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Lecture 25. Electrophilic Aromatic Substitution Part 2

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Automatisierte Medienanalyse

Erkannte Entitäten
I amenities there so cute and cuddly looking you can't forget the heavier than the commodity driving but he said that in In southern Florida of very large numbers of amenities have been dying due to the toxicity caused by red tide this is made is something you sometimes hear about even over here on the West Coast and ultimately the problem is caused by a single-celled algae against you might refer to that called comedian ravenous maybe allergies not perfectly correct term there's talk about why this red tide the organism creamier brothers is causing such problems with amenities but and it really boils down to 1 molecule of 1 class of molecules and Seoul
Korea reverses a Dyno flagellate that's got this little spinning with like tale that propels it and here is an example of some water it's it's been just totally overrun by this red tide on and these little guy flatulence caused producer really potent toxins quite often the shellfish the filter feeding these waters are collect this toxins and become super toxic to you and it is this is a powerful neurotoxin called Brother toxins they produced Soviet shellfish should have been sitting in those waters but it's something called neurotoxic shellfish poisoning and this molecule is a super-duper Dupre Bloomberg potent inhibitor of sodium ion channels which you need for proper nerve function you do not want to be ingesting anything with this and so is an example of the molecular creativity of this tiny organism was little thing here is a better synthetic chemists and any human on the planet Earth synthetic chemists have managed to synthesize this from scratch using the kinds of reactions you learning can 51 B and some some more advanced stuff of course and all that it takes about 120 330 stepped up to make a molecule of with this kind of level of complexity that's well within the bounds of what synthetic organic chemist can do Adam by adamant bond-by-bond constructing molecules OK let's get back to our liking got among the department tutors put a note over here on this side of the border and I'm sure you can see that this review session and I think he'll at 100 tonight from 5 to 7 I'll bring you I clickers so that's a great service is the the date that the department peer tutors are putting on for you so try to take advantage of that OK so let's get back to what its get back to our order of business here for today so that work like I said we were going to 1st cover 5 new reactions 5 new substitution reactions all of them electability aromatic substitutions and I was going to give you 5 different recipes for making bonds to benzene rings for substituting hydrogen atoms non-elected negatively groups with substituting hydrogen atoms on benzene rings with other stuff that's useful and weary talked about the 3 most useful elective Ilic aromatic substitution reactions I should go but halogen of benzene ring I should have put nature groups and benzene ring in order and awards nite carbon nitrogen bonds should you have to make carbon-carbon bonds using the Friedel Press crafts installation reaction and just before we left I should do this recipe for Seoul station making carbon sulfur bonds but sold fun acid functional groups and benzene rings in the last of the 5th reaction that we did not have a chance to get to yet was addition of simple alkyl groups and and and I would say that this is the reaction has the most exceptions that make it so slippery and hard to remember what would talk about that fits reaction electrification of Friel crafts calculation as opposed to a solution OK
so here's the Friedel grass alkylation Pitt looks amazingly like for your grass installation and the only difference is that instead of using this acid chloride type of functional group were just using simple alkyl chlorides you already know how to do substitution reactions on on alkyl quiet you did that without sides we needed the Williamson synthesis but not joining the benzene rings can attack and let me just point out that what's school is happening here is that we're replacing many Chatham with and isopropyl group in this particular case so I already mentioned you once that when you do Friedel crafts alkylation insists on not installations but calculations you always have to use this benzene starting material in excess intrinsically inefficient that means at the end of the reaction 90 per cent of that area starting material everybody's original is not reacting just sitting there so there's an intrinsic inefficiency it's only a efficient with respect to the LPO chloride so I just want you remember that I don't consider this to be efficient with respect to the all right you efficient it's inefficient with respect to the benzene ring starting material it's only efficient with respect to the alkyl chloride where you throw in 1 mold local chloride you can get 1 more product and that you'll never get all the benzene to react is you always use that success and I expect you to indicate that its present in excess by writing the word access if you show me that but it's a start up the mechanism for this reaction it's the same mechanism that we already all for freedom feel Craxi's Silesian so instead of having the court attack attached to a carbon deal with the clot attached to an Alco group and were using the same Lewis acid aluminum try chloride powerful Lewis acid that is really desperate for some lone pairs on Elektra negative Adam like chlorine oxygen or places like that so it you a powerful Lewis acid like aluminum try chloride in this reaction mixture it will coordinate the lone pairs and coin will attack that in order to make this activated complex and so what we've really done here is we've turned chloride from the printed leading into a super-duper Dupre Bloomberg leaving group well that's a super powerful leaving the majority to the chlorides on here but can fit the man there's a negative charge and I just attacked aluminum was neutral before now and this intermediate it's gotten negative charge it's called an illuminate an complex in something as a negative charge and the chlorine which nice to bonds must have a positive charge so we put that positive charge down here tiredness and so now this whole thing right here is a coup for heat great-great-great-great leaving Group you write you can write in great yourself but that is just a fantastically was OK before and how it's just amazing and said that Claudel part right off he couldn't stop the chloride now from popping off and and which you generating a reaction mixture floating around very lonely very desperate is a cargo can iron until cooked if you have a free cargo Caroline in the presence of the benzene ring ,comma even know benzene ring pie electrons are very reactive it's it's barely reacted enough they can do this it's reactive enough to react with the cobbled have so we draw the couple can I'm here it might not always like to draw the substituent unlikable cannons kind of bugging me today that I can see everything attached of destroy that each day such as secondary cargo can I'm in this case on the and when I have this benzene ring here we can attack the couple can finally make a new carbon-carbon bonds and we generate this uranium mine an intermediate soap and hopefully you guys have been doing a lot of drawing of a reunion mine intermediates and I'm going to be super careful to draw the proton on the carbon because of our draw that enough ,comma I'm going to forget it and then I'm going to be in big trouble so here's my Renea mine intermediate and I got some sort of arm of a conjugate base floating around "quotation mark use my my back pain you anything can pull that Proton all that Proton is so easy to pluck off because I this this Renea mine intermediate really wants to get back ceremony trade red pen here really wants to get back city just like we've shown before so there we go we re aroma ties and now the benzene ring is happy again it is regained their Matus city and look at that I now have a nice approval group this is mainly not only good for adding a secondary or tertiary centers on 2 benzene rings and I'll show you if you want to put a primary carbon with a C H 2 there were going to do that a different way explained wire in a moment all explain to you why that's an issue only whites only going to be really useful for making secondary or tertiary centers now this new Friedel craft stuff I'm showing you this aluminum tray quite that's mighty convenient just taking old outfield chloride it will work with an alkyl bromide just fine aluminum tricorn also works without the bromides work perfectly well it actually doesn't matter how you generate the Carbol cat eyes if you know other ways to deny couple Caroline's you can get those to do Friedel crafts alkylation as well so mistaken example overreaction that found that you may know which is the reaction of double bonds with sulfuric acid there got to set supplied Bonds use a regular keen years a benzene ring regular out genes are more nucleophilic these benzene ring electrons are happy it if I put this but I put this benzene this Al-Qaeda in my solution with a powerful acid like sulfuric acid what will happen is that I'm simply going to probe made that al-Qaeda and that you've already seen this before we knew hydration of double bonds so there's my symbol for an acid DHA the Newland programming that and it will generate a cargo can I knew already knew this stuff from Chapter 10 this this shouldn't be new to you the idea that you can probably a double bond and shouldn't be new to you that that regular CC double bonds are more reactive than benzene rings so now that you've got this complicated can and he keep you look at that cobbled together and you can't tell whether I generated that with aluminum dry chloride or appropriated a double bond it's going through the same reaction with the benzene ring so if I run this reaction using benzene is my solvent such benzene is a cheap solvent on then this can do that Friedel craps business so pipe bombs in in the aromatic Rincon attacks that Cobol Caroline and I'm not going to draw mechanism we don't need this he but that a Armenia mind intermediate all distraught to heroes to show you that I'm skipping something there I'm skipping drawing the uranium mine OK so it doesn't matter how you generate a couple can I'm ambitious aluminum try chloride is so new and cool and we try to encourage you to use it in this chapter because you haven't seen before but another bad side of real grass reactions so the side is that happened you already knew this the Carbol are really Wiley species that I tried to do a Friedel crafts reaction on this using that aluminum try
chloride business on the problem with this is is if I use aluminum for accorded to try to pull off on this that this chloride I'm going to end up with a primary Koble Caroline and there is no more self-loathing creature than a primary herbal cat on a is 2nd you generate this this is trying to figure out ways to me to be rearrange migrate or do something to get something that's more stable and out race that you just cannot win it's a race that you cannot win because if there's any group here like this hydride can migrating give a more stable ,comma can it is going to quickly rearranged so watch this if I just move this hydride over like that it's analysis a vastly more stable Koble Caroline and that's faster than this type of a couple can I can react with benzene so you can't you can't outpaced this with an elected filet aromatic substitution reaction before this primary problem that I'm can react to the benzene ring on it's going to do for crafts reactions so it's going to do a migration to give tertiary ,comma contract and that will do for your crafts sums obliterate FC here meaning that we do elect to fill a charismatic substitution at that table ,comma can so don't do Friedel process South relations with primary available it's always going to rearrange there's no primary al-Khalayleh bromide whatever that is not going to rearrange before it it adds to a benzene ring so in other words even know you started with this primary alkyl here light over here the product you get it's not going to look like that going to be this tertiary thing due to the rearranged so much as 1 of the problems so there's always problems with Friedel crafts alkylation is all you have to use excess benzene ring starting material locally allege rearranged so this limitation after limitations after limitation and I believe I'm missing a word here Friedel crass alkylation without aluminum tranquility you don't always have to use aluminum try chloride ions 2 general cargo can science and I think you you knew that I think you need to generate public events in other ways for those that surface reaction you 905 powerful read recipes for doing electrical work aromatic substitution reactions from and so now let's take a look at a different issue now that you know these 5 powerful recipes for adding substitutes to benzene rings we have to touch upon a really sticky issue here and that is what happens if there is a substituent already on the benzene ring what happens if there's something already there so that the problem now becomes if I've already got 1 substituent present on my benzene ring is that there is no non equivalent positions that I can substitute yeah I'm trying to draw these hydrogen atoms in the more clearly there's 2 sets of protons or methyl there's 2 sets of protons that admitted to the methyl group and there's 1 proton down at the bottom that appeared to the methyl groups and they're not the same oracle Pera and met positions are not equivalent there's 3 different products that you can and will get this reaction so vital Friedel crafts not a certain artificial pressed doing electrical a coronation a substitution reaction on with this chlorine and FEC of 3 recipe ,comma let's take a look at the ratios of these products that we get so the Ortho product there's there's 2 war tho protons it turns out getting 42 per cent yield and then there's 1 other product that's present in about the same amount and that's the spare a product it's not exactly this is identical yield on but it's pretty close to a one-to-one ratio and that's typical whenever you get or so you get about the same amount of parent or 1 every year period at about the same amount worth of it's not exactly 1 but close enough to the important thing is that there's almost no man parked in here that you look at the the yield of the metal product and it's so small that can ignore that I really miss this reaction basically just gives you also in paragraph and so we have to explain and I need to give you a set of rules so that you know how to predict GI going to substitute the matter positioning the high yields of that remind going to substituted the author 1 pair of positions and get that and so we're going to spend a lot of time trying to explain to you how to predict this effect at the bottom of the slide I'm showing you some basic numbers here for rates and ratios of substitution now I've got 5 really 4 types of canonical substituted benzene rings and what I want to do is I wanna compare the rates of all of attack by Electra files on these and Ampera positions so that you can see 1 of the major sites of attacked depending on the type of substituent is attached to the benzene ring some kind of showing you a summary here and then we're going to go and explain why you see these types of numbers so let me start over here by by trying to basically look at what happens when you have a mother foxy group or hydroxy group or an amino group important point is that there's a lone pair that's what distinguishes that this is a very good powerful loaned her donor and lone donor activates by residents positions like this the worth opposition I could draw similar residency arrows to show why there's so much minor character the war-torn pair positions and maybe not surprisingly look how much more reactive the auto impair positions are thousands of times tens of thousands of times more reactive than the matter position there's no resonance structure I can draw that will explain why this matter position should be more reactive it's less reactive In fact it's actually deactivated relative to benzene rings so all these numbers are relative to the substitution rate of a simple benzene ring there's no substitutes the reason why this is less active is because oxygen is Elektronik so alkyl groups accelerate the rate of elective alike aromatic substitution so if I put toluene and benzene toluene as that enough it's more reactive than benzene and not everywhere just the author when the pair positions away more reactive than a simple benzene so if you have an alkyl group you also favor or so and pure products OK but let's keep going on this list would happened to be the halogen on your benzene ring chlorine or bromine were less frequently iodine a flooring here all of the sites substitute more slowly than a benzene ring it's hard when you got a halogen on air to get elected Faust at the it's not that hard you can most your recipes work it's it's slower than benzene ring with it's almost at the tent this slow work or 100 times slower but all the positions are not equally slow it turns out that that the auto and pair positions still react faster than the matter positions it's the mayor position that really gets so the environment and we get to nitro groups and this will be the same for carbon you'll groups ourself on a gas it's now it's different from all these others that I just showed you it's it's kind of hard because there's so many zeroes the big lesson here is nitro groups really slow down electrified like aromatic substitution they really slow it down but it's not equal all positions there really slowing down or tho Ampera positions and the men position is the substitution the men position is slow but not quite as much so as a result you favor substitution here at the Met position and you know I'm not really quite clear I should put this
in blue I wish I had to do over again I would draw on these numbers in blue here and these numbers in blue because the favorite sites of substitution or the author pair positions and were looking for the biggest of the 3 numbers here so when the nitro group is on there ,comma yes so I meant to put the . 0 3 . 1 and blew up the . 0 1 so here the biggest number the 1 that's least deactivated is that many positions but this August had allotted time explaining these numbers some things make it faster to substitute benzene rings things make slower and they've affect the positions of substitution something different so when you start off with a substitution already on the benzene ring and you do electrical work aromatic substitution it's going to have an impact it's going to affect the rate of substitution and it's going to affect the regional chemistry some units off by and I'll show you the sort of classical analysis of how do you think about the effects what's the impact of having some kind of a substituent benzene ring and here I'm trying to be very generic by just giving the symbol wide to some sort of a substituent and then we'll talk in more detail about about what what y sport will take some cases individually and the important point is that there's 3 different sites we can attack to auto positions which 1 pair position and then there's 2 different matter positions so you here you can see with my error pushing I'm showing what happens if you have a substitute adds to the Ortho position relative to some substituent that's on there and what you can see is is that we need you at work go to some substituent you generate this uranium mine where you can see that the Carbol cat iron With that NTP orbital that has only 6 electrons the carbon is only 6 electron is right next door to watch why it's going to have a powerful effect on the care it's either going to stabilize it a lot or destabilize it or it's going to do something so there is a very powerful effect when you substitute author that why exerts a very powerful effect on an raised strong but all right effects but I mean just effect so high is going have super powerful effect on Oracle substitution that so expect whenever that Snow's take a look at what happens if we add to this matter carbon radio put it got so you can see if I pick up these electrons and take them away from the Pericard overweight non-drinkers substitution it by attack the pair her position I take the electrons away from the matter position and that scratch this out because I can tell now I made a mistake here that belongs only here there we go but I take the electrons away from this matter carbon mainly the Carbol can find there well but if that's not such a good situation media control resonance structure to try to somehow found on move this next to to some of the other substituent and we're going to have to analyze these residents structures when we draw this really mind to figure out what's the impact of why would we substituted that opposition so what I'll do is I'll move down these electrons here and take them away from the carbon that's right next to why and when I do that I can make more clearly see taking a look at that and this and this resonance structure for the uranium mine once again the White is right next to the horrible can when you substitute or so or parent that why group ends up right next to the Carbol Carolina near Reunion Island residents structures so once again when you you substitute Parra there's a very strong effect very powerful effect of Y the couple it can't really super stabilize at work in Release super destabilize depending on what YES and then we'll look at that in just a moment but it's also 1 pair of usually had similar effects they exert similar effects on when you do water tho in Paris substitution y y groups exert similar types of effects and also that the matter position and so it's the same narrow pushing ahead before right this is you can't tell from my hero pushing more and substituting in this case I'm lifting up the electrons and substituting the matter position and I'm lifting electrons away from the pericardium and so that leaves a positive charge down here at the pier position that and I know I can't see any effect a Y on that but maybe if I draw some kind of a resident structure may be why will end up right next to the my Buchanan again so state these electrons and swing them over that'll make that cargo can I'm happy it's now when I draw this uranium mine resonant structure so I hope you've been working lots of problems in Chapter 18 in the gorge in ski Smith textbook on because it will have lots and lots of chances for you to practice during a reunion line resident structures and this is the kind of question that they loved ask you about on standardized exams to professional schools like the and captained the DAT OK that's still not happy that looks like just a secondary cargo can maybe there's another resonate if I keep drawing resonance structures all get to some residents structure where there's some way for why to have an influence their slim move that that by residents will be satisfied that horrible Caroline 1 more time so here's 1 more mind resident structure here's my substituent met position Mt you know None of that success I don't have any more resonant structures I can drop None of these residents structures for medicines titutions arm put the wide group right next to the cobbled Caroline so the bottom line is that we use substitute water when Parra wise either gonna make a couple can I'm great courts can make that Cobol kind can I'm really stop and when you put substituent elective Ilic aromatic substitution at the Met position you know the ones kind of 4 away from those cobble Caroline's it's it's not going to have a strong effect may have a weak effect but it's not going there was a super-duper strong effect like it will adore tho 1 pair positions so now let's take a look at what what happens out will we put real groups in place of instead of the strict fictional sort of why symbol but would like to analyze some patterns of arm of electrical aromatic substitution so that we can see How either but it is wiser donor how's that going to affect the uranium mine worthwhile some "quotation mark kind of positively charged substitute how that might make the couple caring very uncomfortable but guess what I'm going to do here is I'm going to try to imagine the effects of these various types of functional groups and what I'm going to use I'm going to draw up a real adamant place of why for those reunion mind residents structures but I'm not going to draw 3 of them just because it takes too much time we don't have enough time lecture to draw all 3 of those different types of uranium mines I'm only going to draw the or so substituted uranium mine resonant structure so when you substitute tho too 2 but then added that as a lone pair on for example nitrogen it doesn't matter whether are is a hydrogen atom and help your group there so if if you add 4th to 1 amino group the Dow communal
groups just imagine how great it is to have a lone pair right next door the lone pair condoning right into that it does condoning right here To that I can right into that To that cobbled Kenai and stabilize it will satisfy the architect rule so residents if you got a nitrogen under substituent residents will really stabilized on the addition at the auto position because that Armenia mind gets super stabilized by the lone pair and think they can resist a I have to draw this despair substituted a reunion mind so we just to prove to ourselves that it it's the same idea that he substituted the pair position when there's an amino group on the benzene ring you end up with you can draw residents structure that looks like this In once again the lone pairs right next door to that empty cobble and once again that loan Perkins supra stabilized but you can even make your Aero you here Kerberos end to show you making a double bond or make it attacked the positive charge as long as your precise bottom line is the lone pair donated that complicated I'm so it doesn't have just 6 electrons so any 1 of the substantial instead as a lone pair will have the same effect it will help defray the substitution of the author 1 pair of positions because those long pairs will will be able to donate in turn up on to the NTP orbital it in 1 of those Renea mine residents structures so we were still in Paris all of these substituent have long pressed favors substitution at the Hawthorne pair positions because they stabilize the reunion once you're there's a very similar effect when you have an alkyl group on your benzene ring in Siletz redraw these Reunion Island resident structures so we can see why it's so good that Oracle in Paris when you have an alkyl world and it really doesn't matter what the Al-Khobar rupiahs all of Macon Ethel group so here my reading minds here is 1 of the important to renew mind resident structures when I had the the author position so I have more thorough revision label costs and mediation should label at this is Paris substitutions and here if I had to the Ortho substitution of an alkyl benzene with better Renea mind that's like tertiary Koble instead of secondary and you know that tertiary ,comma Irons is better than secondary confidence that Alcatel group will lead to a more stable cargo can I and likewise if I had to the pier opposition of an alkyl substituted benzene ring & up within a Renea mine in which 1 of the arena mine residents structures is a tertiary cargo Qatar so idiot out the group's and benzene rings the others no longer is an alkyl group but you already knew that alkyl groups can stabilize carbon can not as much as a lone pair but any kind of an alkyl groups on you know Ethel Isa probe all TB on just has season ages there what will lead to or so in Paris substitution OK so that's these are the kinds of substituent that favor in Paris substitution and since I'm making a big deal about that maybe it should be obvious that don't always favor auto in Paris substitution and as I mentioned with that nitro group there's something's that will favor Medus abstraction and let's take a look at what types of substituent arm will will favor medicines to so I'm going to do is I'm not going to draw the Renea mind residents structure for the menace of sitution product ironically I'm going to once again draw for these types of substituent and knows what particular about these last charge plus charge is a partial positive charge on the sulfur because oxygen the electron withdrawing but could stir up by drawing attention helped kill Kilimani whereas 3 methyl groups on this and they could be 3 protons as well but when I draw the arena mind if I draw the reunited resonance structure that would result from attack or so to that that substituent this take a look at and what that's going to look like and I hope you can tell packs Sox pictures folks but if you're an electron deficient ,comma carried the last thing in the world you want is to have some sort of cast iron right next door to you that's the worst situation on the planet Earth so what you'll find is very similar weather you substitute Warsaw repair if you have some sort of ionic type of substituent or electron division substituent you do not want to substitute or so when Paris you'll end up in a situation where there is no doubt about what were that on positively charged a R Caddick group is totally screwing over that Armenians intermediate so met substitution is kind of the default here it's because all of the substituent screw over water when Paris substitutions so badly that you only get medicine sitution so it's not that they make matters better it's just that they don't make it as bad as they make the the the Warsaw 1 pair so there really mess up the author Paris substitution so badly he can you get medicine institution is the default here in this case is not only of at least 1 of these possible carbon yield derivatives this last group here can be either a key tone methyl it could be and how the high-revenue H. attached here can be an ester Withers and all our group attached to the carbon your bullets start up despite drawing out this Sereni mine resonant structure where the key town just so I can be more clear about the about the effect of having a key town at that position and I'm only going to draw 1 of the possibilities is also substituted I this also substituted reunion mine resonance structure so when you add to the auto position of a benzene ring that has a carbonyl group attached to it we have to remember that there is another resident structure for carbon deals that we need to think about oxygen as lecturer negative and when we draw this other resonance structure and make oxygen happy by giving oxygen the air the electrons now we can see why this is so bad the real at the true effect of a carbonyl groups constituent is that a Carpentier was kind of like a cobbled had when you get to camp 51 see you're going to 1 million reactions were you had nuclear files to carbonyl groups and they can 51 LB labs at a high drive to a key tone group and all that is because the carbon carbon has a substantial partial positive charge so once again this is awful it's awful so if you have esters Quito in benzene ring they really mess up substitution at the author 1 pair of positions and it's the same for and my trial kind of group OK so far so substituent have a powerful effect on the author when the pair of positions that were really powerful effect data help substitution at the author position like things that lone pairs but they really messed up from substitution at the Warsaw
1 pair positions and by default leading with medicines situation is the preferred reaction pathway and so I expect you to be able to draw new mine resident structures released compare them so you can say Gee does that substituent that was already there have a good effect a a bad effect on the uranium mines ,comma that's that's kind of standard stuff but when you look at standardized exams like the and catch the people have go awaiting all those types of exams the Graduate Record Exam GRE in chemistry to go to graduate school OK so you know when you put a substituent directly next to a Aqaba can there's 2 completely different effects that we need to think about oxygen has 2 completely different types of effect on neighboring Koble cataracts and I want to dissect out those 2 effects and treat them individually because they're not the same and other effects number 1 of the enumerated these effect Number 1 of these 2 effects has to do with the fact that oxygen is electro negative there are lots of protons in the nucleus of oxygen there's more protons in the nucleus of oxygen than there are in in the carbon nucleus and that's why cart oxygen is so electric negative SOS protons in the nucleus of oxygen so if I put electron negative ad oxygen nitrogen chlorine fluorine
next to a cobble can I'm you'll end up with this effective Elektra negativity that some clients sometimes that's called an inductive affect some books call that inductive the fact some books call that polar effect because they're afraid to use this word inductive effects part of what is just elected negativity so I hope you can see that she felt that elected negative Adam here that's not such a good thing that but there's a completely different effect on top that you have to add to or subtract from the competes sometimes with this this destabilization so actually just to make this clearly drawing a reunion hand the has an oxygen substituent at that position like we've already done before so when you have an oxygen substituent on uranium mine intermediate on that this effect of of that Elektra negative Adams to destabilize so so that's destabilizing the Cobble can in fact that oxygen the negative effect destabilizes Koble canteens at all the positions or right here in this position also met up era but the strongest effect is when it's close by Close to You are the stronger that Elektra negative effect is if you wanted to estimate that I'm sure you could break out cool loans law and say charge times charged abide by distance and come up with some number it's distance dependent but announced abilities other the effect and then residence donations the move a completely different
effect from that of from that Elektra negatively affect lone pairs it doesn't matter what the lone pairs attached to can donate into cobble cannons look here's the resonant structure so you should already know that you can have resonance stabilization of Arbil cannot and this is a completely different effect because this is a stabilizing effect so oxygen has 2 different effects 1 Carbol Caroline's oxygen substituent have 2 completely different effects In a lecture filler charismatic substitutions so 1 effect of oxygen substituent so it is that they destabilize cobbled irons because the Electra negative but there's a 2nd effect this residence donation effect that stabilizes as stabilizes the Iranian mines so which 1 is more important and that's superior easy for me to tell you it's the resonance stabilization is more important resonance stabilization wins out over this destabilization by Electra negative ads over all the power cobbled Caroline I would rather have that Elektra negative oxygen there because it has long pairs I don't care how electoral negativity In its full range the most electric negative and the periodic table if I recover can and I would love to have a fluorine atom there because flooring has long appears to condone and satisfy the active that tells you a little bit about the importance of the architectural so so number 2 is the most important residents donation wins out over lecture negativity so if if you could have a long-term next to you in your car broke out I go for that so that's the way to win become stable look it's only some at this huge summary now just spent a lot of time trying to explain to you or so a pair of all these Iranian mines and really all you need to do is memorize this 1 shot said will you need in order ordering mines but this 1 shot radius summarizes all these effects and I expect you to know this Charter moreover I expect you to know how to use this chance that's the important thing that I would never ask draw this chart on that's not the kind of questions I asked on the team so let's take a look at this and take a look at these effects here so the 1st important point is that what I've done is I've ranks different substituent if you have 1 of the substituent on benzene ring this undergoing draw out of a benzene ring here so we can clearly see what I'm talking about the fight of benzene ring that has 1 of these groups on there and maybe all symbolizes why here that could be any 1 of these groups that's my mysterious symbol so I have arranged them in terms of things is to make electrical aromatic substitution
fast and amino groups are the best at that they activate benzene rings and make them react super quickly and we call these groups Towards the top here we call these activators and we referred to benzene rings that have these groups as activated so amino groups of lone pairs those activated benzene rings on Alcock the groups of lone pairs those activate benzene rings up and might you can tell there's a carbon appear on this this is carving a minor worlds because than nitrogen stores alone still activators so all these things look toward the top are more reactive and I guess I'm comparing everything here to just a regular benzene ring worse if the substitute wizened age that suspends it's all these things about this -dash minor react faster than dancing now take a look at the substituent toward the bottom the divide halogen the by carbon you would like and Esther and on and the hide a key tone doesn't matter as long as there's a carbon directly touched my benzene ring that's going to act more slowly than benzene gas cause benzene rings to react more slowly ammonium groups nitro groups are the worst they really slow down benzene rings so down near the bottom of any 1 of these substituent I would refer to as a deactivated and I would refer to 1 of those benzene rings that has 1 of these is deactivated spell the activators and the strongest is the nitro group the 2 groups really slow down electrical like aromatic substitution now there's this kind sunlight convenient generalization that when you have these activators on your benzene ring those tend to react most quickly at the torso and positions yeah these activators favor also Paris substitution Gee that's convenient activators favor or in Paris substitutions and if I compare that down below with benzene rings that have deactivated and let me give it a different symbol here for deactivated dishonor using the same symbol if I have deactivated down here all of these favor substitution at the matter positions because the Hawthorne pair positions or slowed down so much it's not the matter positions are better they're just not screwed over so badly so if I have any 1 of these like a nitro group of about nature group it messes up porcelain in Paris substitution so much that you only get substitution at the Met position now unfortunately there is not a perfect match I can give you a simple rule that all activators auto Parra well maybe I can be that show you that there's a break in this generalization when you look at the groups that are also in Paris on that favorite on Paris substitution it's everything above this line right here In other words halogen I'll just wait worthwhile ,comma appear even allergens which a deactivated switch slowdown elective elixir aromatic substitution or the kind of the fly in the ointment so they are deactivated but they still favor tho In Paris substitution anything below allergens in in our ranking here he's favored murder substitutions so you can see there's not this perfect match between the activators and deactivated in war-torn pair allergens are this outlier collagen even know there's they slowdown down electrical aromatic substitution are still pair directing because this next substitute you add To add your tho impair position so that's going to cause some consternation it's going to take something that would otherwise be simple to memorize and turn it into something that's that somehow not easier memorized and always gave me and gave me pause when I was trying to to use that kind of information but how do you use this how did use this kind of a sheet here on I'm going to give you yet 1 more exception for the Friedel craps reaction but you know for bribery actions not 5 recipes for adding substituent and I told you the real craft reactions will have exceptions and it's made exceptions that make this whole chapter of he added good after memorize 5 reaction that I'm positive that but it's all these exceptions were going during throw-in in this awful pair business that makes it a lot OK so here's this year's this exception for the free grass reaction yet yeah I hope this is the slide gift yes
thank you for the virtue Clooney and that's OK so before we get to that exceptions are had jumped the gun there have what I want to show you how not to use that those rules from that the generalizations we had from the previous life 1 1 take-home lesson that you might get from the previous slide was some sort of role like all nite groups those Armeta directors those are deactivated that's what that previous Wilbur slide you off but I want you to be super careful about how you use that would that mean if I say that a nitro group is amended director so here's what you might be inclined to say you might be inclined to say now we covered this in class nitro groups matter directors by means of nature groups all they had to the medal position no no that's not what it means when I send my children the matter director what I mean is that there's a nitro group already on the benzene ring the next substituent add Meadow right that the way to analyze this problem this would be the incorrect analysis it's not that you can I this ring the way analyze this is to say all there's a chlorine group on benzene ring and if there's a chlorine Rubin and benzene ring chlorine groups also parent directors that's the way to use that those general rules and if if clawing groupers and also pair director what that means is I'm going to get out of 50 50 mixture the war tho substitution and I don't have to draw the other so it's substitute product because it's identical to out of this you'll get about a 50 50 mixture about 1 to 1 just always assume it's one-to-one of both or so in Paris substituted products that's the way to use those rules In other words it doesn't matter that nitro is that as a matter director you look at the substituent that's already there on the benzene ring if you wanted to to synthesize this matter chloral nitrobenzene product here on the way to synthesize that is to start with the nitro group on the benzene ring 1st if you want to synthesize this compound over here you need a nitrate the benzene ring 1st and then now you can use this walled nitro groups Ahmed director now the next substituent you had no matter what it is the next substituent will end up matter to the nitro group so now we use our chlorination recipe chlorine at the Seal Street and that's how you make their product so you need to learn the rules which groups Oracle pair directors which groups demanded directors and if you can remember those rules you're going to be stuck because I promise you every single instructor on their exams is going to put questions like this where you have to strategize which groupware put 1st in which 1 is the author of the director on that's exactly the kind of question that you know you're going to end up sitting on on a standardized exams so that 1 last thing to show you before we leave in it's his it's actually not that complex to show you that kind of essential here because this will help you did get geared up for an it's an exception for the free autographs reaction and that is that you cannot do feel crass reactions on benzene rings there 2 deactivated and how deactivated can't shouldn't be it's this deactivated anything below this line is to deactivated for you to do feel crafts so in other words if nitrobenzene right that's the most deactivated all and I use my recipe for a Friedel craft reaction at that nitrobenzene just going to last it's going to be like how can it be kidding me take shit and get outta here because you know you're not going to react with that you can only do feel crafts reactions with things are above this line so that the wall here is anything that has a matter director you could not do for your graphs alkylation you cannot crafts installations which is not reactive and if you want to make this compound you can synthesize this compound here but the way you would have to synthesizers is you have to be very clever and strategize you have to start With the other group on the benzene ring start with that acid sealed already there the carbonyl group already there and then put on the nitro group that that carbon but was already a matter director and so if you use your nitrogen recipe that's what would give you the product is but a big X here you're not going to do in any field grab some nitrobenzene alternately watches what you're going to find is it anything that is a matter director you don't do feel crafts on Nos too slow but what we'll see later I don't know if we'll see later will just sit sit right now I think that have amino groups on art to activated and you can do for your craft on those either so do not do feel crafts and I'm not going to explain to you the problem with having amino groups and benzene rings but there's only this narrow window of reactivity where you can do for your graphs reactions installations calculations and you need to know that window on super important that you don't try to do feel craps
on rings 2 activated to deactivated OK so will come back on Friday and we're gonna finish all this stuff up what we have covered most of the major stuff for this chapter would have to learn how to fill around its on and
there's a review session tonight the department here 2 years that 5 to 7 PM that
Chemische Reaktion
Chemische Bindung
Elektron <Legierung>
Fülle <Speise>
Bukett <Wein>
Weibliche Tote
Chlororganische Verbindungen
Gesättigte Fettsäuren
Aktives Zentrum
Setzen <Verfahrenstechnik>
Spezies <Chemie>
Funktionelle Gruppe
Amine <primär->
Konkrement <Innere Medizin>
Klinisches Experiment
Chemische Struktur
Lewisit <Giftgas>
Biologisches Lebensmittel
Aktivität <Konzentration>
Hydroxyoxonorvalin <5-Hydroxy-4-oxonorvalin>
Single electron transfer
Advanced glycosylation end products
Geißel <Biologie>
Gekochter Schinken
Advanced glycosylation end products
Nachwachsender Rohstoff
Induktiver Effekt
Funktionelle Gruppe
Applikation <Medizin>
Organische Verbindungen
Schwefelorganische Verbindungen
Chemische Forschung
Chemische Verbindungen
Einsames Elektronenpaar
Schweflige Säure
Einsames Elektronenpaar
Potenz <Homöopathie>
Substrat <Boden>
Chemische Struktur
Chemischer Prozess


Formale Metadaten

Titel Lecture 25. Electrophilic Aromatic Substitution Part 2
Serientitel Chemistry 51B: Organic Chemistry
Teil 25
Anzahl der Teile 26
Autor Vranken, David Van
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/19494
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2013
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
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: 00:10- Red Tide Kills Record Number of Manatees 01:02- Molecular structure of brevetoxin A 02:56- 18.1: Five Important Electrophilic Aromatic Substitution Reactions 04:21- 18.5: Friedel-Crafts Alkylation with AlCl3 and Alkyl halides 09:37- 18.5: Friedel Crafts Alkylation without 14:32- 18.6, 18.7, 18.8: Substituents Affect Rates and Regiochemistry in E.A.S. 20:43- 18.9: Compare Arenium Ions to Explain Regiochemistry 26:41- 18.6: Substituents that favor ortho, para substitution 31:13- 18.6: Substituents that favor meta substitution 35:56- 18.6: L.P. Resonance Donor Effects Outcompete Inductive Effects 40:32- 18.7: Summary of EAS Substituent Effects-Know This Summary 45:43- 18.10: Special Rules for Friedel-Crafts Reactions 46:33- 18.9: Don't Confuse the directing group with the new substituent 49:58- 18.10: Special Rules fro Friedel-Crafts Reactions (revisited)

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