Lecture 20. Phosphorus Chemistry


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Lecture 20. Phosphorus Chemistry
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Vranken, David Van
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UCI Chem 201 Organic Reaction Mechanisms I (Fall 2012) Lec 20. Organic Reaction Mechanism -- Phosphorus Chemistry Advanced treatment of basic mechanistic principles of modern organic chemistry. Topics include molecular orbital theory, orbital symmetry control of organic reactions, aromaticity, carbonium ion chemistry, free radical chemistry, the chemistry of carbenes and carbanions, photochemistry, electrophilic substitutions, aromatic chemistry.
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OK so as our final lecture in this class work which is
finished talking about sulfur chemistry would drop down from the 2nd row to the 3rd row and were going to finish up by talking about phosphorus chemistry and when introduce you to some of the functional groups so we're going to talk about today we can cover everything have would have focused on these 4 types of control those fast beans and that we have 3 Al-Qaeda L'Oreal Group pondered the phosphorus 0 3 carbon fast response at a fast speed when you switch to phosphorus had a bond change the name and in particular with oxygen we call this a fast fight this kind of species where there's 3 oxygen is on here and more specifically I would refer to this as a phosphate ester company general I would simply say that phosphide over there and whenever I see these talked to and focusing relentlessly on those long there's on phosphorus this will talk about that in the chemistry so it's very easy oxidize phosphorus 3 will talk about that solicits phosphorus with an oxidation state of 3 is a proper this has an oxidation state of 5 down here this is a past the dockside bully contrast that with oxidation state free up about soul at the oxidation citified this is the most common functional group you'll see it's a past the oxide wary Oxo ligands sticking on top of phosphorus and if you do the same for a fast fight we don't call them phosphide anymore we call that a phosphate and you should be familiar with this functional group because it's the backbone of DNA and RNA and its the key functional group on phosphorylated proteins are so good talking about ,comma what kinds of things change as we drop down from the 3rd row start from the 2nd row nitrogen to the 3rd Road phosphorus so they remind you of some of the PKC about the basest city the lone pairs on nitrogen and what we'll do is we'll look at the peak of the probe native nitrogen compounds the traveling is a common base and we can say something about the basis city the lone pairs on travel by looking at the acidity of the conjugate acid of traveling to so ,comma if you compare travel Amin with tried panel as you might expect trade panel amenities it's not basic at all if you look at the PKK for trade and ammonium it's on the order of minus 5 were restrained from ammonium is on the order of 10 to 11 years 11 is my approximate number that it's
extremely difficult to stick a proton on try fennel ammonia that's because the lone on nitrogen are donating into major
alone there are donating into this price system individual residents structures all over the place that's exactly why aerial Amin the sole reacted and electrical like aromatic substitution because these 19 lone pairs reducing up their prices system making more nucleophilic civilly good resonance here with nitrogen detached benzene rings on if you look at the corresponding phosphorus compounds just in terms of PKA and I'm going to draw Beutel groups here because that's the most common philosophy it's about the same for trying bullfighting but you look at the PGA it's pretty similar that's a pretty similar basis the desired to a proton stuck on there is pretty similar for both for a fast only species 1011 sort of it within the same ballpark if I look at trying to ban all fast phony impregnated try
fennel philosophy now the PKK is significantly different from the nitrogen case instead of being
away at the minus-5 in other words this is a super strong acid it if you could figure out how to stick a proton nitrogen that would be a very strong acid but a needed intractable fasting is not a super-strong acid is not super-duper acidic and we can trace it back to the length of these carbon phosphorus bonds so yes there is a very nucleophilic lone pair on this fasting and hypothetically a sum donation and is price .period system of airing ring but look how far away that of course and trying to exaggerated so you'll remember but so far away you don't get good donation form partial PC double bonds here goes back to this issue that yes the waddles very bigger and faster but it's so far away you don't get effective donations and that makes this lone pair more
basic spending less time donating into the price system so it has more room so we have to move more leftover
reactivity still react with protons OK so found so trial kill philosophies are more basic than trial philosophy and so on and so and to try to Errol policies are more basic than the corresponding 2nd row Adam systems with nitrogen then return to a mechanism that you've probably I hope you've seen before for many mechanism the reaction I hope you've seen before and sought more than a chemistry for what he called for a 1 of for all the way from this description is not the
reaction on this is a description of a part of this process is so here's a reaction that you might have seen before and sought more organic
chemistry and involves taking a PB 3 fastest try bromide and using that as a reagent to substitute the hydroxyl groups of locals primary alcohols secondary locals here could you tertiary alcohols the stood geometry looks like this you take 3 equivalent of alcohol free trade Ronald for each phosphorus tribal my condition that allows you to substitute wages that's a very at the very useful substitution reaction because there's all kinds of things you can do without bromides you can turn them into green yard regions you can substitute them now with nuclear files OK so a reaction I hope most of you've already seen before maybe something that was never mentioned you before is that this reaction is acid catalyzed probably with every fiber of European you
want to somehow uses oxygen but you have to make P bonds in your product probably wanted U.S. into reactions and then I want to urge
you to wait that that mistake this talk about the mechanism for this reaction the mechanism of the reaction starts off with proclamations and books starts off with proclamations of the of the phosphorus lone that's why acid is essential if you cannot buy PDR 3 that doesn't have some acid in there and once this reaction starts history generating acid from the get-go and so the initial step here is that you probe made but phosphorus and the 2nd you put a proton on there you've turned that phosphorus into a super-duper electrified phenomena that a proton on-air look at that if you want to make a bond of phosphorus now it's easy to make a bond of phosphorus now it's easy to attack the officer proton transfer reactions a are generally very fast and
so now we've change this the story becomes very easy to attack good draw nucleophile here like
ethanol the T O H shares my long hair and there's that phosphorus and so that those numbers on the ethanol the alcohol want to attack this it's scary electronic gear there is a proper instead AT & T 2 the most Elektra negative ligand Proton is not the most Elektra negatively can get indeed to the 2 1 of the bromine here surrounded with a trickle by pyramidal phosphorus so here's my my equatorial ligands years my axial Lincoln's on here so here's that now and I'm trying to figure out whether I'm going to stick his nations step because I'm confident you can figure out that after I have yet you need to use the programming that Proton from the foxy nucleophile standard that is treating all by pyramidal intermediate that's not at the
end of the trio by pyramidal intermediate no
charge on phosphorus it's neutral don't freak out over the 5 bonds the phosphorus this is not a 2nd will Adam perfectly happy is an intermediate with 5 bonds member phosphate over the stuff I bonds focuses perfectly OK then intermediate but that's not to say that leading groups don't want to leave now the axial Leading Group will prefer to leave as just Astaire electronic preference and so I get right back to attach Rahim yuletide intermediate and so in that Tagesspiegel intermediate I now have this is a foxy group attached for all I know is Electra Philip fast phoneme species and so now and that bromide is now floating around and I'm going to draw right over here as you can see that it's ready to attack carbon while that phosphorus and oxygen really want this pair of electrons here and so they're simply going to take it and I've
got 2 choices for hydrologists this reaction that I can make the electrons from appeal double
bond or I can get the electrons to to the oxygen and of resonant structure for that meant simply going to draw the residents structure so here's mine but unusual intermediate here good use my mind is in use my Plus and so now to finish up this this stage of the process what I need to do with need to stick a proton on all miners using acid and then pluck a proton off phosphorus and not going to draw those those 2 steps will draw the 1st step here so I think he conceded that the idea that it can use a minus and so just do this 3 more times and that's what allows you to farm Carter ran out of room there and that's what allows you to replace on those all wages on your alcohol would be art groups to look at what we're doing this was the key
step right here the fact that bromide came in indigenous into reaction in order to pop off a species that had this
sort of found phosgene oxide character and don't freak out over the 5 bonds to Foster's that pentavalent of let me give you a name here so we know how to describe this ,comma fast rain the call possible rain intermediate trade all by pyramidal 5 bonds phosphorus on this architecture he drew intermediate when you when you substitute Esther derivatives of carboxyl gasses it was the 1st of 4 . 4 4 points in the form of expression of the will of the people who will be have begin 1 extend this idea that when you have phosphorus with long appears be impregnated
cancel Sokolov phosphide it's not PBR 3 but phosphorus but with some bonds
on there and 1 as a head like to talk about themselves some patterns of substitution I want you to compare just mentally don't please don't write this down because I'm assuming that this is stuff that you already know where if you don't know this season to which of these is easier to attack with Allcock said yesterday ether the Hester there is no reaction where you can substitute or abide by having this is very easy to attack a carbon Hill if his idol known anyway to get hydroxide online to attack and he threw in units into reaction OK but now it's talk about phosphorus because I want to urge you not to extend what you already know about carbon to phosphorus could because it's not the
same as the struggle little table here but only was I'm drawing off past tester instead of a carboxyl against must try
to imagine the reaction of these 2 different species of past fate Esther verses of past fight Esther with nuclear files and so were the relative rates of hydrolysis of phosphate 2 verses of frostbite armed with hydroxide online look the relative rates it exactly that's not exactly opposite it's Tom Brady chanting you can't even imagine attacking Anita oxygen with phosphorus a thousand times faster rates of attack and substitution at passers-by it's less reactive when there's an oxygen atom on top of it and if that is in any way hard for you to understand that good draw this resident structure so you can see that there's no minus
right next door that's already donating the fastest now you can imagine what I it's hard for hydroxide unite to attack of faster but switch over to an acid
catalyze reactions was lead acid to catalyze the hydrolysis of these 2 esters of phosphate ester reverses a phosphate the phosphate esters still loser here that's still the least reacted these spares if you want to make phosphorus oxygen bond you should use firefights and the relative rate differences now but also of extended his 12th of the small matter of the right the right numbers euros you get the idea is Wayne Wayne Wayne more reactive to substitute this under acidic conditions I just showed you why that's true I just showed why and so much faster when you probe made of phosphorus lone-parent fast by it makes its Super Duper Deuba Dupre fast track at that fossil feces and
you can't do that with a phosphate ester pro making this is still a lone pairs on an oxygenated only OK so far sites are very
fast to exchange and they give you 1 example of a of a reminder of how difficult it is to to substitute phosphate esters where phosphate esters substitute quickly so if you if you look at the rates on you look at the hydrolysis of try methyl phosphate and without Cox side was rated you the typical mechanism that you draw looks like this and you kick the electrons of of up to the oxygen all minus the land up with this pentavalent phosphorus intermediate on 50 per cent 8 Of the
substitution that takes this down 2 To the product in this case I guess I
should say should have hydroxide and nine-year apologized analyzes know we have a product would be so this would be the product 50 per cent of the product we attack trainable phosphate but with hydroxide and comes from attacked at Cardiff favored his soul plots to attack at phosphorus you start to see attack at Cardiff this is how it making sultanate Esther the reasoning makes all the ministers is not because you want to attack at Salford's because he wanted U.S. into reactions occurred so the same idea with phosphates which is very hard to attack here at this phosphorus fastest so if you're clever and you want to make faster Sarksyan bonds you should use falsified it's not phosphates and but all of the 4 . 4 4
but for all of the people of this what they do and modern DNA synthesis they don't use phosphates these falsified on a typical phosphorus oxygen coupling reaction is going to be a picture of my DNA strand and suppose I wanted that 1 when I'm doing a chemical synthesis of DNA are making the victim 50 Maris 60 merit and I'm now waiting on my 50th subunit on subunits that you use the reagents using deep in modern DNA synthesis are basically thought of individuals isopropyl correctly asserted isopropyl amenable are basically I don't you worry about what the protecting group is on that oxygen so this is a
subunit used for DNA synthesis it's called of passed parameter and there's a good trial a trifle methyl group theory
take off with innocent 1 reaction and your other substitutions on your DNA-based that some sort of based there 3 of the 4 bases need protection on there so when Wannamaker phosphorus oxygen bonded DNA synthesis you don't make phosphate esters initially you know that's what you want the phosphate esters connecting the you have what you do is you take this spot remote region and you rely on the fact that if you put in an acid it's now very fast for calls to attack that and substitute and in this case they substitute the nitrogen the super-secret Aceves called Tetris all you need to know that the bottom line is there an accident that accelerates the rate of oxygen nitrogen substitution and when I control the whole mechanism because they can be more complex structures all can also substitute the nitrogen don't worry about that the bottom line is indeed a synthesis of
minute-long reaction scales was the last time you did reaction took 1 minute or
less for and and now it doesn't work like that typically would DNA synthesis it's so optimized its so fastest substituted failing take off that that plus charge there but this is the way you make losses oxygen bonds in DNA synthesis these fast right now nobody wants to make Polly phosphide that those bonded also sensitive to acid catalyzed substitution you gotta get rid of this so what you doing DNA synthesis is you oxidized this now and the region combination that uses iodine in water and that converts and its super fast it's not it's not the same mechanism is this other 1 will talk about this but it is super fast to oxidize fast
fights and Fosse's fasting oxides and how well those bonds are stable right we do this initial Esther
exchange under acid catalyzed conditions with a past but then when you want stabilize bonds you convert that to a phosphate and all those bonds will sit through round after round of DNA synthesis and be perfectly stable so this is this is modern DNA synthesis that takes advantage of the rapidity a fast Lancaster exchange what about phosphates and Thorstein oxides in the field of advice and the I think the but the from the woman that was for the good of the all
"quotation mark about many many
many reactions in organic synthesis are driven by the formation of phosphorus oxygen bonds for these things that we call another toward white-collar sweatshop call that of Foster's oxygen double bond was not so clear it's not so clear how I should draw this this is just like a oxygen double bond is another resonance structure that I can draw in which all bring these electrons of the more Elektra negative oxygen atom and I control this he like structure with people so minus what you'll find is that I don't like this and everybody else was like this because we're too darn lazy to draw like this there is no time ever in which he did it helps to predict reactivity by growing like
you always can predict reacted by going like this just becomes burdensome to draw these charges around so because I'm lazy and
because I always think of it like this I continue to grow like this but I would urge you to draw like way because that way you're ready to use the old minus the nuclear file when need to 4 ready to rationalize why things will attack phosphorus OK so it is very facile to to oxidize when you leave tryout fast being exposed to air and they oxidize very rapidly so if you open the top off your tribunal fast bottle tribunal fostering you can expect it to be very rapidly oxidizing the philosophy the philosophy in oxide so it in the case of Troutville fasting is and this kind of correlates with basis city Alltel fast beans or more reactive than tribunal toward acids the more basic and they also attacked oxygen faster so tribunal Feinstein oxidises very fast
on and very reactive whereas trade some of us even tho you can open a bottle of walk over to the balance kind of
literally school belittled it out putting your reaction and you don't have to worry about all getting converted the fast enough so OK so it's very feminine manically favorable reviews media some on some bond energies here in many many reactions you'll break bonds to things like carbon and oxygen monitors reminders about 90 k cal from bonds and so if you can break bonds between carbon and oxygen and replace them with bonds between phosphorus and action and doesn't matter how I draw that doesn't matter whether all these people as reminders that bond with draw people also miners repeatable Bondo is energetically very favorable 137 K Kallstrom more and for the tribunal on 128 giggles from all
I'm positive I have these reversed that happened and that's what's in my notes I'll fix the
notes later have but I'm super positive that I reversed those in my notes they have drawn here the bottom line is this her very much more favorable than any bond between oxygen and carbon and you will find in many many reactions where you see people dumping tried Botstein they're trying to strip off an oxygen from carbon and end up with this that provides a huge Chernomyrdin and driving force has comeback enjoyed a mechanism for the cyanide oxidation and because this transformation is driven by the formation of this little if you want to call it a double bond that appeal double that is less than 50 per cent CPI character between the peony and it's kind of like a sulfur oxygen double what is it really a double bond there's not much Pike this would drop this mechanism for iodine oxidation if you're
staying philosophies on on your Teal c played by dipping it in iodine chamber this is this is what's
going on but the so iodine in the presence of of fasting you should expect that that longer fasting on Foster's will very quickly displays that and will give you this fast only an intermediate fall are here all of it is a matter where the origin of cops grew outfielder fennel and I have discussed only in it's easy for things to attack things like water but the water present it adds opposite the most electric negative group that steer electronic preference to give you a tribunal by pyramidal fostering intermediate but I don't want to show the deprivation of the water that comes after the attack of thinking guys get the idea that that after I attack with water ethical the
Clinton I've got this fostering exposing or just do a good job of going now now I make
something leave and the leading group believes that as desired died I of cancer the intermediate that you get what we want to do that it looks like this and now all I have to do is remove the proton and I could see how I generate of pw bond if that's the resident structural and to draw you can see how a generation pw bond so in DNA synthesis is what you're doing you're just treating your phosphate ester with iodine and water and you end up with a phosphate esters very stable if you ever wanted to convert all of phosgene an organic reaction to a fasting outside you could use the antioxidant you want and it will make a passing outside and PDA hydrogen peroxide may be less control men refused to
wear through the reaction on and nobody does it that way but still busses long attack things
that's the basic idea consulates talk about that more explicitly In a classical very old reactions I sure dates that dates back to the early 19 hundreds maybe 1800's don't know the cold are boots off reaction more specifically this is called the Micaela service off reaction but it's not really important if so the dig up fast might like this try light would be a good 1 for this and you mix that with an Hale lied about people who who be running innocent to reactions there is no really
acidic protons here but a good electrified bet that non-binding lone pair were below 1 phosphorus is
very big and very nucleophilic overlap with singing star here to essentially action and intermediate that you get 1 of these boxing I'm going to draw with all the bonds there could be people who will so the intermediate did you get now has this on this fast phoneme sold there and I'm going to take my brewing counter and move it to the other side so I can see how ready it to clear that carbon-oxygen bond right who wants to generate a P double bond Lodi pond here there's a huge driving force and kinetically that's very fast well still have to heat the action substantially but I thought wanna say that fast that's the slow step right there it is clear that carbon Oxman but
ultimately what you get out of this this is a fascinating and this is what
use for a like reaction was a little bit of a actions but you can use this for all the nations in the global Horner Wadsworth Emmons authorization procedure and you make these reagents for uh these reagents for Warner Wadsworth women's reactions on using his Abu Sayyaf article reaction this this particular type of species where there's 1 carbon phosphorus it is like a phosphate ester worries of Bronstein oxide What is that we call this a fast bowler that owns that sound tells me fast-food meet Esther tells me that there is a common oxygen sorry carbon fast response it's not just the phosphate ester Fossett has 3 all Cox agreed on this so fast from investors OK so I'm just trying to play up all the it's so hard the
phosphorus the last oxides on it is
hard at the phosphate and install show you something ironic that maybe is maybe is not so ironic and that is that you can have a phosphorus firebox phosphorus species the attack very easily here's the reagent it's very fast Everybody calls the sparkle 3 by phosphorus oxen chloride and this is not like a regular phosphate ester with some of the this screening not reacted images of the show you where let me just remind you why this should be so reactive typically make up phosphate ester like this there is some donations not great but there some donation between along piers in the phosphorus many hard for other nuclear files to
attack if you're coming along with your lame pathetic alone there there's already 3 reports that alone donating in their carried away your
way and that we come back Foster's Oxy chloride and I'll try exaggerate this OK yeah others things along pairs of the Bills home away away away away from the phosphorus according to elect a negative but there those Lombard and not really deactivating the phosphorus is extremely reactive is nothing like a regular phosphate ester in terms of reactivity there is a difficult place where you take advantage of the Super Duper Elektra Felicity of that phosphorus in particle 3 on the the so you're not a type of electrical again aromatic substitution ,comma deals my reaction so I hope you're familiar with some sort of lecture villager Maddox substitution reaction "quotation mark Friedel crafts a Salesian begin at a steel groups that benzene rings but there's 1 particularly a steel group that you can't added that the formal group for you haven't held that where you creating a wild-eyed and the way you do that fill you affected all my reaction you don't use aluminum tried for his typical field craft regions this this is called the bill's married because it's the key intermediate this reaction if you want and now the hard carbon carbon bonds to this benzene ring this is the the region procurement so does electrical look aromatic substitution I'm not going to draw the mechanism for elective look aromatic substitution from I expect you guys to know that in the end is not the end result but before you work this up to you now substituted within a gender-bending ring it's gone spin-off sale as a byproduct senior and you don't make another hide initially you make this and many but I don't know anybody who works to keeps
that you always work that up with water and idolizes the Yemenia mind so this is the way you
et al the heights to aromatic rings using Elektra filler charismatic substitution is the bill's Meyer Hough reaction toward you get this quarrel in many instances that's not just a regular Romania miners and leaving groups attached to that of many among the way you get it is you mix POC 3 cockles 3 with Indiana and that's typically used as a solvent for the reaction let's talk about the Woodstock about the reaction of PUC all 3 living and phosphorus Oxy chloride is so reactive that the lone pairs on attack laughter
from the point of it all of a sudden decline with
mariachi music dinner as as a common solid for organic synthesis is take your part museum avatars of dumping of POC all 3 closely chloride with their distinctive job going OK so the lone pairs on the on the very nucleophilic like a reminder for why that's nucleophilic years alone parent nitrogen is donating in for not going to draw that resident resident structure amused take my hero wakes and won't have to many years OK so the longer the oxygen can attack and they attack opposite the most electronic group must select a native groups chlorine not not the oxygen on here is that if you understand the activity that you could draw like this right so was more like a negative 0 within within an ionic charge on it according to Consuela
committed the attack opposite 1 of the 3 clearing the new generate intermediate that looks like
this and this is 1 of 2 possible residents structures that I could draw for if you wanted to draw the double bond 0 you could kick electrons after the oxygen it's the same thing to focus you end up with this prospering intermediate this pentavalent fostering intermediate Antonello pop off 1 of the leading groups and there's another resident structure you could have drawn from that hammered if you wanted that would be the equivalent of what I'm drawing here and in other chloride ion popped out it is floating around looking for something to do so it shouldn't surprise you that chloride will eventually attacks here at this carbonyl species working many minor resident structural missiles practicing leads to withdraw attacking the car and I don't want to draw the substitution mechanism here but told the court adding we might as well see this coral phosphate leading group ready to leave and as soon as you add on to this species it's how how ready to push out leaving the it's OK to put the cloying goes back right but eventually it's going to push out the coral phosphate Leading group and that gives you your byproduct for this reaction the byproduct for this reaction now has this 0 minus attached to phosphorus which helps to satisfy some of its desire for electrons and other intermediate is this bill's Meyer reagent can go and attack stuff very reactive role married to
I think that it over typically in new at 1 equivalent of this
figure then say you have this floating around in the presence of this that 1 0 minus takes away less reactive but this that the bill's Meyer Hawk reactions and case let's talk more about Lostine outside leverage for now I'm not going to title level simply call this the appellate reaction is a reaction it's useful work for substituting wages with bromides under mild conditions that PTI 3 things nobody uses that typical organic chemistry labs is the color reaction because it's true mild and the regions that used for the Intel reaction Bromo form and I'm going to draw up a sorry carbon capture bromide and I'm not going to draw carbon interim I like this I'm going to draw 1 of those carbon bromine bonds you can see that we're going to break that right off the bat and we throw in the tribunal last season without and that's the magic system and a thousand years In a million years I don't think you could have guessed what's going to happen there were no attack has no substitutions like this I know you want to attack carbon you want to attack carbon so badly that's a logical everything you've ever done is attacking carbon and making bromide actors leading Group and it doesn't do that that may exist who would have
thought that but that's not the online bustling that's the hardest
part about getting a mechanism might Filippelli action is remembering to attack the bromine and no don't attack the card value that is basic this is the kind you can base from Brummel once you've got this basic and I am here and I will very quickly the probe made in order to give you Bromo form byproduct ,comma chloroform that use for a solvent this is called form animal invented that being back in the 1800's but that's what it's called and said Now you got this Alcock C-minus species I knew the fast phoneme plus species and so caustically react with each other the bothers me that I'm not showing
the oxygen attacking from the back side of the world but whatever the Soviet proximal will attack opposite the broom as you get this
past Vereen intermediate pentavalent phosphorus it's OK no charge on 5 monster phosphorus so you can kind of see what's going to happen here we've got this great Leading Group now that's bromide it's going to leave and once the bromide leads it's ready to come back in an attack something so when the bromide leaves we now have you can see the fasting oxide component of this reaction just ready to take off it is that's what happens when you inject a bromide it yeah means that it is what it did in the last year in gold nor did not mean to do that kind of thinking I don't know what whatever sorry it sickens me that I did that too look at there's the bromide and iron them out just come right in and did you already could make appealed along you want that's the thing that's what leads to the phosgene oxide but will give you a product where you know substituted the alcohol and your byproduct as in most tribes of Osteen reactions instructional fasting oxide sets apart the mitten overreaction does something very similar them it's an overreaction generates a leading group like this and it's an overreaction carboxyl late and I displayed 6 and I'm not going to talk about them it's not reaction not really important OK got just a couple of minutes here so To me finish up by talking about the degree action I expect
that most of you in the I expect you covers the village reactions on 1 it will just remind you of what that's all about the soldiers
supposing that some Geraldo died and what you do with all the hides in a deuce you're buying anywhere else if make them you attack them with things and 1 powerful way to attack them as a way that makes of double bonds so if you take is the degree agent about a trifle Boston with phosphorus with 3 final groups so there's not buying bonds the fastest women the draw of more explicitly just you can see we've got 5 bonds to phosphorus that's OK phosphate esters that bypassed the phosphorus and that your reagent when you mix in this meeting
reagents this fast this past willy-nilly species of it allows you to make
carbon-carbon double bonds and the byproduct for this reaction as you might expect to strengthen fasting on the side of the huge driving force for 4 generations of byproduct into it's good talk about the mechanism for the I'm going to draw a resonant structure for those in which I give the electrons to carbon for drove his residence structure here this because I call it a fast Millard 1 why call anyway because I think of it like this I think it's like a Caribbean island that stabilized pioneer neighboring forcefully in group and so when you put this in the presence of oxygen of carbon compounds particularly allies in the tournament's history Mosul reacted and this ends up doing on the a reaction that looks like this will talk about the transition state prison just a moment
new put a prime years they don't
have the same labels because of an amendment might bother you to have the bonds depositors don't be bothered by that that's OK they did not trying to isolate this nothing it's stable but there's no problem having intermediates with buy bonds to foster fostering like that then I get to choose our hypothesis group off I'm going to do it so makes appeal double bond directly but you could simply give the electrons oxygen at people's this and so this is what allows you to make these stew products here and I don't talk about this step right here in were arguments through the decades about is this really concerted there earlier to question reaction like this was finally resolved some that initial calculations In the children yes there is concern if you look at the
transition state for but for this varied reactions to the
transition state looks like this in the transition state you got this nucleophilic species here with this carbon out the fossil you coming very close to the Allied and as he gets closer and closer and closer and closer and closer and you start to attack and build up negative charge you this oxygen and negative tone charge starts to come back in an attack sat on the phosphorus at the same time is not equal In the transition state you go about 44 per cent of the carbon-carbon bond here but in that same transition state there's only 1 per cent of appeal it's not equal by the time you're over the energetic ,comma you're starting to form a little bit of a bond here but not a lot of that important even at 1 per
cent means that you are not going through a transition state that looks like this the fact that 1 per cent bonds says the transition state does not look like this the trend is a does
not look like a simply when drove Delta miners and Delta plus the transition state does not look like this carbon simply attacking and this is freely floating around there's partial bombing so you should draw this is a concerted or call that a 2 plus 2 reactions so it's not what we call parasite but it is considered that you will be taken to a to talk about the size reactions OK that's only talk about how you make these illiterate agents if you know if you don't remember that so you use fast feeders nuclear files tried fasting is not great just like it's not a great base but if you them enough for the overreacted enough electrify also and you can do as into reactions so in this reaction it takes 2 days at room temperature so as not to try
Belfast is nowhere near as good focus the tryout alkyl philosophies and the reason you want fennel along here is because as
long as you've got panels that means there's only 1 group that can be the probated and that's the method you tribunal passing another hole where are you going to do about it and if there's 3 alkyl groups on and now you need a very very very strong base to pull a proton awful fast on himself so a ones just straight lithium and I know maybe you're going to want to say we tried to attack the phosphorus would be local lithium but that's not what happens it's faster for the alkalinity into the program and so that's how you make elected U.S. into reactions to make possible insult and then in the 2nd set you super-powerful bases to particles protons off and that's what you throw in with your held up against that's it for a prosperous chemistry and that's it tells you if there is a discussion section tonight at 5 o'clock on its optional Europe the accompanied like you to be there will over some of this phosphorus and sulfur chemistry and examines it's good for me now is that in this room we will close the today we offer all the problems that led to their hands and like these lectures on online we


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