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Lecture 13. (Pt. III) Addition to Pi Star (π*)

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they we're going to try to finish up what additions to pies
.period politicians to cover news today and so forth but I think of pies star I always think of carbon heels that's sort of the classical funk precede bond formation but when we left off we were talking about the equilibrium constants for additional of water reversible additional water to various different Ronaldo hiding key tones and some want to talk about kinetic rates of edition that the equilibrium for finalization arms but that the rates of addition to these various during term compounds it'll give us a chance to look at the effects of rings and rings sighs on I'm going to give you a set of relative rates for reaction of sodium lauryl hydride it's kind of a prototypical nucleophile on certain and ionic character to it's the and I'm going to sign just a simple a sacred the tone acetone to a relative rate once we can compare everything to ascertain so this be true friendly a psychic who found which interesting here is that cycle hacks and on which pretty common substrate reacts about 10 times faster than any sector In a looks pretty similar to me it's not a steric effects I don't think you could argue that this is less interested in acetone and so what's going on here which is 10 times faster cycle tender notice pretty similar it's a little bit slower I don't think that affected that meaningful what's important is the comparison between cycle of exon Armbruster said sentence that's the kind of affected you can take advantage of when you're doing a selective reduction of out of 1 of 2 key towns in a molecule and then of course if you get 2 or more strained system this is not happy on this is even a little bit more for fastened cycle accident so when we compare the so OK there's some differences here I don't wanna get too caught up in these differences are if you compare this to the difference in reactivity to an the like bends outside that's a pretty common allied you get a real sense for a difference in the rate this is 12 thousand times so far faster than those so so I'm going to pop a little bit on this tiny difference here we try to keep it in perspective right out the height and weight more reactive than any he told us we're talking about here so I don't slayings difference for
cyclists and rights so Aleksandras is not less hinder this morning by any sort of measurement you could use what you have to do to understand the
reaction of cycle owners in the transition state as your nucleophile comes in and doesn't matter whether it's coming in axial or equatorial as your nucleophile comes in into to cycle accent known here starting to go on sp 3 hybridized here and let me help you see that there art eclipsing interactions here in cycle excellent only by draw out the substituent at the outcome position these protons these bonds right here the clips with the CEO and that's not good that destabilizes the cycle accent on grounds it because this carbon Hill because this is their speed to hybridize this comedy was stuck sort of in the same plane is the CH bonds and as you go in the transition state toward something that's more territory the like you relieved that eclipsing interaction now
if I stood down this right here with my eyeball and I looked down bond would find perfect eclipsed
anything drawn on good chair with say with cycle hexane isn't all that excellent Equatorial substitutes correctly you can see that there is perfect so perfect bond staggering not perfect eclipsing the perfect bonds staggering here that this ch bond is now not overlapping directly with either of these 2 lines so you will leave this eclipsing interaction on display here this is eclipsing in it's bad and with cycle accident by adding to cycle Hixson on you really need the eclipsing you really that eclipsing interaction and not just in the product that in the transition state leading the product now and we come over to 205 member grain right there's there's multiple different conformations for a five-member range that you can drop of confirmations from five-member range where you can get around that eclipsing you've got 1
eclipsing interaction is no waiting you'll have at least 1 eclipsing interaction but over here this
carbonyl can buy set these 2 CH bonds to really only have 1 eclipsing interaction on the right 1 eclipsing here and that's because this ch bond is in the same claim that these 2 H bonds are not on the same plane is the copying of CDs have worried that eclipsing election right here between this and between Karniol between the CH bond and that equity bond when I come over and dropped from the products for that reduction the high-grade reduction now I do have eclipsing interactions and so you can see why for this motorcycle Penta known and that's a little bit slow unit will leave at about the same as acute as a regular recycling he told you didn't significantly relieve eclipsing interactions by adding the cycle painted so sold eclipsing destabilizes away it hurts cycle excellent makes it a little bit reactive and these differences between 5 and 6 member she told you can take advantage of those when you're doing so this when you're trying to selectively at nuclear files focus analysis switching gears from just plain key and let's compare them to other types of Chrysler's groups for the 1st time since but but but but but but but but it was 1st some anti-drug 2 different types of part of the polar double bonds Florida London Amien Rais is a key town which of those do you expect to be more reactive to its nuclear files I would
expect the carbon Hill the CEO pipeline to be more active oxygen is more
elected negative and nitrogen and respected the lower the energy of the loom lows by replacing codified Carbonera place with oxygen respect all those orbitals to drop more than if I replaced it with nitrogen so I would expect there to be more reactive so look at reactivity I would expect nuclear files to react with this because oxygen is more Elektra negative in nitrogen but compare that I can take up a similar sort of analysis and applied to the positively charged species so if I compare Knox Sonia mine on so that's oxygen with 3 bonds that could be appropriated ,comma 1st appropriated in mean I expect the same trend of whole oxygen is more lecturer negative and nitrogen I expected to be easier to add to appropriated oxygen then to
appropriated and 2 but what you can't possibly know is the comparison between these 2
what happens if you compare just a simple plea tone verses and many online you couldn't know that right 1 of them is charged but it's nitrogen nitrogen as a selector negative but what about when output of formal positive job on there and salt illustrated this is an important relationship you notice that and many of my rounds on more reactive than the there more reacting each you couldn't know that you couldn't know where there is more important than its nitrogen right nitrogen over years was selected negative or the positive charge makes monitored so remember there's always been a minds more reactive Quito here's you take advantage of that fact of giving an example Australia something called a porch reduction thank you for the good of the people who work with at portrait action is based on this reagent there's other regions that you can use for this if he takes sodium cyanide he takes only moral high during your place 1 of the hydro groups with an electron withdrawing group makes it very choosy so here's somebody went and took Boraine added cyanide so now that electron withdrawing Soriano group on their this region becomes very choosy I'm not as Belgians-he operating in there you get the idea it's choosing now that's ironworkers electron drawing so if you take enemy who plan you mix that with a key under the porch reductive amination emissions in use this kind of choosy reagent final Boro drive and it's commonly drawn like this another carbons attached to walk on the way and these would be
typical conditions aqueous methanol 5 that's
acidic conditions you run this under acidic conditions it works best if you rented under considered conditions that adult if you will allow the conditions of it to become basic is the reaction proceeds which is what happens when you get bird that doesn't work very well but as long as control the pH and keep it slightly acidic you'll get good land but we'll get it on good formation of the amid this is called a reductive amination reaction to what's going on here that's going on is that your forming many minor finally dropped the equilibrium more appropriately you don't have to generate a lot of the many man and you just have to generate a little bit of many a minor even the tiniest amount of many mile so the byproduct of this equilibrium water this is a five-step mechanism I'm not going to drop all 5 steps for any plans for a minimum my information I expect you to know that we talked about that and discussion section I think in our 1st discussion section and that's 1 of the fundamental mechanisms that you need to know so who cares it's 5 steps they're all fast when ever under acidic conditions not too acidic not in hydrochloric acid whenever you make some easing the town's people equilibrium mountains of the many minds and what I just say about the tones verses in many minds what I said is that many minds react faster than so when you put in a choosy reagent like sodium immoral hydride you don't see reduction to make an alcohol this just sits there and assignable lot as collided collided collided never react when Senegal hybrid collides with this in a very quickly reduces this it is all draw that hydride reduction that's fast so reduction of the key owned by Simon Bolivar slow production of the many minds is fast gaining any reaction to any specie anytime you have something you can generate a callable Kanye and that will very quickly be reduced by Sanibel hydride Sanibel right but only reduces things that have positive charge like Koble can say or a medium ions on if you don't been too much acid here but the wages scored in hydrochloric acid you'll start to predict the tone amended the will reduce on so you have to carefully control the pH for those reactions talking many minds react faster keep that in mind but will use that just a little bit the that but they word we're going to take a little experience here would stop talking about the tones and allied ground moment and will start talking about
carboxyl aghast and derivatives that's a bull's-eye take
a comics alike as a derivative is and it's reacting too slowly and so I put a really good leading appear like bromide maybe there Esther was lower the acid chloride was slow the insulin I can rely on my nucleophile coming and displacing this this carbon bromine to make some sort of carboxyl it and I hope you're not drawing a seven-year paper because it's killing me to draw this this is wrong at every single level of detail and from the beginning of class and try to convince you that this is that this is wrong at every level of detail and Sony just remind you it is always easier Dad the pie star write a hydrologist carbon bond breaking at the same time that the nuclear follows adding that the center of the action I just on a century actions if I draw it like this if you do this thing
you're claiming it's going to rest until whether you drew on the same side of the opposite side you just units into action so it's
never faster in this kind of comparable cases to add to signal it's also faster and apply so emitted from I knew every single time and there is some leading refiner ,comma he'll he yes there is a stigma star orbital it's him on the back side of this ,comma next bonds linearly with sickness stock ,comma sp yeah there's some sort of sickness star orbital back here the nuclear get into that no nuclear whatever do that all nuclear powers will prefer to add to piste soldiers right out High star for this Yuletide that's where you had it is always faster no matter how good you make the leading group that we have simply makes it even faster than the carbonyl livestock so you always get a two-step substitution process through tradition followed
by elimination this is the way carboxyl aghast derivatives always substitute so you go through
a territory Nedrow intermediate that's the territory drew intermediate and it's going to abbreviate that can territory dual intermediate and then the 2nd step you push out the leading group usually the 1st step is the slow step middle the lumbers on the opposite side so I can see it now they're ready to push to Sigma star and break that carbon exports it's in the 2nd step that you can donate and this is start and that's the lone pairs right nearby that are doing so to steps addition elimination and I expect you to know that this already but this is the way carboxyl Gaston acid substitute was not elimination to make CC piled on its elimination a cardinal bond OK so on
so if you if you're not up on medical practice and products like acid substitution reactions like fisheries
verifications and Esther hydrolysis acid catalyzed hydrolysis civilian and still it involves some step that that looks like that the beginning remind you about arms of a problem that often arises when you try to make the town's for Bulls I wanted to convert disaster into a tone by replacing this Smith oxide Leading Group History common functional groups and if I want to convert this into a key town you know and I guess my example here I have found a litany of I'm going to get a poor yield for this reaction that is 100 per cent sure and it's not that vandalism is not about it good enough nuclear it is a great nucleophile and not that of oxide is not enough Leading Group is plenty good to
leave when there is an iMac Alcock said the problem is this that the problem is that the initial additionally draw the bond the little of violence there there are no
problem that that's fast even at low temperature until generate this territory intermediate there's the leading group and then this is going to push that out here that lone pair on the oxygen is very nucleophilic and this can now be pushed out to give you a key and unless I do otherwise that let him still needs to be on that key that don't have it suddenly not there but it's still there from natural however lithium got on there so I made a mistake you mentioned that so I just added my new newfound over the problem with this is not getting them within that the problem is keeping the federal officials from adding a 2nd time this is now more
reactive then the Astor I started with ancestors are less reactive because that donation in the car
he will makes as listed on and when she former Quito made instantly reacts with any leftover from with and the more Quito you generate the fastest on this reacts so what you end up with this double additions and nadir enough reagent 11 left over starting yesterday present as well so it's very hard to stop this little additional withdrawals some synthesis we simply add nuclear power like carbon nuclear files to esters because you can't stop it when edition but there's a trick you can use that's commonly used in the vote it would also but the study a carboxyl gasoline you want to
convert it to a key town without double edition but you do is you convert that come oxalic acid not into Ernesto but it is something called a line reads the image and it's
very specifically This is the end medical and the foxy so this is what you have Al Cuellar the institute so for example if I had not been a lithium to this In generated a attacked Friedel intermediate is my fellow Group but then again it's the same initial step here I had the pie star and now I've got this species in here that has this month boxy group used 5 out of way from the military this alone burn oxygen is poised to donate into this and former stable he later that late now you just make this a generic here and the latest stable it doesn't fall apart to regenerate a super-duper reactivity tell that just sits
there until you're ready to work it out so it was like this is not going draw the
bonding here but that's stable this territory the intermediate could you get a stable solid stable country to Lincoln and then upon work up it sounds absurd Locklear solution the whole contraption decomposes in falls apart to generate the key town "quotation mark this this so this is work up here World Cup and so if you wanna stop at the key town in October edition use wine examined because it creates this stable contact tracing intermediate OK so let's wouldn't talk about making carboxyl gas and so this is a way to make
carboxyl to me comics alike acid derivatives kind of innocence less reactive toward substitution because you slow down the elimination step and so what do you do if
you want to accelerate the additions stepped to the carboxyl gasses during and I want to ponder a fundamental question because 1 of the most reactive types of carboxyl Aghazadeh derivatives and you should know about our acid chloride is an used so you should know that you can take a carboxyl gasoline treated with vinyl chloride is so seal to and making acid chloride but if you don't remember that all dried out for him what the that's money the Caleta money reaction works every time
and the super reactive 1 a comparison mom someone a comparison acid alliance with of some of the so we can talk about the
relative rates of reactivity what you find is that if you look in organic synthesis is you don't use these with equal frequency he's acid chloride 1 of the last time you saw somebody acid Brown line or when was the last time you saw somebody making acid fluoride you unit you can find cases but is very rare for legal and talk about the water of reactivity we tested bromides more reactive in fact here to active make acid bromides try to store them the slightest bit of water and it's gone so that's very inconvenient acid fluorides away to 1 reactor while you go through the trouble of making an acid realize it's not going to be very reactive so I want talk about this ordering the reactivity he said terms of the nascent courts at just the right balance of the really reactive as Florida is not on this not so reactive that just falls apart when you put it in the bottle and next week to come back and half of its decomposed focus on come back and talk about this sort of relationship which I know why is it that acid fluoride is so much less reactive enhancing clause you can't explain that with elected negativity chlorine is way more electoral negative and carbon this is laid out the Electra negativity of selector negativity of foreigners for that's on standard elected most electronic and Adam in the periodic table of chlorine when you drop down a row and apparent table is only 3 . 2 so it's not as electorally and when you get to bromine that the drop is
not his doing but it's it's even less Elektra negative thing .period
iodine has about the same Elektra negativity not even talking about a slider that would be crazy reacted on the belt has about the same Elektra negativity escorted OK so they couldn't otherwise it's not because of elected negativity can you predict the acid fluoride would have would make nuclear falls under the coming faster and so wise to what I wanted was a 1 look at the carbon halogen lengths in these compounds because that's the secret understanding this water of reactivity it's not the Electra negativity so they come overnight drawl the acid chloride like this and I look at the bond lengths and acid Floyd fluorine is the 2nd row out just like carbon is like oxygen just like nitrogen has got a very typical or maybe a little bit shorter on but it's got a nice kind of secondary role like that carbon fluorine and so in
comparison of acid floor of acid chloride that's
the secret understanding why has a clear idea so we have I'm hugely exaggerating because I worry that if I don't exaggerate what remember someone to exaggerate their and our communities and draw the acid bromide and it's not as bright and not really exaggerating and it's it's over exaggeration but that's why there's this difference has to do with bond lengths when you drop down from the 2nd row with carbon nitrogen oxide referring to the standards of 3rd World 4th World the periodic table you end up with longer bonds and what that bond length effects is it affects the ability of these electrons to donate back in the piste now what is
misshapen huge orbitals on carbon chlorine so big and so far away you don't get effective overlap
Back in the ,comma and it's that overlap it's the donation into the carbon deal that makes this colony less reactive that's why esters are less reactive than the so this animates acid Florida will flooring Silber electromagnet that's helping but you're screwing up those reactivity by having a lone pairs only back in you don't get that really with Corena modern with the Goldmans forget that so those to all you have is the bill's played electric utility was bloodiest ready convince you hear that his donation of fluorine is important because it may not be so obvious to you so that what some evidence that this is an important feature that right about that a hair here if you're a nucleophile trying collide with the current number of hiring a company with a long that always right there and to compete with that you
might say Well I don't like that plus
in that residents structure but they show you a little comparison here that I hope you understand this balance between the fact OK flooring his electoral negative and should make it more positive here on carbon fluorides elected negative dealt a minor stroke plus if I were a self-respecting nucleophile and then not negative charge I would definitely want to attack that Kerviel except for the longer flooring getting in the way so treading get straight the effects of flooring this contrasting effective elected negativity which makes them more reactive verses donation which makes that less reactive and can put it into perspective I manage dropped 3 different can irons for you and I feel like I've shown you part of this comparison before on bullets imagine of fluorine substituted
Koble can what's the effect of flooring you know that .period Electra negative that I had a really hurt by intellect a negative ouch is cobbled
can with a positive charge it turns out that a flooring substituted arms giving you relative stability of these Carmel Hanna as a flooring substituted cobbled Caroline is more stable than 1 that has no flooring on them so yes flooring is Electra negative yes OK but it's still so good to have this donation the overall it's better to have a warning on travel cannot even knows .period electric negative that donations so stabilizing it overcomes that you couldn't have known that you couldn't have known that the donation was more important in stabilizing than the elected negativity is destabilizing says 1 time and I expect you to remember that if you put 2 floorings on it's
even better it was touch even better but
I don't have 1 year in something that I just happen to know that it is a Taepodong three-floor rains and I don't know what I don't know is where it falls in the sort of 3 forums is worse the 3rd foreign doesn't help you Bond denies this this 1 falls somewhere in this region 3rd flooring doesn't help you just get the lecturer negatively affect soul of this series this is the most stable and this try floral compounds falls somewhere between the way to think about is it's is that while you can only have so many flooring is donating in that horrible and I'm at the same time the 3rd one's kind like others nowhere left for me to donate and as a sort of descriptive way to think about that if you really want to on all this good news is that
OK so I to Florence of flooring his Electra negative yes but the long present foreign condoning attempted to remember 2
it and is just this it was the best schools some going to show you a special type of algal condensation called the the opening condensation that very common way to make making the known derivatives on animals taking allied with a 1 3 die carbonyl compounds so I'll show you 1 of the most common ones that Sollecito acetate so you know that the probe I hope you know that the protons between the 2 carbon heels acidic and so you had some sort of us secondary Amin based in
this way but was and don't worry
about the easy I'm not trying to make any comment about the stairs selectively get a mixture of the appointed as a dozen conversation makes the UCC double bond reaction if you go back and look at all the nominated goal conversations almost always using paper again or die at the Lummi not try Colombian died at the landing not tertiary and secondary means every time and there's another weird thing about no enable conversations usually add acid in what's that about right if the mechanism is simply to have debated the pros made here wire they adding acid in the reaction that can't possibly help that the nation they can't possibly increase the amount of the elite this president and this is a classical recipe for a noble nuclear condensation and 90 per cent of all cases
what's going on here is not what you think it's the best Amin is not simply in there
formulate the point of the on the acid is to make the Yemeni and I'm going to draw all the talk of the town ,comma In all ,comma of this so the ideal conditions for old conversation or not basic they're actually just slightly acidic a little below pH 7 under those conditions you have this silver Dupre reacted to minimize many alliance or way more reactivity tones this is a classical Nagle concentration if it when you draw I'm not going to drop the mechanism there's a five-step mechanism to show how you get from an allied with many mine I expect you to know that farm that
mechanism for any my information so when this adds no Myrna a talk a lot
about you as nuclear falls later so I'm not going to draw the deprivation step I just wanted to get to this stage here where we this is what we all so you get to the stage where you have this intermediate and long Justin affair which staff should I show you so in this particular case you'll have this Our group on here and you have the means and Somalia set up to do an elimination reactions this is going to be the 1 CB type elimination hearing and approximating this under the slightly acidic conditions of the reaction and only draw this intermediate or otherwise of just be talking in total abstraction so you can't claim that it's hard to form and all
because we started off on mechanism not so wrong that this nucleophilic in all and we said that the conditions are slightly acidic so it makes total
sense that we're going to have some of this paper biennium Group on there and so this nucleophilic prices this here if he all was simply push out believing that and that's what leads to the final known this proud so all the steps are faster this simple mechanism that you might think of a meter deep probe make this and make a late and having late added the elder and it wasn't until people study the mechanism as they realize these are all going through many online this isn't the the power of the many online chemistry OK very powerful stuff that dates back the state back to the 1940's and 1950's these reactor no 1 eagle reaction it's a very powerful and general Sisi bond forming reaction and there's tremendous insight in this idea that in many of my arms are way more reactive
in Quito for many mines are yet more reactive than carbon
is Sony so let me just proved to be clear about what's going on here is if you look at the relative molecular orbitals energies for 5 stars for a carbon he'll it up I star and many my hand is some nitrogen is not elected negative as oxygen when it's a positively charged nitrogen then that orbital is even lower in energy it's on that that making that work so it was who this stuff was sitting in
the literature at 450 years until Dave
McMillen realize what she maniac news that further reactions was overtaken 202 will talk about the parasite quick reactions like the deals the reaction on 1 of the 1st things you learn about the deal all the reaction is they work better when there's a carbon Hill on the dying file and the reason why cover heels make this passes because it lowers the loomed energy for the EU for this double bonds and other words the way they think about a deal reaction as you think about the dying is the nucleophile attacking on the other side is the dying attacking the diagonal files so if you take this reaction which may not be particularly fast and you add a secondary meaning to this soldiers right catalytic and importantly effects of Cairo Amin there will be this vast equilibrium formation of a small amount of Of this column many and that is now more reactive in deals all the reactions or nucleophilic addition reactions is now more reactive than the starting center Malahide starting material so nuclear powers like the dying will attack that faster and of course this Knox's nuclear phone comes back in ads and ads the mechanism for the parasite quick deals the reaction for plus and this was Cairo you can imagine it will influence which faces this of this dying a file that you had to know that controls the stereo chemistry you couldn't have known you couldn't have guessed that this equilibrium would be so fast this is wise by David McMillan had run the experiment was a graduate student in her apartment that's why he had run the experiment to see is this
faster than the what is that many mind faster than the simple because all the reaction and so in this case it turns out to be faster so the initial product on hazardous
ammonium I'm still on their many mind formation is is reversible draw the year the double bonds down here on this Norborne hearing system and so I made my information is fast and reversible and so you very quickly idolize this and ultimately what you get out of the reaction at the end is not the many minor it's the elder you can't even tell there was ever in many minds in this reaction mixture your only adding a catalytic amount of the so this is fast hydraulic this formation of the Romanian mines in the hydrolysis of Dominion mind is fast under many many different types of reaction conditions so on and so any time you want to make
some sort of an Carbondale group or any known more reactive you can simply throwing a catalytic
secondary since it worked best of the conditions here are not really basic slightly acidic you'll at the fastest rates for condominium information but so that field organic catalysis is what was that 1 simple insight minds of more reactive and on the card but it's a last thing we're going to talk about its conjugate addition reactions in other words when have any known like this you can imagine nucleophile that ignited to the or to this made carbon recognize of the data and so let's talk about that In order to set us up to understand that the distribution of products the reduce likening these reactions there's a couple of pieces of information that we have put together a government assistance and so I wanna talk about 1st top about the effects of conjugation on
reactivity to remind you of something we said already and then I want to talk about the effects of substituting carbon atoms with more Elektra negative Adams at all but I agree
with the move for the Southern remind you of the effective conjugation I'm going to drop some sort of ammo diagram where I want to compare the around the reactor to the energies of the homos in I'm going to start off with ethylene so here's the pie orbital for ethylene it's down here not very nucleophilic 1st pie snobbery Elektra fell like it's never easy so when the throw and I mean it doesn't just attack Ethel it's not a fast reaction I'm if you wanted to add HBO or process that's not overreact about the
fortunately but if I take a tiny but I am conjugation to this and it doesn't matter that is another double just simple than it could be said of of benzene ring that I
attach on the same idea if I had conjugation to address what it does is it Soups up the reactivity of this the nuclear file so Pinal gets higher energy and it makes it easier for nuclear balls to add back to this suitor better electrified soap I gets higher price targets lower that's the effective conjugation the more conjugation you have images of some sort of central line near the more I see the whole raised than the more I see below raised 1 and so we've already talked about that the time of course we'll go out to make this an infinitely long that's molecular wires that was the 2000 Nobel Prize for somebody just extrapolated that to end the
very long lengths and realize that could make molecular wires that that's 1 piece of information I expected in so let's talk about a 2nd effect that's the
idea of replacement so if I take a dying like this and I draw out these orbitals Pine pies star is knowing what would happen if I replaced this Carbonado alright replace with oxygen with not without with With all if I replaced that carbon atom with oxygen and I look at the energy of this this pie warble an elegant dinner Dupuy star the effect of replacing carbon with a more elected negative Adam is that both of these should drop pie should drop I started drop everything to drop Sigma in signal abominable that oxygen snowdrop drop in energy so that's the effective replacements overdraw out but the energies of any known verses and guy eating what I expect is that both of these should
not be lower in energy and you kind of knew that you
kind of know that this is known would be less nucleophilic than dying you kind of knew that you kind of knew the tongue-tied bonds aren't as nucleophilic is CC vitamins unilaterally you kind of knew that it's faster at Aqaba heels and is added to buy bonds you already knew this was going use this stuff unless a case that I think I expect you to know this would you couldn't know is the shape of a five-star and dying from 1 that tell you that but it want 4 of the victims of
somewhat you try to think about what time five-star should look like on the way for a simple
dynamic to draw a simple line like this and in order to make prior piste we have to Image's mixing simply orbitals together so I wanted all imagine looking at some purists top down all you can see the tops of the CPU orbitals and I'm going to start by drawing these people orbitals animal drawings and freezing here and so what I'm interested in is the low if I were to attack a dying the foreign and it had a nuclear files were dying while I expect for the Regio selected it turns out that this is the shape of the rough shape of building overnight these carbon atoms Indians contribute more P orbital character supplies supplies .period voluminous case the two-minute problems do you could not have known that now let me show you how you kind of knew this but you didn't know it so you take a nucleophile and you added the beauty dying where would you add where would you prefer to you already knew that you prefer to to the end and maybe you made up some ridiculous argument at all I want to generate a resident stabilize carbon I'm like that's not why you at the it's not because of spirits the reason why it's faster to at the end of a dying is because the was bigger than if I have a lot of people orbital and try where can I overlap with you overlap better with the hands the cards at the end that's why nuclear files attack dined at the end so I would
need is remembered as do at a five-second calculus of 5 microsecond calculation it will show you the people that the the piste star are on the bigger
audience focus now let's tried to map this picture on top of this picture that I showed you over here for offering you know the school and try to combine those 2 effects yet so I want to try to do is I want to try to draw on edge on depiction and I feel like I'm going to need a new a new board for this moment trying to depict taking this sort of orbital thing into account I want to try to drop I not for a dining but for the moment and we will win so fine a nucleophile and I want to attack need only draw this this edge on here and trying to draw looking sort of it at the site of that for the edge because I want to see the P orbitals now and remember what I told you I told you but the orbitals are bigger audience for a dying and I'll feel like I'm doing this just this year what I'm going to do is I'm going to give you some numbers called coefficients that will more accurately express the sizes of these sold it and about how much Pete character got mixed in with a full P got mixed into make pies here each 1 of these Adams contributed some peace character this carbon atom contributed some of the orbital to make this this piste orbital this carbon atom contributed some simply but how much did they contribute they don't all contribute equally and all we do is we look at the coefficients tell you how big these are In this comes from linear combinations of atomic orbitals LC AO theory might have remembered that the software Ganic fire sigh from from peak and so I draw out the coefficients for this on here's the coefficient of 0 . 6 2 for the carbon at the end here and it's plus soldiers arbitrarily but facing 1 here and then I look at the coefficient for this oral here and it's minus 0 . 4 3 minus I phase at the opposite direction and then I look at this 1 over here to minus . 5 3 is the coefficients size and I look over here in it's plus 0 . 6 0 so I face that the opposite direction so in other words a nucleophile comes in and doesn't want to come in from the side because it doesn't want to have on destructive interaction with this you'll coming from the birdied tangle over here so I got a clear picture here for compounds that have nuclear files that have big occupied orbitals nucleophilic orbitals will tend to want to come in either on the carbon from the oxygen that's what this pictures tell me if charge was a relative it Cologne interactions were totally irrelevant it might be almost equally probable to add to the carbon the oxygen but Cumming interactions are relevant the relic is known nucleophile no good nuclear buzzer partial negative charge they would never went ahead on oxygen so if you pay attention to colonic interactions they'll tell you carbon will sign it he pay attention to the 2 of where price big you'd predict either end but if you pay attention to charge than there's partial positive year partial negative here From OCR much in just a 2nd best so this simple picture of a dying predicts they will react at either end of any known only think about charged it doesn't predict that let's take a look at which charge
predicts renew this comes from calculations of the limo picture tells us 1 thing if I look at that's the
charges recalculations talk to residents structures for any known so 1 resident structure for any known by John this charge separated resonance structure in this reminds began nuclear powers want to attack ,comma unilateral enjoy another residents structure could swing this double bond over unusual or it like this this is a different charged separated structure and both of those resonance structures reported that the resonance structures predict that there will be partial positive charge at the Kerviel comment and partial positive charge the new label these This is the alpha carbon and this is the beta copy of carbon made carbon clumps of colorful ,comma because they will be partial positive charged that the beta
carbon but how much charge it turns out from calculations you can tell that the relative charges are 1 . 2 5 the carbon Neil and only 0 . 2 1 the patent
position there isn't much less partial positive charge at the base of position if you're a nuclear file that has lots of negative charge you're going to tell 1 attacked the carbon if you're nuclear that is a very nucleophilic almost all and you're looking for good overlap you're not going 1 0 attack here even when attacked there Our expectation is a highly charged and ionic nuclear files will tend to attack here where nuclear powers that had been orbitals still models will tend to attack there and this explains the differences in the yeah that's it's really related hard it's really about what
sort to just this this is not so that I don't mind again hard soft doesn't died I don't what intervention
corrections and Colom's equation that's why I break it down to 2 columns lost focus let's go and draw some just drop sort of conclusions here so if you want 1 2 edition would be my champion nuclear files for 1 2 additional if I wanted to add 1 2 at the carbon you so for example something like this if I did not want to added the beta carbon I would want to have something that's supercharged that is all has all the negative charge concentrated in some little .period floor would be a perfect example this is like the naked little pinpointed negative charge if you like you would expect vastly faster rates of additional here with a positive charge is closer to 1 . 2 5 I think I raced there in addition here the Bangkok similar infighting Alcock
side and putting on coordinating poorly coordinating counter Ryanair I would also expect that very naked Alcock and the more
naked the better lithium not-so-good cesium naked said and I fell below 1 2 so you want to make things go 1 2 use things that of all the charge concentrated in a single point so it is this gets closer and closer and closer to the partial father charge Colombo predicted that's going to be an attractive in action now it's contrast so we call this 1 2 edition because we normally label these 1 2 3 4 these are good nite nuclear files for 1 2 edition if you want 1 for addition addition to the beta carbon here would be some great nuclear files it was an e-mail late and more importantly I 1 3 carbon Illinois where the negative charge in this case but it's not on the nucleophilic carbon between way your knees oxygen so now when you
have some sort of collective on this case since there's not a lot of negative charge on the carbon Lemieux put a circle in there it turns out land of attacking 1 4
if I took him he very little negative charge on a nucleophilic carved it turned out that attacks for the medical violate an iron which very big Adam all that negative charges spread all over the place it's not concentrated in the world .period you end up with 1 4 editions the meeting of phosphate again a third-row atoms were you expect vastly faster rates for 1 4 missions over 1 to focus so charged super pinpoint charges like to attack the Kerviel carbon on things without a lot of negative charged him to attack out here on the floor again I think we're done with high stock for now ,comma got problems on the problem said and sorry I went over
Enzymkinetik
Exon
Single electron transfer
Oktanzahl
Kohlenstofffaser
Besprechung/Interview
Chemische Forschung
Wasser
Hydride
Chemische Verbindungen
Computeranimation
Aceton
Sense
Organischer Stoff
Sterische Hinderung
Chemische Bindung
Molekül
Systemische Therapie <Pharmakologie>
Reaktionsführung
Reaktivität
Setzen <Verfahrenstechnik>
Ionische Flüssigkeit
Natrium
Primärer Sektor
Körpergewicht
Chemische Struktur
Chemiestudent
Protonierung
Reaktionsführung
Übergangszustand
Chemische Bindung
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Substituent
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Konformation
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Hexane
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Bukett <Wein>
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Funktionelle Gruppe
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Spezies <Chemie>
Chemische Bindung
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Kohlenstofffaser
Besprechung/Interview
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Orbital
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Natriumcyanid
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Operon
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Substrat <Boden>
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Spezies <Chemie>
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Setzen <Verfahrenstechnik>
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Fülle <Speise>
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d-Orbital
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d-Orbital
Feuer
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Orbital
Konkrement <Innere Medizin>
Chemische Verbindungen
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Konkrement <Innere Medizin>
Tiermodell
CHARGE-Assoziation
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Besprechung/Interview
Stoffpatent
Vorlesung/Konferenz
Base
Orbital
Konkrement <Innere Medizin>
Wassertropfen
Kohlenstofffaser
Besprechung/Interview
Vorlesung/Konferenz
Cäsium
CHARGE-Assoziation
Lithium
Kohlenstofffaser
Besprechung/Interview
Sauerstoffverbindungen
Stockfisch
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Oktanzahl
Phosphate
Sammler <Technik>
Kohlenstofffaser
Besprechung/Interview
Ordnungszahl
Adamantan
Periodate

Metadaten

Formale Metadaten

Titel Lecture 13. (Pt. III) Addition to Pi Star (π*)
Serientitel Chem 201: Organic Reaction Mechanisms I
Teil 17
Anzahl der Teile 26
Autor Vranken, David Van
Lizenz CC-Namensnennung - Weitergabe unter gleichen Bedingungen 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen und nicht-kommerziellen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen und das Werk bzw. diesen Inhalt auch in veränderter Form nur unter den Bedingungen dieser Lizenz weitergeben.
DOI 10.5446/19230
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
Abstract UCI Chem 201 Organic Reaction Mechanisms I (Fall 2012) Lec 13. Organic Reaction Mechanism -- Addition to Pi Star (π*) - Part 3 Instructor: David Van Vranken, Ph.D. Description: 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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