Lecture 10: Electrophilic Addition Reaction

redefinition of Chapter 9 analysts .period on Chapter 10 alright so we went over acid catalyzed ring opening of Parkside the ceremony known to do that in an acid catalyzed reopening of the parts and we always attack the nuclear bomb attacks on the most substituted side when we haven't they catalyze reactions or we have a strong nucleophile and no acid catalysts the also is the attack on the least substitute side OK so we want to get that straight far-right so it is we went through the mechanism under basic conditions or with their strong nuclear so it was so fast I applauded her going so fast laughter I will be slowing down today along with the strong nucleophile under basic conditions for With a strong nuclear file do not parts at 1st and then you could follows the attack on the UN but we substituted side so we strongly good files or base catalyzed attack occurs at the less substituted carbon it's pure essence so the least tended side of the better OK so I know a lot of you or except that I was going too fast and you probably really upset to see you Alcock site as a leading group right you will notice that were very upset by the right this is the Alcock Cox side acting as a leading group notes in the same molecule right you're wondering about that you're losing sleep over that so I'd like to start the Italian last quarter in Chapter 7 we can have an said as a leading global that's sure looks like an approximately group to me and what I told you last quarter you have my classes and we can have on our part said a leading group we will under certain circumstances there will be a few exceptions which I will present to you and now presented to you exception number 1 papers will be the only 1 with this exception number OK so I there's 2 reasons why we can have a all as the leading group in this case are number 1 the three-member bring is very strange so the approximated is at a higher energy levels they strain is really by lengthening of the seal bond in the transition straight the states or not so obvious so the transition state but is lower so let's compare to energy diagnosis compared energy diagram where we don't have a Parkside the exact same thing you can see what's going on here so I have a 2nd energy diagram .period because this reaction does not take place this would what we said couldn't happen in Chapter 7 here would be article while we never Nikopol' communion attack will kick off a mail Cox side so that's what's happening here and we said that reaction can take place and indeed it can take place but we have so this is already more stable remember we set apart sites if they're not a three-member during a really stable we so stable we use them as solid so weird that going on here and then all right here we have a high energy transition state because we're trying to have a Alcock said leaving groups so that the high energy transition state and so this reaction doesn't take place now and see the same thing with an epoxy adhere to their topside here so the starts or higher energy level right it's much less stable than any easier said starts often higher energy level and and if you think about their Ames training for this ring forever triangle we have an equilateral triangle we have 60 degree bonding goes right on India in transition state were actually starting to break that bond sold dozens responding to look like it's getting better it's starting to move towards 90 it's it's widening that bonding all right here so this is not doing well here yet this bond angle but this 1 Ingalls lighting that lowers the energy the transition state so here we have such a huge energy of activation reactions can ever take place here we have the energy of activation that is actually something we can that as it's small enough that the reaction can actually happened so that's what's going on here and that's why we're allowed to have this let's label but Slave'wins here so here's our aim pop science and we're doing here is opening up the pop so that's the Parkside reaction over here we just haven't ether there were trying to do something similar here dime ethyl ether here they were attacking with 0 are minors it really doing something very similar but this is no reaction and it all has everything to do with the fact that now while we raise the energy of the starting material made a much more reactive and lowered the energy the transition state that makes up the energy of activation much smaller sent me a much smaller Huge in the energy of activation over here it doesn't happen it's too high for any of models to have enough energy to overcome that energy bill all right so we showed you their new base-catalyzed mechanism in our decent examples of other good nuclear files that are going to attack on the least substituted societies are not acid catalyzed reactions here's a number of them but basically I drew them so you can see what's happening here and will show it so saluted the Falcons in it's been attack on Congolese substituted side just like this and so if you have a good nucleophile that will open up the Parkside if you don't have a good nuclear file you need add acid catalysis so if you just Tavener Parkside American also needed a the added Osyka talent catalyst or based catalyst to get that reaction to go but if you already have a good nucleophile we'll need to add a catalyst paid so all of these are going to go to the same thing all were basically doing is changing and changing the nuclear here so that's why I left everything off I drew everything except for the new fathers I want you to just focus on the new aware Wellesley and we could also have in 3 here so notice most of them have the nuclear file step 1 and then you add water in a 2nd step OK so we have to be followed here and then we open up the ring to make Alcock suddenly from me with water in the 2nd set ammonia it it doesn't you don't need to add water for this 1 but all the rest have so also I wanted also point out to you and this is something about this orientation we wanna start getting used to looking for structural

patterns in our molecules and so noticed something here we have a nucleophile on 1 and then we have a hydroxyl on the next car so we have a nucleophile here came in and we have a hydroxyl on the adjacent carbon nucleophile hydroxyl nucleophile hydroxyl nucleophile hydroxyl so if you see that pattern in a molecule that you're ass to synthesize you can think to yourself I can make that by attacking an opening up of side so you we want used to looking for certain common structural features and then I will make it easier when we do all do more serious emphasis on this midterm here were pretty much on the most number of steps we've had is gone 1st 1st this is where you have to fill in regions 2 steps right there were pretty much eliminated 2 steps for mid-term 1 by the time we get to mid-term to we will have more consensus as problems where you have to come up with more than 2 steps so maybe 2 maybe 3 maybe 4 or 5 of 5 might feel really hard test questions case so worried we were were increasing difficulty rather rapidly here this test it's 2 steps were limited to 2 steps are interesting application you could feel like a part reopening to synthesize Bronco dilated so this is just an example and shows you and why we don't need to add a 2nd water step with ammonia this is an ammonia derivative but watch what happens here the nitrogen is going to strong nucleophile no acid catalysts it's been attack on the lease substituted society and then we're going to kick electrons up onto oxygen let's the products that step so a lot more complicated molecule but we're doing the exact same thing so don't be thrown off by all these extra items in this molecule and so on nitrogen group here notice will we attack within a mean we get approval needed nitrogen compound we saw the same thing in Chapter 7 all right so what the reason we don't have to and add water is that we can actually get a proton from the ammonium ion in this molecule right now sometimes we have to so on and in this case we can actually do what we call an intramolecular different nations In truth molecular the probation so the oxygen is going to grab the hydrogen were gonna break the nitrogen hydrogen bombs and 8 so ourselves we can do in terms of political deeper probation sometimes we can't you have to be really careful if you're going to be doing an intramolecular nations have to count the Adams this is 1 2 3 4 5 you have to count 5 or 6 at so intramolecular different nations and this would be a five-member during transition state if we had another added be 6 it has to be 5 or 6 if you only counted for this couldn't have intramolecular so this is our 1st example that will bring more examples later but I can do an intramolecular different nations and um let's Strother product so if any of you have asthma word had bronchitis with asthma where he had trouble breathing you had this compound this is albuterol so this is albuterol that's the generic some other names for it provincial dental interviewed breast-feeding those are all there and they help you read it opens up year on year after year airways and that's how they make their compound Salizzoni by must be able to make a 5 or 6 member transition state I'm so let's go back a number that too so we make sure we know we're talking about here 1 2 for 5 so that have been in order to renew Proton it's a five-member transition state yet it has to be a you right has to be able to reach cocaine all right so I promise you alternative to dehydration of primary alcohol so we sent dehydration of primary alcohols doesn't work very well and as you're going to see next week in week 5 you're actually going to do it dehydration of a primary alcohol and land and you will be very surprised if the product that you get it's not what you want it's something else so we wanted that alternative that's going to work reliably for us on 121 happens but you will get something that will surprise you so that we want to do is instead of doing it dehydration to make announced take the alcohol turned it into a good living and then doing the 2 elimination so here's a here's some ideas here PBR 3 parenting more societal chloride purity a Notice of abbreviating period Q Why are you could certainly do that on the test out or tousled chloride purity or HBR since the primary alcohol you can use each year are just fine but when you do that you're going to get L kill hairline used the bureau repairing you're going to get it also chloride if he's final chloride purity or you're going to get a tossup if you Stossel Corrie purity and that and you're going to do you see what would face would we use if we want to get you to 1 of the primary alcohol what base when we use what would be a good faith that would give us a lot of too interview topside right hindered base if we don't use TurboTax wouldn't admit we're basically going to Geneva here without any delineation please remember that if you if you primary outfield he lied anyone elimination you have the user interface for our rights that is home that's

Chapter knowing that Stalin Chapter 10 it is power I

out means we worry talked about outlines a little bit at the beginning of chapter a right talked a little bit about the instability about things still need to know all of that and the simplest Al-Qaeda's ethylene so just 2 comments about similar stopping you can also have interlocking which means the outing as of the end of the chain you can have an interlocking which means the often is in the middle of a change any of the evidence as cycle of Al-Qaeda is part of a race so let's remind ourselves about the structure of analogies right here we've got our pipe bond so these groups overlap here and they overlap on the top and the overlap on the bottom right so this whole area here is bond overlap In this center here or were making it that's your signal bond here so that sigma bond between the 2 carbon soap so counting as a single born in a pipe I signal bond of electrons are closer to the nucleus when the closer to the nucleus held more tightly analysts reacted the army the uptight bond on the other hand electrons are farther from the nucleus as electrons getting further and further from the nucleus the on the nuclear solicits pull on those electrons Ocampo was strongly so I'm very held word with help of 1 an electron sorter held more loosely or more reactive so the pie bond is more reactive so in chapter in the talked about how to make pipe bombs on in this chapter review talk about what happens with bombs when they react with other calls OK so I'm surprised carbon-carbon double bonds to foreign foreign in synthesis it's easily converted into many other functional groups as will see in this chapter and it's also used for drugs pesticides valuable chemicals but by far the most the most the way we use Elkins the molds isn't polarization reactions to here's an example of polyethylene we take an ethylene and we polarize it to make a really long carbon chain and this is what it would look like and that's 1 of the many other compounds that you run across in your daily life all of the plastic served glamorized on so really ever really important some functional groups to talk about alright so here's the deal I got really happy with myself last nite

because I finding upon podcast were molecular formula degrees among saturation last quarter because you needed it for spectroscopy so I might buy put the podcast on our website under the practice if you already don't haven't calculated agreement saturation you could look at that podcasts really sure podcast OK so that takes out 1 and so now all of a sudden here and I no Linklater

I mean nomenclature and attending meetings podcast last year I'm so I was so thrilled so that's also 1 of the factors like value leisure sometime before to return to you need to look at those 2 podcasts you will be responsible for the information and then all of a sudden I looked at the sky and now I was ready I was avoiding looking at the schedule I did not want to know how far right behind we were I'm I finally looked at the scandal last nite and we're now what we are now exactly where we're supposed to be so I was very low myself also so you no

longer have to be embarrassed that unbalanced stands in the other classes away far ahead of us because we're going to be pretty close to where they are right now are maybe not but we're on schedule

so worried jump directly to reactions about Balanchine's you'll only like broadcast on live it's because it has a lot of this stuff the trans fats the the and saturated with animated 3 months and make a 6 it's a really interesting and very relevant to your daily life so I will ask you a test question on that material so please make sure that you do that part the most characteristic reaction of Keynes's is elected filling condition so here's what happens in a lot of addition reaction we have Alpena we have an electrifying acts so the young kids actually acting as a nucleophile here it's a nucleophile these guys are all electrified also I generic way of writing letter follows the plaster generically writing profiles and you see with over long and I'm wanting to happen is that on the X Y is going to break apart 1 side's going to get the wine 1 side's going to get the ax and we're going to have to decide which which side that goes that's 1 of the things we have to learn in this chapter so this is an elector filet addition reaction and we have many

examples here we can add a warning bring to go over all these examples in this order we're going to start with Ajax and this what we have to do so do age Axel hydrogen 1 side acts on the other worlds energy water that's going to require an acid catalyst Elijah site hydroxide on the other with bromine CH 3 C O 2 is just the solvent we we are going to play with the naked eye from compound on here we're going to do bromine and water bromine on 1 side of hydroxyl on the other and then by the time we get to this chapter you'll be able to draw the correct product here I know Woodside Roman goes on outside the hydroxyl talk about hideaway aeration we get a hydrogen in a border once I know we oxidize that the boron is going to replace the .period hydroxyl their replaced the boron and then another addition reaction is age 2 adding to an team To giving you an AL team and would actually save for Chapter 12 so Chapter 12 so we have now synthesis of several

different new functional groups can taken out here we can turn it into an alcove life that's fantastic that we can do that because after failing to really important synthesis we can taken out can end up Arpino we can turn it into an alcohol we can also turn it into what we call a visible died will try that again this old diver and we can convert also into what we call all hydrant so Rome over the bromine hydrant for the hydroxyl role we're going to learn all of these reactions except for the last of which was safer Chapter 12 I'm going to start their duty in this order will start talking about uncle he lights 1st and then alcohol so much talk about additional that HBO June knocking opec so we scrolled a little wrong here and analysts kill stock instead of fixing a little bit more

figured out how to simulate ceiling experience a giant No wait staff they chapters not working this reaction OK and so on were going to do is run in a river in reactor .period applied want and we learned back in chapter in 51 A that apply bond is the site of electron density site of electron density therefore this is going to be on nuclear file HBO our super super strong acid we know we have a very polarized on HBO upon here so we have partial positive on the hydrogen partial negative on the bromine and services electron deficient hydrogen therefore electrified and then I it with no attempts to show scarier chemistry at all because we will get to steer a country I'm just going to have a hydrogen going alongside noticed I've chosen something around that's not that symmetrical so I don't have to make decisions about which hydrogen gets that which carving it's the hydrogen at which carbon it's the bromine and when the symmetrical like that you don't have to make those decisions alright by an unknown however jump

directly to symmetrical double bonds because the more interesting and that's what we're going to have to figure out right so that a symmetrical when young King has on symmetrically located double bond to isomer products are for I'm in it so I was going to do is only to drop the skeleton From the carbon in 1 color so we can focus on what's happening here so there my carbon skeleton we know in addition reactor-ready get rid of the pie bond here that's registered help myself here are changing colors here so we can see what's happened here so 1 possible product is a hydrogen on the left and the bromine on the riots the other product has the hydrogen on the rights and the bromine on the left in terms out so that we get None of the 1st product In this reaction this is the only product and on within about 2 or 3 minutes you're going to be able to tell me why can carry I promise you'll Yeovil Town

main product 1 which the halogen is bonded to the carbon of a double blow with the greatest number of alkyl substituent so reaction that gives only 1 of several possible constitutional isomers is said to be Regio selected hydrogen halide edition is due out Keynes's as regional selective and follows what we said what we call ,comma calls role I'm a countercultural says the halogen of the hydrogen halide attaches itself to the carbon of the keen bearing the least number of hydrogen a greater number of the case of rat arising out rule let's see if we can figure out why we get that but we want to be able to explain the original selectivity of the reaction but 1st we

need to talk about the mechanism so it's to the mechanism version number 1 of the tools we can use to figure out what mechanism is is by doing kinetics on the reaction we change concentrations of the reactants and we see the effect on the right and if we do that but we can swing for this particular reaction what we find is that the rate depends on the concentration of the AL In the hairline How do we know that we do a reaction double the concentration here we see that the rate doubles so we double great doubles and redouble their summary doubles and then just to make doubly sure that we're not we're not wrong we doubled and what happens to the quadruples rated double gold In the rate quadruples so what so we can

conclude that the reaction is 2nd order so the 1st the 1st thing appears in the rate equation is the Al-Qaeda Cizik exponent of 1 the 2nd thing it appears the rate it's equation is that as an exponent of 1 so the other 1 and 1 together we get to it's a 2nd reaction and we also want conceded the reaction is by molecular and what that means is that

since both of these species are appearing in their rate determining step that means that they after it collided near a determined step so they all keen on HBO are must collide in the rate determined which I will abbreviate RDS determined steps let's look at the mechanism the alright so what's going to happen is the

pipe bomb the site of electron density hours electron deficient the electron deficient madam in HBR is the hydrogen so the area was going to come from the carbon-carbon bond were going to grab the hydrogen and going to break the hydrogen bromine bonds what kind of reactions that so as base for actress upon suggested this research and so on for transferee approach onto proton transfer so Bronson Aceves we can also call it a little assassination action we can also call the nuclear file reacting with an electrified file all of those would be correct if we want to be the most specific we would call the Bronston acid-base reaction OK so so what's going to happen is that when we when we transfer that Proton approach a choice of 2 different places it can go can go on the writer it can go on the left so when the first one here we have the proton going over here to the right and so the hydrogen is going on 1 side and the other side's going be occur because when we transfer that Proton because we're taking both of these electrons and making a new bond a hydrogen sold 1 of these provinces losing intellectuals who have positive charge from or we can put the hydrogen over on this side which leads us to primary covered kind what's again it's not 1 rocket make a primary ,comma pesos that accounts for the region's selectively of this reaction so let's but let's keep going here so this is step 1 this is a two-step reaction this is step 1 alright and then in the 2nd step bromide on is getting tactical account would we call that reaction as soon as someone writes and these are all really familiar so this is a new mechanism but with familiar steps yet at the the new while I mean yeah that's getting a little more complicated than we need to go with his stage are in the and beyond the outfield OK so bromide 9 attacks and we get this product here this would be step to which step is the festival which is a slow this is slow right and this is fast so instead to down here that would be fast alright so so so I'm basically I'm in the 2nd step what's labeled the reactants here this is a Lewis spaces for nuclear file In the carpet Catalan it's a tertiary it is a Lewis acid and a powerful electrified by powerful and in a very reactive electrified so that's intended not to lose you actually can also call it on the nuclear power reactors select about both of those would be correct and right here we have a little bit of a problem here because this is a primary copper Catalan can't form and so what that means is that we're not going to get any of this product so we don't get any of that product we don't get a 2nd step because we can form the core of the cargo accounting in the 1st place so none of this product is formed so we only get this product RX-7 adverse reaction which is a major

tourist at the lectern period applied on tax approach under the hydrogen halide applied once a very weak basic chemipro needed to its small extent my very strong acids Sonoda approach made knocking like we just did you need a super-strong arson so that's important we don't see it happening with regular has to be super strong arson the resulting ,comma carries a powerful electron deficient assassin was opposed like father to possible ,comma Karadzic and form a primary and a US Senator Sheri so this is a tertiary industries primary in the secular actually cover cataracts rapidly with the

nucleophilic a lighter and we as we can see we're really not going to form the primary covered had question toss a gas it would so would be yet Boris solicitor reactions are competition that 1 and was only 1 can happen at the expense of the other because they compete for the same starting material so they're in competition the only product forms repeal bromide you already answered while you already answered y why because we can't form a primary copycat and so we overdid it was awarded to modify Marconnet Council little bits of that is more general Marconnet Council ruled that evidence showed you face to particular for hydrogen halide edition we want a more general way that we can use for more than 1 reaction and that stimulus restaurant remember so this is a more general form of work on a cultural and this is the 1 they were going to be using of course because it is works for we have a lot of reactions to cover in this chapter in this 1 works for all of the 4 edition of an 1 symmetrical leptophilic reagent to a double bond the major product comes from the more stable lower energy cargo-carrying enemies and so that makes good sense here let's look at the transition state amulets that the energy

diagram and the transition states but we start off with their aware they're all came we have to possible ,comma Karadzic inform this was a primary and higher energy this once tertiary lower energy this 1 has 9 enormous energy of activation is so large that reaction can happen this 1 has its much smaller energy evacuation it's still pretty large because they know of making cover cancer pretty high energy process but it's actually a reasonable thing that we can we can do this on energy back to being can overcome this energy activation pretty easily after that we have a very fast very small energy of activation stuff here look at and so on that wasn't really easy reaction and if we could make this provocation and we could do that 2nd step pretty easily but since we don't make a primary covered can count on were not going to do that stuff from the media that stuff here alright so notice something here I want to point out a couple things here the energy difference

here this energy difference right here is about 1 cake so I haven't really drawn this to scale but it that's about 1 k cal from all this energy difference right here between these transition states that's 16 K Kallstrom L so the product outcome in this reaction has absolutely nothing to do with stability here it has everything to do with the difference in energy this transition state that's a during a product out not this difference here these are very close and that's a very large difference here so almost drawing energy of activation here for tertiary right here reasonable energy of activation here we have a

energy of activation to form the primaries energy of activation is huge reaction doesn't happen right so I'm couple things I want to point out because of

formation ,comma cancer rate determined staff of rates formation the 2 copycat incidents the relative amounts of each product form in their reaction will rates information Dukakis inserted by the relative energies of the transition states OK so what do we know about and the transition states about with him as possible what is that transition state look like this 1 right here there's a look more like the product that Stanford is look more like the reactor it looks more like reactants right of parents parcel says that this this transition statements actually the product of that step it looks more like the kind category and then it does the reactor and I'm so this guy this transition state right here looks more like the sound tertiary ,comma cattle than it does reactants and so if we have a really unstable relatively stable however can transition states also going to be relatively stable because they look alive on offer of here we have a really high energy very unstable ,comma carrier that means the transition states also going to be really unstable are right so let's go back here at the height of the energy barrier

determines the rate of the reaction Hamed's partial at this is a good idea with this energy barrier looks like that transition state looks like on the 1st day of the 1st step is the end of Germany which is the rate the rate determined status that 1st step the rate determining step and is in the affirmative Nintendo direct reaction the transition state looks like a product of that stuff In an annual terrific reaction the transition state looks like the product of this step which is the cover cargo-carrying intermediate so since the carpet patterns are very different energies right wrong spot but probably come did says Aqaba giants have very different energies the changes states also have very different energies and so am am underneath this on your 1st you've writing right this right here the higher energy pathway it is high energy all right so

if comparing a primary versus tertiary were not informing final 1 if it's a different here we can form a tertiary and secondary what's going to happen Oregon again bowled we certainly would expect the 1

that's tertiary found to be the 1 that we get the most out of but if we have something where we have all sides models substituted look at this year as well as a matter holders 1004 but they're both model substituted we think it's going to happen there so we're basically wanting to make a prime for secondary ,comma carrying areas secular secondary here is a reaction of the regional selected no the reaction will not be Regis selected right will stop right there will talk more about this on Monday of one-sided Florida nature