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Lecture 13. The Robinson Annulation and the Claisen Reaction.


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Title Lecture 13. The Robinson Annulation and the Claisen Reaction.
Title of Series Chemistry 51C: Organic Chemistry (Spring 2012)
Part Number 13
Number of Parts 19
Author Nowick, James
License CC Attribution 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
DOI 10.5446/19417
Publisher University of California Irvine (UCI)
Release Date 2012
Language English

Content Metadata

Subject Area Chemistry
Abstract 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: 1:40-Michael Reaction 4:19-Aldol Reaction 5:54-Aldol Reaction with Dehydration 8:32-The Robinson Annulation 13:13-Reactions Involved in Robinson Annulation 26:15-Robinson Annulation Example 28:11-Retrosynthesis Example 33:55-Synthesizing Examples 39:55-Other Conditions 41:11-Acid-Catalyzed Michael Reaction 43:30-Acid-Catalyzed Aldol Reaction 45:18-Example Problem 50:00-Claisen Reaction 53:21-Claisen Reaction Mechanism 57:59-Synthesis Example 1:04:27-Crossed Claisen Reaction 1:08:46-Retro-Claisen Reaction Mechanism 1:11:04-Dieckmann Reaction 1:17:41-Synthesis Example
what to buy sell today way today we finish up Chapter
24 and as I said last time Chapter 24 really brings us just enough height of a lot of aspects of organic chemistry it gets us thinking about mechanism gets
us thinking about synthesis it gets us thinking about records and that it analysts the working Chapter 24 he is the basis of a lot of synthetic organic chemistry if it was the
enabling technology that allowed chemists to make steroids for the 1st time chemistry major New York Times for helping in the war effort back in World War Two and being able to synthesize scored zone that was needed as die inflammatory and
this is really your entree into that beautiful campus so what I'd like to talk about today as the material in Chapter 24 that we didn't talk about and and doing things in a slightly different order that I see is more logical we're going to
start by talking about the Robinson emulation reaction that builds upon the ideas from the last lecture and then we're going to move into related carbon you'll chemistry of the Clayson the action now normally when I start I don't really care but I'd like to recast 3 reactions that we learned last time in a moment you'll see why so we
learned about the Michael reaction sometimes called the Michael Edition in your textbook it's taken a lot of the color out of things by calling everything reaction and I kept with that in my life titles here but your pride here me and other people referring to it as Michael addition in the Michael reaction the example that we had we had several of course but 1 of the examples that we had which is fine we took
something that was going to make a nuclear not to basic and nucleophile I said that typically were talking about things where where the conjugate acid right this is a conjugate as of where the conjugate acid opening way this is not to 2 basic words only moderately basic this particular example that was the
last of state has PTA of 12 and I said generally less than or equal the 15 PKK we go through Michael additions and generally greater than 25 we go through 1 2 additions by the way is another name for Michael additional Michael reaction is 1 4 edition soda Michael addition we generating long-awaited generated nucleophile some support and we have an alpha beta unsaturated carbon you'll compound
very very broadly defined alpha-beta unsaturated Teton alpha-beta unsaturated Esther even other things in the broad carboxyl excessive family like an alpha beta unsaturated for you and in the presence of something that allows us to make a
new life here in this case 1 of our 2 favorite faces we've been seeing again and again and sodium as backside in ethanol we ended up with a 1 4 editions of seeking a way to generate a new Wiener like this is all in your notes before for the mechanisms so I'm not going to rewrite it out but I want you to at least process things in your head so we end up with a conjugated edition of the In a way to generate a new Wiener late probation give it the tone and we see we get a 1 5 carbon you'll
come so that was 1 of the things we learned last time another reaction we learned last time was the
algal reaction and we learned that in lots and lots of different forms I started off by teaching the
directed out all reaction I said chemists like to to have control and Sony directed Algol reaction we specifically make an e-mail late 1st and then allow that in late to react with a key tone around the side so the
example that I gave his side will some Texan on 1 of the several examples and we treated with LDA and ths LDA is very strong base
conjugate acid Dicer Amin has a gave 40 and then we added a 2nd step we added
tone around the Haida said this is a very general receptivity and used iso Durao the Haydn this particular example
to methyl Copa now and then we carry out meekly
workout and I wrote in 1 case a routine we use ammonium chloride and others cases generic page 3
0 plus when you get from throwing away the kept throwing acid into water like the and water the so the
product in this case
was a beta beta hydroxy carbonyl compounds and the last class of reactions we were really was a variation on the Algol reaction so algal
reactions can occur under many many conditions the Her with strong base
like lithium dies problem it can occur with a weaker base a moderately strong base
like sodium hydroxide and so the other example these are all sort of archetypes was the outdoor reactions with dehydration that's where we lose water in the end so here the mechanism is to generate Nina light it adds into the carbonyl compounds and work out you program may the be Alvalade the artsy and so alcohol
reaction with dehydration generally occurs under conditions where you've mixed components together Rivera and heightened wise of allow the heightened basis to repeat tone and Anonima lines of allow
behind which case you've crossed out reaction in the example that I started us out with was the apparent Algol reaction it was about the within days and I said historically calcium hydroxide had been used by rebel will distinctive this with sodium hydroxide when he reduced reaction and actually if you do this it gives a kind of a mediocre yielded 15 50 per cent yield and so this reaction the Algol reaction with dehydration is
very similar to the Algol reaction here you win in the "quotation mark operating conditions generate Minot Light daddy light reacts with another molecule about the height to give a beta hydroxy carbonyl compounds but under these equilibrating conditions you generate another arena like that then undergoes elimination of hydroxide so mechanistic Lee through things you've all seen before by the way just long on this topic of color she also hear this reaction referred to as the Algol condensation a condensation is a reaction were you moves so small molecule so when you
have put 2 molecules of acetaldehyde together here were losing a molecule of water so it's a condensation reaction the Clayson reaction which will learn about later you're losing a molecule
of alcohol which is why it sometimes referred to as plays and condensation alright so I wanna play at these 2 radiation different reactions together now in in sequence in the sequence I've talked about the reaction we're
going to learn about is the Robinson and humiliation In out start with a specific example of this particular the tone to Mathilde cycle taxi into 4 dialog and also saying in general we can say let's say in general but tone once the dichotomy of compound but but but but but but but but but 4 but and were going to mix it with and now forbade unsaturated
carbonyl compound in other words something something very much like this over here I'll start and this is the kind of the archetypal involved I'll start out with this key town I suppose it's you packed name is is review team to all every practicing organic chemistry does Robinson emulation will call this methyl vinyl Tetonia nickname because you have on 1 side of the tone of methyl group and on the other side of final group if you really want sound in the know you could call it in the case anyway this is an
archetype forbade unsaturated carbon you'll compound all right then short and for they'd unsaturated can also more specifically in alpha-beta unsaturated he only because of going the that OK and again we're going to mix this with some honestly in the real Robinson Letterkenny get baby exposure to the Robinson an election in the real Robinson and elation base is
kind of a sticking point in it's not always as easy as you just makes things together with the first-base you you try and were going to this particular
example use sodium hydroxide and water so the 1 about 1 of her favorite conditions that Allstate a suitable base here we have time now even give you an example of an acid
catalyzed Robinson and ulation reaction but OK here's the real beauty so we next phase 2 components together Carbondale compound Keatonâ 1 3 died carbon compound something that conforming alight and alpha-beta unsaturated carbonyl compounds something we've
seen is Michael sectors in the presence of states and the student from opponents come together in a series of reactions to
form would see these 2 components come together in a series of
reactions to form a Hecht the known as the annual look at
that and you say My God how that occur obviously there's a lot of chemistry going on here this particular Tetonia happens to be important it's called the the and Misha the tone
and it's used as the basis for the synthesis of some synthetic steroids synthetic steroids are the basis not only a quarter zone as I mentioned before but for for example birth
control pills so these are very important compounds OK so what's going on here is we're going Alleanza let me since I've been writing all of these archetypes a Keatonâ 1 3 dichotomy Yellen alpha-beta unsaturated of Teton let me ride out the key thing here the key
thing is that we're forming a cycling accident In other words the key thing the new feature that we've added is a six-member grain containing a carbonyl group on site while Pakistan
known but also a double bonds so "quotation mark XT alright so what's going on here we're going to break this out just a moment in 3 different reactions in sequence so the 1st
reaction is a Michael reaction Remico editions of some of the 2nd reaction years and how all the reaction the EU and the 3rd reaction is dehydration of successful if you want to remember something just come up with a crazy way of
remembering that new look at this and say in the hell does that occur that's crazy that's mad we're just gonna go ahead and remind
ourselves ADD the Robinson and
ulation is a mad reaction are but I'm not so I will show you how this occurred all however rather than by now we have written Cordaro mechanisms for every 1 of those reactions I just erased we've written
occurred Barrow mechanism for Michael addition we've written Darryl mechanism for Ronaldo all reaction and we Mitnick barrel mechanism for the base promoted dehydrated dehydration so I'm
not going to ride out the Kerberos I would expect you to be able to do this but I am going to think us through all of the intermediates so we have an acidic carbon meal compound the cycle hexane died alone we have a basis the most acidic thing is the cycle hexane die alone so what we end up generating 1st is
Oneida light were under equilibrating conditions some reactions so I guess I will write here to help us keep track this is the end stepped the Michael step of our man reaction so we're going to generate any e-mail late but I and I'm like so and that's going to act as a nucleophile and
Michael addition reactions we talked last time about different representations in keeping residents structures straighten your head if it's hard for you to think about pushing all those arrows the arrow down from the carbon meal From the double bond to the allocation then just go and take of the other residents structure you if you want go
ahead and think about it this way we can just say Well I'd rather think about this resonant structure I don't generally draw this residents structure presents a more minor resonance structure the more major contributor has the negative charge on oxygen but this is a fine residents structure as well regardless of
how you want to think about your residence structures in
Michael addition reaction you're e-mail alike is going to add to the alpha-beta unsaturated carbonyl compound to give you a new late in the 2nd step of the reaction and you've seen that you on your valve From the nuclear file from that source of electrons to the Electra filed to the data position of the Michael accepted we saw that yesterday Tuesday
now under equilibrating conditions we have water if you did the reaction sodium hydroxide and water you'd have ethanol use ethanol another perfectly good solvent sodium oxide in ethanol you can even mix it up and the sodium hydroxide and ethanol protons go on protons come off peak key tone is on the order of 20 which means the latest pretty basic PK of water is on the order of 50 is 15 . 7 in case of an alcohol if you're using alcohol with the 617 times come on
continents go off and so such aliens are Michael addition reaction but we're now you formed a
product that has formed another that's a 1 5 dichotomy remember use we've learned that you can recognize Michael addition product because
there's a 1 5 relationship 1 2 3 for private 1
5 by personal comfort are right that Sir Michael steps we learn that the algal reaction can occur even intermolecular fashion intramolecular fashion and we learned that in equilibrating solvents and hydroxyl like solvents like water Her like alcohol protons come on protons galore every possible position here can formulate some of them don't lead anywhere in other words every possible help of position conforming away some of them don't lead anywhere protons come
off protons go back on some of them do what I'm going to generate media late it's going to take this on in our next steps so we can imagine if you wanna ride occurred there are mechanisms your face your hydroxide pulling off the alpha proton pushing electrons to form a double bond pushing up
electrons onto the oxygen of warm
and in the light now that in light is
poised the former 6 members bringing we said 6 six-member brings like to form we've seen Our Algol reactions occur intramolecular leader for 6 members rings 5 members so in our
next step that being late attack the proximal sovereignty over it 2 years and now the way like so and again I'm not trying Kerberos you should know by now how to draw your arrows down from the oxygen in the form of
oxygen double bond oxygen carbon double bonds from the double bond into this part of annual carbon and off onto the oxygen to form this sound-alike in a solvent protons go on protons come off and salons
that we have lots of protons whether we're in water flow urine alcohol as a result the last steps His Matias and thus are Algol reaction has proceeded With the last
step is dehydration by now we should be pretty well set up the CIA on the reaction conditions protons on protons go off in all different positions but if we pull off the proton next the Carbondale here were set up to formulate they can undergo elimination and elimination is going
to give us a stable conjugated you know so again I'm just going to go ahead in Groff intermediate not Kerberos and so you can imagine forming this year light so and then late pushing electrons down and picking out hydroxide to give state while the invaders and central needed for the the new company and so this
reaction actually in many many cases works pretty well and the 2 companies come together in 50 years 60 or 70 per cent yield to give a news cycle hex you know the answer questions at this point the stereo our the great question what Cesaria chemistry this compound is Tyrol here what we 1 in then hammered the other inanity maybe RDS both alone and in the absence of something Cairo to direct the reaction we get as much of 180 as the other and 1
of the big areas of organic chemistry these days he is being able to direct chemistry began a single entity Amir walleye the steroid hormone receptors in your body of all if you want a birth control there you want and aunt died of birth control drug I inflammatory you
want the handedness of the drug that's going to fit into the receptor properly you don't wanna to be taking twice as much drug where half of the drug can be inactive working B I have a bad effect In the case of the drug thalidomide which was given for I believe morning sickness are in pregnancy in the fifties the children ended up being born with birth defects and many other drugs have had this particular various that effect in this case need to Amir of the desired drug causes birth effect alright so Hey what's a cutting-edge jury of chemistry is being able to make just 1 and it turns out that in this particular Algol reaction the amino acid Crowley can catalyze this to give as a basis for how well actually for new mean pathway which I might give you in the discussion section to go ahead and generate just 1 Amir preferentially so remember when you read about CBS reagents for a reduction and I said This is just giving you a taste of this whole area of of asymmetric synthesis likewise in the asymmetric synthesis of the real and short owner related key tones a little taste of it is that the use of a Cairo-based for this place and Cairo Amin can give rise to a single and good question very important and this becomes more important when you have multiple serious centers in the molecule someone mentioned for a moment now let's say for a moment that we had a 2nd Mathilde group at this position I'm not going to draw out then you'd be saying Wait a 2nd now we can get to Diana staring Merck products I wonder which 1 forms than you might think well let's see wonderful thing go Ecuador real maybe will have thermodynamic controls and that kind of gets beyond the scope of work but very very big and important is that you're just getting a tiny taste of them in his introduction to about ones in in this part of carbon chemistry that as I said it's sort of a gateway to to tons and tons of really important or dairy industry alright I want to since this is such a big thing I wanna give us another
example many but not all of the examples do involve 1 3 died carbonyl compounds because quite frankly it's easier to generate being late to do the Michael reaction when you have a 1 3 dichotomy all compound itself and analysts give us enough forward sends another 1 3 dichotomy of compound Baedeker Westar were gonna see this fate aikido Western later in today's lecture In what I want us to see gains of Mike is the
Robinson and relations with a slightly different key tones and get a little faster and a little better at our thinking our way through this reaction sometimes start by drawing
the Robinson undulation product mail in this case I'm choosing specifically not to use sodium
hydroxide why don't I wanna use sodium hydroxide why am I using sodium methyl oxides some of the we have been at the last in the molecule and if we were to go ahead and use sodium hydroxide we would attack Imdieke ends loose ends upon a fight yesterday group and then end up with the carboxyl aghast which would actually be carboxyl laid under the reaction conditions so in general if you have a natter Lester you wanna use sodium at well and you wanna use sodium at dockside in ethanol theater methyl ester saved 1 EU sodium methyl oxides in methanol in a and
ulation products in this town again it's this cycle taxi known and I want us to think it through now a little bit faster I want us to tell learned how to see these reactions forward and backwards so let me show you know Johnny and all I in chairman probably look at this but then take it apart with retro synthetic so
Johnny and Kim and I look at this and say I know this is a cycle of Maxine knowledge and I know all cycle taxi announced can come from Robinson and relations and I know that in its reaction we can break we can think back words about forming the alpha-beta unsaturated bonds but also the bond that's between the 3rd and 4th positions of the beta gamma belongs to this to the Cardinal of the cycle of vaccine known so we can break this molecule
apart in 1 giant retro synthetics that and say all this had ,comma world could come from this disaster and this know
that's a big bite that's a big bite to taken 1 mouthful so I want to show you how to break this apart represent Seneca Lake into smaller bite-sized
pieces but but but are so great in this apartment
to smaller bite-size pieces we've seen alpha-beta unsaturated carbonyl compounds can come From an algal reaction and dehydration so I can walk at this
scene now I can look at this alpha-beta unsaturated and say this part of the chemistry has come together remember reaction rights of this part of the chemistry can come from and how it it all ended dehydration so when I take that back words retro synthetically I say all the immediate precursor to that it could have been yes In other words I will write alpha-beta so I'm gonna write here cycle hexagon in all this is more likely when John East Kowloon Kim's clinical that Directorate synthetic chemistry involves a Robinson and elation but if you can't do that go and
look at this and say it all well this is my close by the end of the year the at that point you say all this is like Chloe "quotation mark that this could have come from and how long reaction so
I say all this is an alpha beta unsaturated Tito and now you look at this next component you say all this is a 1 5 iPod Video the company founded 2nd numbered in either continuity doesn't really matter this is a 1 5 dichotomy compound that could've come From a Michael said there's the airmen are and they did and so and so we begin gold backwards and there were this particular precursor and known the
take years in this sector I wanna see if other people have questioned I hear a lot of mumbling This is good I want hear noise you should be talking about this so this might be the only actually help or have a you know the way so not so this is the same question U.S. beef or in a different form basically in our Michael addition whether you think of your evil life like this or whether you think of it like this it's the same thing so yes if you're thinking about like this yards from an Al-Qaeda but remember it's both at the same time so I think that the and this should be it can't act at this point in everyone's development here this show me something your wrestling with you what actually have actively wrestle with this chemistry to make it makes sense to you you have to to be thinking and saying I'm not sure on this I don't understand so this is good these are exactly the questions you want ask there now and didn't give you 1 of the questions that I like to ask synthesize the
following from similar companies but the the the the and again I'm taking real examples that have been done in the laboratory and some other molecules have some complexity and some personality to them so here's here is an example of the real compound that can really be synthesized in the laboratory and I
want to show you my I thought processes seize on this is the same thought process that I outlined on the upper part of that blackboard I said OK I look at this molecule and I say I see a cyclone taxi known
and I'm going to think backwards and I know in in the Robinson adulation immediately cycle
axiom known says the Robinson nationalization Robinson nationalization and so I look at this myself case in the Robinson and relations reform
the alpha-beta unsaturated ponds and we form despondent over here and so I look and I say right thinking backwards to the word is that get me well that's going to get me this the tone here yet this is hardly the 1st time around that's going to get me to this key tone over here that's going to be this half of the molecule and it it's going to get me to advance they know like some happens to be the same
known we just used over and again that example and I want to work this through now in the forwards and by the way there's a lot secret here so I start with a little genteel and I said You know cycle hacks key towns in general :colon without being part of a 1 3 dichotomy of Kendall Robinson adulation plain old cycle Texan only plain old Ahsan told Kendall Robinson emulation but often you're going to get a lot of algal reaction and other stuff going on there's something special about this she told it's even a little bit more acidic than regular Quito members have regular PKA 20 what's special about the offer position of this 2 close to the benzene it's more specifically that Proton when you pull it all off you're going to get in and out I had that both an e-mail late and then select so it's a little extra said that instead of being PKA 20 it's going to be a little less maybe PKA 17 so a little bit better and Michael reactions are so
to run the reaction in a existence now we only this ends up being kind of a one-note at this point once you see the secret to run the reaction in the forward since we take our key towns plus Cereghino then we mix them together with some days I'm taking a real example from a real experiments of the authors of this experiment use sodium hydroxide and ethanol if that but you just in your own mind and then write war in a wheat over here it's not going to matter the reason they use ethanol is organic
compounds generally with lots and lots of carbon and lots and lots of Greece don't generally dissolving pure water unless they're very small and so it's generally good to have an organic solvent and ethanol good solvent for organic compounds the reason they use sodium hydroxide is you know it's the lab and open a bottle of sodium hydroxide and it doesn't hurt to have some hydroxide around but if that you because it's not the 1 I always used to just go ahead and write so the fact ethanol should work just as well anyway the practice the product here
same thing now I've been riding over and over if you're feeling Q lazy just like PDT
and there's your product of Burundi's elections yeah as I said with the Robinson manually should result in a chemistry occurring in all often the details end up being conditioned depend fact when I look at the graduate level Tech but I can find you a dozen different conditions that have been used for Robinson emulation I don't want you to know that all of them but I want to
show this to you for 4 1 a set of principles here and this is an acid catalyzed example and I would expect you to be able to to use these conditions in fact they're kind of specialized but what I do want to do is just show you something and mechanism that ties into something that we talked about earlier again this is a real example so this
particular example is a site while Hecht's and on its way to methyl cycle nonplussed methyl vinyl Teton plus 3 propane prices plus 3 bewteen 209
in the UK has particular Robinson adulation if you want to write it on paper you wrote it the same way I did there you'd be fine in practice you actually get a pretty crappy yield that way on if if any prospect and so in practice this 1 experimentally was done
with sulfuric acid and benzene a reflex again as a 61
would be expected to know that but I want us to look at the mechanism because it ties into something that I talked about before and the point that I
really wanted to make is that we're getting acid
catalyzed chemistry here so you're getting an innocent catalyzed Michael reaction I want you to think about that for a moment
remember early on when we started introducing the chemistry of Renault's Indiana lights I said he will Dean also are more nucleophilic than regular AL teams but they're not stupid nucleophilic they only react with really good electrified health and so acid conditions we penalize at all different places and so let me show you acid catalyzed just want to show you the gist of the acid catalyzed
Michael reactions sold in sulfuric acid protons command protons go off you generate mean all just a little bit of protons come on protons come off you generate approach be Keitel McGinn transient Leonid
small amounts now here's my point in all also good new odd super good nuclear files the only moderately nucleophilic G tones are super good electoral files and alpha-beta unsaturated Tetons orange super good Michael acceptors but by the time you approach makes the Carbondale now you've really stupid
things up and so at this point you go ahead and now you're really nucleophilic so you go ahead and like so and I'm not going to ride out the whole mechanisms in detail but at this point you carried out in an acid catalyzed Michael addition reaction here and then you talk to arise over to to the Quito now all of the
reactions we've talked about it can happen in this acid catalyzed manifold so Samantha acid catalyzed Michael you can't have and how gold in acid catalyzed manifold the 4 so just
imagine taught time arising the product that I had written over there before so now management talked to Imagen utilizing and imagined program the carbon medial and again you should be able to work this out on your own in fact I think there may be a problem along these lines in the textbook OK so you can see justice before you can probably made you can generate meaning all again you're set up for an intramolecular reaction so again we're gonna push electrons cell in the acid catalyzed manifold again I'm not writing out super detailed mechanism I'm just sort of sketching stretching things out for you all right so that's there and then of course you pull off a Proton rider in Asotin sulfuric acid and benzene protons command of times lost souls now that brings us here so if you want just the hell of it I will ride out my product over here and if you want just for the hell of it I'm all right out of my product over here but again you should be able to to go ahead and work through this on your own hard itself the
last step and this 1 I know you didn't do because you've been doing it back I think it was in Chapter 8 where we were there doing acid catalyzed dehydration of alcohols to generate our teams and I
think it's also a problem 24 from reads for a fire remember correctly alright so under these conditions against strong sulfuric acid protons go on protons go off everywhere in the molecule you can probably make your age group you can program a year hydroxyl group could becomes a leaving group leaves with its electoral is sticking out water and so now again in this sort of stature all the mechanisms that sets us up for cargo can information that some positive positive charge over here and that sets us up for a loss of a
protons just right minus the triple alright so the big picture here is not those reagents that free-agent happened to be for this particular reaction the big picture here is that this manifold you know life with a Michael accepted he when a probe native Michael except being aligned with the carbon meal were With appropriated carbon dehydration by and he won CBE mechanism remember that's what I call that we talked about a Michael
recover we talked about the Algol dehydration under basic conditions its elimination union elected the conjugate base it means you pull off a proton and doing elimination or elimination by way of forming a Carvel cattle
however if that's what I want to say about the Robinson emulation any thoughts survey questions at this point all I know the thing is like that of what the world is with the our last year House case somebody needs to answer this question and more investor reaction does the double bonds go here and now let's say
Over here someone needs to answer that question whether they're both unsaturated zone 1 case Your imagine dehydrating conjugated yes and so on all of these Robinson adulation conditions were learning about 100
thermodynamic controlled and even if you go ahead and have a reaction of currency give the beta gamma unsaturated compound transient late summer dynamically the thermodynamic product the deepest energy wealth is the alpha-beta unsaturated compound protons collide protons come off you reprogram make you get a cargo can you deeper made to the more thermodynamic stable Alpha Beta centuries and of course really this Robinson annual Asian chemistry because it is under thermodynamic control is much more subject to sort of the whims of thermodynamics and the whims of side reactions say worries started us out in the directed chemistry where I said it Damn it said dammit we organic chemist wanted to take control ourselves we do that by generating generally if we want reacting it with the carbonyl compound we want in the place we want it may or may not be the kinetic product it may or may not be the thermodynamic product but we controlled the reactivity alright I wanted to take us now to some more vary
very old chemistry that place in reaction workplace in conversation so we've
been seeing all of these 1 3 Carbondale compounds we somber Lonoke Esther we saw Seto acidic Aster writes diet for Moulin a Ethel react so to view it we've seen assets he'll acetone so we've seen that these 1 3 dichotomy of compounds and of course we saw cycle taxi cycle hexane die all and we saw cargo as foxy cycle Texan on these 1 3 dichotomy all parents come from somewhere and it turns out
that come from some other chemistry that's also really beautiful and and really simple once you understand so if we take that philosophy today and we treat it with sodium math oxide and ethanol 1st of all right want to indicate we're doing that a person that stepped then we carry out maintenance worked out with some 8 minutes after that in some guy who dates Seattle you're not cooking things together you just throwing it in before shaking things in a separate toward final you get after Louis Sito
acetate you get Apple's react so to view of 3 out so you can always OK so this reaction involves more carbon geochemistry of the precise it that we've seen before under these conditions you can formally Milan you don't form a lot of remember ethanol PKA conjugate asked the at the gate of the conjugate method of sodium at dockside conjugate effort is ethanol PUK about 16 ethyl acetate Nafta PKA
25 so unanimous equilibrium and sort of right at the edge of where I said equilibria kind of count you have this acid-base equilibrium with the plus ethanol that equilibrium wise way way way way way the last then right PKA the European 25 PKI 1617 the text produces
16 Solomon 60 s 9 orders of magnitude equilibrium constant tend to the negative knowledge to the left I just right on the cusp I said attended the 10 10 PKK units difference is sort of like within Bolivia can become significant so USA set up to generate Nancy Bitsy agency will be probably intellect and you have .period day of ethyl acetate sitting around so that Apple acetate can react with that itsy-bitsy exhibit of Italy In the course water we have we have not
later the nuclear file the fire at the last data has Carbondale it's an
electrifying electrons flow From the nuclear file to the electoral filed by now we should be used
to pushing our arrows this way if you need a little much right the other rents the structure of the inner like electrons flow from being alive tell the afterlife acetate to give rise to a territory illegal intermediate member territory he'd roll intermediates are in
stable they break down our oxygen kicks back in Carbondale carbon-oxygen double bond is very strong and we can expel all leading
Europe the fact that I believe but the 2 we get our
product what kind of sort of saying Arafat slide is good base here PKA about 6 16 for the conjugate assets and
a 1 3 dichotomy of compound was reasonably acidic
speaking of Apple is you know acetate is 11 this is really the
the key figure in the chemistry of this is what I'm going drives this chemist American writing long years this is what drives the chemistry of equilibrium lies nails to the right they give rise 2 0 you're talking a late I'll write 1 resident structure you prefer to write another 1 you can Flats ethanol on again our idea of people this bricks
so that equilibrium 5 orders of magnitude to the right that lasts reaction draw lives this chemistry and you notice in this case Our chemistry is is actually striking metric and base because at the end of everything we've used up 1 mole of sodium at dockside and generated 1 mole of our inner light of that felicito acetate so this chemistry requires a full equivalent the Algol reaction in theory you could get away with just catalytic pace you had it absolutely at the end of the the reactions were not done yet here I've just given you the mechanism for the conjugated addition at the end of the reaction you add acid literally the way you would do this chemistry would be to take some sodium at side put it in a flask takes a methanol throw in some sodium to generate sodium and fat side throwing Samantha lasted take spoil it up for a while after you boil up for a while until the reaction has has gone to completion you'd let it cool the room temperature or maybe even put in an ice bath traveled by Lou date we assess it and do a liquid liquid extraction rate distillation to isolate your product so some students look in the same way as sector were adding hostage why hasn't the Apple after hydrological there's a big difference between copying between heating and for a long time letting in methyl esters set on Astor's sit with incidental hide realize it but if you don't he did you just let them come in contact for a short time that doesn't hide relies you're asked all right so 1 of the things that I always like to do is integrate particularly in this chemistry that is so rich and so fall of relationships and since this is I like to talk about how you synthesized molecules how do you recognize that so I'll
give you a typical problem will show you my thinking on it and show you some of the beauty of this chemistry so let's go ahead give us a little diversity hero make methyl ester our selects synthesized this methyl ester From simpler competence you can even in the middle of it going to be 1 2 3 4 5 6 so at 3 2 at all 3 acts so many people to Level 3 Oxo hexagonal away authority to set the size methyl 3 after the 2 home 3 I had sat away from simpler company-owned alright so I work this compound and I
say alright we've now learned nuclear but we've now learned enumerators synthetic clothes that we've learned that when we see a bigger die carbonyl compound we can cleave the bond between the health carbon and 1 of the
carbon wheels in the Clayson type reaction so I look at this molecule and say synthetically under splendid back after this wealth doesn't matter right now and I'm thinking retro synthetically some sort of group there that's going to leave and this that's Mathilde Newtown away then I'll look at and say OK wait a 2nd the fewer the same thing of all for carbon carboxyl aggressive family compounds and so also say are I have got a synthesis of this we've been talking about plays in chemistry I'll just take natural Viewtown away trading without the last I better use sodium and backside in methanol so I don't train sister quiet by reduced-sodium at Parkside in ethanol I transistor applies get some or all of the at last I mean I go ahead and after cutting it up on carrying out maintenance work out of it but you know it's going to take me to my desired product and the
but Our this is where this chemistry really gets beautiful and where there's chemistry really gets rich when different people can look at things the same way in different ways and both come up with the right answer that's profound because ultimately building molecules is suggested if this set of many different right moves that could be used to put together a molecule and so 1 person can look at the alpha-beta unsaturated Carbondale compound that drawn here and say I'm going to break this bond between the health and 1 of the carbon deals and another person can go ahead
and walk at the same molecule and say I'm gone I'm gonna break get carbon I wonder what happens now not every move ends up being a right move sometimes you get problems and that's where you think things through in the forward but this particular example happens there have to write moves to it because I break that bond retro synthetic late than normal I come back this way and I
say where does that leave me OK well I've got this format known I've got this key town here and it's got to symmetrical output Harbin's and I can imagine another Mathilde proof here I could do a different sort of plays in reaction where
I take Diamond Hill carbonate but sometimes all right away and a sometimes alright overseeing 3 there of course interchangeable an alternate sodium and fat either just different ways of writing the same thing out there it's only a matter of fact side in methanol and a answered OK does that make sense let's say I guess well there's only 1 component that can form a new life there's only 1 type of being late that conform with original lies to the left or the right it's the same thing that evil can attack this carbonyl compounds and ultimately then the same chemistry former Ted readable intermediate kick out of that dockside malleable 1 3 dichotomy over 1 3 dichotomy always was more acidic than that oxide pulls off the protons and I come up With a reasonable synthetic growth a reasonable alternative synthetic To the compound that I asked the question about
and that's beautiful let's prevailed we call this reaction across plays in reaction to of the Glazer names on capitalizing Italy's trying to appease likened the crossed Algol reaction were really talked about 180 analyzable component generally a key told reacting with another nominee analyzable component generally and held 1 can have a cost place in reaction let me give you another example the
example I mentioned earlier it's the 1 we use in our Robinson adulation so I thought it would be called so cycle accident on simple compound treated with it is just a on the example above all treat this with sodium at dockside In ethanol and then treat it would die Apple carbonate of die Apple's carbonate is the Dalai ethyl ester of carbonic acid dime Mathilde carbonate is the dime methyl ester
of carbonic acid there in the same family problems and the plus for oxidation states to 1 higher than a carboxyl like so still higher than 8 82 0 3 higher than now the same thing think we as
worker generates cellulite usually attacked the Apple carbonate that generates from 1 3 died Carbondale and at dockside at dockside
off proton generators stable light after 8 weeks work out approach may seem like a reaction in gives you your product this business about generating a stable legal life is really really important this is the thermodynamic driving force behind the Clayson reaction and also show you how portability if I go ahead and take something that can
form a stable legal light sultanate on the likes of butyrate asshole to Mathilde probe panel away and again all envisioned propping it up with our favorite conditions sodium at dockside methanol but followed by 9 a year's work up you might think following a 2nd OK that's just like all these other examples that I've been tossing out on the blackboard and you might think OK we envision generating mining light ads then we get a place and condensation
we get a 1 3 5 die hard where that problem Noel acidic out of Net thermodynamic driving force it is necessary for the reaction is 5 PKK units remember every order of magnitude every factor of 10 equilibrium constant at room temperature is worth 1 . 3 6 kcal per mole 2 5 times 1 . 3 6 were practically up at close to 10 kcal per mole of driving energy for that reaction carbon-carbon bond is on the order of 80 or 90 kcal per mole carbon hydrogen bonds have similar stories straight 100 kcal per mole there about point is we're adding energy difference that on about 10 sort of forming bonds and with help that energy we just can't drive this equilibrating chemistry itself this show you what that means that means that if I try to do the reaction if I mixed the product
will the the reaction conditions this is an equilibrium this reaction goes backwards in other words if I take this hypothetical product that I somehow managed to make it in there are other ways to make it and I treat it with sodium at dockside in ethanol we are not breaking this product that part of the 2 molecules of of Ethel license butyrate the reversal of a Clayson reaction and we call it the rector a place in reaction to I'm going to leave it to you to work out the mechanism I just
got homework problems up from the textbook and Chapter 24 1 of the problems about two-thirds or three-quarters of the way through I think involves director of and I just looked at it very quickly quickly so you want to think about the mechanism there have give you this
reminder came that that mechanism any mechanism in reverse is there any anywhere versus reaction anyway action in reverse goes through the same mechanism in reverse member that's what we call microscopic irreversibility so if you can write the the mechanism
for the Clayson reaction in a forward since you can write it in the reverse since just started the last step obviously you don't have that deeper nations but started the a breakdown of the text retrieval intermediate and envision adding a nucleophile to that vision adding about outside debt and push Maryrose then you'll be right back at ya reactants Paris we saw that the Algol reactions that occur in trouble accurately we saw that 5 and 6 Member brings were particularly stable the same with that poison
reaction accepted gets a special name the Diekmann reaction the and may in the end the reaction also called the Diekmann politicization the because were out molecules so I'm I'm gonna take the Dalai Apple Astor of the 7th card flight carboxyl like asset quality of this year the forward since see this in reverse sensitive moments a 1 2 3 4 5 6 7 and will envision treated get with our now favorite conditions of sodium at dockside in ATP and all of and we have worked out with some ministers in the product of the reaction Is this after Leicester same methyl ester we used in our Robinson
emulation reaction the mechanism such just the poison reactions what the students ratings for the 1st time in intramolecular reactions they get freaked
out so let's go ahead and do sort of an abbreviated version of the mechanism located where under equilibrating were under equilibrating conditions we generated cleaning he needed the itsy-bitsy wet bed of light on getting punchy up here we generate 18 a bit of partying alike Our are I can react in trouble electorally we push our arrows arrows up onto the oxygen and forms a six-member during part of the intermediate Arteta volunteered media is a six-member during 6 grain is generally a good things they
generally conform these the take Redrow intermediate can break down kicking out at at Fox side member you can generally pick out anything up to about including 25 PKK as a leaving group From the detector he'd intermediate remember it's different than an into displacement that PKA of of 25 which I said was kind of the cut off we saw that may help a reaction that also plays in the rector Clayson reactions the ones that we knew right out that mechanism you're going to have to do and say I don't know about that step you're kicking out a leading group with a peak every conjugate
acid 25 OK 73 Verleger media breaks down some of the wasn't thoughts I'm not going to draw on all my lone pairs of electrons and that final step that and equilibrium that line is way way way way way to the right polls office fountain generates are usually don't like declared war on Monday in light of the negative charge on however that so let's think
about what we just saw but was the there's a product we use that product in
Robinson undulation we use that product to make something very complicated from something a lot sense we've now seen how the mandate that product from simple to you make that reacted from simpler molecules we've seen 2 different ways that matter we also saw how to make a alpha-beta unsaturated carbonyl compounds those are made by now the reaction with the hydration so carrying you can make it from another all reaction with dehydration OK but what about this 1 will remember this is our right to
rescind Vedic analysis that we've been learning about 2 1 3 dichotomy of compound the way we see it over here you break it apart retro synthetic delays like this my yesterday and if you count that as 1 2 3 4 5 6 7 1 2 3 4 5 6 7 that's just but at the at the foot of the butt of a pop back into the vacancy 1 way to break it apart but you can also see a 2nd way to break it apart we saw that way just a moment before that way of breaking it apart the break that part of the site hacks and all and diarrhea would operate and that's really the beauty of
being able to to recognize these relationships and solar array and with a very simple the problem of simple line is being lazy I figured I in this with a problem that analogous because we've seen so much chemistry in these past these past 2 lectures and in the past for lectures that your heads are probably spinning right now and that's OK when you work the problems that spending is gonna stop things are going to crystallize in your head and you have to work the problems saying a sort of nowhere examine problems but instead of
looking at exam problem I just said it's the sword I always like to ask we've seen 3 of them today I I think it's really set salaries this compound the French from simpler molecules of the monthly from parents who Bloomberg well buy this by bus .period I don't think that can fool you this is just an analogy to what it would know lower the cost you
have it up on the black so 1 3 died carbonyl compounds can splitting apart in 2 ways we can splitting apart at
this farm here that I just need to be able to count correctly 1 2 3 4 5 6 usually at this point the clients from Miss killed so I've gotta make dying after a dip awaits the dire methyl ester of has said you could make that from site while taxiing if you want didn't and will treat it with sodium methyl chloride and methanol the you sodium at that side because I have met last Thursday don't wanna hydro lies them with sodium hydroxide it's
upon a fire them if you want the technical I don't want to go ahead and
transistor find them we carry out neatly as worked up because we've got approach made that an but there's a product and we also know of a real long narrow onto the other black words we also know that can
format on that so we set out when the 2nd week
in new request Clayton take cycling attended known we'll take our favorite base sodium methyl oxides nominating life a little easier for you I've done these reactions myself and I have often done these reactions with sodium hydride as a base but their about a bunch of bases you can use animated simple would use sodium and fat side in methanol use sodium hydroxide sodium hydride and I'm baffled carbonated solvent ignorance answered work up the old saying we haven't seen a lot of variation there and then
to a different ways to the same product to write answers are right we will pick up next signed with the figure the flextime time is the economy and talking about Chapter 25 have a good day for the


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