that you can easily see stereo chemical relationships in particular and the relationships between substituent but here there's a different relationship I want to point out ,comma group and that's the relationship between these 2 groups here and this double bond while look at that so that's the double bond you see over here and that's the 2 methyl groups that were on the dying file and the 2 new bonds the state reform purely highlight those new bonds 1 new bond of the straight and use the other new bond trade there and I expect you to be all recognized more born all ring systems I don't think it's very easy to draw these in using the the Sapling online home works but there will be problems in the back of the chapter where they draw things in this conformational trying now I hope you can see just how difficult it is to see the cycle Eckstein when I draw in that conformational drawings there's a cycle hexane ring in right this is exactly the same molecules about and it's really difficult to recognize that cycle Alexine rank and I expect you to be good at that even when I draw the conformational drawing I expect you to see that there's been 6 carbons searing arranges there's an AL team in there and that that could be made to deals old re-election not allied drawn like this and we we call this abridged by Cyclops system there's 2 types of bridges here on that that connect this I'm going to give those names every deals the reaction with a cycling dining generates abridged by psychic system and 1 of those bridges and is going to have an al Qaeda right to generated new 6 six-member bring Al-Qaeda and so this bridge at the bottom down here that's called the out Cambridge and then there's another bridge appear underscored circle and I'm going to call at the Al Cambridge such a different regions and why is it 1 I'm taking the time to tell you the names of these 2 bridges to distinguish those 2 types of bridges it's because I want to distinguish the relative positions of these 2 methyl substituent and here's what we need for the those it's another showing you how to draw Norborne all by cycling cooling system that's good practice over here the minister drawing most of my part of the chair I won't finish up the last 1 and you're not as good at drawing cheers as I am and maybe you are maybe you've been practicing over and over like I used to do when I was an undergrad and so is my 2 two-axle substitute and I'm not going to draw this last provenance just going to draw across here so here is my Norborne ring system no matter how often times like the to the bonds that are closer to me because it makes me feel like it's more three-dimensional please give me a satisfying feeling of 3 dimensionality but that's my Norborne ordering there is my out Cambridge on the bottom might help Cambridge and the top and we have names special names for these 2 substituent they're not the same 1 of those constituencies on the same side as the outing bridge the other substituent is on the same side as the AL Cambridge and the older experts have given these 2 substitutes different names they call this substituent down here that's on the same side as the AL Cambridge they call that the Endo substituent and then this this this substitute on topics on the same side as this out Cambridge they call that the XO substituent and that's obviously going to be important and I'll explain shortly why that's important OK so noticed this relationship here and that they had no substitute and Al-Qaeda however bridge on the same side and that's not so easy I feel like that's not so easy to see when you draw that flat drawings words it's very easy to see that relationship when you drive up with this conformational drawing the bridge by psychic system OK so the substituent can have 2 different orientations XO or Endo when I was a postdoc at Berkeley the guy work next year was doing deals all the reactions and he wanted the XO product those reactions and he ended meaning his cat excellent was such an obsession for him it was fun to go to his house in excess of moving here OK so why am I making a big deal out of Andover is XL so I I told you that in 90 per cent of cases and maybe for 1051 it's 100 per cent of cases but in 90 per cent of cases there's a carbon substituent on your dying of files 90 per cent of the time maybe 100 per cent of the time and so let's try to imagine what the product of this reaction would look like if I did it deals or I'm not going to go there are pushing your understanding is dashed line so I can see that can activity is and the 2 new carbon-carbon bonds and going to form between now and I'm going to draw no I'm now Muybridge doesn't have just 1 carbon Muybridge 1 that to carbons and so I'm very good at drawing the viewer not going to be quite so good at drawing me here I'm going to try to draw this this conformational drawing that allows me to see the AL Cambridge in the Alps bridge beginners Malkin raid on the bottom during my help Cambridge on the top and then on the other side had the 2 carbons from my dining a file and will you get when you look at the products of deals overreaction With cycling Dion the Carbondale substituent ends up in the end position the Carbondale substituent ends up in the Indo position and so that's the preferred mode of reactivity is called the older Endo rule or sometimes called the and and it's pretty simple the carbonyl ends on the dial ends up on the and opposition from just write it here so I can see that and what happens if there's to carbonyl substituent well you'll get a mixture of 1
company along the bottom and the other carbon the but they're not identical someone so you need to look at this and his draw down here you need to look to make sure that you draw all the product so that the Carbondale on the scene on is on the same side as the Al-Qaeda bridge now costs there's a new sterigenics center actually multiple new sterigenics centers in this molecule so Of course and underwrite plus the here to recognize that there's a mirror image that's formed OK so but the cobbles and open and no position on it's going to take some practice for you to recognize they can imagine when I drove like this how hard it is to recognize the 6 carbons and that there's a it's hard to see that there a cycle had seen in this product images remind you where those Carbajal number these current 1 too 3 4 is going to combine with province 5 and 6 to make a six-member terrain where is that six-member bring it here 1 forms a bond with 6 6 is attached to 5 5 was attached to 4 in the new causes a new bond from there 4 was attached to 3 and then there's too right there it's not it's not easy it unless you practice to see the cycle Eckstein rings and by cycling drawings so you have to practice with them 2 just be prepared to practice OK so there's other sections in the book here and I'm just simply going to point out that what is section 16 . 1 4 say this product we'll go through and I will give you all kinds of deals all the reactions to practice with on and I expect you to work a lot of problems in the back of chapter to practice deals all the reactions and incorporated into synthetic routes on sections 16 . 1 5 tells you that we have conjugated diamonds they absorb light and longer wavelength then when the diamonds isolate when Al-Qaeda are isolated and I'm not going to test you are so generally the more double bond you have in a molecule on the longer wavelength light it's going to absorb most most organic molecules don't absorb visible light but don't have colors but we have lots of double bonds they tend to be can be colored I guess that's it for Chapter 16 armed there's lots of problems in the subprime homework do those by Sunday nite and that's good start on Chapter 17 us we can try to finish up by tomorrow so that when we get started on Monday they were totally clean slate to start with chapter 17 is very short it's basically teaching you OK this is a benzene ring and here's some compounds that have similar properties with benzene rings ,comma so recognize them and I feel like a lot of this chapter is reduced so there's not very many problems in but in the Sapling online homework problems said and that's why making it 2 1 Sunday on the of less than a full week to do that ,comma and which is still be working on that stuff next week because we next week we're moving on that Chapter 18 is very quickly but a lot of money reminders so this is not new stuff and it's going to point out to you that when you take us and allocation what he would do without keys and can 51 we add things to them if you add bromine aggressive works that's not the case get them so when you add bromine across a double bond home in their reacts very easily and efficiently to give Transkei bromides and those of an anti-American really worried about the point is that outlines a reactive and in Chapter 10 we showed you reaction after reaction after reaction that you could do a double bonds edition of HCl hydration and hydro bore ational bonds a reactive but if you take a double bond it's part of a benzene ring from we didn't make a big deal about this he had no reaction now this is exactly at odds with what I told you in the last chapter I told you that we have conjugated double bonds the double bonds are more reactive than regular isolated double ones so what's going on here now death to redouble ones all conjugated why is it that in this particular arrangement these pipelines are less reactive than a typical of King there is something special about 3 double bonds not for not a double bonds with 3 when entering like this In dancing and this is not just some bromine thing these double bonds and benzene art reacted with any of those reagents from Chapter but it from Chapter 10 HP are war aviation sulfuric acid and 1 it's not that they don't react OK so let's talk about this that's with this chapter is about but so peculiar about the double bonds in a benzene ring that they don't react like regular double but that's what's making them so special is that these double bonds and benzene have a very special form of residents that gives them a special property I'm going to draw on that other residents structure so here's 1 residence former benzene and find those double bonds I thank you 0 pushing to see that other residents structure so he's a double-headed arrow here In all draw this other benzene residents form so I moved this other bond here here in here and I think he's arrows to push back so this this special type of resonance with 3 double bonds in a six-member ring on confers a property called aromatase the interim intercity generally means that those double bonds the pipe bombs on reactor that's what you should associate Eramet city the if you want to do any sort of a chemistry with those double bonds should and screening white-hot reagents there are more aggressive than anything you've ever seen before because those double bonds are totally happy with this special type of residents and in the next chapter Chapter I'm going to show you those screaming hot reagents many of you 5 recipes for Super wide-eyed screaming reagents there so reactive the bill even react with these and reactive double bonds and benzene and what particular is that in the end even when I do show you lose the super-secret reactions the 2 secret for you to see right now your head will explode but if I show you these reactions they knew they don't ever add to the double bond and disrupt double bonds disrupted intercity those double bonds are still there in the products what I'll show you a Chapter 18 is when when you finally do learn about the special reagents the end products still have a double bond there what has happened is that they replaced the hydrogen that's what we're going to see when benzene ring double bonds react in Chapter 18 were going replace hydrogen atoms it's a different type of substitution reaction you've ever seen before it's not as 1 it's not a to we substitute hydrogen atoms things that don't look at all like leaving groups focus of benzene rings are clearly special this Karameh to city property of 3 double bonds in a six-member ring on his super special it makes the overall molecules very stable and it makes the double bonds in the benzene ring reactive those double bottom benzene rings a super happy like that don't try to take away that arrangement that guaranteed to see and you're going to be going uphill and energy let's talk about the
nomenclature and as you know I don't don't testimony effect nomenclature but I've got sapling problem online problems it do because the standardized exams seemed to think that important it at this stage so I'm gonna show you 3 common bands character benzene ring derivatives these are considered Peregrine Systems are they have their own special name so if you have a methyl group on benzene we refer to this as toluene we don't call it methyl benzene I IU packed people decided that such a common molecule they were not going to call that methyl benzene were going to call toluene so he had a substituent to that you'd call it chloral toluene that's a Peregrine Systems it's 1 of 3 you can go to these hardware and by gallon cans of toluene it's a solid that's good for stripping paint on doing who knows what else here's another parent tendering system With but managed to move on but then we don't call it a amino benzene again they got a special name for this we call this an island and you simply need to know these 2 words that myself because I'm going to point to something it's see that and over there and I I want you to know what I'm talking about so we don't call that don't Benzinger and then the last 1 is to put a hydroxy groups and I feel like maybe you guys might have used this as a nucleophile or something like this is a nucleophile the Cannes 51 of the less we don't call this hydroxy benzene we call this and so that's a for
derivatives you might refer final comments the need to know the special needs right and never going to say hydroxy benzene or amino benzene methyl benzene and money is 1 of the things focus on talk about how to name things that substituent on there so if I if I had a benzene ring with a hydroxy group in a core chlorine on their the parent compound is the final all not the and there is no special named for a chlorine on a benzene ring on so the parent compound would be fine all so if I wanted to name this I would refer to this as a core phenol this other 1 over here I'd call Clairol final and this 1 over here called the coffin all and since the fund all the parent range structure here the hydroxy group is assumed to be at the 1 position sigh now number all the other substituent relative to that hydroxy group because the hydroxyl group is part of the final parent compound so in other words the way I number this as I go in a way that makes the chlorine had the lowest number and this would be to chloroform all I don't need to say to quarrel 1 fan all because they dropped his all position once so that's that's the way we number of that compound that I the chlorine over by 1 more Adams now that's 3 choral finale and this is a high-impact nomenclature indentified moved over by 1 more Adams so that it's farther away 3 for that's for chloroform these isomers of each other they have different boiling points on different chemical properties the they move differently on TLC plates thrall distinctive on the constitutional isomers now there's a different meaning way to describe the relationship between these 2 substituent dispensing with when I had to substituent that directly next to each other on a benzene ring attached to carbons that are directly next to each other I would describe the relationship between those 2 positions or so I would call that the war so I summer and expect you to know what I'm talking about when the 2 substituent so directly next to each other that's worth and if I called that were folklore all every chemists would know what what I'm talking about when the 2 situations are separated by 5 and I guess I would call by 3 carbon atoms then I would call that not more so we have a different we call that medical world and the relationship between those 2 groups is that they are matter to each other that's the way I use that language the 2 substituent tho where the matter and then the last possible relationship is when they're on opposite sides of the benzene ring and we call that relationship peril so if I said Eric or open all day and every chemists will understand that means they're on opposite sides that is worth all matter Paris is this super commonly used in I'm going to use it and we're going to use it throughout the next chapter so you have to get used to that that naming system on hence the top on worries the numbers that I pack meaning that there will be less common for us looking out these names are used so frequently or so matter and terror the chemists usually abbreviated that it's in italics you can't tell that I'm writing in italics and doing a good job the Badgers right folklore often all that's understood to mean or so for a final if I write them coral final it's understood me matter MCP BA that little land that's manner madam proxy benzoate gasoline and PBA little enemies met this year's parent coffin all of the right often all every tennis will understand that means terror so earlier laudable something called pair toluene Silvana gasses that P was spared so we've been using this without you knowing what the mn the PDO meant to on and so I expect you to practice that but words were we already covered spectroscopy ballet's cover spectroscopy again but I expect you to understand spectroscopy and benzene rings the Limoges remind you what we already said it will covered our spectroscopy baton chapter of 40 so what we say about benzene rings and carbon and my spectroscopy it's super easy style so where do you find benzene ring carbons and see 13 March you find in this range from 160 2 110 and it's in the same range the final regular-season double bonds there's a tiny bit of aggravating overlap here with with Esther derivatives from about 155 168 that overlap region because I feel like my bad luck is every time and got some carbon and that overlap region I can tell immediately whether there's an ester but and benzene and carbon but when I look at a finalist a dialog right now I expect you to freak out initially when you look at that but after you freak out just stop for a minute and there's all kinds of useful information in this in this 13 animosity MFA that this is part of the birth control pill that finalist dialog all but we can immediately see these carvings 1 2 3 4 5 6 and the sea 13 Take a look right here from about 110 to 116 but counter peaks :colon 1 2 3 4 560 isn't that amazing 6 peaks that correspond to those 6 carbons and the benzene ring of finalist Rodiles and got all these other carbons there who really cares about those but I'm just showing you how easy it is and how distinctive this region of the carbon 13 NMR spectrum is at a very minimum I would expect you to look at the structure of a finalist reviled and predict how many peach you would expect to see in the 13 spectrum on then I would expect you to know that those carbons appear somewhere in this region from 110 to 116 so we've already done that kind of stuff I hope that's review for you I'm just trying to show you this wildly at complex spectrum see that it's not too complex for you to say anything you can say something about that OK so see 13 is pretty easy Prince that's review Proton-M spectroscopy and then using derivatives so again is reviews I expect you to know that that way downfield here somewhere between about 6 and a half pounds know you can have things out as as far out as 8 and a half hours from 9 beatifically to about 8 and that is the region for protons directly attached to benzene rings so if I look at them spectrum for toluene these protons on toluene will will be somewhere over here around 7 parts per million that's that's the benzene ring area the spectrum and the protons ever not directly attached to benzene but 1 common away those are typically around here 2 . 2 parts per million so there's this region for protons directly attached to benzene rings and there's this region for things that 1 carbon away Incirlik protons and other words so let's just confirm that we will get that let's take a look and ethyl benzene and I see 10 protons just by looking at the integrations 5 age to and 3 I hope it's very easy for you to identify these 5 protons they're all on top of each other at 7 . 2 parts per million years those protons right here these are all these protons all jumbled on top of each other In the aromatic region of the profile ,comma spectrum so I hope you would know that that 5 age is all those protons jumbled on top of each other then down here around 2 . 6 parts per million that's the protons in the desolate region that's the protons that attached to the carbon that's attached to benzene there you go and the last set of protons years 3 age signal at the methyl group and just by looking at the chemical shift there's nothing special about those that these protons over here so I expect you guys to already know something about Proton-M or spectroscopy that was just a little review prompted to other sections in this chapter 17 to talk about cool interesting compounds and want us 1 had its final reading that OK get
started on those of us that when line problem said I want you to be done with those by Sunday nite so we're ready to cruise into Chapter 18 which is very long Chelsea on Friday


Formal Metadata

Title Lecture 22. Conjugation, Resonance, Diels-Alder Reactions, Part 2
Title of Series Chemistry 51B: Organic Chemistry
Part Number 22
Number of Parts 26
Author Vranken, David Van
License CC Attribution 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
DOI 10.5446/19491
Publisher University of California Irvine (UCI)
Release Date 2013
Language English

Content Metadata

Subject Area Chemistry
Abstract 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. This video is part of a 26-lecture undergraduate-level course titled "Organic Chemistry" taught at UC Irvine by Professor David Van Vranken. Index of Topics: 00:13- A molecule today, a barrel tomorrow 00:42- Fracking 04:57- 16.12: The Diels-Alder Reaction 10:42- 16.13: Diene Requires an s-cis conformation 14:53- 16.13: Stereospecificity in the Diels-Alder Reaction 21:08- 16.13: Drawing Bridged Bicyclic Products of Diels-Alder Reactions 29:41- 16.13: The Endo Rule for Cyclic Dienes CHAPTER 17-Benzene and Aromatic Compounds 34:05- 17.1: The C=C pi bonds in benzene exhibit low reactivity 39:19- 17.3: Disubstituted benzene rings: ortho, meta, and para relationships 45:06- 17.4: C NMR Spectroscopy 47:14- 17.4: H NMR Spectroscopy

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