AV-Portal 3.23.3 (4dfb8a34932102951b25870966c61d06d6b97156)

Lecture 20. Radicals

Video in TIB AV-Portal: Lecture 20. Radicals

Formal Metadata

Lecture 20. Radicals
Title of Series
Part Number
Number of Parts
CC Attribution 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
Release Date

Content Metadata

Subject Area
This is the second quarter of 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. This video is part of a 26-lecture undergraduate-level course titled "Organic Chemistry" taught at UC Irvine by Professor David Van Vranken. Index of Topics: 00:17- Pycnogenol 00:42- What is Pycnogenol? 01:11- Molecular Structure of Pycnogenol 03:22- 14.8: Splitting by More than One Type of Proton 07:55- 14.9: Time Dependence of H NMR Spectroscopy-Bond Rotation 09:42- 14.9: Time Dependence of H NMR Spectroscopy CHAPTER 15- Radicals 15:37- 15.1: Radicals-Reactivity and Stability 21:04- 15.1, 15.2: Reactions of Radicals-a specialized arrow symbol 24:55- 15.3, 15.6, 15.7: Selective conversion of tertiary R-H to tertiary R-Br 29:35- 15.4: Mechanism for Radical Bromination 36:26- 15.8: Carbon radicals react on either end of the p orbital 42:15- 15.10: Allylic Bromination 48:06- 15.13: Anti-Markovinkov of HBr to H2C=CHR 50:39- Chapter 15-Radical Summary
Ice shelf Water Vancomycin Stratotyp Alcohol Bottling line Chemische Nomenklatur Stuffing Circulation (fluid dynamics) Man page
Phenols Sense District Sodium hydride Setzen <Verfahrenstechnik> Recreational drug use Activity (UML) Chemical plant Hydroxyl Gold Ethanol Man page Klinisches Experiment Magnetometer Enol Altbier Benzene Setzen <Verfahrenstechnik> Naturstoff Phase (waves) Headache Gas PEEK Singulettzustand Gezeitenküste Protonation Circulation (fluid dynamics) Preservative Water Vancomycin Gesundheitsstörung Computer animation Curing (food preservation) Gasoline Radical (chemistry) Azo coupling Inflammation Proton-pump inhibitor Chemical compound Breed standard Extract Lambic Isotopenmarkierung
Digital elevation model Setzen <Verfahrenstechnik> Bohrium Chloride Calcium hydroxide Chemistry Optische Aktivität Alkene Molecule Electron Altbier Insulin Library (computing) Toxin Hexane Oxide Coordinating European Council for the Development of Performance Tests for Transportation Fuels, Lubricants and Other Fluids Substituent Organische Chemie Doppelbindung Topicity Multiprotein complex Electronic cigarette Food additive Emission spectrum Lava Vancomycin Azo coupling Zunderbeständigkeit Bromine Cobaltoxide Stuffing Biomolecular structure Ethylene Ionenbindung Recreational drug use Atom probe Action potential Wursthülle Methylgruppe Man page Cyclooxygenase Lone pair Ageing Magnetometer Lactitol Elektronentransfer Atom Halogen Process (computing) Setzen <Verfahrenstechnik> Mixture Alkane Solid phase extraction Arginine Bromide Hydrogen bond Carbon (fiber) Protonation Electronegativity Amrinone Water Hydrogen Valenzelektron Computer animation Functional group Radical (chemistry) Chemical structure Lambic Nitrosamine Ammonia
Semiotics Chain (unit) Antioxidant Haloalkane Bohrium Cell growth Chlorine Atomic number Calcium hydroxide Molecule Electron Click chemistry Elimination reaction Toxin Periodate Koch (surname) Walking Katalase Chemical reaction River source Solution Electronic cigarette Lava Vancomycin Optische Analyse Dominican Republic Hydroxybuttersäure <gamma-> Chemical compound By-product Bromine Cobaltoxide Thermoforming Stuffing Stereoselectivity Biomolecular structure Calculus (medicine) Ionenbindung Biosynthesis Kohlenstoff-14 Sodium hydride Reaction mechanism Spaltfläche Wursthülle Bis (band) Man page Diet food Ageing Stress (mechanics) Magnetometer Elektronentransfer International Nonproprietary Name Mixture Atom Process (computing) Setzen <Verfahrenstechnik> Area Selenite Pond Solid phase extraction Semiotics DNS-Synthese Hydrogen bond Carbon (fiber) Protonation Spawn (biology) Electronegativity Hydrogen Gesundheitsstörung Computer animation Radical (chemistry) Functional group Anaerobic digestion Coordination number Coca Pan (magazine) Carbon dioxide Substrat <Chemie> Base (chemistry) Stiffness
Ethylgruppe Kohlenstoff-14 Mixture Katalase Protonation Methylgruppe Man page Vancomycin Gesundheitsstörung Computer animation Radical (chemistry) Functional group Library (computing) Substrat <Chemie> Bromine Biomolecular structure
Semiotics Setzen <Verfahrenstechnik> Atomic absorption spectroscopy Bohrium Battery (electricity) Hausmannit Operon Hydro Tasmania Calcium hydroxide Molecule Electron Aerosol Sauerrahm Nana (manga) Elimination reaction Medroxyprogesterone Doppelbindung Concentrate Mashing Oxycodon Addition reaction Chemical reaction Anomalie <Medizin> Electronic cigarette Wine tasting descriptors Vancomycin Hydroxybuttersäure <gamma-> Bromine Medical history Cobaltoxide Biomolecular structure Pipette Stereoselectivity Ionenbindung Kohlenstoff-14 Species Reaction mechanism Benzoyl Sprayer Plant breeding Substitutionsreaktion Hydrogen peroxide Wursthülle Man page Nobelium Ageing Magnetometer Enol Lactitol Acetonitrile Active site Calcium ammonium nitrate Mixture Atom Process (computing) Setzen <Verfahrenstechnik> Phase (waves) Pond Arginine Peroxide Hydrogen bond Deposition (phase transition) Carbon (fiber) Spawn (biology) Hydrogen Gesundheitsstörung Drop (liquid) Computer animation Radical (chemistry) Functional group Chemical structure Substrat <Chemie> S-Adenosyl methionine
Chemical reactor Vancomycin Computer animation Microscopy Firn
study by the local Trader Joe's supermarket yesterday morning to pick up some water and I turned around and I stalled on the shelf behind the checkout stand there were some
bottles of something labeled technology knowledge and never heard of but that sounds like a chemical name ends in all its it's some sort of an alcohol it and so I immediately got interested in what is pignogenol that they're selling to people it says here that may support healthy circulation exclamation point so what is this stuff turns out the
pignogenol is an extract of the part of these pine trees called the maritime kind and that the trader joes version of this is isolated from the French version of the maritime prime-time Skymaster very excited about the idea that you knew taking pine bark and extracting some useful things that maybe I could make to yet of my own pine bark at home and have some therapeutic benefit to that to
my disappointment it turns out that pignogenol is not actually won chemical compound that has an ideal act like to a it's it's actually the extract is actually a lot of different compounds dozens of different compounds on it in order to label anything pick Eugene also pignogenol is this crude extract the U.S. Copia as laid down the law saying it has to contain these for natural products that you'll find in lots of different plants in extracts of you'll notice into to these are very similar Vatican in taxable in these 2 were not us quite so similar Cafe gasoline gasses and a common feature of all these as they are phenolic they have hydroxy groups attached to benzene rings anytime you have a hydroxy group directly tied to a benzene ring you can expect that at antioxidant activity of the kinds of preservatives that they put in dictatorships have hydroxy groups attached to benzene rings but that's not that spectacular there are a lot of companies now sell technology in all these extracts that come from this French maritime on and so the question is does pick Eugene all this this bark extract releasable healthy circulation I don't know that there's actually clinical trials that have gone on many different clinical trials nothing beyond Phase 2 of which would be the gold standard of approval maybe it does look like it probably does of course still disastrous so destroyed their lots of compounds that can in the UK and improves circulation and would be related to things like heart disease Alzheimer's disease anything involving the brain headaches inflammation of men applies so so it may be active ports that but there's lots of things attractive for circulation is it's going to be the next big hits like the Staten drugs that have all gone a long way to cure heart disease in the United States but I'm not going to bet money on them but very cool the name is very cool OK so women exam coming up on of on Friday so remember to to be here in your seat at 7 55 so we can start date in part because we had a very limited amount of time you know there's a classic comes in here after us every your ID for that already Postiga see descends on the great book and so be ready to assigned seats but the problem set for a is do this evening and I got 1 last little snippet to cover about for a couple of little snippets here to cover about a before we start on this next chapter which is radicals that I didn't quite have time to finish on so there's 1 important feature that I was leading up to it and let me just let me just succinctly state here that this splitting really complicates an and it can make a margarine and simple seductively simple looking compounds will have complex looking in on Mars if you have multiple different types of coupling going on so stick an example of this type floral arm Tyrol compounds and don't worry about the name that is 3 protons on here and what happens if the coupling to each other with different magnitudes of coupling constants this will create huge headaches Indiana Moran we refer to this these types of effects is higher higher water splitting off and and basically I'm not going to have this on my exams higher water splitting it here taking became 52 then you need to know about higher water splitting if you made cycle Texan owners some sort of TV will cycle examining the can 51 while you weren't able to interpret all that and because of this type of high water splitting so just to give you a sense for what's going on here imagine taking 1 P 1 proton and Marquis and then having its Split by some neighboring protons to give 2 peaks and so prices but that peek into 2 pieces now will look like this and there's going to be some coupling constant associated with that soldiers measure that coupling constant J equals 7 her as it doesn't matter what the coupling constant I'm just trying to help you imagine what happens when a peak it splits into 2 peaks by some magnitude and now let's imagine there's a 2nd Proton is splitting this and now this this on this peak get further Split it's another more splitting and now this can further be split again by an even larger magnitude so imagine taking this pair of peaks and
on all I can do this with my fingers here and splitting the parakeets even further to make for PCs and so what you'll end up with is a pattern of 4 peaks here it is now explained again and I'm really exaggerating this you so now I can go from 1 piece but with 2 different types of splitting it can create for pizza out of so you could still see there's that original coupling in here but in addition to that there's a bigger coupling which I have grossly exaggerated so that new bigger coupling there would it's more than twice as big a can tell by my either just imagine it's only twice as big as 15 hours so this is what happens when you have 2 different types of coupling that aren't of the same magnitude that you can go from a single it's too acidic for peace and what is important is that those who were peaks are not a quartet that is not adequate technical that adult little doublets here's a double-double double extended my spectrum here's a double of its and the reason I know that's not a quartet is because a quartet has peaked ratios of 1 2 3 the 3 2 1 and I don't need to see any exact integration there to tell that is not 1 2 3 2 3 2 1 those sets of 4 peaks here look closer to 1 2 1 2 1 2 1 so that's not a quartet so every time you see for peace even as they look like they're equally spaced it has to have at 1 2 3 2 3 2 1 ratio for Duke to call a quartet eases double that of it's OK so splitting can become very complex when there's more than 1 type of protons and I'm not going to put examples like that on the exam on it's important stuff for interpreting and not Proton Mars for more complex structures hands enough said about that and again it makes Proton very complex but once you learn Proton and what makes it very powerful to help you deduce the structure of organic molecules OK so an important feature that I already mentioned them Mars has to do With the equivalence of protons that is created by bond rotation so 1 of the most common situations where you encounter that is a medical group so in other words all of these protons on a methyl group and on every methyl groups are indistinguishable by an animal the ages on a method would bring this to indistinguishable because I can rotate about that bonds and once I rotate you you can't tell which Proton was which before I rotated and so that crosses all the protons on any method would be indistinguishable but remember you cannot rotate about but a double bond on the enema timescale on the laboratory timescale on the timescale of your four-year degree here UCI that double bond will not rotate that meets the age cities next sister the brown leaders into the bromine is never going to experience the same environment as they age that hinted to the browning so you have to look for a double bonds but there's a potential for ages attached to double bonds due to be distinguishable and to give unless there's just some weird cemetery be different if there the 2 protons on 1 card of overseas you double .period so bond rotation can make things identical not all processes on the molecular scale fast relative to to the Panama experiment and so this is the last thing that will say about Our about Denmark so on rotation makes things equivalent makes the ages of methyl groups equivalent on the timescale and give you an example of another process it's not bond rotation that makes things equivalent and it's it's kind of not important she cared so much for this on for this chapter but coming up in Chapter 25 at the end of 1051 seats this is going to be sprung on you go all you knew this but you will have forgotten by that and some just going to tell you now I'm right and I'm telling you you're going to forget it so that when when you're told you're supposed to remember it all of that the little jobs some neurons focus when you take means like ammonia ethylene mean that's the whole chapter 25 is all about it means there's a long hair that makes that parameters and so when you look at that you might think that these protons could be dire scary topic if there was some Cairo's center nearby or some other kind of center in the molecule but the important thing about it means is that they rapidly in invert and again will cover this in Chapter 25 the idea that means rapidly and In this inversion process kind of like an umbrella flipping inside out is so fast that those 2 protons will be able to effectively switch their environments so that fast rapid process there having prototype of that flipping through means arm and makes protons and most amino groups indistinguishable if you haven't managed to group the pages on 2 Gruber indistinguishable even if they look like they're dies .period dies during topic so on just right never dies scarier topic no matter how many other scarier centers or other features are in the molecule Tyaskin radio the company and it's because of that last
fast-food take a look at another type of process that is not on rotation that can allow protons to switch places very rapidly so you need to imagine this picture were retaken molecules and I'm going to do my best job here to draw a chair Nunavut years of practicing but I hope you've been practicing drawing cheers so in my example of chair and when I dropped the 2 protons here on the right-hand side the writing and carbon molecule they're not identical 1 of those times axial and the other Proton is Ecuador and that's not the same so I have an axial Proton Equatorial Proton the distinctive that experience different environments coupled with each other with other protons in a different way axial in Equatorial but with different coupling constants but because shares slid very rapidly on timescale Indiana experiment what happens is you pulses with energy and the molecule sits there and wallets sitting there waiting to emit its energy back will flip many hundreds of times so drawing the chair flipped Virginia so I don't know what you're good at drawing 2 different types of chairs cheerfully but you need to flip that year I'm good at that because I've had lots of experience but you should get good at that I remember when I was an undergraduate at just sit in your chair after chair after chair practicing to see how good I could write you may think all to work I was and what I notice that most of my colleagues and going into organic and you into that kind of stuff it turns out that it will draw interest of PC anti-terror cleaner relationships that still really important skills so now the top Proton was axial it is now in Pretoria In this Proton was going down that was Equatorial is now axial so that fast armed wing flipping causes axial an Equatorial protons to rapidly exchanged so unless you have some big bulky group on here that prevents when flipping like a TB will grow on you can expect cycle had seems to rapidly flip on and cause the siege to the ages the siege choose to exchange positions so in other words when I go take the spectrum motorcycle hexane I don't see the difference between an excellent tutorial protons they'll look identical but in the last issue of the above things that might prevent splitting is something very talked about before that is hydrogen-bonding so as we mentioned before you can't see any typically in most cases so and 95 per cent of cases you what you won't see any splitting between OH protons and that the protons the on adjacent cartons and that is simply because hydrogen starts there's so many zillions of different ways that this can hydrogen back and forth between except a Radames and soldiers put a water molecule here there's so many different ways that Proton can bounce back and forth with water molecules on them on time scale with the Chelsea and any coupling between protons in the neighboring Proton so don't expect those are things that are fast on Newmont timescale that this proton transfer of this bond vibration of a hydrogen bond is fast and in time scale so you don't see splits but they selected friend come again when not going higher water splitting on my exams but you should know what that is and when you run across that for example when you run across a doubling of Dublin you should know G that's not a quartet is something else going on but this was no longer Chapter 15 it's it's actually there's not a lot of it looks like there's a lot of stuff in that chapter but I'll show you why there's not a lot of stuff in the chapter in Toronto radicals you can have people that are radicals radically different from what 1 talk about radicals in the context of organic chemistry and what I want someone to give you a series of of mutual radicals that that will be common when we discuss radicals in organic chemistry so we can talk about stability and I'm going to to show you that we know If you want to have an unstable radical Amistad by drawing this radical This is what I would consider to be a reactive radicals it's an oxygen atom and it's an oxygen atom that has only 7 electron but it's not an outcome oxide mining it was no H on an oxygen NOR group the it's missing something in what's missing is the 8th electrons and oxygen as a lecturer negative you know that so you can imagine how angry that oxygen and is that it only has 7 electron here's an elected negative toxin and I promise you that I think is going to pluck some sort of an atom from somewhere in order to make itself had very selfish very angry it's going to pluck an of something and will cease and stuff like that to get sticker less electoral made about something that's not what I'm going to use I'm going to draw up but some radicals in terms of increasing stability increasing stability and and at the high end here this is the most reactive and least stable so now and I'll Cox the radical is the least stable in this series but it is the most reactive and the most and have so it's compared to a halogen I control of chloride it's the same idea but I'm going to draw bromide which is more commonly does more useful chemistry bromine is not as lecturer negative oxygen so you can guess it's it's not happy but it's not because it's not going to be as reactive as an oxygen based radical and so you know if I compare these oxygen radicals and more reactive than sealed yelled out and once again is only 7 valence electrons bromine and when use the term architectural because bromine is not in the 2nd row of the architect rule is only for 2nd row Adams and so you can have more than electrons on a bromine atom but in this case it once the valence electrons because that's the important ideas here OK so what of bromine radical as more reactive than a radical that centered on carbon so that if I come over here and I draw a series of carbon-based radicals and each other drug use and black so it can be consistent here I'm going to start by by drawing 3 different types of carbon-based radicals and the difference here will be whether the primary secondary characters attrition a primary radical is less stable than a secondary radicals and that's less stable than a tertiary radical so as I go through this series Of primarily 2 secondary and tertiary they get more and more stable again the carbon doesn't have an architect it's only got 7 electrons that can't possibly be happy but the more alkyl groups you have the happier that carbon radicals going to be the more alkyl substituent and this just like out I don't think it's that that's that weird cargo can a happy because they only have 6 electron but acting out programs to make them happier so it's the same idea with radicals tertiary radicals but there is this this change stability as we walked through this series that the primary radicals are more reactive and less stable secondary radicals are in between and tertiary radicals I tend to look rather stable to me is not stable enough for you to isolate them require some weird structure on the list of those 3 types tertiary radicals are the most stable and primary radicals were actually very hard before OK the last structure on Monday joined the series is a rather special type radical it's a radical that's primary but it's a special type of primary radicals and that would be 1 that has the carbon-carbon double bonds next door another words not not where the carbon is part of the CEC double bonds that would be just insane and crazy and state but if this if this CH 2 group is attached to a double bond problem that is going to have extraordinary stability and we'll talk about them so that I would consider that to be a really stable radicals and we call that an hour that OK so there is this trend collector negative Adams they want 8 electrons not 7 oxygen radicals are angry and reactive carbon-based radicals are more stable but that depends on how many alkyl groups attached to many if you going to form a carbon-based radical and you really want to form a tertiary carbon-based radical 1 that's alone this OK so we're going to
on introduced various different type of error pushing for talking about radical reactions I hate this because it's so hard to get ready there are pushing down the idea that just for 1 chapter I'm going to introduce a single type of pushing that we only use in this chapter and we never see again the chemicals me because I feel like pedagogically that's not a good idea so let's let's take our angry oxygen radical who it really wants to have electrons and with just imagine that advances into a piece of your DNA and look at that Proton and not Proton that hydrogen atom there the hydrogen atom has an electron it when oxygenates radicals collide with your DNA they will pluck hydrogen atoms off the genie back this is why everybody talks about free radicals and all what you should take antioxidants and it's not toxins where it's free radicals on oxygen that they're worried about what will happen is that this oxygen will pluck off on it this hydrogen atoms and it will leave behind a carbon-based radical that's more stable the original oxygen radical the oxygen base radical was not stable now that oxygen is happy and need some way to depict this process where the change moved from carbon dioxide you and brings with it a single electron and we can't use the regular error pushing that we've been using on throughout the book and will continue to use wrote the book we need a new type of error questions and the types of errors that we use ,comma recalled official heroes so here's the way we use fish appears I'm going to take this bond here we know that the HC bond has to bring 1 of the electrons in the HC bond goes back to carbon and solve depicted with a half headed and there notice that little cafe looks kind of like official upside down so we call these officials here or have headed areas you may not have noticed this but when you do the Sapling problems setting you draw arrows Ferrero pushing mechanisms if you click on the area it toggles back and forth between double-headed in single and work some form of sampling problems where you use that feature where you click on the use tactical whatever mouse click on the Aguero and Soviet toggles back and forth between the double-headed in single OK so there's a 2nd electron respond when I break that bond and do something with it what I'm going to do is I'm going to depict using a 2nd of the 2nd electron and bond we combines with this With this from single electron this unpaired electron and oxygen in order to make a new bonds some notice what happens I don't show some error going from electrons in attacking protons none of these heroes ended on a proton this is totally different from the regular error pushing that I will use before it's an accounting device just as an accounting device to help me see where the electrons go this 0 . electrons and 1 of the electrons from this bond combined to make annual wage from there I'll just darkening blue so minimal it's dark and handed it to see there's 2 electrons enters the 3rd electron can still sitting here on carbon OK so that sufficient hero pushing and we won't use this ever again after this chapter so I'm not a big fan of forcing you to stop and on this new type of error pushing that alone but we're going to have to do that and you may end up on some standardized exams that some .period staring at the stuff and you'll need to know how the house its focus on a new type of error pushing just for this chapter ends and not beyond this chapter yes no there's nothing in this chapter 15 will be an example this is all for the final exams and will be wrapped into the final exam somehow the the exam on Friday will just covered through Chapter 40 in March after with at 11 12 13 and 14 but that's not to say if you still have to investors are lecture today in OK so well OK so please this reaction the reactions of radicals turn out to be but sometimes not obvious at their occurring underwent stress the seating mechanisms you don't understand many times those involve radicals let's take an example of a reaction that involves radical and it looks like it involves raid reagents that you've seen before where take bromine you've seen that region before simple helpings and think you've seen regions flexible before those generally don't react but if we choose our conditions carefully look at that I just added a leading group think of all the things that you can do with that continue to eliminations as in wondering actions the 1 elimination reactions when we get to Chapter 20 will show you how to make a super-powerful nucleophile called the green yard reagent out of that I could start something that has no functional groups on and using a simple reaction and there's 1 secret key that I need to remember here and that is we need something to make this work basically we need something to generate radicals and that is energy is 1 type of energy use light you need some sort of photon source in order to get some radicals going in this reaction and the book gives you another way to do that all those less common and that is he less of a fan of showing you heat is a way to generate radicals because it looks so much like a non radical reais heating stuff we've been doing another chapters I have generally choose you know the book says OU's use either 1 I'm not sure why they tell you to do different things when 1 I just tell you like OK so yes if you hit it hard enough you could get some radical stuff going on but it still doesn't notice nowhere above the hero does it say radical right you you can't just look at the reagents and wall as soon as I see light and thinking about OK there's another byproduct here you may see a former New Carbon bromine bond because I'm trying so hard to make a big deal out of this but I want you to notice that something else happened here and that is that I broke the Scot denied him by and in some ways that's as important as seen in the fact that I formed a new common roaming so at that age Soviets in the byproduct for the reaction the byproduct of reaction we generally don't care about is each yard so they were 2 bromine in 2 1 went to the Al 1 wanted HBO Now hypothetically you could do the same thing with the problem is the chlorine ends up everywhere right if you take chlorine and apply the same conditions you end up scoring all over the place in this case above what I showed was the reaction is selected for tertiary indeed there is a phenomenal degree of selectivity here and it goes like this but when you do this reaction tertiary or ages Alcatel carbon hydrogen bonds are much much faster to react then secondary algal hydrogen bonds and that's much much faster in fact I've never seen a case where this
reaction can apply 2 a primary calculus hydrogen bomb it's very selective and in general in almost all cases you only use this for tertiary carbon hydrogen bomb so you notice of all the different types of in the substrate only 1 day after the tertiary Ch the problem with chlorine when you try to do chlorine in this reaction he reacts with every type of CH pond nite and since that's useless I'm not going to put it on my exams I'm not going to discuss that I'm not going to ask you questions about coordination and there is no use to that because it gives you a horrible mixtures of stuff but why should why should we spend our time but what what's ironic to me is the book lovers that heckled subdivided is good as questions about stuff that's not useful but it's abomination is useful could because it's so selected for tertiary expenditure and it's going to be useful to you now that it now that I've taught you how to add function rooms where there was no functional group before you can think of all the synthesis questions and I'm going to ask you where you start with simple outings and had meaning groups to them out of nowhere OK let's talk about the mechanism for their reaction to what's going on there when I bromine hands and candlelight heat so I'm going to draw 3 steps here the 3 steps involved in that rumination reactions and start up by drawing up In bromine and the key thing is that whenever I see 2 electoral negative ad oxygen oxygen chlorine chlorine bromine and bromine with 2 elect negative ads tugging on each other those bonds are weak and all have a tendency to pop apart to give too radical not to give up cargo can and our dog cat 1999 but to give to radicals that Aguero pushing to depict that bond cleavage and we have a certain name for this we call this whole analysis the bond is cleaving ,comma lyrically and even way so that each bromine gets a single electrons and that's how we depicted with that official hero pushing and so that those products that we get out of there are 2 bromine radicals now that's what I call the bromine bromine bond week it's not like every bromine bromine Landis it is falling apart it's only if you normally get a tiny amount of these things in solution so that all just destroyed small amounts you only get tiny tiny amounts of bromine radicals floating around in your reaction mixture OK so what's the energy just remind you of the energy that were using it in order to In order to create that on like this 1 and we always symbolize that with with each new so Planck's constant times at times the frequency symbol new at equals each new ones for the book puts or heat I favor the light so you'll find that when I write questions I was right polite version because that's the distinctive from anything we've seen in any other chapters OK what tiny amounts of br .period doing as they float around in your reaction mixture got the .period floating around in it's not happy with draw the 7 electrons it was not happy beyond minus is happy with the charter yacht doctor With just that unparalleled from isn't happy and so when it comes along it collides With an allocation ch bond it's going to abstract a hydrogen atom it is going to pluck off a hydrogen atoms from that part of it and as I drawn it's a tertiary ch was a particularly easy to pluck off and I need the uses aerial pushing to depict that marriage should you works I need to show how this carbon hydrogen bond breaks so I'm going to form a new B R H bonds all do that by taking 1 electron from here now take 1 electron from here that's going to former Bureij bond and it's going to leave behind 1 electron carbon atoms and again that's this very weird official hero pushing that you have to get used to this there's might be arranged bond that's happy per cent so now the carbon is unhappy maybe it's not quite as dangerous as the bromine radical was good renowned in this situation where the carbon is not so happy you know carbon once had the electrons and so let's take a look at the fate of this carbon-based radical all draw again down here and now what would have happened not hypothetically it could bounce into another tertiaries carbon age but from that would be a very slow hydrogen atom transfer and notice how I'm avoiding calling this a proton a Proton has no electrons with the when br .period pulls off the H is bringing an electron with it and that's a hydrogen atom H with an electron is a hydrogen OK so when when this carbon radical runs into a B R 2 molecules right not all of the br to normalized only small amounts of the home lies the rest of the bromine just floating around his R 2 and as soon as that carbon radical bounces into a bromine it abstracts it pulls off a bromine atom and I'm going to use pushing this characters and once again to depict so the 1st reaction we extracted a hydrogen atoms and in the 2nd reaction is carbon radical abstracts of bromine from Riyadh to most of the bromine is just the floating around as br 2 and never got formalized in the end result of this process is that it makes a carbon bromine and now the carbon is happy and what's the leftovers here now we're back to the yard so you could see he was going to happen the diet is going to come back and find another haloalkane so you start would be our dogs that after 2 reactions you've regenerated another R . and this change process will continue in a chain it's called a chain reaction over and over and over and over again and the end result is that you're converting C H bonds in the cotton grown bonds that's the end result of this process and at any point in time there's only small amounts of radicals floating around in reaction to notice the language that I'm using on the institution and market test you understood the language that using as I call this hold analysis where Cleaver bond where bonds simply flops apart as only weak bonds that do that oxygen oxygen bromine bromine these 2 steps down here I'm using a different turn that we never use we have used before next abstract I abstract Adam had struck the hydrogen atom up above here here I am extracting another at the carbon radicalism distracting a bromine atoms and words it's taking the atoms and 1 of the electrons from the bond so those are very classical radical reactions over the use of force lingo descriptions that use this look at radicals and generate some scarier chemical
consequences that arise when we talk about making carbon-based radicals so when I come but let's just imagine going to take a substrate here try to draw this out the way gives me a little bit of room but when it is a major draw Cairo center and here's my protons it's shares there's only 1 tertiary Proton hearing the substrate so this carbon atom in the center In it I have a methyl group going back I haven't group coming forward and either approval group so methyl ethyl improbable been so there's only 1 tertiary CAT Fund the substrate if I if I take that and I apply it to my conditions of bromine that's 380 use lots before this and then I shine a light on that in our
land we have you know it's not a fancy light light by from Home Depot so you don't have to use super fancy light with most of the common reagents and the product of this reaction is that we replaced the Ch and his mind you carbon bromine bond and immediately I'm thinking cash I really wanted some S N 1 reactions with battery to elimination all the things you can do with a ,comma tertiary carbon bromine bond but let's take a look at what's going on in this reaction and I'm not going to show how "quotation mark you hold lies the bromine bromine bond generate br got and I'm not going to draw I guess I could draw when I draw out this this hydrogen atom abstraction just to give us even more practice With this fisher caricaturing years are br . floating around it's looking for some choice easy Proton hydrogen atom that it can pluck off here's the bond Celtic this electron use official Caro will take 1 of the electrons from the siege bond and there Idaho depicted I'm going to form a new Bureij so what I do the other electronic within this carbon hydrogen bonds I have to do something with that so why I take the remaining electron from that ch pond and all deposited on the cross so once again that's the use official Caro the point is that we make a radical here that is essentially playing it's not perfectly plain error but it's essentially playing so I'm going to do my best to draws resulting radical as a planar species a job so here's my my radical and here's my my orbital my empty not empty it's half field this is happened although and it's very people it's almost like there's no significant difference between the top and the bottom face after this radical and draw that 1 unpaired electron I could draw in either the topple over the bottom of it spends 50 cent it's time each will come back and even face the local so the important point here is that this is essentially playing what that means is that as I showed you before this and radicalism happens it's going to react with a B R 2 so when 2 comes along the B R 2 can collide with either top face to the bomb phase of this molecule 50 per cent of the time will collide with the top place the other 50 per cent of the time the bromine will collide with the bottom face and so in the end what you end up with is a mixture of products where 50 per cent of the time the carbon bromine bond is on the top and the other 50 per cent of the time the carbon bromine is on the bottom sold all my fish gear operations here so you get an equal mixture will lose the state even if he started off with 100 per cent of carnality ones sterigenics center there will end up with a mixture so here's away again I'm going to show my care personal take 1 electron from his car and radical and recombined with 1 of the electrons from this bromine bromine bond that will make a carbon roaming bond notice I never showed anything attacking bromine that's not the way Fisher heroes work now include 2nd electron from Edeline brilliant bond and I'll give it to the other bromine and that's simply takes experience and practice strongly sufficient care to get a feel for how they work OK so because these carbon bromine radicals are essentially plainer but you get to this effect were dead the top or bottom with equal facility so top or bottom of the the of that cotton radical that's nearly plane in now there are other reactions of that involve radicals that arm and in particular the book has an entire section about Floro carbons In fact this is the basis of of the ozone layer being very sensitive before requirements that they used to use when I was a kid in in all kinds of aerosol spray cans on the former colleague Cheryl won the Nobel Prize for showing that this type of radical abstraction process is a problem and destroys the ozone layer and I we just don't have time to put their minds and read about it in school and puts you in touch with the history of our department that I want to ask you it's most of school we focus so replacing tertiary stage bonds with bromine super useful by you can start with no functional groups whatsoever and introduce functional but that's 1 of 3 important reactions in this chapter initially important reactions also mindful of the action number 2 see you can replace tertiary C bonds bromine laugh at how awful Buccaneers reactions not quite as powerful and I don't know what the book loves this reaction but I'm going to do is I'm going to take an Al-Qaeda will you've seen you've had an entire chapter on I'm going to show you related we mention sometime in the past but wouldn't go into much detail it's called Enbrel most succession and many remind you what Enron 6 centimeters and don't need to remember it I'm not going to draw the mechanisms for you I don't want you to try to draw the mechanism for this because you won't be able to resemble music sentiment the usually and I italics you pack rules say that the end then I italics if you have to write that out so here's a recipe would take and Romo 6 sentiment and we take life that's supposedly new I'm not doing good it's not actually it's Taichung knew that's the Greek letter New he calls Greek new England and we can replace we can convert to al-Hakim's and our effectively what you're doing is you're replacing 1 of the Ch is that's next to the double bond with the carbon bromine and so let me show you what am that this reaction is amazingly complex What is this and yes for the only reason they're using and pro-Milosevic sentiment in this reaction is that under these conditions under the conditions of this reaction NBS generates
very small amounts of bromine at low concentrations so really it this is a reaction of the artillery just plucking a hydrogen atom just like the tertiary ch substitution reaction so wanted to destroy peer-to-peer because you know what I concentrations of br to do you already know what happens if you don't be are too high concentrations in Elkins they had roaming across double what it would not work if you simply will be are 2 above the year-ago because you would get the diver online so NBS is a super-secret reagent that under these conditions generates very small amounts of bromine at any point in time in reaction to and I'm not going to talk about how that happens it's not important that the 1 thing I will show you is that there's there's all kinds of Lula carbon hydrogen bonds here and I'm just going to draw 1 of them ball drop to have them here and so you can imagine what would happen if a B R . abstracted a hydrogen atom From come from 1 of these 2 positions here what you would generate is a carbon-based radical that is stabilized by residents so here I'm going to draw this carbon-based radical there it is if I plucked 1 of those 2 hydrogen atoms and all draw the other hydrogen and they're just so we can see that 1 of them is still there and that radical stabilized by residents let me draw residents structure and I will use error pushing facial care rose to depict how I get from 1 resident structure to the other so take this electron and 1 of the electrons from this pipe bombs and I'll create the new pipelines narratives and then with the remaining electron that was in this there was on all deposit that electron back on this carbon atoms on the and conceded resident struck from going to create His still another our radical so that's why radicals are more stable than tertiary and there's 1 the sites will draw now this is a very carefully chosen substrates it's carefully chosen because on the starting material when you look it was another set of ch is on the other side the indistinguishable from right bills because the the substrate is so symmetrical the CH chews on each side of the double Bonda indistinguishable and moreover it generates a radical that is also by symmetry I been symmetrical so what happens is this carbon radical will abstractive bromine From br 2 that's floating around in small concentrations in the reaction and it doesn't matter which end you extract of bromine atom on because by symmetry if I attach a bromine here it's the same as if I attach it to the remain on the other side you just flip the molecule over and they will look the same this reaction unless you use it on Super symmetrical substrates will give you lots and lots of products and the book is not totally clear about that it only gives you useful product mixtures if you use it on Super symmetrical substrate so I'm not a big fan of reactions that requires super special substrates on his arm so I consider this to be less useful than just replacing tertiary stages With bromine so that's not a barrier so cannot quite as useful as replacing tertiary ch OK so that's the 2nd reaction a little like rumination here's the last reaction that's important in this chapter 3 reaction the importer replacing tertiary ch is 2nd reaction replacing ages using and Roma 6 Senate and yes here's the last reaction so the last reaction is adding HER crossed double bonds and that may surprise you because you've done that before taken out Keane let's take HP are Will you see not for and the key here that should clue you in that something is different is that they write this this is a peroxide it an oxygen oxygen binding conceded has an oxygen oxygen binding so R O is the symbol for peroxide as soon as you see all 0 are you know this is not going to be a regular HBR addition across a double bond so you can recall from Chapter 10 we did this over and over and over again you took out the duet HBO and the bromine ended up substituted at the more or ended up attached to the more substituted carbon that double want what's going to happen up above Indiana peroxide in this reaction is the bromine and ends up at the last substituted double and there's an age they get attached to your article draw for you just to make sure your clear where that each went a chance up at the least substituted so and in the framework of Mark Connor ,comma offices in Tema ,comma cops selectivity we refer to this as anti-American across selectively reduce selectively and it's all has to do with this edition of peroxide peroxides and I think the book mentions always tries to tell you that you can just use the so I've just like for this but really you need a peroxide initiated so many demystify the peroxide business for you but this is the same peroxide that they put in acne creams bends we'll peroxide Oxy 10 you could take a smidgen of this case and put into your reaction you would reverse the selectively getting team iconic off that's very powerful it's very powerful you know how the Hydro bore 8 and put oxygen that the substituted double bond which by including peroxide in Unix here you can reverse the selectively and HPI fashion but this only sometimes what we did in this chapter can we didn't do a whole lot but it's it's this whole fish Shapiro pushing that underlies everything I just showed the 3 reactions here they are the 1st reaction I showed you that you can replace is the tertiary grounded its powerful and adds a leading group where there wasn't a leading group before I showed you the you could replace the Lilic ch is using and 6 sentiment and that's a secret generates small concentrations of bromine and then last I showed you if you add peroxide streaks HBR additions the bromine will Adderley substituted cards and those year
3 reactors over this chapter and that's pretty much it for the rest of it just sort of stepped through