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Lecture 06. Formation of Imines & Enamines from Aldehydes & Ketones.

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Automatisierte Medienanalyse

Erkannte Entitäten
Our itself so I am thinking about where we're
going in the costs here and I'm starting to put together the discussion section problems for next week as well as thinking about what's important in their home appliances of cold reaction mechanisms involving the chemistry of carbon yield compounds and these are really on my mind and I think we're going to be working on them in discussion and I'm going to want you to participate a little
more discussion we're going to get up to the blackboard and put our thoughts and really work together I'm
thinking about these problems alright itself were in the midst of the chemistry of the towns and now the hides and we get a little bit of a basic introduction of their chemistry last time we introduce how we name them we introduce some ideas about reactivity at the carbon group we
talked a little bit about their spectroscopy and then I introduced
the idea of how I like to to think about reactions of carbonyl compounds with nuclear files and I like to think about there being sort of 3 types of nuclear files from broad types that very strongly basic nuclear files like hydride an alkyl groups things through the PKK groups for which the PKK of their conjugate acid is a very large number in other words things that although the conjugate acids we call it a very weak acid would not to any measurable extent dissociate in water and came like methane doesn't associate to methyl and I and even know it is a technically a very very weak acid if you work out an equilibrium for a all of a compound with PKA of 50 in water and try to figure out the concentration of the conjugate base and a the concentration is less than 1 molecule well under 1 molecules so basically things like methane and hydrogen don't associate and water we then moved on to a category that I roughly group is moderately basic nuclear files and not that's a lot of things where you think of the conjugate acids as weak acids from hydrogen
cyanide for example PTA 89 . 4 this
Associates and water a little bit so you have cyanide and iron and water which actually acts as the nucleophile alcohols and water were sort of at the lower edge of that category is very weakly basic nuclear files and then finally I mentioned so very hot leg mentioned very weak nuclear files things were the conjugate acid really is a strong acids things like an alcohol over the conjugate acid or relates to is as strong as it were sort of often the negative numbers there and in our 3rd lecture will be talking about that class but here I wanna continue our discussion of the category of moderately basic nuclear files and I just wanna laid 2 examples from the previous lecture to talk about what they taught us because we're gonna go on now to looking at at the reaction of an means With carbonyl compounds with towns now the hides and means all and that moderately basic category the PKK of the conjugate acid the PKK of an ammonium ion is about 10 or 11 and we saw what set the stage for these reactions in 2 different reactions we saw the reaction of hydrogen cyanide with the generic Teton around the height of not meaning this to mean acetone purse but any sort of Tetonia Al the highs and the reaction was the former aside and all hybrid and then the other reaction we talked about last time was the reaction of a video reagent again I'll just sort of writing the ACM Iger nearing the degree agent right or CH 2 A P P H 3 double bond and remember we talked about there being resonant structures of this so we talked about the being 2nd resonance structure of the video reagent that had eluded form in other words had a separated charge and only because phosphorus
can take an expanded architect only because phosphorus can take 10 electrons around it could we write this other
residents formed here and then the product they're back again generic morale the Hyde with this sort of CMI generic fitting reagent is and the now what these reactions set the stage for for is the idea that nuclear files like to add to the carbon group we see that hydrogen cyanide we can think of it as dissociating the the licensee and minor storing water reached real class and see and is seen minus adding to the carbon the resulting Alcock side and and then picking up a proton from another molecule of hydrogen cyanide a from hydrangea mired in the case of the vetting reaction the start of this theme was very similar in other words we start our mechanism by electrons flowing from the nucleophilic species in this case the basic carbon the car and I like carbon to the oxygen but then at the same time electrons flow onto the phosphorus now From the oxygen now phosphorus really really loves oxygen and where the theme for today's lecture dead-set phosphorus Boeing's onto the oxygen and then pulls off the oxygen and so the oxygen is now taken out of
the molecule and this is the same theme although not with the poll from the same matter not with the poll from phosphorus that we're going to be seeing in the reaction of enemy nuclear files with
key towns and the hybrids so by way of diving into things let me start with the generic generic reaction here but if we have some compound organic chemists often use are groups indicate unspecified alkyl groups sometimes even even alkaline hydrogen so I'll say if we have some cheap town around behind this is a very general reactions it happens we trade with a primary amino and I'll use double primer to indicate just that we're talking about some of our group here not necessarily the same our group a primary a mean of course is an enemy with 1 Alco group under the nitrogen remember it's a confusing and alcohols of course the only alcohols the alcohols with 1 or group on the
oxygen so a primary alcoholism alcohol where you have an aura C H 2 connected to the alcohol were you have no
other car only 1 other carbon as secondary alcohol is an alcohol we have 2 carbons connected to that carbon like I suppose open all and a tertiary alcohols is an alcohol we have 3 carbons connected to that carbon like to assure you can all but in the case of a means because you can have multiple are groups and the nitrogen we call a primary and mean and mean with 1 Alco group by nitrogen we call it a
compound with 2 Alcove groups on nitrogen a secondary Amin and a compound in a meeting with
3 alkyl groups and nitrogen tertiary Stone With the primary means of energy tone around the high they react to your textbook indicates catalytic asset and we will and invoke this In the mechanism and I'm gonna write a little caveat on this sometimes because the tones and and and means can react without the presence of catalytic acid remember at catalyst ends up facilitating the pathway but that doesn't necessarily mean the reaction can't occur without it plus there various sources of each plus as you go through the reaction you're going to generate products species so the product of this reaction is in meeting the where the nite regions group is derived from the primary means and the has this structure and again on organic chemists terrible about writing balance equations but the other product of the reaction is water and that actually gets important in driving a reaction so I'll ride out the name of for this I'll just say and the in maybe I'll I'll give you a concrete example of this reaction so for example if I take then Zelda the member bends out the height is 1 of those Alva Heights whose common
name is so widely used that we would never probably never call it anything else and let's take Denzel Amin as are other partner in this
reaction in usually it takes some heat to drive this chemistry but really what this reaction takes the reactions in equilibrium in other words and all right it later as such right now I'm writing this morning a synthetic fashion but the equilibrium water and the Amin exist in equilibrium with the key around the Heidenheimer Amin and the real problem is if you're trying to make this chemistry when remembered chemists often try to control the chemistry and drive the reaction to a product in other words get rid of all the starting material and form as much product as they can as possible you do this in your Campbell lab class when you're what monitoring by TLC and you're saying is my reaction done yet isn't done yet can I work it out have I used up all my reactions and the problem in an equilibrium is that unless your employer shall liaise principal unless you push it you will often end up with your reaction never called being done because done is in the middle so the way that chemists often right derived drive this reaction is by doing it in a solvent that water doesn't dissolve in such as benzene sometimes they use toluene at reflux reflux means boiling now benzene and toluene have a very special property benzene and water toluene and water cold distilled form what's called in a sea of troubles in other words the benzene drives the water up in the vapor phase and if you go ahead and then have a receiving vessel
water heavier than benzene if you have a little receiving vessel under the distillation apparatus underneath the condenser the water and benzene drip back in but once
the distillation once the receiving vessel fills up with benzene the benzene keeps losing back into the reaction flask and continuing to distill while the water goes the bottom of this apparatus is called the dark Dean stock trapped after its inventors and by carrying out the reaction under these conditions you can get your it in new textbooks new textbook rights "quotation mark while said this particular reaction proceeds just fine without nascent catalyst although acid catalyst will make it go faster and so here is our evening prime time and again at least for now I'll be good about balancing my inflationary writing water and sometimes still here in mean derived from and how that related referred to as an the Amin so right that out but the and sometimes you don't hear of an immediate derived from a key town as being
referred to as the key to give me let me give you an example of a key generally informing the examples I have chosen a real examples from real experiments just to show you typical conditions that 1 employee for this chemistry so the example
of give is methyl cyclo Hexham known in the end of the you fennel laugh El-Amin it turns out that the there's a lot of really beautiful chemistry but it means any means that we're not going to talk extensively about today a new text but doesn't presented extensively but they can be really important and carbon-carbon bond forming reactions and I told you early on and we've talked about synthesis is to build up molecules build up greater degrees of complexity this is how we make new medicines for
example this is how you make chemically synthesized steroids and so forth and drugs and so on if 1
uses a Cairo Amin and I'm not going to drop particularly in anti-American here Wednesday and go ahead and form a valuable need from this Turns out the meetings have stereo chemistry to them about the carbon nitrogen double bond and not surprisingly if you have a choice you want a form the least satirically hindered product Maine formation is thermodynamic I guess I was writing pH for benzene years sozzled continue to do so in the information is thermodynamic and so you form the thermodynamic less stable compounds and hear the experimental conditions are very similar the reactions done in toluene benzene boils that a little bit lower temperature than toluene toluene boils at about 110 benzene at about 80 degrees and reflux singing in toluene books child you you again with the dean stock apparatus that drives the reaction and of course you get water as a byproduct of the reaction which you collect and being stars trap if I had my choice personal
life between using benzene or toluene I prefer to use toluene benzene is carcinogenic and so in general people like to work with it as much it's
not really carcinogenic we never it's is really a carcinogenic it's not super carcinogenic we use it in an experiment in the cam 160 lab costs that I I would use you just work with it carefully like you do when you work with other toxic chemicals question here and you'll Octavio yes it is the bribery of NH 2 thank you very effective very much the and once again thank you where they that letter to the next .period so let's talk let's talk about the mechanism of indeed formation and so now now we come to this stage that's been set by the Vedic reaction we come to the stage that's been set price I all hybrid formation and by the pedigree action where nuclear files like to add to the carbonyl compound the Carbondale of tone around the Hyde is Electra felt like and the oxygen can under the right circumstances go away it can leave and obviously it becomes water because I've written water several times so let's see how that happens so as I
said the reaction is catalyzed by acid is an intermediate that forms halfway along the way called
him I am an hour or an amino carbon all depending on whether you prefer more common name or the name the book prefers for it and that intermediate is slow to breakdown that's where the water is about to leave the reaction acid catalyzed is that Stepford makes it occur more quickly so what I'm going to write out for you is a mechanism of acid catalyzed Amy information even for the most part we can think our way through the mechanism South we know all that means is reasonably nucleophilic I told you the PKK is 10 or 11 for the conjugate acid in other words it is nucleophilic to attack a carbonyl compounds so here's that generic Tito morale that I that I started with and going to be a good person and try to remember to write in all of my charges all of my lone pairs of electrons and to use Kerberos always show the flow of electrons during this reaction so here is our enemy yeah I mean
has electrons the Carbondale once electrons electrons to flow
from the nuclear file to the Electra filed course we can't have 10 electrons around oxygen and just as insight on the information electrons flow up onto oxygen to give an autopsy on iron species all of these steps and indeed all of any information is in equilibrium in other words every step that can occur forward can occur in reverse in fact under identical conditions if you go through the reverse process the hydrolysis severe means it has to occur through the exact same pathway that the Amin formation occurs because that's the lowest energy pathways so we added power and we to the Carbondale and now we have a species where we have a negative charge in a positive charge in approach time's going to get transferred a panel that bank and loans With all the proton transfer workers you could think of it as occurring in ones that use textbook at implies this and I think for where you're right now In terms of your thinking and particularly for carrying out this reaction In the presence of the Get by and are Prime's here I think for carrying out
this reaction and benzene ring toluene I think it's reasonable to think of it that way but that's all right this
is proton transfer and that you could also think of it as occurring with remember you have some catalytic acid of course you have other molecules around you have water around eventually I think you could also think of it as occurring by picking up of protons and then losing a proton but you don't really have water in this reactionary large quantities but you may have a little bit of catalytic acid anyway however you wish to think about this I think is fine whether you think about this oxygen for pulling off a protons or you think about pH plus some acid that present transferring of protons and then pulling off a proton or even the reverse I think it's fine in other words 1st falling off a proton with the base like Amin and then putting on a proton and so I will right all of these ways that I think are valid for thinking about this so at this point what we have done is we have gotten to know as species that looks like it should be should be a neutral molecules this species is an intermediate it's not in general as stable species in general you can put this species in a bottle we call a ham I am and how him
might have you're going to see here a few completed the chapter reading you'll see that term I ask the towel and my I tea towel can my I have now these have all been hammered out it
China now is another unstable species in which you have to nitrogen someone oxygen and I am and is 1 in which you have 1 on the nitrogen out 1 nitrogen in 1 OH wage groups you textbook also refers to this as enemy no carbon all the carbon is a very old term for alcohol so amino Cardinal is a fancy way of saying them amino alcohol which is a fancy way of saying a molecule that has an amino group and an alcohol group that happened to be attached to the same part in any way In general this is not a stable intermediates I'm going to )right parenthesis unstable in other words it's going to break down and that's going to be the remaining part of our mechanism is another question the people I think it will happen this year per person you mean Over here because of you mean 1st have and you have hit you have had an absolutely beautiful question so cell the question that's being
asked from the from the front row is a really good 1 and it cause may cause me a little bit of thought and a little bit of consternation in putting to be together today's lecture and the reason for it to the question that's being
asked to which is an extremely valid 1 is why don't we produce the Carbondale oxygen 1st by accident and what's causes me real consternation the mechanism I'm giving you is the best 1 for this reaction catalyzed by mild acid however and it's the 1 that most sticks closely accords to experiment for the rate determining step being the breakdown of the him I am now which we will see in just a moment however if you for example look at other sources or you look at Wikipedia's or Moss not Wikipedia the organic chemistry with the text from the University of Michigan you will indeed see that mechanism and it doesn't accord quite as well with experiment even tho it represents very sound mechanistic thinking so coming back to the question of why I I'm writing the mechanism this way because this is important because you're thinking is sound and mechanistic and specifically not for writing the mechanism even know experiment is different Why am I harping on this why am I now taking the time of 200 people because you're going to have to worry about this later on when we start to come into our last segment and you worry why is there a difference between the mechanism I wrote
here and the mechanism that were gonna write with very weak nuclear files here is the reason why I consider that this mechanism that I have written to be a more realistic more valid mechanism of better mechanism so
we're doing this reaction with catalytic amounts of assets in other words this reaction is being done with a little bit of toxic gasses which I will show you later for example more some acidic gasses were just with the amount of inherent gas and that's present you have 1 mole of Amin president of means the basic so the strongest asset if I of strong acid with him redefined mix a little bit of HCl member of less than 1 equivalent a catalytic amount of acid a a little bit of toxic gasses which also you later with the meaning of the strongest acid that's present well-being the ammonium ion or N H 3 plots are 3 plus is a very weak acid or a weak acid to keep consistent with my terminology PKA about 10 or 11 o'clock that can't it is a relatively base its weaker than water water hazard PKA of roughly for the conjugate acid from a growing amount of negative 1 . 7 o'clock group is even less basic it's Acevedo the electrons are held more tightly to the oxygen atom so the PKK of the conjugate acid approach make that carbon deal is into well into the negatives negative 3 negative for somewhere around there in general and equilibrium where you have 10 orders of magnitude or greater generally doesn't get involved in a mechanism it's just too far To the
left for an ammonium ion PKA 10 or 11 to be probed needing a carbon yield when we come to weak acids we're going to see a different
mechanism because now we just got the strongest now you don't have an Amin present you don't have that faces and so we're going to have a weak acids being acid catalyzed were yes you partner now we take the flip side in favor of this mechanism the flip side in favor of this mechanism is your nucleophile is decaying for the conjugate acid of about 10 that's like cyanide that's like other nuclear files that we see happily added on acid catalyzed step To the Carbondale so this 1st step occurs without proclamation of the carbon yield however the thinking is not Wong it's not bad thinking to think about it in the otherwise so back to my consternation at putting this lecture together itself like gaining some consternation is I wanted to follow the order of the the textbook here and this is a nice reaction because it introduces the principle of a nucleophile that's not phosphorus calling the water out and I think they made a good choice but mechanistic late today's mechanism is the oddball mechanism because you precisely have the conundrum that you've decided so thank you for raising that it really is good and coming to Europe .period as students about should I be confused about this mechanism or I'm feeling confused or the parallel although I need to know that if I'm feeling confused yes this is the 1 of all the mechanisms that we're
going to see today's mechanisms are the ones that will cause you the most consternation next Tuesday's mechanism should end up showing more elucidation and so my consternation in
presenting this was do we wanna go with the most confusing 1 person and I decided to follow you textbook but yes if you're scratching your head you want to a low that's Laura at this point ,comma him I ask to have my hammered now undergoes acid catalyzed breakdown but in a very very special circumstances can Miami analysis certain him I am analysis can be stable but in general they're not and the rate determining step the slowest step is the breakdown of the him I am acid and it can be as simple as some of the the other water that's president or other advantageous sources of acid or it can be a little bit of added acid which in the end although again you're going to find some mechanisms writing as H 3 0 plus really would end up being a protonated ammonium ion we would really end up being approximated Amin so some source of acid is going the transfer approach on but you can think of electrons as flowing From the oxygen total assets back onto the vase maybe I'll skip the Kerberos at that point just because we're very good at that what's onto the oxygen so both of these patterns are basic and to get over the Hot Sulphur headed back basically reversible even promote the nitrogen but if we're headed back if we're headed a now we have to get over this hump the nitrogen has the push out a molecule
of water so protons come on and all every Louis basic acid in the model molecule by
sometimes they go onto this oxygen and when they do were now set out to overcome the rate determining steps in this that electrons push from the nitrogen and push out of the water molecules and I guess since I've been on that actually write this in a separate line this incident fell this year so here we have our him I am program natives on the oxygen atom and now in the final the pet ultimate the rate serving staff now we're going to break this guy down In this rewriting this species in electrons are gonna fall from the nitrogen and push out water and again every step in this reaction mechanism is in equilibrium looks now we're going to get a double bond tonight Virginia they are right now but now we're ready to finish up our mechanism and in the final step but the mechanism so now
we have our ammonium ions of
and as I said this is the rate determining step but but but but but but but but but but but but but but now in the final step of this process is organisms we take a proton all off but the electrons flow from the base of the protons we pull the proton off but but but but but but but we end up with the and you notice in these various steps I've written here the 1st step where the base is proud mandating the oxygen the 2nd step were protonated intermediate is broken breaking down and in the 3rd step where we're getting our
base back you see how the acid is acting as a catalyst for a little bit of acid gets invoked at the beginning but it comes back at the end it's really generated at the end so if you had a catalytic
amount of ammonium ions president now that ammonium ions would be given out at the beginning of but by by the end of this catalytic cycle would be regenerated also right How can a missile remember and I thank you for my lone pairs so remember this nite nitrogen and is estimated to hybridize this carbon s fetal hybridized self you have 120 degree angle here and 120 degree angle here another question yet you could use a water and the only reason I'm not using water and not use engage the Rio for this well actually the main reason is in the presence of a mean and we have a mean present in the presence of a mean you get only a minuscule amount of H 3 0 plus remember three-hour-plus PKA 1 .period negative 1 . 7 ammonium ion roughly 10 or 11 so you have very little water Association to hide only mind but yes and as I said for so many reasons today's mechanism is the oddball mechanism for so many reasons today's mechanism is hard to think about and this is 1 of them yes we will be using age 3 0 class and age too
well in Aurora wage in Tuesday's mechanisms but here realistically speaking most of the acid we're going to to have around is going to be the ammonium ion now coming back to this
Proton here because if you're thinking and on your toes you're probably saying Well why or why is this counterpart made this is even more basic then in a typical alcohol so we will coordinate this in your own generating a little bit apart native species this is the toughest part of the breakdown of that intermediate other questions Our another great question is that long pair of electrons taking up a little more space that the BSE PR theory 10 geometry of molecules yes a little more space remember methane ammonia water the hydrogen bonds in methane 109 . 5 degree angles hydrogen is antimony about 107 I don't remember I think it's 107 . 3 degree angle they get pushed ever so slightly 2 degrees closer together hydrogen and water 104 I think it's 104 . 5 degrees about 2 degrees closer so yes technically this bond angle is probably closer to 118 degrees rather than 120 degrees but 120 118 is a hell of a way away from 109 . 5 107 so it is sp to hybridize I saw another question and Our it 1 last question follows the lead of those the will oversee make mixture of both
in spared question member out teams no corollary to the double bond diocese very America's so the
question is receiving it means handed so itself the answer will we yes we will if we had let's say a national group and an apple group here former mixture where the very close to equal but if we have 1 group that big like a methyl group and 1 group 1 group that's relatively big like a methyl group and 1 group that small like a hydrogen as in and out the Heidi mean al-Din then indeed you will have exclusively the trams or if you have 1 group that's very big like the math along the cycle Haxtun known that I showed the other that's less faith but if the roughly the same yet you will get to it and are so we've walked through so we've got another question Will this reaction at all I love it I love the question and this is every consternation I was thinking about putting together today's lecture so brilliant brilliant brilliant question where everything come I think it will and I
think it Walter it this is good and how many think I'm asking the wrong question yeah alright it
turns out that in general in general remains of this sort are unstable In general they go on to form other products in general whereas you can put most Indians in a bottle remember by stable I mean things you can put in a bottle you can isolate the amino carbon all the hair Miami now intermediate in general you can't put about although I can give you examples where you can in general you can in general you can put an album either a 210 million in a bottle I showed you 2 wins at the start in general you can't put this 1 in a bottle now just to check at the beginning of putting this lecture together I was curious I went to 1 of my favorite sources which is organic said the seas and indeed they have a preparation of 1 very very special such Indian With try floral methyl groups which are very electron withdrawing in very special here but in general this along the image in the article in which is in primaries and secondaries in general that is too unstable and undergoes further reaction so yes you would form a transient only as an intermediate and then it would undergo further reactions are right now the stars before coming back down to earth here because this is what we have had a really
important discussion of some reasonably heady topics we have wrestled with mechanism and this is good and this week's discuss this coming week's discussion section from
Tuesday on I'm going to ask you to wrestle with mechanism so this is but we have been engaging in thinking about it we have asked questions that are deliberately outside the box and outside the textbooks this is exactly what you should be doing so I want to come back to to earth with a few basic principles here on the ground us because the other thing that comes with heavy discussions is this is confusing this is scary will list on the exam so let's come back with some general principles analysts 1 of the principles of what I mentioned here is that it means formation is an equilibrium in other words in writing these reactions and thinking about synthesis I've said yes we can drive this equilibrium where organic chemist we can do anything we can make anything we can push compounds to go in almost any direction that we want them to go but let's not forget once gentle yea if you don't take out water we come back to this reaction and it's an equilibrium which means it is just as valid to write the reverse reaction and if we don't take out water and we throw our immediate together with water or we can go ahead and reaction to the universe again was shattered the his principle it is just as valid to
write the hydrolysis if instead of throwing deems start trapped on their instead of using benzene ABC
tropical heat is still out water I go ahead knife throwing lots of water then I get the corresponding back alright further I want further generalized because again organic chemistry can be scary and you say what general principles that I take away OK in general the reaction of a moderately basic nuclear files and regally basic nuclear files with the tones and Alabama minds is reversible we looked at Sianna hybrid information that's an alley on the and by the way reluctant Sianna hybrid information that reaction is reversible all you can drive it in the reverse by
distilling outer using answered to probe made THC and driving it away as a guest so AEM general the reaction of moderately basic nuclear files like
comedians hydrogen cyanide a weekly basic nuclear files will talk about how the heart about alcohol's next time in general that reaction is reversible and the general the reaction of strongly basic nuclear files is not part of of the of another words in general when you add in Alkol nucleophile her green yard reagent during her down lithium compound during a satellite to Wiki toner Ronalda hide in general 88 coming back out in general if you add a hydride nucleophile to a toner now the it's not coming back out and have flung part are the exceptions and those exceptions go beyond the scope of the course but they end up being absolutely fascinating mechanistic playing to if learned occasional purity and chemistry you may have learned 1 weird example called the
chichi Bobbin reaction were hydride nucleophile comes out the fund name if you if you didn't learn at Google it just for fun Alright Again not
staying grounded in this is not that people really fret about in staff more organic chemistry let's go ahead and just look at a couple of species that we haven't seen before this ridiculous the cheese is cold and hot cinnamon and if you look at not seeing any assailed haven't seen this before but I know how to format because I can't think backwards retro synthetically you can say all that just of funny-looking Amin called hydroxyl amino reacting to it and how the high and so you can think back words you can say I I'm smarter than that and I think that he thinks I have I know how to make that I just react hydroxyl a meeting with his elder maybe with a little bit of acid catalysis filet steak another funny-looking species called the fennel hybrids don't it used to be really really important to make derivatives of carbonyl compounds because they were 1 of the ways people characterize them and if you look at this you can say all again I'm clever enough to to figure out how to synthesize it I just realize it's just a funny look the immediate derived from acetone and fennel hydrazine and sell these principles that were learning year for forming and taking apart molecules really ends up
being much much more general now we've talked about crime primary means and we've talked about ammonia surprisingly and now I want to move on the secondary means and show you the conundrum that they
presented tertiary means really can't go anywhere they can add reversible but you can't even pull off a proton and form a am analysis Paris when people get tired of riding out long words like primary and secondary still often go ahead degrees and also 2 1 on I mean is another is a shorthand for secondary and secondary means with towns around the hides produced she's holding a meeting and I'll give you an example of this reaction 1st again I gone to 1 of my favorite sources for this word since then so I've taken cycle Haxtun on this turns out to be reasonably important 1 and unfortunately you text that doesn't do real justice to the beauty of this chemistry because it's useful in making steroids in chemical synthesis and asymmetric synthesis there was pioneered by a fellow named Gilbert story really brought into brought into very high utility by him maybe I'll put something on this week's discussions section if you take a Keatonâ Ronalda hide that has a hydrogen that at that position adjacent to the car business and you take a secondary meaning and again you subjected to the same types of conditions that we use people benzene reflux removal of water with Indian start trap you might not even see that written you might see acid catalysis this particular example it doesn't require acid catalysis tied general you might say ,comma sometimes acid catalysis accused her of your concern you could write Tallis so what we've done here is we've combined our secondary made an Archie to form a
species called any leaner meaner and again I'm
going the good and write a balanced equation and remind us that we have an equilibrium that were driving fired stock distillation we drive that reaction removing water alright so I guess I will also write in parenthesis medieval walls here sometimes with catalytic Carson alright and where I want to close our discussion is to just talk about the mechanism for formation of the new meaning and maybe maybe a little bit more about an hour so just as in the case of our primary Our Amin is a nucleophile the Carbondale is electrified the Amin is a moderately basic nucleophile it's a good enough nucleophile to attack the Carbondale like cyanide it's reasonably basis so just as we had done in her our previous example while going to now assume assuming that you can get yourself all the way 0 0 the Miami now attack of the Amin
onto the Carbondale proton transfer and at this point again we have some
catalytic acid this is probably the most confusing and worst 1 and what's what your name by the way was good question you ask Kyle and Kyle as this very good question about a 3 0 loss and so here I'm going to be a little bit vague but honestly arrested is probably in this case the ammonium so we have our equilibrium here you have a small amount just as we have done before you have a small amount of here and now In our intermediate again I'll be a good person tried a bully balance my equation here may be all you can do branches down here just to complete things are so now we come down to the crux of the matter the breakdown of our protonated him I am and nitrogen has a long pair of electrons it can give a good portion replaced electrons in order to form a double bond we'd push out water and up until now everything everything everything has been the same as we did in the end information so here we have many but at this point we have ourselves in a
conundrum because in the case of the Iranian ion formation we could now
call a proton the nitrogen and at this point we're stuck we can whole a proton offer the nitrogen there's no approach on the Pollock the nitrogen in many lands can be stable species under special conditions but in general their intermediates it's something else that carriers and let me show you what else so remember I said that we have to have baby proton so here's our medium while on we can think about this 2 ways and they're both valid ways of thinking about this so 1 way you can think about it is you have based president of the base among other things is the basis of that just got released over the American can be Indian you could think of it as being water so we have various basic species around 1 way you can think about it it With baseball's office from time and I'm perfectly happy with this view and we're going to be taking of you very much like this as we move into I believe it's Chapter 23 and discuss the chemistry being light we per-share protons from the pressure electrons from the base to the proton we pull off this Proton repost electrons in forming a new double bond and we pushed them up onto the nitrogen all of these steps irreversible and Cybal show you arrows I will show you an equilibrium Aero rather than Here we go and that's a perfectly
valid way of thinking about this now equally valid is recognizing the fact that we can think about there being 2 residents structures of the Yemeni among them and
cannot use residence Aero we have a major residents form in which everyone has a complete but the electoral negative nitrogen there's a positive charge we have a 2nd resonance structure a minor resonance structure in which the positive charges on the carbon that's good carbons electromagnetic less Elektra negative the nitrogen but it's bad in so far that the carbon doesn't have a complete architect so we have a major resonance structure and a minor residents structure and we can think of our base as falling off a proton and if you're more comfortable with this type of way of doing that you can say the base polls offer a proton and we push electrons union year the guests I 1 you wanna keep track of my hydrogen several will ride in the hydrogen there until we have appraised a face and is a bold valid ways of thinking about the same thing alright well I think that's pretty much wraps up the
chemistry that I would like to talk about I will probably bring in some
carbon-carbon bond forming mechanism with in Amiens into our discussion chemistry to show you a little bit about the beauty of their chemistry and a little bit about Kerberos with them I will see you want to stay
Falle <Kohlenwasserstofflagerstätte>
Chemische Bindung
Hybridisierung <Chemie>
Elektron <Legierung>
Bukett <Wein>
Advanced glycosylation end products
Zulauf <Verfahrenstechnik>
Elektrolytische Dissoziation
Funktionelle Gruppe
Präparative Chemie
Aktivierung <Physiologie>
Setzen <Verfahrenstechnik>
Gangart <Erzlagerstätte>
Roher Schinken
Ader <Geologie>
Spezies <Chemie>
Organische Verbindungen
Stereospezifische Reaktion
Amine <primär->
Primer <Molekulargenetik>
Alkohole <tertiär->
Kleine Eiszeit
Chemische Forschung
Chemische Verbindungen
Chemische Struktur
Proteinkinase A
Biologisches Lebensmittel
Einsames Elektronenpaar
Potenz <Homöopathie>
Chemische Eigenschaft
Chemischer Prozess


Formale Metadaten

Titel Lecture 06. Formation of Imines & Enamines from Aldehydes & Ketones.
Serientitel Chemistry 51C: Organic Chemistry (Spring 2012)
Teil 06
Anzahl der Teile 19
Autor Nowick, James
Lizenz CC-Namensnennung 3.0 Unported:
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DOI 10.5446/19410
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
Abstract Index of Topics: 4:10-HCN Addition and Wittig Reaction 7:13-Ketones or Aldehydes and Amines 10:32-Aldimine Formation Example 15:23-Ketimine Formation Example 19:55-Mechanism of Acid-Catalyzed Imine Formation 33:28-Acid-Catalyzed Breakdown of the Hemiaminal 44:33-Answer to Student Question 47:50-Imine Formation 49:49-Reversibility 53:15-Example of Reversibility 55:50-Enanamines 59:04-Nucleophilicity of Amine 1:01:50-Imine Reaction with Base

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