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Lecture 05. Aldehydes and Ketones: Reactions.

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Automatisierte Medienanalyse

Erkannte Entitäten
good morning so today I I want to
start talking about Chapter 21 and we're getting into the meat of the costs right now so we're talking the whole overarching
theme of a huge portion of the class is carbon yield chemistry and when I introduced the costs an overview of the costs and the very 1st day I said there are 2 main classes of reactions of part of compounds that are going to be a lot of our thinking 1 of them is reaction at the carbon compound with nuclear files and the other is reaction of the Alpha carbon as a nucleophile and will be learning about that later but now we're going to really be delving in To the reactions of carbon your compounds and particularly the hides in the tones with nuclear
files and we've already gotten this team and we're going to see now some variations on the theme that we've gotten is if you have a carbon young competition between 2 owner and held the high and you have
a nucleophile I'm going to describe that nucleophile as a strong nucleophile making more specifically will say 80 strongly
basic nucleophile war even a
nucleophile that's not quite so strongly basic even let's say a moderately basic nucleophile and on elaborated on this in a moment of the people of India
either of these types of conditions a
neo-con panicky tone morale the hired more specifically is Electra fell like enough at the carbonyl compounds that the nuclear file is going to attack the carbonyl we've already seen this reaction electrons flow from the nuclear file to the carbonyl compounds carbon yellow-card carbon you can't have 5 pairs of electrons around the carbon so concurrently as electrons flowing as the nucleophile this is approaching the
carbon electrons to flow in our people land to oxygen in the overall result now is that we have now outcome oxide and I and all right that is 0 minus we have 3 lone pairs of electrons around
the the oxygen and in very very generic terms because we're going to see a lot of variations of
this flight in very generic terms if we hadn't sold source of age supplies and remember of course and going appointed in quotes because you don't have naked each class
it would be a hydro a mile on Morrissey the Gasela were going to see lots and lots of variations here anyway some sources of a
proton some source of beachfront plots can program native power Alcock side and I have to give you an alcohol lights and so that's what you've seen already were going to see some variations on this but we're also going to introduce and this is where things get really needy were going to introduce the reaction of carbonyl compounds with weekly basic nuclear files and again in the most general overview now I'm gonna write
this as our partner Neil compound the Jedi alone around the time of the blast a weakling basic nucleophile and again it's a little hard to generalize but let's envision some species that in general is not going to have a negative charge not all strongly basic nuclear files have negative charges but many of them do not hold weekly basic nuclear files don't have negative charges but let's say in general they don't and will
invention that that nucleophile still has an electron pair to share you using weekly basic nuclear files before alcohols water those read basically the files and sold along with our weekly basic nucleophile but the a marriage for a moment that we have some sources but in an acid catalysts that will call DH class and so imagine now for a moment that
the nuclear file because the Carbondale compound the key tone around the height is only moderately Elektra felt like a mansion for a moment that the nucleophile isn't nucleophilic enough to attack the carbon but you can set up an equilibrium where the
basic program meets the carbon once all right this as an equilibrium we're now the new program a the and of course you still have your nucleophile With its lone here and now you have your base but the you get all right at this point should know your Carbondale is a lot more electrical life members something that's Elektra fell like
wants electrons in general if you've got a positive charge it's can award electrons
all the more and so now you're weekly basic nucleophile says while this guy really really wants and that is shared by electrons and so we can envision electrons flowing from the nuclear file to the Carbondale carbon the probe made
carbon your compound just as they did before but the exception the difference is it's a lot were electrify like that again just as before we can't have
10 electrons around a province so as electrons flowing from the nuclear file were putting electrons up onto the oxygen atoms and at this point now where we have our
territory he drawls species but it's already coordinated and we
still have our bases In our positive charge is on the nuclear file and so at this point the
base the conjugate base of the acid catalysts can pull off the prompt but at the end of this
sounds a little bit of strike to right now
don't warrant because we're going to see lots of concrete examples and in many of these concrete examples some of them not ones that will see
today but later on this species can undergo further reaction and so over the course of the next 3 lectures
this lecture in next week's lecture will be exploring these themes in Carbon Hill chemistry and specifically in the chemistry of Alba hides in Quito I
right so that that kind of serves as the overview of what we're going to see over the next few weeks over the next 3 lectures let's started by talking about how the hides in key tones more specifically in talking about their properties and how we name them naming by now should anyhow pretty easy for a year you can recognize the idea of getting a
principal identifying a principal chain of for carbon chain for example in this compound tells us
that's a derivative of butane and soda name it we just call it you to now the the hype can only be at the end of the chain so we don't need to go ahead and put any numbers to wait on the other hand if
we have a key Tony let's take
this example now of course you can have a key tones Carbondale at various points positions we got identified the principal chain along this chain in this molecule is the 4 companies of 5 carbon chain we look at the molecule and we say
OK and then tried a number it so I put the carbon meal at the lowest position so that the 2 position so and we have enough of a group that the 3 position and we use ONE indicated the tone so this compound is real methyl stupendous known only that's that's all
there is To naming compounds by way of the idea have names for how behind in the towns now there are so many Al the hides in key towns that have common names that we would maybe never even used the systematic name so for example if
I look at this Hitomi for those with his
feet on acetone exactly I think I'd
be very hard pressed to say program known foreign just because
its common name its nickname is so ubiquitous by did say proper known because the only position the carbon could be at is the center position I wouldn't even have to put a number it in
general small compounds that have some history of them
have trivial names have common names that usually become the ones that roll off people's tongues this out the hide here anyone for Malahide is 1 carbon and water we call what's the tube carbon what's the 2 carbon assets ethanol is right the 2 carbon alcohol and CH 3 CO 8 years a gas said and so this is asset outside and again
it's real name words systematic name is effort now but nobody is going to call it that
was the naming things as a substitute his version of this Saldivar hiding here then Zelda lied you even
know it's systematic name with the fennel method now anyway for the most part
nomenclature is jealous dishwater other than perhaps systematizing in your mind the anatomy of a compound so let's
take a moment to to talk about some of the properties of how the hides and he tones you probably all had the opportunity to work with acetone if nothing else it's a common solvent that's used to watch you're you're glassware if any of you were wearing nail polish out there you probably
used it in smelled along with that philosophy stated nail polish remover it's a pretty volatile liquid
instead of boiling point of 56 degrees so it has a high vapor pressure as I said it's a liquid 1 of the things that 1 can do is put types properties of compounds into
context comparing them to size compound so for example if I looked at a size compound containing just carbon
if I looked at ISO butane ice of Uday flight-comparison has is a gas with the boiling point of negative 12 degrees
so I butane of course can only have vendor walls interactions among the molecules it's and
on polar molecules acetone can participate in dipole dipole interactions it's got a great molecular dipole to smissible with water it even dissolves some in organic compounds like sodium iodide dissolves very well and in acetone and if we go further so I said butane has Federal's interactions so
very little welded together acetone brings inventor Wallace was stifled interactions by the
time you get up to to ice appropriate all the boiling point is even higher now it's it's a liquid with a boiling point of 82 degrees and of course there you get hydrogen bonding as well In its interactions I don't want to spend too much time we're going to get more flavor reactivity later on this week as we gold but I won't give you a general feeling that in general the tones are more reactive than Al the hides in fact finder makes sense we're going to see more of what we talk about hydrates I think that's where really really brings home the point that let me just say
comparison down the high purses acetone so acetaldehyde mind is more
reactive abroad similar purposes and the main difference in reactivity that I think of this is mainly electrical
electronic and other words you're Europe Carbondale in both of these compounds folded in acetaldehyde and acetone is
reactive toward nucleophile but here and here as an elder height is more innovative more elected village because the car video was more electron deficient remember methyl groups are electron donating so in addition that having the carbon yield I you have 1 dipole here donating in electrons and so in the other case you have 2 sets of
donations the methyl groups to donate so you're less electrical here the carbon was less unhappy you also have a steering component so
between the 2 of those the electronics of the the donations from the alkyl groups and the spirits of the math of groups it's more like felt like God
at the inn acetaldehyde residents will also affect things so for example been Zelda high versus acetaldehyde I'd been Zelda Hyde has resonance stabilization of the carbon also it's going to be a little bit less reactive and say acetaldehyde what I will write to electron donating groups here but but but
but but but but but but 1st 1 of fluorescent Elder said alright
I wanted to take a moment to talk about some of the spectroscopic properties of carbon yield content and may be the way to do it since obviously and I are a spectroscopy they all have a card stretches of defining factor may be the way to do this is to look at certain differences among them and so let's talk about IRA spectroscopy of typical carbonyl compounds 1 way I think cheap but things straight in my mind when I think about the very subtle differences in carbon stretching frequencies is just to keep in mind the progression that in general as we go from investors to how the hides to answered is taking its own steps and is in general the Carbondale stretch moves to slightly lower wave numbers slightly lower frequencies there is a typical aliphatic gas there is about
1750 to 1735
when their numbers a typical height is about 17 the 1729 where numbers typical carboxyl like dancing is about 17 25 the 1705 wave numbers that typical key towns for let's say you have difficulty he tone is about 17 25 to 1700 In a typical animated is about 69 to 1650
so outside of animated all of these sort of end up in overlapping ranges
and as I said he's the kind of general values in other words if you have conjugation like offends our the high that's going to shift the Carbondale frequency by several tens of wave numbers so in other words you want get these bands and they're not purely diagnostic on their
own but then other factors that include you when we talked for example about carboxyl like gasses and we said it's pretty hard to miss the
carboxyl against in the "quotation mark had managed to slot
Esther Elder High teacher told pardon me
incident and so if we look at say a key Taliban verses and answered there's not a heck of a lot of difference they fall essentially in the same rate range but a car Excel a carboxyl against it has a very well-defined always stretch that's really broad from about 17 from about 30 500 to about 20 500 Asians well-defined but very pronounced
remember I drew it out for you before it's this big ugly encompassing blob that starts well above the CH stretches and ends well below the CH stretches may obscure them and has kind of all features Stewart it's pretty hard to miss as long as your molecule is a gigantic Lee huge in which case the carboxyl group is only a small part of the molecule so for the
most part if you saw he gets say 1715 wave numbers you'd say Well there might be a key Taliban might be an acid but then you look down and at the region around 3 thousand and you say Oh my God there's this big
blow here it's gotta be a carboxyl like acid so similarly there are other corroborating features albeit
sometimes more subtle for example Esther you can sometimes not always because the fingerprint region is pretty crowded you can sometimes see the serial bonds single stretch at about 1300 to about 11 hundred but again there's a lot of stuff so all put this sort of influence persists as you might be able to accept it
out to gentle hints of course NMR spectroscopy brings in other occasions we talked about a H 2 next to an oxygen in Astor and we say that so about 4 parts per million and so that would include you when and how the hives also
have little hints for example the Carbondale since the course vehicle How the height hydrogen gives you a couple of bands from the CH stretch the CH stretch typically shows you right at the lower edge of the CH stretching region about 28 20 and 27 20 shows a couple of bands associated with it is sometimes hard to pick out because the right on the lower edge of all of the other ch stretches but if you look hard sometimes you can pick it out however there are going to be other
spectroscopic features for example Indiana more respect for that would include you in state to announce the height of the presence of the
CH group which will talk about in just a moment
or as I said there are a lot of factors that printers sort of general aliphatic carbon stretching
frequencies so 1 of the big things in conjugation as I just mentioned so for
example if you take a look at cycle hacks announced cycle hacks non-hazardous carbon Hill
stretching right in the middle of where you'd expect right in in the middle of where you'd
expect for a Teton right about 17 15 here from the other and you go motorcycle-taxi known the
conjugation of the double bond with the key Tony dollars and weakens the streets ch stretchered shifted to lower frequency to about 1685
wave numbers we've already seen this in talking about Nova reviewing some of the chemistry of alpha-beta unsaturated carbonyl compounds when we were talking about chemistry and we explain that there are many different resonance structures 1 of the residents structures as a single bond character some minor contributing structure but it shows you how collectively the various pictures of the molecule end up indicating that the carbon-oxygen double bond isn't quite as
strong that it doesn't stretch at quite as high frequency this same type of effect occurs in other sorts of alpha-beta
unsaturated carbon your compounds of example if we look at it you only key tone is also at about 1685 wave numbers now another thing that can change the Carbondale stretching frequency is rings strain so attacker luck instead of its cycle Hexham known if you take a look at site will used known now you've got a four-member during and of course the bond angles in a four-member grain are
much smaller than in the six-member bring in cycle hexane and cyclo hacks and the carbon-carbon bond angles can be
essentially what they desire to be at carbon sp 3 carbon responded to an S P 3 carbon bonded to an S P 3 carbon wants to be 109 . 5 degrees at S P 3 carbon bonded to an 2 carbon bonded to NSP 3 carbon wants to be 120 degrees but by the time you get down the cycle of known all of your angles getting forced to be much much closer to 90 degrees as a result of that you're having to use more Pete character in making up the ring bonds that leaves more as character for the CEO behind and remember s
orbitals are lowering energy so that's going to make CEO bonds stronger which in turn means it's going to vibrate at higher frequencies so cycle of you've known ends up having overstretching frequency of 17 18 wave numbers and I'll just jot this says more PT
character in the Ring leads to more as characters in CEO bond and that leads from Lucille this same effective ringside cycle Butte known to pretty rare they don't occur commonly
you don't find them and many molecules like for example steroids and other sorts of very few natural
products contained on the other hand cycle painting rings insightful knowns are much more common and even in a cycle Penta known you can see the same effect of a stronger CEO bond so for example when we compare cycle dependent known cycle hacks and on our Carbondale stretching frequency is still about 30 wave numbers higher it said it out 1745 and as you can see if you only relied on these general CEO values and you set up the only thing that's at 752 1735 is an ester that Carbondale must be in Astor you'd be wrong because there are many
factors that perturb did with you said all the only thing in that table it's at 1685 is enamored so it must be enamored you'd be wrong on on those because again there are many factors that determine this is why the confluence of infrared spectroscopy and Annamari spectroscopy and good sound chemical 1 mechanistic thinking and being able to read other subtle clues in the spectrum like a single bond stretch ch of event held the were the not-so-subtle all wage of a carboxyl exists that ends up being very Our well
in NMR spectroscopy there are also some general things to keep in mind in 1 of the things that I like to do when I think about marked is sort of put things in broad classes Alcalde ch is generally if there's nothing perturbing then show up from about . 9 to about 2 ppm about 1 to 2
ppm for methyl group and methylene Gruber must find group
respectively more toward . 9 4 methyl more toward save 1 . 4 4 methylene and more toward 1 . 5 at 2 4 Messiah did l if you have a hydrogen it's next to a carbon you tend to have sort of a general area that that
hydrogen might be and that sort of general lay about 2 to 3 ppm
depending on the type of hydrogen itself for example of methyl group off of a carbon tends to be more about 2 ppm and then all of these are approximate numbers all but tell days to indicate certain general effects of methylene group it'll be a little bit further downfield maybe 2 . British ppm if it's a methylene groups it'll will be a little further down the field still may be about to . 6 ppm and so this is kind of a good starting point for reading and Annamari spectrum by the time you're having a hydrogen that's directly attached to what carbon that's attacks not to Aqaba meal but oxygen you've kind of moved into the
3 to 4 ppm range so with C H 2 that a part of ethanol this is going to be at about 3 . 4 associates to that part of efforts is going to be at about 4 . 1 2 years after the Allied
ch is another very characteristic feature in the spectrum and hide ch is typically about knowing and intending ppm
1 of the things that's interesting about how the hides is your coupling constants for most J. coupling with the exception of double bonds most J. coupling is about 7 per cent of the words when you see a
triple-A or you see a quartet for ethanol to sold spacing of those lines is generally about 7 hurts apart it the high because of the electorate negativity and because of the hybridization of the the high carbon the J. coupling ends up being considerably smaller between the adjacent hydrogen is year J. value is generally about 1 to 3 parts now the implications of that is when you look at a compound that say has an apple group added and in the high group in it you look at the Apple group and you
say Oh it looks like a typical Triplett for the Mathilde lines are in this pattern of spacing used you and then you look at the Al the High Museum I got
the lines were so close together what's going on what's going on is that it has a smaller coupling constant and so being able to recognize that clues you win Houston say I haven't the Hyde next the 1 hydrogen arrive and how the next to hydrogen and I guess the other thing out touch on very brief in this year's see 39 a MAS spectra of the most defining feature of the hides and key towns in the sea 13 and more spectrum is the carbon meal you text that gives the number of about 190 to about 215 of tedium for now the hives G. Jones the Carbondale of the town's tends to be a little bit more toward the downfield and a little bit more toward the
210 215 the Carbondale carbon Ovalle the hides tends to be a little bit more toward the outfield and maybe 195 being sort of a typical value for Al the heights these of course numbers are very
different than what you see carboxyl like Esther can you still have a copy Neil carbon standing out very far downfield but now it's more like 170 or 180 feet years textbook that a very nice job of reviewing chemistry that you've already learned that I'm just going to have to mention a few things on the synthesis about the hides in Quito and things that you've seen before in earlier chapters but so when you were learning about how the hot weather when you're learning about alcohol's you learned
about oxidation reactions to make out the hides and keep tones that I mentioned this
briefly when I was talking about carboxyl against Sadr's chromium 6 is a very common oxidizing reagent often in the form of potassium makers potassium dichromate or sodium dichromate for chromium trioxide a
general and indeed old-fashioned and somewhat toxic and carcinogenic recipe for
oxidizing Karbacher oxidizing secondary alcohols 2 key towns is to take potassium dichromate sodium dichromate and sulfuric acid In water sometimes called Jones's reagents and that is a general oxidizing agent to oxidize secondary alcohol to tone your textbook introduce you to the concept of selectivity this reagent oxidized his primary alcohol directly to carboxyl like assets but if you take a primary alcohol or associates to old age and bring life right is a little bit neater here or CH to old age and you treat it with the reagent PCC period Enumclaw call made often in methylene chloride you need an animal on hydroxyl like
solvent you need and hydrous solvent for this reaction methylene chloride as a nice job for this then you can selectively
oxidized a primary alcohol to endow the hive t
tones and hides are in a higher oxidation state then alcohols key tones and Aldo hides are in a lower oxidation state and carboxyl like acid so for
example if you take an Esther with the selective reducing agent like died down you can reduce your Esther right down to the corresponding held the highs and again I
mention this 1 before but I doubt it reaches died down followed by In a week's work
out with water-related real classy acid can reduce you're out the high you're directly to Ronaldo hide and of course the other product of the reaction is your corresponding alcohol you textbook also reminded you that their selective reactions to reduce us to
reduce acid chloride acid chloride are extremely extremely reactive you'll learn as we go on to discuss
Esther and as we go on to discuss other members of the carboxyl aghast family that acid chlorides react directly with water they react directly with our with alcohol because the chlorine is electron withdrawing and they're very likely to select you can selectively reduce the acid chloride down to an
elder height with these very attenuated
form of lithium aluminum hydride lithium aluminum hydride which we've added 3 equivalents of Budin altogether this variable nonreactive lithium try to the taxi aluminum hydride allies healthy old the U 3 in this reagent barely barely wants to transfer a hydride but the hydride is nucleophilic and not just the very electrical like acid chloride can be reduced selectively to the elder antigen you need some type today we worked up this water at since alright so that kind of covers reactions that you
use seeing offered for reactions in which you're transforming oxidation state without really changing the structure of the molecule you've also learned about some reactions that transformed the structure of the molecule
more profoundly while changing oxidation state so for example you've learned again in past chapters about owes analysis you can take an hour and treated with ozone would you generate by passing an electric discharge
silent alike tried just discharged through oxygen and then you can reduce the resulting always
aligned with dire I'm methyl sulfide meeting last words sink and water you can reduce the resulting always and I knew clean hence the lines you cleave you're out into to Carbondale hangouts 2
sir to out the hide Searcy tone and now the depending on what substituent you have on your part your group again by way of review your
text books reintroduces various reactions of alkaline so this is all a quick quick survey of things you've seen before so textbook reintroduces the mock-up of carbon addition of water across out kinds to give me give tones
so for example if we have a terminal alkaline and we
treated with sulfuric acid and a catalyst typically Mercury catalysts like mercury sulfate a HGS 4 In the presence of water we Adam bowl of water across the alkaline in America McCourt since the 1st product is an e-mail which will be talking more about later seeing all undergoes start-up summarization to give the corresponding Mathilde heaped on
organic chemists are all about control
being able to to control it the Mosul activity being able to control stereo selected that and being able to control Regio selective beneath the natural Regio selective body of additional costs and Al Qaim is the product of an alkaline is to put the substituent on the substituted carbon and that has to do with stabilization of cargo can answer canister that reason have developed the most selective reactions that do the opposite and so Hydra abrasion which 1 8 c Browne Nobel Prize ends up heading in the entire market sense in other words if you treat an alkaline with reverberating derivative beach to read and then you carry out an oxidative work up with sodium hydroxide and hydrogen peroxide you end up in getting the entire market of the cops since together the corresponding how the height of anyway your textbook gives a few more reactions and does a nice general
survey all synthetic reactions but I think it's really all review
tyrant when I would like to to do at this point is to really get us into the need of the material in the media of Chapter 21 is
going to be what I alluded to in the beginning of class this edition of nuclear files and 1 of the concepts that I've been harping on and will continue to harp on is the notion of PKK as a way of thinking about strength above base or strength of an acid or strength of a nuclear files so when I think about the reaction of carbonyl compounds and particularly the tones and elder hides with nuclear files In my mind I sort of grew nuclear files
into different types I think for example about some nuclear files as being very basic let's say Mary
strongly basic when already seen examples of this boy Our minus Alltel nucleophile yard reagents and Odonnell lithium reagents of course these are not needed card the covalent bonds between magnesium and carbon war between lithium and carve it but you can think of them from amassed mechanistic
point of view as AA-minus did things like hydride
nuclear files and again typically were not talking naked hydride we're not talking about each miner says a free species were talking about hydride in lithium aluminum hydride war in sodium bore hydride
nevertheless these end up reacting in many ways like each minus and when I think about these nuclear files I think OK
if I were to think of the conjugate acid of the nucleophile already rates flora and haloalkane I would remember all hasn't PKA of 50 and how Kane is a very weak acid it's not answered that if I poured into water I'm going to measure antiprotons and the acidity of the water will still be P 875 for put now came into water well would dissolve but if I
could dissolve but it wouldn't affect the acidity but if I had a strong enough basis I would need a very very
very strong base to
pull off that Proton ditto the conjugate acid of
hydride is hydrogen the PKK of hydrogen and up until this year output approximately the PGA of molecular hydrogen is about 35 then by comparison I might think of let's say from various strongly said 2 moderately strongly basic and these are all loose categories but for moderately strongly basic nuclear files can't think of things like hydroxide and I an al-Qaida and that means are a major issue for the primary Amin and did all I can think of a secondary Amenas or to when age and cyanide and not all of the conjugate acids here fall
in the realm of of but you would typically called a weak acid the things that you would think of as being a little bit acidic but not strongly acidic the
decay of the conjugate asset of hydroxide the conjugate acid of hydroxide of course courses water the PKK water is 15 . 7 the conjugate acid of alcohols is just about the same maybe a here weaker depending on the alcohol about 16 to 17 the conjugate acid of means is ammonium salts or NH the class for primary Amina or 2 NH H 2 plus for a secondary meaning
that PKA of conjugate acid of enemy of an ammonium
ion is on the order of 10 211 sometimes a law higher sometimes lower but that's a reasonable number and the last 1 of hydrogen cyanide which is actually wearable start our discussion of
reactivity because it has a nice simple reactivity hydrogen cyanide is often called the Hydro's ionic acid is
a weak acid with the PTA of 9 . 4 Our so that takes care of what I call very basic and
moderately basic nuclear files and you could probably predict that there will be others in that category
things like hydrogen sulfide where you have a similar sort of PKA but this is plenty to get us started then at the other end of the spectrum we come to what I'll call weekly basis nuclear files and by that point we're talking about things like water and alcohol it's very important to remember Water and alcohols are at the end of a terror compound so there's actually 2 PUK used to keep in mind if I'm thinking about water as a dates not as an asset as we just said but as a base I need to think of the conjugate Water that's the only a mine on each three-year-old applies the PTA and the hydrangea my on this negative 1 .period service if I want to think about the conjugate acid all and alcohol acknowledging that acid is ROH too last now a talking negative to and again is a sort of approximate values all old child approximately negative to turn negative rate start like to
start the discussion of the reaction with the reaction of strong nuclear files reaction about the hides and the tones with strong nuclear files and start with something with which you're quite familiar
because we've been talking about it for a while and that's the reaction with various types of alkyl nuclear files so that they take sodium must satellite Syria must set alight as I mentioned before is 1 that you probably can't think of a more ironic than covalent so it's sort of a nice analogy acetylene is pretty special the remember we haven't asked me to carbon Sowards allocations have a PKA of about
negative 50 of about 50 and AL teams were still kind of similar in 44 by the time you get to howl kinds and you have all that s character in the ch behind the CAT Fund is reasonably acidic is acetylene and are negative 25 so so I a satellite is still a very strongly basic
nuclear file and if I acetone with sodium a satellite and then I carry out make worked up with some acid you can write it is a story of Gloucester you go into the camp stockroom and you get some sulfuric acid and some water research some hydrochloric acid some water Uralkali enhance your Uralkali and and and on the overall result is an alcoholic reaction that you've seen in the last chapter and you've also seen as central to the displacement all before was so now let's think about analogous reaction of hydrogen cyanide and gonna write this 1st sorted in a way that may not be so obvious why the reaction is analogous verified
truly my alkaline might help my idea acetone with hydrogen cyanide maybe a little bit of
faces a catalyst we have an equilibrium of form a Suyono hydrant the hydrogen cyanide ads in the so the acetone and we get a product that really in many ways looks very analogous To the addition of a settlement now hydrogen cyanide is not something you wanna work it is probably the
most common the most poisonous commonly encountered compound in the EU organic chemistry lavatory hydrogen cyanide is
typically fatal at 50 mg to Dostum were specifically it's right on the edge of gas and Elect this boiling point is 26 degrees if you've ever work with methylene chloride or with each other in the camel have you know how volatile those are a few spell it evaporates immediately negative about 26 degrees evaporates basically right at room temperature so it's practically gas which means it's very easy to breathe in 50 mg so only slightly safer is not work with hydrogen cyanide as a guest but to work with a solid cyanide source and answered if we take sodium cyanide and sulfuric acid you generate hydrogen cyanide in situ and so it's equivalent but at least you're not trying to dispense this path which would have guessed this thing teetering on the edge and this is a very good way add cyanide to Aqaba compound to which each tone around the hive sodium cyanide is nasty stuff this was used in the gas chambers in Nazi Germany to kill people by this very reaction and it used to be used in our right in our gas chambers to kill people where he would mix with sulfuric acid so this is not a nice stuff to work with its very poisonous bite from a chemical point of view what we've done here is very cold we've formed carbon-carbon bonds and this is the basis for building up 1 basis for building up much more molecular complexity by forming carbon-carbon bonds from simpler molecules Argentine curiosity
what mechanism cyanide In what mechanism the cyanide to a homicide believe it binds to hear him before
so sigh and made carbon-monoxide nitrate dioxide I think all combined to your him modeled the various degrees but it's a nasty nasty places however I thought you were going to ask what mechanism does that add to the carbonyl compounds have and that the that question is 1 that actually brings us to the heart of of the mechanistic chemistry that we're talking about so that we can think about this mechanism as involving cyanide as a nucleophile and cyanide is a good enough nucleophile to add directly to carbon yield compared with so hydrogen cyanide is in equilibrium with cyanide and I and sodium cyanide and sulfuric acid is in equilibrium with cyanide and I have been so cyanide in can add to the carbonyl compounds like cells just as we've seen before electrons flow from the nuclear file to the Carbondale carbon from the Carbondale double bond up onto the oxygen you add you form on an island in Oxy and then in the 2nd step that Oxy and I and can program they can right is meeting from the hydrangea mile could probe made from another molecule of 8 CNN as well but electrons flow from the Oxy and to the hydrogen that in turn pushes electrons out of the OH bonds back onto the oxygen of and we get our society of Pfizer and so on what you can say here really a big
degree of analogy between the chemistry that you've seen thus far were that in alkyl metal and this new chemistry where were just standing a moderately basic nucleophile moderately basic nucleophile exists as an Anaheim and you can add to the carbon yield you get Alcock side and I and the side and I think people it the only big difference is with strongly basic nucleophile you can't have your Proton source present at the same time because the strongly basic nucleophile would react with your protons source and would be quenched whereas
the week the moderately basic nuclear can exist in equilibrium with the protonated form and so you don't have to worry about it being quite alright yeah textbook pedagogically does something that was very interesting at this point and at 1st it sort of surprised me and then I thought about it and
it made sense so the rest of this chapter is going to set us up for more complex reactions it's going to set us up for the
formation of a means the formation of acetaldehyde formation of him I answered tells as well the hydrolysis severe means the hydrolysis of the formation of the new means and all of the reverse reaction and at this point the textbook introduces a reaction that's a little bit of an oddball it introduces the Vidic reactions and when I thought about it pedagogically and actually made sense why they're doing this I think very few textbooks introduced the varied reaction at this point the Senate action is the reaction of a key tonal Ronaldo hired with the phosphorus elected to form and Elcano right this out and justice sectors but the gist of the reaction is that a nuclear is heading into your key morale the height and ultimately were pulling the oxygen out and replacing them following not half replacing their adding to it as we did here but were replacing it with a fully with the nuclear file and that theme is going to come up in the rest of the chapter In the formation of acid towels in the formation of INA means and in the formation of a means so let me ride out the reaction and explain how it works so we have a key town Ronaldo who might really have a carbon nucleophile called AD and delayed now right out the structure invariably it's of phosphorus In the Eliud services called admitted reagent In the election is a species where you have separated positive and negative charge said so we call this a phosphorus Illinois because we have set separated positive and negative charges on phosphorus and the overall reaction that occurs here again in very generic form is that we now will place the oxygen to get an owl came as a byproduct of the reaction member delegation writing by-products of reactions you get trifle philosophy and oxides try fell fostering oxide is not only something that's easy to forget about as a byproduct of reaction it's also a pain in the neck to get rid of that you're carrying out the the reaction in the laboratory there's a
lot of anatomy here 1 of the things you'll find it is in shorthand we often write pH as a fennel group so then write things out in longhand now for the conjugate acid of the phosphorus unless the
conjugate acid all the phosphorus Illinois is a try panel last volume salts and I'm now I'm writing the benzene is explicitly so you can see at least 1 time what we will for the rest of today's lecture
be riding out as pH and the main thing is being a vast phoneme salt you have a proton and that Proton is a certified by the positive charge and the stabilization that phosphorus mine
so the Proton is acidified it's a PGA is about In other words it's
right in that range kind of like a satellite a kind of like acetylene as far as its PGA goes it's at that very sort of lower range of strongly basis and there are 2 things that a super
stabilizing about this phosphorus 1 thing that stabilizing about the phosphorus is of course that you have the negative charge next to a positive charge the other thing in all right outside my explicitly for a moment here pH pH pH the other thing that specially stabilizing about phosphorus is
phosphorus is in that role of the periodic table it's down from the role from carbon and oxygen and nitrogen and and foreign it's in the role of periodic table where you can invoke the electrons were you have d orbitals and so we can write a resident structure that has more than 8 electrons around the
phosphorus and together these 2 residents structures up a more complete structure of the phosphorus so for these 2
reasons we have a good degree of stabilization a good degree of acidification of this Proton verses what you would expect for a plain old Qaim which would have a PKK about 50 alright so let's go on to talk about the mechanism of this reaction you can
think of the mechanism of this reaction as occurring in just 2 steps you can think of it as occurring in 3 steps reflects rights into and I'm going to write it now awaiting tell you why
it's been so much concern so you can envision that in the 1st step in Europe last versatility has a nucleophilic carbon and an Electra fell like
phosphorus and so 2 things can happen at the same time electrons flow from the nucleophilic carbon to other electrical like Carbondale carbon Adam and at the same time they can flopped onto the oxygen flat form a bond with the phosphorus so I should say we can go ahead and have a electrons flow like so forming a four-member grain called enacts a fast-food chain How right out the name for it and this is a media intermediate that actually can be observed experimental it's been debated in some detail whether this reaction occurs in a concerted fashion meaning both of these bonds are formed at the same time or whether they form 1st with the carbon-carbon bond and then in a 2nd step with an oxygen phosphorus fondant consensus from experimenting calculation seems to be on the conservative coming down toward the concerted mechanism but in some textbooks and in some places you will see a need to immediate right now but where are we still have a charges
separated in other words were 1 bond is formed before the other
visitor mediators called updated 18 and I have personally seen people yelling at each other over the distinction and
mechanism for your purposes it's not so important the reason this
reaction has been so hotly debated is it exhibits some mysterious selectivity toward forming a Cissell came just a little bit of Styria selective ease but enough to raise people's attention and for this reason also a lot of interest in a
2nd step but the odds of glass containing breaks down and the arts
surpassed contained breaks down again in a concerted process giving rise to the Albertina and try settle last seen outside like cell
and so through these 2 steps edition of the phosphorus the carbon yield to form an
OC so fast that tame and then break down of the OCS a fast pertaining to the allocation and the dried fennel fast-fading outside we can go ahead and form a new carbon-carbon bond
question was what I was you know what I would do if you like the rest this is the 1st time the 2
substitute which 1 here were before substituent side so 1 of the substituent says pointing out 1 is pointing back 1 is pointing out 1 is pointing back and getting well beyond the scope of the costs and you can read more for starters on Wikipedian the article cited there is this issue of walleye in certain circumstances you prefer to form of this upset the species but understood that for now because it gets well beyond the scope of the rest of the Class AA and I wanna talk about at this point about what 1 can do with it this is an incredibly powerful synthetic reaction we just want a carbon-carbon bond the carbon-carbon double bonds stitching together the 2 halves of 2 pieces to make a more complex molecule that powerful and it's interesting and it's mechanistic really interesting and for that reason Georgia where it won the Nobel Prize in 1979 for the discovery of this reaction let's just take a look at how 1 does this in practice so I'll show a couple of examples let me show how I'd do a very good reaction of cyclo Hexham known and so 1st I will go ahead and just show you the reaction of the phosphorus elated and all right in the other resonance structure both of them are correct Finex the phosphorus led and cyclone this is the phosphorus with derived from Apple's so I get the Ethel at the at Philippine compound I've added in these 2 countries comments and the other byproduct of the reaction is strike an philosophy not I like no in practice the way 1 carries this reaction out in the laboratory is you go ahead and you make the phosphorus selling yourself to Ivanovo philosophy and is a good nucleophile you can take an electoral like ethyl iodide and mix them up and you get try fennel for Estonian iodide pH 3 P C H 2 CH 3 plus time miners and now and again in the
laboratory you would then make your own Illinois you would go ahead and you eat tree you're Ethelred try fennel faster volume on diet with a strong base like bugle lithium fluoride in with
indicated the normal isomers 1 mural lithium sometimes you just want the lithium or you could use sodium and undermines both of them were strong enough vases remember the peak head of the conjugate acid of let the others that few conjugate acid is butane 50 the PTA conjugate acid of sodium and my is ammonia PKA
of 38 so they're both good enough basis to do it so that it will
generate power phosphorus illiterate Philogene try fennel fostering it's appalled and so that's kind of kind of music I want to close by comparing and talking a little bit about selective Wally this reaction is so powerful why the belated reaction is so powerful even so I won offer a comparison to the elimination reactions that you've learned about the 1 thing the to elimination reactions will just look at the 1 example if we want to make this same came my doing and 81 elimination reactions I might imagine starting with slight low had the knowledge in trading at 1st with Apple magnesium bromides and then doing worked out do you know the corresponding alcohol and now if I were to treat alcohol with sulfuric acid may be a little heat under dehydrating conditions share I get some of this product that I set out to make by the venerable reaction but I did it as a mixture of products in which we would also get the internal how he's and so much of organic chemistry is about synthesis and about control and the control that the Vedic reaction provides fees vary very powerful now as I hinted at before the other element of control and it's only partial control is that under certain conditions and in certain circumstances you can preferentially get this is came so if we have a Monroe substituted the very agree agent in other words a minute reagent that has just 1 hour our group behind and we have and how the we allow them to react we get a mixture of products assistance friends Alpena it's pretty hard to get just 1 pure while you can sometimes get the trains here but the Twins isn't surprising because trends out things are more thermodynamic was stable but what's interesting is that sometimes under some conditions this is product can be a major problem and this is surprising because it's Contra thermodynamic the more stable out
is the trends out came in the Cecile King of the 2 substituent from into to each other if I have sisters to Beauty and
the 2 medical groups gently banging into each other but says to butane is about 1 kcal per mole less stable than trends to beauty and part in part because of this surprising property of the varied reaction people have yelled at each other and debated and studied the mechanisms in tremendous steps next time we will pick up by talking about other reactions will talk about it means formation and new me information and their mechanistic reverse
Chemische Bindung
Hybridisierung <Chemie>
Fülle <Speise>
Elektron <Legierung>
Mas <Biochemie>
Bukett <Wein>
Internationaler Freiname
Elektrolytische Dissoziation
Aktives Zentrum
Setzen <Verfahrenstechnik>
Gangart <Erzlagerstätte>
Energiearmes Lebensmittel
Oxoglutarsäure <2->
Internationaler Freiname
Spezies <Chemie>
Alkohole <tertiär->
Dipol <1,3->
Konkrement <Innere Medizin>
Chemische Struktur
Fluid catalytic cracking
Aktivität <Konzentration>
Chemische Eigenschaft
Kettenlänge <Makromolekül>
Chemisches Element
Reaktive Sauerstoffspezies
Bukett <Wein>
Gekochter Schinken
Ermüdung bei hohen Lastspielzahlen
Advanced glycosylation end products
Single electron transfer
Funktionelle Gruppe
Aktivierung <Physiologie>
Acetylneuraminsäure <N->
Phantom <Medizin>
Organische Verbindungen
Radioaktiver Stoff
Entrahmte Milch
Chemische Forschung
Chemische Verbindungen
Proteinkinase A
Schweflige Säure
Einsames Elektronenpaar
Potenz <Homöopathie>
Substrat <Boden>
Primärer Sektor
Chemischer Prozess


Formale Metadaten

Titel Lecture 05. Aldehydes and Ketones: Reactions.
Serientitel Chemistry 51C: Organic Chemistry (Spring 2012)
Teil 05
Anzahl der Teile 19
Autor Nowick, James
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen 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.
DOI 10.5446/19409
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
Abstract This is the third quarter course in the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: 1:08-Carbonyls and Strongly Basic Nucleophiles 4:01-Weakly Basic Nucleophiles 9:56-Naming Carbonyls 14:22-Properties of Ketones and Aldehydes 16:59-Reactivity 19:38-IR Spectroscopy 26:04-Conjugation 32:12-NMR 37:52-Synthesis of Aldehydes and Ketones 47:14-Reactions with Nucleophiles 54:25-Acetylene and Hydrogen Cyanide Examples 1:00:16-Workup of Cyanide Anion Addition 1:04:15-Wittig Reaction 1:09:44-Wittig Reaction Mechanism 1:16:24-Making a Wittig Reagent 1:18:14-Wittig Reaction Examples 1:20:11-Stereoselectivity

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