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Lecture 15. Hofmann Degradation, Diazotization, & Aryl Diazonium Salts.

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Lecture 15. Hofmann Degradation, Diazotization, & Aryl Diazonium Salts.
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This is the third quarter course in 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: 2:13-Alkylation 10:19-Hofmann Degredation 14:56-Silver Oxide and Water 16:43-Hofmann Elimination 17:18-E2 Elimination 24:29-Conventional E2 Elimination 26:47-Elimination Example 31:29-2-bromobutane Example 36:39-Aromatic Chemistry 40:21-Diazotization Reaction 52:12-Diazonium Ion Reactivity 55:29-Dizonium Salt Reactions 1:05:05-Synthesis Examples 1:18:27-Alkyl Diazonium Salts are Unstable 1:19:53-Nitrosamines
Halides Alkyl Groups Alkyl Halides alkyl chemische Reaktion chemical end systems lead model Lecture/Conference Amino Gamma control compounds Zigarre mixture chemist ammonia
Alkyl Groups Halides Bromide Methyliodid Chemieingenieurin breakdown chemische Reaktion methyl Methylchlorid Magnetometer Lecture/Conference biaryl compounds Zigarre mixture
Stop biosynthesis organizations Methyliodid alkyl chemische Reaktion charge variety methyl man Ammonium Alfred Lecture/Conference Gamma salts Delicatessen Hab Ammonium iodide
acyl type Augentropfen Methyliodid alkyl properties Kaliumcarbonat proton solutions Tensiden methyl firm Ammonium molecule conditions Drops Lecture/Conference salts History mixture basic Ammonium iodide membrane
biosynthesis Substituted chloride Zigarette interface aromatic man Ammonium electron Lecture/Conference phenol sulfuric acid benzene rings conjugate Halogene Angiotensin-converting enzyme Substituent chemical element type nitrogen capacities Methyliodid formal Katalase AlCl3 chemische Reaktion charge end Säuren polymer basic
conformation sugar Geochemistry mechanism factors Morphine chemische Reaktion chemical man molecule Wasserstoff Table wine spectroscopic combustion Lecture/Conference important Gamma chemical structures chemist
Äthylen sodium hydride methyl man Potassium Lecture/Conference Sieden storage Oxide silver oxidation organizations capacities Methyliodid balance steps Ethylen-Vinylacetat-Copolymere Ammonium hydroxide proton solutions Tanning OH- water Iodide compounds basic Carboxylierung Ammonium iodide sequence
Graukäse sodium hydride organizations Bromide Silver iodide alkyl chloride Ammonium hydroxide chemische Reaktion OH- methyl man Ammonium molecule Silver chloride water Lecture/Conference silver bromide standards penetrative Oxide Halogene Ammonium iodide silver
Äthylen bond sodium hydride species methyl man Ammonium Starterkultur electron Magnetometer Lecture/Conference report Eliminierungsreaktionen processes organizations steps carbon proton OH- end lone pairs water Histology salts basic Ammonium iodide
transition states Cocaine chemical molecule Muraminsäure Methylmalonyl-CoA-Mutase Eliminierungsreaktionen Hexane period Oxide fall Double bond Maische chemische Reaktion OH- stability systems reduction Iodide stuff sequence bond Geochemistry activities Propionaldehyd methyl man Ammonium lead Magnetometer Lecture/Conference control stone oxidation silver River mouth areas molecular Arginine Methyliodid KOH Kaliumcarbonat hybrid Adder stone water Wasserstoff conditions function Histology Butane
chemical element type biosynthesis operation hybrid man chemical man flow Lecture/Conference control chemist sequence oxidation
Red Tide Double bond KOH methyl OH- man Ammonium lone pairs Wasserstoff Kalisalze Lecture/Conference Gamma Magma Eliminierungsreaktionen Ammonium iodide
rates methyl Ammonium molecule Wasserstoff Magnetometer Lecture/Conference function Gamma Cycloalkane doses chemical structures Hexane Eliminierungsreaktionen
Ammonium Wasserstoff Lecture/Conference Gamma Eliminierungsreaktionen period methyl OH- man
Butadien metals Sodium oxide Emissionsgasthermoanalyse chemical specific Ethanol Natrium Wasserstoff Lecture/Conference Eliminierungsreaktionen basic stuff
transition states biosynthesis Halides Maische breakdown Substituted chemische Reaktion man Magnetometer Lecture/Conference Methylmalonyl-CoA-Mutase Eliminierungsreaktionen basic mixture Butane
type Methyliodid Kaliumcarbonat Hydroxyethylcellulosen chemical water reduction conditions Lecture/Conference control Oxide Butane silver oxidation
sodium hydride organizations Substituted paintings aromatic chemical man electron Lecture/Conference Isomere cell Eliminierungsreaktionen mixture bottles
Toluol Petroleum HCl Substituted chemical man Nitro Compounds Lecture/Conference Amino Naphthalin sulfuric acid benzene rings Methylmalonyl-CoA-Mutase palladium nitrogen Hydrogens dynamics carbon source stocks Chemische Industrie reduction Wasserstoff Säuren Iron amines compounds Xylene
type molecular sodium hydride nitrogen steps chemical man Nucleophilic Substitution Dreifachbindungen synthetic Nitrate Lecture/Conference function phenol Trivialname salts Sodium nitrite
sodium hydride asset chemische Reaktion chemical man water Natrium Säuren Magnetometer Lecture/Conference Iron salts chemical structures Nitrite
probe organizations nitrogen species mechanism Mesomerie Substituted Bis (band) charge man molecule water lone pairs Heck Reactions Säuren electron age Lecture/Conference important sulfuric acid chemical structures oxygen
bond organizations species nitrogen chemische Reaktion case aromatic water electron Lecture/Conference function Amino compounds Hausmittel oxygen form
nitrogen asset chloride proton end lone pairs water Wasserstoff conditions electron Lecture/Conference function compounds Hab basic
species mechanism Mesomerie current chemical man Alpha Ammonium molecule Dreifachbindungen electron age Lecture/Conference active site nitrogen balance steps proton lone pairs water flow Wasserstoff Säuren oxygen sequence
bond species drug mechanism plant deformation case chemical Ammonium Nitro Compounds Lecture/Conference benzene rings Sodium nitrite mixture nitrogen balance carbon proton lone pairs Natrium Wasserstoff Valenzelektron function oxygen bottles
nitrogen balance orbital copper Salzsäure case chemische Reaktion leak chemical orbitals water Eisfläche Table wine Zeitverschiebung conditions Säuren electron Lecture/Conference sulfuric acid repeat Sodium nitrite addresses
water Ethanol reduction age Lecture/Conference temperatures compounds hydroxyl groups benzene rings proton chemische Reaktion chemical
Cyanide bond mechanism Copper(I) cyanide chloride copper Salzsäure chlorine chemical man islands Lecture/Conference variants phenol sulfuric acid benzene rings mixture Sodium nitrite reactor Kir organizations Alkyl Groups nitrogen Bromide rates alkyl Stickstofffixierung organic Adamantane chemische Reaktion source Sodium nitrate Natrium conditions function coupling Copper(II) chloride old mixing cooperation Laundry
Toluol hydrides drug Borsäure HCl phosphorus properties EPDM Adamantane source chemische Reaktion chlorine chemical man fluoride molecule Wasserstoff Säuren electron Lecture/Conference Naphthalin benzene rings Sodium nitrite oxygen
type biosynthesis chain Toluol Petroleum Substituted Syrup aromatic chemical Nitro Compounds molecule Wasserstoff firing Lecture/Conference excitement benzene rings
age Lecture/Conference Sekundärionen-Massenspektrometrie Mesomerie Substituted chloride oxygen chlorine aromatic stability man
power drug operation chlorine blocks man molecule Lava age Lecture/Conference compounds control chemist
Holzfaserwerkstoff Nitro Compounds Table wine Lecture/Conference function control chloride chemische Reaktion Nitrobenzol chemical
palladium areas delta sodium hydride phosphorus carbon valine chemische Reaktion man water Säuren Lecture/Conference salts sulfuric acid FAS
van Lecture/Conference Medroxyprogesterone stuff man
Flash evaporation Lecture/Conference activities Amino benzene rings domain Brom
Flash evaporation Dünnschichtchromatographie Lecture/Conference control Iron Eliminierungsreaktionen Brom chemische Reaktion case chlorine
phosphorus aromatic chemical Diet food lead electron age Lecture/Conference Amino control sulfuric acid Magma benzene rings Sodium nitrite areas green Agate nitrogen Bromide asset formal Katalase alcohols firm lone pairs Säuren conditions function Iron compounds Brom form
conditions nitrogen Lecture/Conference mechanism HCl Mesomerie compounds chemical man
Carcinogens Lecture/Conference meat DNA Substituted Nitrite cancer chemical
Lord a holiday home sold either like to finish up Chapter
25 today on the chemistry of a means and as I as I said before chapter 25 is a little bit of a hodgepodge because we've already seen a lot of chemistry of a means but there's some really beautiful and some really useful chemistry that we're going to see and some of it because we're on the quarter system harkens back to some of the aromatic chemistry that you learned at the very end of the 51 B costs so that various last
part of the 50 B 1 B costs and so we're going to review will chemistry from that and put it all together so what we were talking last time we were talking about alkylation
of Amiens in other words treatment of Amiens with alkyl halide and I said that the basic thing about it means is it's never easy to control the alkylation reactions we know a means nuclear files and we know a lot of alkyl halide profiles and the primary alkyl halide and to a lesser extent secondary Alcoa realize participate in Essen to displacement reactions but at the same time the what we would think would be an obvious reaction of mixing Amin and an alkyl halide doesn't lead to a controlled model alkylation you get proton exchange in you get a mixture of Monona out in tryout collated compounds it's kind of sort of possible to take an alkyl halide and treated with the huge excess of ammonia and get a primary Amin although often in practice chemists use other procedures because you do get over alkylation but in general taking a primary Amin treating it with an alkyl halide gives a mixture of products now on the other hand we can control this reaction if we want to have the alkylation so just by way Of of repeating what I was just saying if we take pencil
means and we treat with methyl iodide right methyl iodide
is a breakdown collating agent primary alkyl halide are very
good at Essen to displacement reactions but methyl halides methyl bromide methyl chloride methyl iodide are especially good also other sorts of compounds like fans alike he Alliance a very very good a like the alliance's well and so if we treat fans mean with methyl
iodide we end up with a mixture of and this is what I was talking about the last time a mixture of Milano John Major and out collated products so in other
words we don't just get I'm just for the sake of clarity all save you
don't don't just yet not just the Monroe out collated product where drawn say a single methyl group and technically we would have it as the the ammonium iodide salt engaged to on now 1
of the these 1 of the things about organic chemist is we really like to control what's going on a lot of organic chemistry focuses on synthesis focuses on making stops taking the reaction and figuring out how to take charge of its how to make it useful and still 1 of the things that 1 can do is to drive this reaction by use of an excess of methyl iodide also you were headed with this just 2nd but we can write this reaction to with an excess of methyl iodide any new database the poll offer Proton because every alkylation gives you an ammonium salt
salt right out this equation and then we're going to do some some with molecules of this sort so instead of getting a mixture of take Bensalem mean and I treated with methyl iodide salsa excess later on you'll see me write it as easy as excess because tennis like shortly excess methyl iodide you really need a base in there I think your textbook kind of neglected it's not super important to you go into the lab and actually try to make some history work but you need a base to Pollock the protons and typically you would do this under the under Henry genius conditions would say solid potassium carbonate in there and this would give you the triangulated product Denzel try methyl ammonium iodide required dieters to counter ions if you ever look
at your eye drops and nose drops or other sorts of products that are liquids that you put in your body particularly in your own eyes contact lens solution you'll often see on the back of it then sold try alkyl ammonium salts these types of salts have having died bacterial properties the surfactants the like molecules that disrupt the membranes of bacteria and so this helps the nasty things from growing in Europe your contact lens solution or whatever so this is part of a broad class of what we would call Quaternary
ammonium salts Quaternary just means remember we talked about a means to me said their primary secondary and tertiary means depending on the number of situations substituent on nitrogen Quaternary means the loss of situations and of course it's because by that point you have a charge on the side of of city question of so
what the they are OK another good question here would it be possible further methyl iodide to add on the benzene ring so 1 of the distinctions I've made we think about nuclear files and we think about electrified of them 1 of the distinctions I've tried to make in the class is the distinction between things that are slightly nucleophilic and things that are very nucleophilic and then things that are slightly Elektra felt like and very alike feel so methyl iodide is slightly elected fell like you need a nucleophile with a relatively available Long pair of electrons to attack and we often use PKK as a surrogate for thinking about nuclear Felicity when you're comparing elements of the same type like nitrogen and go over a series like an animal in nitrogen PKB conjugate acid 5 and say nitrogen peaking of the conjugate acid 10 it's a relatively good comparison to say Denzel Amin is much more nucleophilic Ameline when you're comparing Adams of different types the comparison is a little bit more loops and yet still you can use this general idea that Denzel Amin has a P K of the conjugate acid of 10 it's relatively nucleophilic benzene of course is not at all basic program in sulfuric acid but it's not a very strong nuclear file at all so most of the electrify aisles that react with benzene of our cat ions or else they're very good electrify aisles like halogen simulcast more about this at the end so methyl iodide is in no way a good good-enough electrify to dual leptophilic aromatic substitution on Vinci another example it's perfect is say I'm safer Mao the Hyde the amount of time is not a good enough electrify we talked about how the -dash protonated out the hide trend for Malahide is not a good enough electoral filed to react with an aromatic ring I'll take Amphenol as an example hydroxy benzene which will see later on but if you have answered present the formaldehyde in programming you can get the car being Miami and that's a good enough like the file and that in fact is the basis for the synthesis of of polymers are statistically vapor lights that can be done easily this interface so this having this notion that of things that react with benzene generally very hot electric whilst cobbled Qatar and stirred you cobble Qatar and undergoing a Friedel crafts reaction to a duel chloride an aluminum chloride and the psyllium on an ace acid chloride an aluminum chloride those are the sort of like the files that attacked the benzene more that and talk about some like aromatic substitution in the 2nd part I want to show
you an example and I think this is going to bring us back to some kind
concepts of Styria chemistry and conformational analysis I want introduce us now to the Hopman degradation new textbook introduces it at this point this reaction used to be fantastically
important factors for techniques like in more spectroscopy so when I say when I say that chemists took 50 years to
Turkey to determine the structure of morphine before and Aymara spectroscopy or I or a spectroscopy they were carrying out chemical degradation reactions and combustion Analyses to figure out what molecules they were producing and hydrogenation measuring how much I drive hydrogen was up taken to the Hoffman degradation which also you now used to be a very important reaction the reason I'd like featured now is for concepts of mechanism really geochemistry and conformational analysis collateral which is going to tie into a discussion of sugars so if we
tank mean and I'm just taking started the simplest stupidest I mean I can think of Europe taking after long being with and if we treated with an excess of methyl iodide said you're writing it is excess just a little abbreviation and potassium carbonate some sort of basically pulling off protons after the Athens to our relations you can go on smoothly to to the next step and the next step until you completely out of collated the meaning of the word that try methyl ammonium iodide This is what we would call an exhaustive methylation just like I've written here as part of the Hofmann degradation it happens to be called half made exhaustive methylation but at the at the Borat 114 nowadays are also in the overall sequence and I'll talk about how it works if we now take our ammonium iodide solve their try methyl ammonium iodide and treated with silver oxide in water aging to always silver oxide we replace the EIA Dean Witter hydroxide we replace the iodide with the hydroxide I'll tell you how that occurs in just the 2nd time and of course the hydroxide is a good base and now we have battled try methyl ammonium hydroxide and if we keep this material so I'll just write an arrow with Delta here so now you go ahead you boil up your solution of this compound going break down to 3 components ethylene right like this if you're not comfortable writing it like that just write it like this ethylene plus methyl Amin and organic chemist balance equations of but this
in parenthesis water as the product of show us how we get to this point so 1st let's take a look at the the Silver because silver oxide is a reagent used seen before as an oxidizing agent a mild oxidizing agent that can allow oxidation of held the hides of the carboxyl against it so let's look at what else silver oxide so if you water a lot of metal oxides are basically in equilibrium were equivalent to the hydroxide so if you think about it you can think of a hydroxide as of an oxide as a hydroxide without water water I mean you can
think of it as a silver oxide which was staged to always equivalent to worries in equilibrium with 2 molecules of silver hydroxide now
the main thing about Silver Silver absolutely loves the halogen silver precipitates out with chloride bromide and died and silver chloride silver bromide silver iodide very pretty reaction particularly iodide because silver iodide is the tale yellow solids to just like that I would have 1 reaction I talk to you about it before we
can generate a pale yellow salad the Real to Reel just that this is what we achieved our alkyl ammonium iodide our Ethel try methyl ammonium iodide with silver oxide and water all right is silver hydroxide songwriters sort of in world as silver hydroxide you end up precipitating out silver iodide and getting the time methyl ammonium hydroxide sold but that's just the sort of if you think back to when it started your standard in organic reaction back from GE came days where you would mix 2 different
species to different salts together and you would end up with a precipitated 1 salt and Lashell Jason principal driving the reaction OK but the main thing that's occurring in the real real organic chemistry that's occurring in this process now is the last step the elimination step that sometimes sometimes referred to as as the Hoffman the elimination of the of the
right so it doesn't mean
elimination involves just in 2 elimination hydroxide is pulling off the beta protons and kicking out the try methyl ammonium group so
I'm writing this with ethylene as our example was Ethel as our example for starters because it's nice to see the geometry here and it's nice to see how this can occur so there's raffle try methyl ammonium iodide and you can think of your hydroxide neural derided as always additional believed person put in all my lone pairs of electrons and so forth you can think of hydroxide is acting like a base pulling off the beta proton pushing the electrons into the bonds between carbon carbon and spitting out try methyl Amin and when all is said and done here at the end of this right and Errol noted Ajo Way water reporters plus ethylene which all right like this last try methyl Amin so this is the basis of an to elimination reaction against technically my word and need to worry .period somewhat redundant because 2
means elimination by molecular but the big thing that's important indeed true elimination is that you have an aunt died Perry playing a relationship another words as you look down the bonds you go in a zigzag relationship you doing Newman projection think back to Newman projections in your 1st quarter you have a relationship with the hydrogen is opposite the leaving groups all right died period when the relationship of the of the that's really 1 of the requirements for In each elimination is this geometrical relationship to question I like we are many of which have been used the why couldn't I have you could use and they always so the question is why do we have to use potassium carbonate here and I think the the answer is you really could the nice thing about the conditions you're trying to minimize to displacement on methyl iodide hydroxide at that point is a little bit better nucleophile seal kill some of your methyl iodide but if you were to try this reaction say with potassium hydroxide and methyl iodide under the right conditions of solvent you could probably prior get it to work it might not work quite as smoothly 1 of the beauties of a lot of this really ancient chemistry is a lot of it works really cleanly and easily meaning you just make some things together by general really a recipe here and the chemistry works and that's fall because when you're trying to figure out what's going on knowing this chemistry goes in the same way whether I have an FO group whether I have a propane group whether I have morphine or whether I have cocaine is really really cool and really valuable now here's the here's the cool thing about this city to elimination and this is this actually brings us some stuff I wanted to talk about it 1 of them call things about this chemistry is that you get really geochemical control and you get really geochemistry that's different than other eliminations you've seen before you know that controlling Regier chemistry is important when you take 1 butane you learn back in either 51 Area 51 B that when you take 1 butane you could go ahead and control the the Regio chemistry of edition of water across the double bond depending on whether you use an seamer curation reduction system to give reaction sequence to give the so-called market addition or a hybrid biracial oxidation sequence to give the the on-time mark competition you also learn that in general the jewel in the nation's
history of possible prefer the more substituted products so for example if I have 1 methyl what I want my older 1 mouthful cycle hexane and I take treated with potassium hydroxide and I heated up began as our major product there were substituted Alpena he and are minor product will get the last substituted al-Hakim and that's sort of a hallmark of a typical the 2 elimination in the transition state for a typical lead to elimination you start to feel the greater stability of the more substituted Alpena and so in general you end up with the substituted product being favored over the last substituted product but what's cool about the Hoffman degradation sequence is if we take the same basic molecule except instead of our own leaving grouping being an iodide it's going to become a try methyl ammonium we get the other read chemical preference in other words if I subjected this molecule is this 1 amino are wonderful cycle hexane 1st excess methyl iodide and potassium carbonate vendors silver oxide in water and then take heat now Our main product is the last substituted out in an hour but more substituted Keane is very very minor this all activities you John this we get a relative ratio of 99 toward 99 per cent this is our major product and
that's really really cool and really significant in the city of element of control that you were getting emphasized in the hybrid operation oxidation sequence that you were getting that I've emphasized in talking about chemists in in synthesis so I'm going to just sort of summarize
this man talk why so I'll say that conventional each elimination of and also generally because I can always always find some type of counterexample so I'll say generally gives them more substituted our and then I'll say there have been limitation Jim has Alsatian Paschal steer in Stary chemical requirements of the of you and all say that these requirements often lead to the most stable often leading to the last substituted down came far-right let me give you before we
go on into other examples I want to show you my thinking on the rationale for the differences were sitting on the upper right-hand black water there yeah so here's a
iodide the 1st example from the black other methyl group here you have the died in the axial position you require the hydrogen is to go ahead and have an n-type prairie playing a relationship and if possible you favor the more substituted double bond so here's hydroxide were using potassium hydroxide or just on 1 lone pair here and so we put Ferraro's like so that's going to lead to the 2 elimination to give them more substituted AL team now by comparison here's our example with the cycle Hextall try methyl ammonium iodide now try methyl ammonium is
ISO structural With the church you ever remember church Eurogroup back from 51 a remember how big the church group is the church will work toward Eurogroup wants to keep them out of the way of everything effect can avoided it doesn't want to be axial on a cyclo hexane rain if it can avoid it doesn't wanna be dose 2 things it wants keep them out of their way so it's not great to put a methyl group
axial on side hexane rating but it's a lot worse departed church Eurogroup axial and by the same day and it's a lot worse to apply a try methyl ammonium group axial so I try methyl ammonium group prefers the confirmation where it's which of Nela me just do 1 thing here and I'm going to redraw this this molecule and drawing in the hydrogen and they'll think about our elimination of taxes have given its own black because I wanted 1 and have a little bit of room here to make my point all right so here's here's our methyl group we have a hydrogen here consume more hydrogen on and I'll just write it as CH 2 years are try methyl ammonium group like so here a hydrogen so like so and like so Our axial an hour Equatorial hydrogen which
hydrogen is-n-type period .period which 1 has a zigzag relationship to the try methyl ammonium group which 1 we're trying to 1 of do the
1 on the Cariacica here there's exact relationship so here we have a ghost relationship not only tight relationship In
here we have an aunt died during plenary relationships and so hydroxide can come in and flight so take care kicked and do our duty to elimination now the reason I heads to the reason I qualified my statement over here often leading is I was
going to give you a counterexample and involves some really cool confirmation stuff I decided I am not going to at a beautiful example where you've gotten and dietary playing a relationship that leads to the more substituted out for your purposes a new textbooks shows a few additional examples you can figure generally less substituted Alan keen but just keep in mind this direct and stereo chemical requirement also you 1 more 1 more specific example for comparison and then I'd like to to move on to some aromatic chemistry I just kind of kind of a simple example again harkening back to the 2 elimination that you learn learn back at 51 Area 51 51
days it will take to promote butadiene by by example here will treat it with a strong base member of David bases we often like sodium in ethanol as you can generated by throwing sodium metal into ethanol they react give sodium oxide hydrogen secondary
alkyl halide since strong bases tend to give elimination you don't get a Williamson Easter synthesis and themselves
you get please says the 2 new team than the 1 you use all right to mutiny and hour )right parenthesis mixture exists in transit a breakdown what which amount you have a which and then the 1 bewteen the get them or substituted down season the last substitute out came and in general
reactions like this favor the more substituted out it's not 100 per cent preferences but it's a good preference in this
particular example we have an 81 per cent to 19 per cent ratio in other words it's it's for parts of of 2 butane to 1 part of 1 muting now by comparison
we take told me butane and we subjected to the
same types of conditions in other words we go ahead and we take to amino views saying that we treated 1st with as with excess methyl iodide and potassium carbonate then we treated with silver oxide in the water and then we heated up so it's a Hoffman what's it's supposed to be a Delta to indicate where heating it and we get vastly vastly predominant God the 1 you can to butane which again I will ride started with a squiggly line is 5 per cent and 1 bewteen now is 95 per cent so a very very big preference
for the lap for the last substituted out so in a way this is sort of the antithesis the opposite of Yurok seamer curation reduction Hydro abrasion oxidation control in that now you're going the opposite way and you're exerting Regier chemical control the answer questions at this point at all OK why I draw like this this means chemistries squiggly line means scarier chemistry unspecified so
this equivalent to and yes and we often use we often use the squiggly lines cell for example if I'm going ahead and saying let's say contained all and I don't want to specified stereo chemistry of it 1 2 painting off Zaccagnini either since I simmered trans isomer a mixture of isomers it could mean a mixture of the
trends as the R and S S 5 murders so it basically a sort of all all-encompassing but we haven't seen from the apartment at the end of OK if if you're going to remember a good question because this is confusing for students and also as I said the Hopman elimination is not that important if you're gonna remember 1 thing from not meant elimination I'd remember 2 things 1 of the things I remember is airtight Perry playing attack always wants and died Perry pointer attack that's this theory electronics that's how your bottles lineup then this simple rule is generally a it's going to give you the last substitute out team but because of the reasons for it you can and I could come up with an example where you have the more substituted out being the new text but doesn't even touch on it so it's kind of kind of filed a little bit of this and other questions sorry I wanted to take us back to aromatic chemistry because the aromatic chemistry of Amiens is still firm it's really the basis of all commercial organic chemistry and it's something that you didn't get in Chapter 3 teams so by
way of refreshing refresher
elector fell like aromatic substitution is a great way to introduce some stituents onto been you can get simple benzene compounds benzene and toluene and naphthalene and xylene which is dynamical benzene toluene and methyl benzene you can get them all from petroleum their present in crude petroleum and so Petroleum is a great source a great feedstuff so if we
take toluene other chemical that's a great thing stock for all of chemistry he is about to to chemicals is nite Rick acid and sulfuric acid visa are readily readily available early as sort of chemical industry in the U.S. and so taking a benzene compound in treating it with nitrogen acid sometimes with sulfuric acid gives rise to nitrobenzene elective fell like aromatic nitrogen learned about that before and then if you reduce the nitro group for example by catalytic hydrogenation with hydrogen and palladium on carbon basing 10 HCl reduction or by iron and HCl reduction is a zillion ways to do it you can get the Amin parrot it's Paris amino toluene but it's called told you with Diena
of tells you would Dean if you want to know the trivial name not gonna write it down because that's 1 that search handling should know toluene issued no phenol all you should know hydroxy benzene peter out Touliu Indians kind of 1 for
people in the know OK here I want to show you now there some chemistry of this and this and get us into some new places both mechanistic Lee synthetic so let's take our Peter Liu at the scene and we're going to treat it with sodium nitrite in a N O 2 and answered your textbook always uses HCL and that's largely final makes some distinction about using Gatesy HBO H 2 SO for affordable Oregon and give you a little bit of subtlety and you want to keep this cold because the product that we're getting is not very stable and it can blow up and what you get out of this year's and Harold only installed the guy's sodium salt of course is the nitrate is the triple bond to nitrogen and the reason this isn't very stable is this is 1 step away from releasing molecular nitrogen and molecular nitrogen into is the world's greatest leaving group now I'm going to get into some chemistry that shows us what happens when the nitrogen leaves until largely Atherton 1 type of chemistry nucleophilic displacement Union molecular horrible Karin
chemistry but I want to show you 1st this day solicitation
reactions alright alright this out as isn't as they should alright is a lot of
chemistry going on here and a lot of it's just simple acid-base based demonstrate we sodium
nitrate nitrite rather is the sodium salt and nightdress acid and I'll take us all the way back the freshman chemistry and writer Louis the structure of the nite tried iron in all even remember to put my charges and if we just approach may a take the I tried and I'm not going to show you the Kerberos but if we imagine H 3 0 plus radiates Rio Plus is the strongest asset that can exist in water in each two-hour detects rights HCL and writer Kerberos prior not quite as correct anyway if you go ahead and right this out now you know that you will have an equilibrium where your back Idris assets AHL and all this is again sort of freshman chemistry now if we
imagine another Proton going on to the molecule protons go online and often strong acid 1 of the places the pro-Taliban can go His onto the LH for you this and electrical like aromatic substitution think of all the way back to the mechanism of nitrogen acid and sulfuric acid to generate the NO 2 plus the nightdress a mile or so let's go
ahead and will write a approach nation age Rio plus over the enroute international probe the oxygen I'll be good person remember all of my charges and loan pairs of electrons and now unimagined water leaving this is all organic chemistry right now now unimagined water leaving with its lone pair of electrons and so all right 1 last equilibrium here all right this up-and-down just for the heck of it and then go ahead and just take us to the more substituted the more important resonance structure if you don't like the residents structures writing you can write the 1 in the textbook I'm going to give everyone a complete act yet here so we'll just push out of the water so this species here is called the nite result is called the nite result mine on following now the
main thing is even now this is an inorganic species even now and interlocks very different than a lot of other species you're seeing in organic chemistry basically it's the same chest of what we've seen a lot of other positively charged compound they tend to be elected felt like we can push arrows and form bonds Seki rise to new bonds to them so let's do this
and very using abbreviations for Our role and right old is sort of generic aromatic and so all right a N 2 in this case to represent Hollywood Dean but of course it could represent animal and it could represent any other remedial group on in record so here's amino groups said just as water laughter and I guess I can't even balance my my place is here and say to world just as water left we can have in attack and so I will write my nite resulting in minor on lifestyle and now we just imagine what really is the reverse of that reaction there except for nitrogen attacking in other words alone pair comes in we up electrons onto the oxygen didn't think of this as a series of equilibrium if you like I think I like we
an asset being cast said protons on protons come off everything with a lone pair of electrons so what's going to happen at this point is we're going to swat them protons around we're going to talk to arise you textbook prior rights
chloride as a base I think it's Priolo bit more reasonable to write right water is the basis of this right reached you all and I can give you a Kerberos you're not going to give you Kerberos for absolutely everything Sardinia ,comma narrowly put our electrons onto the nitrogen now this compound here it's not stable under the conditions were gonna talk time arrives at the very end all show you another compound of this class that stable we call this compound and Nitro submitting Justin and with a nitro so group on hands Nitro something nitrosamines when you have a hydrogen on them when they're from primary means living right is more clearly when they're from primary means they're not stable and they talk time arise but on the other hand secondary means gives stable ones and those the nasty compounds the necessity personages question but this 1 title that's Sinatra's something that's
unusual for an alright where it has said and we're going to continue to talk time arise again and again 1 of many beautiful things about really seeing things from a point of view of current Barrett is against start say in many ways this is like a Quito here in other words we have worlds not a Carbondale it's a nitro subgroup and here we have an alpha hydrogen and so we can imagine swapping protons around so in this particular
mechanism here is an item Cimmino started this and and then we're going to try to memorize protons on protons go off all different positions so just as we've talked time arrives just as we've talked arise cheap at the site of cardiology tones and now the hides we can tight time arrives here 1st step in the pride in the top timers nation in acid is going to be putting protons go on and off all year long pairs so I will go ahead and put on a proton here like so it just like we are well not just like but I will show you there's a 2nd resonant structure that I can right here if you just imagine pushing in this lone pair of electrons and pushing up electrons flow and oxygen and by this point you should remember that different resonance structures are in different molecules that just different representations of the same thing I could write 1 I could write the other but it's really easy to see where we go from here if we look at the next 1 just imagine at this point losing each last maybe for the sake of balance I think since we're just doing talk Tamas Ajan I'm actually going to write plus age plus year I'm giving you a little bit of authority under the mechanism of course water is supplying age 3 allied Ronnie is supplying age was alright minus 8 plus of course water is acting as a basis for taking all of that Proton and so now we just imagine that Proton coming off like so and now we're going to continue our chemistry was the question 10 electronic books that make you think you 10 electrons and nitrogen far-right itself let's continue with our species here and imagine putting on another Proton other words we just have H 3 0 plus transfer Proton on the year protons go on protons come off every lone pair of electrons and now the final step in this whole sequence remember were headed toward the is only a month high on the final step In this sequence is just that the nitrogen questions in its lone pair of electrons kicks out water and so we go in triple bonds in when the positive charge and nitrogen and lone pair of electrons .period speech to all and so we have our guy is ammonium ion over here all right In a way In
a way what we've done is just review a lot of Carbondale chemistry because basically everything that you've seen here to step the mechanism but everything you've seen here as Carbondale chemistry with federal Adams with nitrogen and oxygen just pushing some protons surrounding kicking out leaving group were wanna go I don't want to dwell on the mechanism I think it's worth seeing I think it's worth thinking through and I think it's worth taking a few moments on your own after class to think through it but where I wanna go right now is what we do with these guys ammonium salts because it's a gateway To all of aromatic
chemistry to the earliest drug chemistry to die chemistry before that in some cases daily chemistry is strong chemistry already so here we are at higher dies sodium ions derived from tell you would deem the 1 that we got from Knight Trading benzene reducing the nitro compound and Daiei's enticing with sodium sodium nitrite and HCL and I said You wanna keep that hold as it can explode alright but the main thing is that if really heated up we end up losing nitrogen means we can get a Qatar and I wanted to talk about the cargo can with in a Carbo can carve talents are not stable species with very few exceptions they're not things that you could put a bottle they react right away so I'll stay Harold cobbled can I don't think you've seen 1 before the hotel yellow more about it in the 2nd but the main thing it doesn't stick around very long and any sort of nuclear file and you know reacts Nunavut deformable bond our is sort of a generic new plants will go through specific specific details in the 2nd but the point is that it reacts with nuclear files it does not want to stick around the thing this year member of course what you have here before think about balance you have a hydrogen and describe any of a hydrogen and carbon all you've got as high and this is this nitrogen and it takes away its lone pair it takes away its pair of bonding electron and Winnie was that were carbons without
anything on it it leaves a tribe balance with a broken heart and an empty the to work at all now
it's pretty bad to have an empty as the 3 orbital as 3 3 orbitals style or hiring energy have more repeat characters it's really really bad I don't have an empty as toward at all because you just want to have electrons in there getting getting stabilized itself what reacts as a nucleophile well anything anything that surrounds him react is a nucleophile this is S N 1 chemistry in the case in some cases Alanson copper in the world that were
complicated then but basically all right this is S & Wine reaction where nitrogen leaves sent it's replaced by a nucleophile so if we do this reaction and water in and I'm going to make a slight tweaks to the conditions you don't absolutely have to do this but for the most part acids are interchangeable in the basic reaction 100 go up going into the same day isn't his Asian chemistry with sodium nitrite but I'll use sulfuric acid leak is sulfuric acid is a little bit less armored less nucleophilic for its counter and hydrochloric acid songwriter aides to ourselves more and better remind us that you always do this reaction initially in an ice bath if you want keep both of your hands so we're gonna write 5 degrees Celsius in whatever
temperature irrespective of the and then we're going to heat it up of course this is in water so all right age too well basically you do this and I would aid reassesses the product that this reaction is
creates solid pink Rios solid just tell Mathilde ethanol and we don't want to reveal name
for its what's happening is the water is being a nucleophile new broke you get a wage to plot course and water protons go on protons go off .period days that we've taken a benzene ring that had nothing on it we nite traded it and now we've got ahead after the reduction in the diaries innovation and the breaking down of the Diocese of compound we've introduced a hydroxy group into the benzene we've access novels and this is really the start of this wonderful wonderful gateway of Elektra felt like aromatic chemistry that you get into here the whole family
of chemistry and a lot of this is borrowed right from your taxable so many of you were subtle tweaks you can substitute just about anything on there I'm going to do this all With tell you would an example so go ahead and continue textbook uses a Scialfa for everything and I think that's fine if near him were to go into the lab by pricing used sulfuric acid year use that use hydrochloric acid here from Advanced's All-Star you how we do it in the laboratory alright to introduce according to the rate right where the nitrogen is you go ahead and do this with copper chloride made saying Well why don't I just let the chloride reactor at more Claude Dupri could the chloride a little bit less nucleophilic than some of the other islands it doesn't track the cobbled Caroline is well you get mixtures of phenol and the chloride copper chloride mediates the reaction you can think of it just as N 1 chemistry but there's really some involvement of organic metallic intermediate anyway we're not going to fast with the mechanism I want to show you about 5 different beautiful reaction so going ahead using Cooper's chloride introduces the chlorine here when you allow them to react they call this the stand Meyer reaction and again a lot of this is really really old chemistry course organic chemistry works at any time any place and Morris on on the moon on Earth all the same way it works in the 19th century it works in the 20th century so I want to show you some more variants of there's a lot of this is just straight from your taxable and cook are same conditions another variant of the San Martin reaction sodium nitrite and this particular example or use HCL as well chloride just isn't that a nucleophile sodium nitrate HCl 5 degrees across this is only with copper cyanide true breast cyanide CUC and is a way of mediating the introduction of a nite trio group with flannel groups like self that school we the carbon-carbon bond reaction the other way you learn to do this was Friedel crafts alkylation and Friedel crafts a salacious there's lots and lots of other things you can do with this as well I introduce a bromide to introduce a bromide saying anything sodium bromides a reasonably good nucleophile by copper bromides even better you don't want a mix up your bromide in chloride so again your textbook I think says HCl but I would use HBO here they're both available you basically want keep keep your eye on separate itself copper bromide these are all examples Cooper's bromide CUB at these are all examples of what generally fall under the broad headings of this inquiry action and it's a great way to get into some aromatic chemistry let's put the
emergency Haggard shifted to the test and I'll put it to the laundry back so couple of couple more reactions and benzene chemistry basically basically you can put almost anything you want almost any sort of Adam you want except alkyl groups in this way itself give
you another example of natural this ones in your textbook but it's the same with the the same basic suggesting that I want to show you 1 that's really important will use it alright I want put in fluoride a lot of drug molecules containing chlorine in place of hydrogen gives them better biological properties chemistry that introduces this pretty well these high is more boric acid HBO for were just taking strong acids and sodium nitrite HBO for sodium nitrite but then again will do this at 5 degrees Celsius and then we're just going to heated up this basically serves as a source of fluoride right through World War EPS said just strong acid that serves as a source of that minuses source of fluoride ion and the overall result is that you get the flora benzene out of fear our you play an absolutely anything here now I want to show you how to get rid of that and why we will see in 2nd hour it's the same thing I'm doing all of these examples would tell you again but you could do them with benzene you could do with them with amino naphthalene you could do that would try methyl benzene alright that cargo and can be reduced it can take up hydride and a reagent that allows this to occur as fast acid H 3 PO 2 and so if we go ahead with the same chemistry sodium nitrite days solicitation with acid your text uses HCl that's fine I would probably use a duet for here because I want in on nucleophilic count rise again 5 degrees Celsius reached 3 P 2 ends up
being like a source of hydride it's kind of it's something that kind of like we saw in the US Cannizzaro reaction remember the can is a reaction from discussion hydride gets pushed often Adam by an oxygen pushing electrons down it's kind of the same just with phosphorus answers and here's the
cool thing I'm not writing
anything we've replaced the nitro group with hydrogen we've reduced it so we John Daly's at times and reduce OK I want to show you why all of this chemistry has me in your text so excited and why it's the gateway there's so much good aromatic chemistry part so I won't come back to something straight out of last quarter
and right what really is a very trivial problem notes it's the wrong type John and there's always does that I will try it may be you think you we will try 1 I waved the white flag of surrender the fire 1 where another will will muddle through we always there are on the 1st now the honest-to-goodness truth is 8 times that of simple aromatic compounds are available benzene toluene and these are things that come from petroleum we learned how to get to handle and when all is easy to get to so I'm gonna do what typical sort of problem I do synthesizers molecule from benzene or a more simple had sort of thing said but on the final word simple-minded substitute compensable murders substituted aromatic are this is a great time to renew the chapter of a chain remember all
those good concepts of resonance and stabilization of Cobble Cap Anson Elektra fell like aromatic substitution and reagents to carry this out and if you think that you will remember always just north of
apparent director if you think back a little more you
remember in Electra fell like aromatic substitution you go through a probable can and that it is the oxygen is stabilizing to that Pablo Qatar and so all age isn't always so Parra director and it's activated we also remember that electoral files like chlorine undergo electrical like aromatic substitution so
if I take a and I treated with chlorine sometimes new textbook will use science right chloride ferric chloride as a catalyst to tell you the truth the choice of whether you use a catalyst is a little bit depended on how good a nucleophile your aromatic is if you have something that's activating you may not need a catalyst if you have something that's deactivating you might be the catalyst pulpwood Vera chloride in brackets here descent might not use it if I don't need it I think you textbook a sapling actually sapling I think doesn't and you text does inactivating cases because as I said if you don't need a catalyst you don't need the point is that's a relatively simple
operation when all is readily available organic compound you've done Elektra fell like aromatic chlorination always North apparent director in general Parra predominates over war tho so in general you can get mostly the power company and that's good there we will try Johnny's Eraserhead C which was 5 members chemists are control freaks we want to be able to do what we wanted do and we want to do it the way we wanted do it because different compounds useful you may make a drug with the power chlorophyll all compound is a building block but you may want the matter quarrel when all
building block In again synthesize this molecule from simple comparison saying criteria there alright so now we have a problem the matter how we slice said so the problem is we already know that the all age isn't worth all apparent director this activating chlorine is also an author of Harare director and so we're kind of shocked if you look at this you say Well we
can't go ahead and just directly corner but now you think Wait a 2nd Wait a 2nd Reno the group that's embedded director wants a matter director and to the nitro group is embedded director and so we get this idea ahead if we can take nitrobenzene and chlorinated as it would go better and then
we can draw upon all those other chemistry to get the control that we wanted so imagine now you take your nitrobenzene chlorinated at this point I plywood would used their chloride again this is something that maybe John here Kim would worry about war in the lab when to use it you might literally set up the reaction and monitoring by TLC and see whether you need the catalyst so nite grow is deactivating medical director so you can medical or
native analogous area I can see my way to the rest of this
I go ahead and I you go ahead I hydrogenated new H 2 and palladium 1 carbon that gets us to the analysts but then I
can take the adolescent and I can die at
times In our view sulfuric acid again my personal preference and I think the general experimental preference I will die as a ties to make the dies only salt and then I'll treat with phosphorus acid H 3 PO 2 looks up from getting ahead of myself here that's the next example I wanna give I will live the heated up heated up in water policy delta water your running the whole reaction in water so basically it's just
just heat that they and so at this point you get
to the final and the chorus the
question OK let's try 1 more example I wanted what it really give you give you a scope this this next example happens to be a problem and saplings so you'll enjoy paying attention to this
and again starting with simple stuff synthesized 1 of 3 but I've tried remove yeah
now you look at this and say we really are in trouble domains the North apparent direction I can start with benzene and brominated get Bromo scene but if I die brominated get mainly Parra-Bernal been seen very little or Bromo benzene I can't get one's member or so we story right so tho Bromo benzene worth worth so died Bromo benzene is To bromine sheer terror diagram of benzene would be winner bromine to remain here but there no way to get over and so now you really need a spark of inspiration so others reminders the Aurora
is worth of Powell director and the slightly the slightly deactivated now
you need a flash of inspiration the flash of inspiration is the amino group isn't very good tho director and activating and so here's a flash of
inspiration the flash of inspiration is to say OK we've been doing down the road a zillion times with analysts and I go ahead and I can brominated and 1 of the nice things about elimination and chlorination is you get a lot of controlled that is you can put in 1 bromine
you can put into world means you can put in 3 bromine is because rumination is deactivating so general you have control if you just use a little bromine and keep it cold you won't go you'll get a monochrome of you put more bromine you get a diagram of more you get a tribal so we imagine training this
with excess mean but maybe with iron catalysts honestly in the case of an when you price don't needed I think I think sampling doesn't use it I think you textbooks does Johnny and Kim window into the laboratory had some bromine monitor by TLC if the reaction goes they would pray not at a catalyst of its sluggish
state price some iron tried bromide as a catalyst heated up the point is you can go ahead and brominated once Parra twice more thorough 3 times were tho again and now you look you say all my bromine where I was and he said always 2nd I gotta get rid of that nite group that amino group we just
days ties and reduce it off with phosphorus acid so if I go in 1802 iii and you can use HTML a sulfuric acid honestly it doesn't matter 5 degrees Celsius at age 3 I appeal to we get the 1 in green light for informal company we've achieved this concept of control sorry I wanna mentioned 2 things 1 of which is we've been focusing on health on aromatic immediately so the big thing about aromatic comedians years you can isolate the dies owning compounds the not very stable you know 111 letter warm up to room temperature in general because they'll release nitrogen which makes for a volume of release heat which means they blow up so you want give my scold you want using quickly what we get this cargo Qatar and that's really not very happy now if you go ahead and do things without alcohol a means instead you have a very different chemistry Alcalde only insults are unstable so there is really no this beautiful controlled chemistry you end up getting into cargo cat and chemistry in a very uncontrolled fashion so if I take Cyclops appointment of benzene mind-set if I take cycle Hextall here and I subjected to the same conditions a N O 2 sodium nitrite paid CL even if I keep it called the problem areas you never really know have any time of the diet is only a mile on so I'm going to go ahead and say not stable but the forms transient late but it doesn't get as it gets us into cargo cattle and chemistry basically as soon as it forms the nitrogen leaves with its lone pair of electrons and you get all you want and as an asset 1 products but in so that kind of leads you nowhere as far as
useful chemistry secondary a means of course remember if you think back to the mechanism secondary means you
can't talk time arises secondary Amin secondary means for Nitro some compounds housing more specifically frozen and means of so let's take a dive Nathalie not just take the simplest example animals treated with the same conditions and a N O 2 and HCl this is a nitro 17 hour ride out the resonant structures father of male tonight frozen Americans are really
really bad actors they're carcinogens there there DNA but they react with DNA the mess up your DNA and so this is why hot dogs and cured meats that have nitrites in them are often deadly you particularly if you grill those cured meats because it
makes Nitro civilians that the meets tastes really good but it messes up your DNA gives you cancer or the last thing I have you read about there's some very nice guy chemistry that's written about not using Elektra fell like aromatic substitution on dies only and that's very beautiful just take a look at that it's still really nice for you to read about it will pick up next time talking about the following chapter will pick up talking about I think it's Chapter 28 at this point