Lecture 25: Substituent Effect and Friedal-Crafts Reactions

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Lecture 25: Substituent Effect and Friedal-Crafts Reactions
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This is the second quarter of the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: 00:43 - Ring Activating 07:06 - Ring Deactivating 15:57 - Effect of Sterics and More than One Substituent 21:19 - Methoxy, Hydroxy, and Amine Substituents 29:41 - Friedel-Crafts Alkylation & Acylation 42:19 - Nitration of Aniline Derivatives
Electron Functional group Substitutionsreaktion Chemical structure
Übergangszustand Substituent Sense District Stickstoffatom Reaction mechanism Resonance (chemistry) Walking Substitutionsreaktion Man page River source Wursthülle Computer animation Metabolic pathway Functional group Resin Covalent bond Ausgangsgestein Bandtrockner Chemical structure Benzene Cobaltoxide
Substituent Übergangszustand Resonance (chemistry) Chemical plant Wursthülle Man page Water Computer animation Resin Halogenation Generic drug Covalent bond Chemical structure
Lone pair Neoteny Computer animation Electron Halogenation Weakness Resonance (chemistry) Ausgangsgestein Chemical structure Soap
Substituent Area Metal Sense District Atom probe Toluene Resonance (chemistry) Substitutionsreaktion Ocean current Man page Steric effects Wine tasting descriptors Methylgruppe Nitroverbindungen Computer animation Electron Halogenation Functional group Ausgangsgestein Benzene Periodate
Water Acid Computer animation Halogenation Colourant Substitutionsreaktion Hydroxyl
Reaction mechanism Chloride Solution Chemistry Electronic cigarette Reactivity (chemistry) Ethanol Water Solvent Acid Computer animation Halogenation Functional group Human body temperature Hydrolysat Amination Cryogenics Mixing (process engineering) Wear Dipolar bond Periodate Tetrachlormethan
Vinyl chloride Stickstoffatom Reaction mechanism Walking Aluminium Sulfur Chloride Memory-Effekt Computer animation Electron Functional group Isoliergas Kaliumchlorid Addition reaction Benzene Cobaltoxide Periodate
Systemic therapy Molecule Computer animation Functional group Bromide Alkylation Walking Benzene Sea level Verwitterung Solution
Computer animation Functional group Yield (engineering) Isoliergas Alkylation Ocean Benzene Solution Process (computing)
Stickstoffatom Aluminium Substitutionsreaktion Chloride Solution Chlorine Reactivity (chemistry) Acid Computer animation Electron Halogenation Functional group Ausgangsgestein Benzene Derivative (chemistry) Base (chemistry) Isotopenmarkierung
Hydrogen Computer animation Stickstoffatom Electron Resonance (chemistry) Walking Chemical structure Cobaltoxide Base (chemistry)
Stickstoffatom Reaction mechanism Nitrogen fixation Concentrate Walking Containment building Wine tasting descriptors Reactivity (chemistry) Water Slate Nitroverbindungen Acid Computer animation Functional group List of gulfs Blue cheese Nitrierung Schweflige Säure Benzene Chemical structure Explosion Cobaltoxide
you have been a why didn't we get started from a little late today as I came right from discussion on questions before we get started anybody alright when workers operating in Spain appears that we are going to have to skip the nucleophilic aromatic substitution reaction part of this chapter of I cover next quarter only do Chapter 25 you have my class quarter but were not enough time to cover so all that you know what we get to that section where we leave off last time we were drawing a upon residents structures we striding through a lot of what we're trying see why of electron donating groups give Bordeaux and Paris products so we did the author or what we saw is that we can make a are really in a really nice residents structure here this morning is especially stable What did you just do it the folk and doesn't want to do
that for some reason as that oldest continue right here especially stable resident structure especially stable every item has come 9 elected a electoral every as an architect a miniature covalent bond so restlessly stable all Adams have architect plus we have of the extra covalent bond so we sort went back as we were doing electrical aromatic substitution on benzene we have 3 Resona structures that when we have electron donated we have more resonance structure because that's going to make things especially stable that's going to mean that we have a lot more energy pathway here since the 1st step is an author making means the transition state is going to be more stable the cargo carries more stable that means the transition state by him as possible will also be more stable OK so that gives us some bankers that the word tho it will receive the same thing is going to happen but with the parent an arena go here and then we're going to get an extra resonance structure all distraught this way I could draw on this is my 3rd structure but Canada right now but that looks like this and you can see that once again we we have this extra resonance structure that's especially stable that 1 here and there's some talk here so let's circle that has we have a long parent oxygen we have a positive charge and there's are especially stable resonant structure so the author imperil always go together I am and you can see the really of authorizes structure that's especially stable if the group goes on in the Internet position there's only the normal 3 that we usually draw so they will look like this and then we can go here and will look like this did that do that right we go here that we go here positive charge right here and the nature repairs so we don't have any especially stable we don't have any especially unstable we just don't have that bonus very stable resonance structure and that's why we don't get any man attack we have on activating groups so I'm in the on-going Perry will write this down below In the auto and parakeets the extra resonance structure lowers the energy Of the cargo-carrying intermediates intermediate any answered by Hammonds partial the transition state the transition state leading to this century that's a lower energy pathway since this is a very on this is a high energy of activation for that 1st step it makes sense that the author 1 pair of pathways of any better I also want you want was awarded moratorium 1 of these mechanisms on the task I'm my usually have 1 where the substitution already on the right just to give you a little heads up on that but what what you wanna make sure that you do is you check when you're doing resins structures can still get 2 points per resident structure that you don't duplicate that you don't draw extra so what you want to look for his and here is the other incoming Electra filed the positive charges when it's in the range is he there is going to be in both Oracle positions here or to the Nitro on the to the Nitro on the right and parents of the nite there will always be the case so he appeared here during incoming letter filed or tho on 1 side or the 1 the other side and parents so doing double act dryer resident structures to make sure that you haven't made any mistakes because if you draw extra resident structures the incorrect cancel out once the correct OK so keep that in mind so let's roll 1 of ring activating substituent auto Parra directing alright so now let's look at world number 2 this is forged deactivating
their talk about a 3rd category now would be the halogen St so now known as items they already have the skeletons for the resident structures drawing nearer noticed that we don't have extra resonance structures for any of them we have 3 for everyone and this time understand use generic electrify all here so I'm going to do I would put the letter file here that's worth attacks In an embittered do matter using that same double bonds now I'm putting them out of position and here a minute uses .period on double bond on the bottom to attack the electrified and that will put the file in the pair position still look like that and sterling on the rest of the double bonds here positive charge will be right here and are just going to go crazy drawn resin structures here so I'm I can move this over here I can also go over here on this side making sure not to duplicate does any may see a problem with that the resin structure register of look to positive charges right next to each other right 2 positive charges on adjacent province very unstable so we drew 3 resin structures but 1 of them is particularly unstable so will circle that battle and on or don't care always going to gather so what that means is that foreign have won it when we really attacking the proposition will have that same thing and we're going to get that right away here that's going to go right here there's are especially unstable 1 right here in the middle so here and here and then the last 1 here will just have the double bond and the other or the opposition here so we'll look like this so when we when we added have ring deactivating substituent still leptophilic aromatic substitution on but the best 119 finished the only finished the matter of the best 1 is the man it's not especially stable but it is I'm also had we fix that I know that 1 got Serena go here so have the positive charge here double bond here we have it in 1 or the position let's put it in the other auto position so we don't have any especially stable but we also don't have any that are out we have to do that especially unstable and you have a question over here b on adjacent Jack Adams looks change that Adams thank you appreciate that on adjacent Adams waters on adjacent OK so in this case the man attack is better because we have a new 3 decent there OK but there there and there are great but we don't have is especially bad 1 that we have an auto plant in Paris so matter attack no especially unstable residents structures so that's going to be that that's going to be lowest energy and cover Qatar most energy Carver Academy and then of course the lowest energy transition state and therefore the lowest energy
transition state questions on deactivating activated rings so much for satisfying adds another reason why did just memorize bearing deactivating are committed director far-right halogen during their own
category soap and I think it's easier for students when I .period allergens in their own category so allergens or slightly deactivating but Oracle parent directing so and the reason is is that with allergens there's a strong inductive
effect so allergens Our strongly like that deactivates the but on them and they have a week but they really weak residents effects they can donate their electrons but they know that they're not really that they don't really like to donate electrons very well they're not Halen's are not very basic so they're not inclined to donate electrons but they they can so loud that the lone pairs but I donate electrons back into the ring to stabilize the cover :colon intermediates what a incidents so so there are slightly deactivated up but they are awful Parra directing and so on that issue show young like draw all of them we just did that and you can do that for yourself but you as you can see the attack with Electra file here it would put the allied to file in the Ortho position we do not have this these long pairs on bromine and bromine snot super-basic so this doesn't really help very much but it does help a little so we get that extra red stable resident structure here I haven't drawn all of them there are 3 more you need to more costume or which you can drive yourself and down we have is extra resonance structure which is not me don't get when were in and out of
position sir about that so extra resonance structure when an electrify file of is In the author of an apparent position not true in the Medicaid so you should try this on your own so this is a halogen Jakarta at half the current figure parts of deactivating parts and activate the activate the they're like activating and that there or the pair directing but they are they're definitely I'm slightly deactivated alright so I'm not 3 categories helped Taconic categorize 3 categories so you can be able to figure out what you're on products are going to be a I wanna talk about effective starts more than 1 substituent
so with or the pair directors parable predominantly as substituent an incoming reagents get larger and makes good sense so if we do nitrate if we nitrates arm toluene verses Isa probe all benzene here we get on 58 . 5 per cent were tho In and around 37 per cent terror if it's Isa properly get 30 per cent were tho and I'm 62 . 3 per cent to parents so as you see we go from 37 pair With a mouthful 62 . 3 per cent pair of with Isa poeple now if that becomes a Turk Beutel we're going to get pretty much all as the tribute group is much larger this is actually area on terror it a slightly favored here and that is the the reason is that methyl is this it does have some Stiritz involved with it there is and there are some of Stewart's affected happier now contribute slightly favored here and if there was no favorability we would have statistically we have 3 spots that can go right so could go auto Parramatta and and the streets thoughts that one-third of the time single-parent and two-thirds of the time it should go on off tho so if there was no so activity statistically there's twice as many auto positions see if there was no slight to many we would get 66 . 6 per cent of auto and 33 . 3 per cent pair so as you can see we do have a little bit more than 33 per cent so actually doesn't seem like with from the numbers appear is slightly favored and that's because Mathilde is Ivory hindered but it has some steric hindrance which would make Margot and the pair positions questions on those 2 so I keep that in mind where we're doing substitution on a benzene ring because when we have more Cabrera directors were using an or in Paris and there's really nothing we can do about it but the more boldly that prepares to more won a directing infected 2 or more substituent conflict so let's say we have electron donating we have like withdrawing the 1 that is strongly activating and Oracle period directing determines the orientation of the new substituent alright so Strong electron donating group Strong although I tried during we have a self-renewal group going on and it turns out that we're going to get or telling parents to Villa foxy group so the 2 proxy rule get so in the battle of the directing groups some of foxy went by far alright so here it is only worth so I mean parent chairman Foxy here it is on tho to epoxy but we do have another word opposition you think we're going to get anything there right here as are other auto positions and that's pretty ended their article in the middle there so we don't tend to get that problem so get author Wanderley substituted side parish here but we would intend to get the 1 where there is a substitute right there now if this was any it's as was a man instead of moment Foxy Nitro wins OK if this was a metal instead epoxy the nitro groups and things in a calm manner to the nite of the soul when we have strong Elektrowatt drying strong donating at the strong donating wins if we have a strong electron withdrawing and weak donating electoral withdrawing lands OK so that is to keep that in mind and that leads us to additional considerations regarding substituent effects and this is where it gets more complicated alright
but the Oxy hydroxy Amin means substituent saw more complicated than they would save I'm the top seed hydroxy means substitutes are so strongly activating that halogen nation is carried out without Lewis acid catalysts FEB 3 A F P C L 3 even without a catalyst multiple held the nation is observed so if we take Amphenol we put it when bromine and no FEB operate just water as a solvent instead colorization so bromine sky like a deep deep red brown and red color and when you added on and instantly to colorize which means about reaction reaction is happening very rapidly at room temperature and all 3 auto 1 positions are Our filled to miles in a final run the
reaction on polar solvents such as carbon tet declared without added catalyst and lower temperature also helps Will at low temperature there when you get Warsaw and Paris Our acts about be careful with ethanol singles I'm an assault to wear Rehavam anoxic group that's going to be the same as final final that means abstentions the multiple coordination even at low temperature without adding catalysts you cannot stop 1 halogen going on events in by so we have a solution for the sun to make this reaction
to sort of ends very highly activated and what we can do is we can turn it into an acid led and that's that's mixed that tones down the reacts the reactivity of Great so this is strongly activated and what we do to do that we insulate the Amin so we're going to use acid chloride and purity and this is Chapter 22 chemistry so you do not need the mechanism for this reaction I'm going to show it to you just so you can kind picture what's happening about when you do that it's now moderately activated so acid analytic you go back and you look at your activating groups you will see that this is now are moderately activated and when we droning and it's so it's not water activated a and it's pretty Boelke isn't it so where we get like about 95 per cent terror many get maybe 5 per cent or throw 95 per cent paraffin this reaction OK so it's 5 % were tho 95 per cent of terror so I do need to provide from Mina .period it's a 95 percent tariff so this is allosterically ended therefore mostly terror but now once we're done with that putting them bromine on we can take that is Group write off again and that is Chapter 22 chemistry this is a hydrolysis that's hydrolysis you do not need another mechanism you will know that soon enough when you get back here to start the 3rd quarter of OK and so what that does is his Santillan back again with the 1 bromine on the race OK and that's important because once souls bromine around there's nothing you can do to get them off so if you just want 1 bromine you have to go through this long strategy and to do this I do want to show you show you how the Amin is
converted to an it's an additional limitation it's similar to the mechanism for vinyl chloride let me show you don't need to know this mechanism but some of you need to see this it helps you to me it helps you make to understand what's going on and that makes it easier to remember the reaction OK so if you are so dire Neil chloride mechanism we there was a sulfur there very similar to this we did edition so hopefully this is triggering of the memory of that reaction from the 1st major all right and the 1 happens after that the electrons on oxygen come down and we kick off chloride so this is like the toss chloride mechanism I like the final Florida mechanism we do have a positive charge on the nitrogen and that's why we have the period 2 d procreate-that that nitrogen so this is not really anything 2 difficult but technically it is material from 51 seats so I will not be asking you this mechanism and incidents across the last step so he drove his right under the tiny acquired mechanism you'll see and similar artists In the last step we program with appeared so that's how we late so deftly when I get it straight in your mind and to isolate the nitrogen we use Aso chloride and parodying to actually put a soul group on the benzene ring to do Friedel crafts insulation that's the ASO chloride and what they'll see all 3 right so to different things with Carradine's so so we have the arson career passing chloride with Peri puts it on the nitrogen potassium chloride with aluminum try chloride puts it on the benzene rings deftly wanna make sure you get those skating here have far-right questions anybody
lots of problems with the 1 a lot of problems
within that leads directly in every across alkylation salacious lots of problems with real grass to program to keep in mind far-right so use of a bromide a L C L 3 regrettably up group along the benzene ring hopefully that is familiar to you by now alright let's say we aren't we start up this reaction by forming 1 molecule of theirs and we have a bunch of this and 1 molecule of this Wichern these rings is more once we put that up long that's more active so what that means is the remaining I have acquired along with my client is more likely to go on this ring the that because this is activated that's not activated OK so what we end up getting it for not careful we don't take steps to avoid this it's going to keep going now we've got to activating groups on the rain that ring is now more activated than the weather wonderful group on there which is more activated than having a level groups on so we're going to get this we're going to get worse tho we're going to get try substituted they're reading attaches substituted big problems here alright so that so the whole thing is about this is an activating group so therefore the product it is more reactive than the starting material alright so we avoid this problem we actually can avoid this problem by using a them using a larger access of benzene solution use large excess of benzene so an instance rather than using a one-to-one equivalent here we use in all logic system so maybe a thousand times more than the so that what that means is that I remember when we have declined title and we get that activated elective file it's more likely to encounter a benzene then it will to encounter when these guys or 1 of these guys are 1 of these guys so that's a that's a way around that so use a large excess of benzene if you ever Friedel crafts alkylation if you just want 1 group going on since keep that in mind for the exam coming up questions on that anybody question do we have that
problem with that sprint across 8 salacious do we have a problem with more than 1 group going on anybody no because it's now deactivated so product is deactivated therefore ,comma over appellation is not a problem say over a insulation is not a problem so we have to worry about with alkylation we do not have to worry about it with a salacious yes you can write access over just right below it Greg it's you can use XAU can use it as a solvent which means there would be a large very large access events
alright travel with full freedom processing installation and alkylation so we've already had encountered 1 problem alkylation goes overboard we get over alkylation problem number 2 deactivated men directing benzene derivatives and calendar give for yields a free across product and should not be used in this reaction alright so that's a big problem that really limits us deactivated Montana directors cannot undergo free crafts a which I'll abbreviate at sea Friedel crafts reactions and I mean alkylation and I mean a solution what would amount halo benzene that 3rd category and those OK for free perhaps we think while sincere deactivated matter directors Hillebrand Zurich deactivated off of terror directors Taylor benzene OK because they are deactivated but the auto Parra directing it has to be bold so we want make sure you look for both of those things deactivated matter director Sohail benzene 0 OK Hill abandons can do Friedel
crafts and none of these guys care so why inland derivatives Hawaii because that's super activated here's the problem this is an electron donating bright if you add a if you had a soul chloride and ALC that 1 of the strongest base that you have there nitrogen nitrogen is the strongest base remember so here's our has reactivity Louisiana Cl the R 5 In order to Friel perhaps we have to have the chloride attacked the ALC 3 and come off clear-eyed does not have a chance as we got increasing basis city this way so the nitrogen is the 1 that's been attacked the ALC analysts look at what happens once the nitrogen attacks the ALC 3 what happens to the nitrogen it it actually almost looks like a could this guy right now the nitrogen has a full positive charge on that's a strongly deactivated Madden director now so we just turn this strongly activating into strongly deactivated matter director so let's label that this is our strongly activated strongly deactivated Sony deactivated plus amended directive so therefore no field perhaps OK so analyzes but is is not working really well for us here but we actually do have a
solution for this the same solution we had burned again when when it was still putting too many bromine is on at the same time face elated Caso here let's get this straight year when we use housing chloride and appearing in the parenting it's gonna put this group on nitrogen when we use the acid chloride an aluminum try chlorine this group is an go on the benzene ring wanna get that straight here this is going on nitrogen so this is the 1 that's like the final chloride reaction this is the from delicate filigree aromatic substitution still what we can do what it is he's now we can do frail crafts and ended the reason we can do for your classes this nitrogen right here is no no longer super basic let me scroll down so we can compare the 2 this
nitrogen right don't do it that much OK
so so I decided to write here super-strong base this nitrogen right here not a super-strong base why is that much weaker base why is that this long hair would much rather kicking onto this oxygen here OK so what happens is that this guy's Conner tied up in this resonance here if that nitrogen takes its long beards and puts it on oxygen the oxygen gets a negative charge oxygen loves having negative charge in resident structure so so so so that hydrogen is not very inclined to attack the ALC all 3 what it's got this friendly neighborhood of oxygen right here can throw its electrons onto so this 1 actually will do but Friedel crafts so what happens in the next step where
is this group going north or repair mostly terror because this this is pretty young this is pretty bulky Our right so there no siege trees when it's it's going on the benzene ring mostly parent but crouched around 95 per cent Paris and now we're ready ready to take back subgroup again Woodis Hydra lies in its just remember what a subgroups on their way to get it off we Titleist so acid and water followed by these 2 different nitrogen which would be pro-rated under those conditions and we've actually found a roundabout way to do exactly what we would like to do so we kind of have to do this roundabout way here last year and so on Dad example anybody
far-right I guess what anyone has more problems we're not dead with problems with 1 alright problem and everything with 11 nights radiation OK should be should work why what's going on here Ryan White Care about work problems you might forget soon as a strong oxidizing agent In primary means are easily oxidized when you have a powerful oxidizing agent in you mix it with something that is easily oxidized on you can get an explosion and that's where you can get an exponent if you do this reaction the explosion if you don't get an explosion but you get top are and that's where unionized probably had a runner actually get target you by the reaction and you think everything's going to work and you end up getting this Torah like substance in the body fast that's black and usually means that your reaction has I don't not what you want to do it said something because immediately into the waste container most of the time alright so we don't want to do that it doesn't work now and not that you have on this 1 hears the tertiary mean that will work very nicely where will the nitro blue Gulf so this is not a primary means this is OK where's Nigel group golf you think Paris once did happen to that nitrogen but as soon as you put it in concentrated nitrogen acid concentrated sulfuric acid 1 of fastest reactions of all yeah so what's going to happen is we're going bring approach now that's an equilibrium as going back and forth so what we end up getting is the major product is actually on the matter product but you also get the other ones depending on which state Iran hero Anderson this equilibrium OK so you're going to get some you can get support appear and you're also going to get some matter all right so that's that's an issue the NH 2 sorry fix that and interior so that will work it will not give you exactly what you want shouldn't gets so you're going to get some more so in Paris but if you have acid on led in nitrates very nicely OK so I I know this works because we do this in my majors won majors on her side and you get this about 95 per cent of nitro In the pair position that's a major product alright so if you have a primary army unit you have inland you wants to nitrate you have to insulated so we're going to do the same exact thing that we've been doing here we're going to a slate 1st that tones down the reactivity that nice nitrogen and sleep because now that won't likes to hang out on oxygen in the present structure and then we nitrate and so then are nitro group is going to going on in the pair opposition mostly so this is the baby the major product and then we hide relies h trio plus H 2 0 heat will talk about this reaction next quarter and you will know the mechanism for this it's not that hard a reaction but I you'll get a pro needed mean treasure and strong acid and so that's why in the last step you want you do a basic work up to to give you hinterland With the nitrogen from the position without any explosions without top and so it is a little bit longer I'm steps but it works Mom it actually works that actually gives you what you want questions anyway alright will stop right there and we'll talk about reactions of constituents on benzene next time