hello everybody my name is emon and sadie welcome back to my youtube channel today we're going to go ahead and cover chapter 11. and chapter 11 is all about talking about synthesis now up to this point we have learned about how to work elimination reactions substitution reactions addition reactions we've learned about so many reagents that when treated with this sort of starting material ends in this product and so on and so forth we have this really big toolbox of reagents and reaction patterns and now we want to really put it all together because ultimately organic chemistry is concerned with the construction of organic compounds from a specific precursor the goal is to start with a precursor and then develop this ordered list of reagents that will transform your starting material into your desired product and so here we really want to gain mastery of being able to determine the synthesis pathway the list of reagents we would need to go from starting material to product now we have seen one or two sequence problems like this these last few chapters from seven through ten pretty much we've learned a bunch of these one or two sequence problems where you can start with a specific precursor and through a reagent or to transform it completely into some sort of desired product and we've built this toolbox especially these last four chapters we've covered right some of those synthesis pathways we've already seen before were one two and very rarely multi-step right but we've we've seen them and we know that they require strategy to deduce now in order to really get a good grasp of synthesis in general and learn to develop a strategy to tackle these problems it is now more than it is now more important than ever it is critical to truly achieve mastery over the all the reagents we've described in previous lectures and videos all the reagents that we have learned that we have discussed that we have worked with from chapters seven through ten now up to this point are very important for us to remember and understand fully because now at this point of organic chemistry we are really concerned with synthesis and synthesis pathways and this will carry on i promise in chop and organic chemistry too so it's really good that you focus on remembering all the reagents that you've been given so far in ochem one they will carry into ochem ii all right so this chapter this video specifically for me i really wanted to focus and refresh your memory on all the stuff we've learned thus far and really just to do practice problems while discussing important techniques i mean the best way to learn how to approach synthesis problems is just to tackle problems of various difficulty all right and that's exactly what we're going to do but we're going to start by reviewing a few key concepts and then we'll tackle all kinds of problems together and we will continue even as we move into chapter 12 and 13 and then in all the organic chemistry 2 videos i also already have up every chapter we cover will end with some sort of synthesis problem because ultimately now that we've introduced it it will be the main focus the underlying kind of objective of learning about functional groups and their reactions and preparations is to ultimately be able to use that knowledge of reagents and use that knowledge of preparation and and reactions to then come up with very good synthesis pathways to get from starting material to end material all right so here's a a really cool summary right synthetically useful transformations a lot of this is substitution and elimination reactions that we've covered in chapter seven um how to go from an alkyl halide all right you can add an you can replace that alkyl halide with an alcohol we covered this all right and then to go back and forth between alcohols and tosylates remember alcohols are not good leaving groups but tosylates are all right how to go back from alcohol to alkyl halide how to get a nitrile from an alkyl halide how to get an ester from an alkyl halide these are all the reagents you need to transform to and from alkyl halides right this was a foundational uh reagent list that we built in chapter seven and this is working with primary substrates you do kind of very similar things with tertiary substrates and you can start with a tertiary alkyl halide and again do similar transformations uh to alcohols um to alkenes of of various substitutions and so on and so forth so this is a very good summary list now also with if you remember from my chapter seven videos we really broke down some of the reagents that you need for all the transformations and key features of substitution and elimination reactions make sure you understand those if you feel iffy go back reread the chapter re-watch my videos reach out to me any or all of those but just make sure that you are constantly trying to build your skills with reagents and what they do and how to move from starting material to certain end products all right now this is uh these two graphs here these two tables are summaries of chapter eight where we learned addition reactions of alkenes we covered every single one of these reactions all ten of them in detail we did practice problems all right i have a summary of these um reactions and their requirements and things to keep in mind like chiral centers or carbocation rearrangement in chapter eight notes and also we started it with as a refresher in the chapter nine notes so if you want that table you'll find it there right so we learned how to start with a double bond how to add things to it like halogens or how to add alcohols and waters to the double bond how to add hot molecular hydrogen to both sides of the double bond halogens to both sides alcohol groups and halogens to both sides we learned various different reactions on how to deal with double bonds and we carry the same sort of techniques straight into triple bonds starting with a triple bond how to add a halogen hydrogen alcohols waters all sorts of things and we covered all 12 of these these reactions in our chapter um in our chapter 9 video for this so these tables are just good refreshers especially if you feel like for the most part you have a general understanding it makes sense how these works but you just want things to quickly refresh your memories for chapter seven eight nine these tables from david klein uh textbook do a fantastic job and i highly recommend really maybe sometimes taking a white pen maybe and just blocking out some of these reagents for yourself and trying to work them out yourself whenever you feel comfortable to do that all right so that's a good way to test your uh what you really know okay now useful techniques we're gonna cover a few all right just again as refreshers all right how to do right alkane transformation so you start off with the unreactive alkane some hydrocarbon chain of any length this one's just three carbons right you have this hydrocarbon we know hydrocarbons are unreactive so this alkane is unreactive how do we work how do we deal with an unreactive alkane if our end goal is to for example slap on an alcohol there or make a double bond how do we do that kind of stuff if we're starting with an unreactive alkane well this is where again you want to go back to all these reagents you've learned how do you deal how do you start off with an unreactive alkane well you could always just add on some sort of functional group and we know how to add halogens right we know how to add bromine specifically you can use nbs right and then there you go you've slapped on a bromine now now you have an alkyl halide and we know exactly how to deal with alkyl halides because that is literally all of chapter seven right taking alkyl halides and being able to do substitution and elimination reactions right so you could do a substitution reaction to substitute that halogen with an alcohol or whatever else or you could do a elimination reaction a nitrile you could do a or you could do elimination reactions remove that halogen form a double bond all right so now that you have this alkyl halide you can substitute alcohols nitros whatever else you want here or you could do elimination reactions and then even with elimination reactions you can go ahead and do an extra addition step to really add specific groups to specific locations all right so we've really learned a lot so far about how to do this kind of stuff step by step now the hard part is learning how to put all those steps together to come up with the appropriate synthesis pathway to go from starting material to end product because we've learned these step by step but now we need to be able to put them together now another thing another useful technique we've learned in our journey thus far is how to create and modify carbon bonds and skeletons we learned that to create carbon-carbon bonds alkylation of terminal alkenes is going to increase the size of a carbon skeleton and if the size of a carbon skeleton decreases then what we could take advantage of is a bond breaking reaction called bond cleavage and we learned that when we covered ozonolysis here so if we want to if our goal is to start with a small carbon chain and our end product is a much larger carbon chain then obviously we have to create carbon bonds and one way we know how to do this is alkylation of terminal alkenes we covered this in chapter nine of terminal alkenes all right and now if we've shortened our carbon skeleton if we start from something like this and we end want to end up with a product like this what we can do is ozonolysis where we cut that double bond right through the double bond and we slap oxygens as band-aids at the end all right another important thing to keep in mind to remember with synthesis pathways is that you can use alternating elimination and addition reaction steps to move functional groups so if you start off with something like this and you want to end with this product all right you're starting off with having a leaving group potentially here but you want to end up with a double bond and that double bond is not near your leaving group right it's a little bit down forward right here's here's our leaving group at this carbon we want to end up with a double bond right here the best way to approach this is to take advantage of the fact that you can alternate elimination and addition reaction steps to just move that double bond along your carbon skeleton so we start off with this alcohol leaving group we can do an elimination reaction form a double bond here then we'll add something to the double bond okay we've done an addition reaction now we can do one more elimination reactions to form ultimately a double bond at the position we want so if you have a double if you have a pi bond okay you start off with addition if you have a leaving group you start off with elimination so if you're trying to move functionality all right whether it's a double bond or a leaving group take advantage of the alternating addition elimination steps to accomplish that and of course we're gonna take a look at that and see what that means in some practice problems one last thing to know before we jump into a bunch of practice problems is sometimes if you're given a starting material and an end product and you're told to develop a synthesis pathway to go from starting material to end product and you don't know where to start sometimes it's good to work backwards start from the products all right and work backwards to pro to the precursors all right so do backward steps one at a time to help develop a synthesis pathway this technique is especially important for complicated pathways and it's actually known as retrosynthesis uh analysis so if you're the one who prefers to work backwards and actually that's sometimes recommended even preferred if you don't know how to get from starting material to end product just go backwards from end product to starting material and we'll do we'll see all of this all everything we've discussed here all right we're going to see every single thing here in some practice problems that we're going to do together right now we're going to start off easy all right we're going to start off with one step synthesis here we want to identify the reagents that can be used to accomplish each of the transformations shown below all right we're starting off with this double bond all right this this ring structure that has that double bond and to this double bond we're going to do a bunch of different things we're going to add to the double bond of bromine and a hydrogen here all right we're going to do we're gonna add bromine on one side or bromine on the other side all right we might cut it up look at this the ring is no longer a ring it's all it's a linear structure now all right what if we want to add alcohols to both sides how are we going to do all of this all right so we're going to figure out the reagents and these are just one step synthesis right so this is just going to get us to you know be a little more comfortable with this and hopefully work up all right so we start off with one step synthesis this is pretty much all of chapter eight here all right because this is going to be addition reactions of alkenes all right just as a friendly reminder and i thought this would be good because i'll dealing with triple bonds very similar with to dealing with double bonds so we might as well cover this all right so we're going to start off with one here let me get my highlighter all right we want to go from this double bond all right and we've added a hydrogen here and a bromine here to lose that double bond all right now the bromine is not going to the more substituted position obviously it's going to the less substituted position so what we're doing here is we're doing halogenation but anti-mark so first thing we're doing here is halogenation halogenation through anti-mark addition right because our bromine is not going is going to the least substituted position all right the reagents we need for this are hbr right and to do the anti-mark version of this halogenation we need peroxides all right that helps us do anti-mark halogenation now if we look at two it's also halogenation we add a hydrogen on one side and a bromine at the other but this time it's mark addition so halogenation but mark addition and so all we need is that hbr no peroxides fantastic now let's look at this third step here okay so we're starting off with the ring strip structure and it seems that we've opened up this ring structure all right and we know exactly how to do this all right and this is through you using ozone ozonolysis we'll cut our double bond in half all right we we preserve the one two three four five six carbon one two three four five six carbon uh skeleton we've preserved this all right but now it's open all right so we've cut right through this and then we've added oxygens to the place that we've cut all right so that means that we're doing an ozonolysis reaction all right let's write this down oz analysis and we know our reagents that we need for this o's analysis i don't know how to spell that don't come at me all right we need o3 ozone all right and then dms all right those are our reagents for ozonolysis always all right fantastic so that's three all right what about four we want to go from this double bond now we want to go from this double bond to two alcohols being added to both sides of the double bond and look at those alcohols all right they're both on the same face all right so they're being added through sin addition all right both on the same face so this is sin for right we're doing sin dihydroxylation both alcohols are on the same face all right and so what did we need for something like this adding two alcohols to the double bond but where they're both on the same face well we needed something like catalytic oh there we go oh so4 and some nmo all right so those are the reagents we used for something like this now five if we look at five still adding alcohols all right but they're not on the same uh face they're being added anti not sin all right we know what this reaction is called it's anti-dihydroxylation all right and the reagents we use for anti-dihydroxylation is coh and some strong acid all right and that's how we accomplished that fantastic let's look at six now what is sick what's happening at six all right we're taking our double bond we're adding an alcohol to one side and a bromine to another all right alcohol and bromine that's a halogen so this is a hydro halogenation all right we learned about that obviously and the reagents we used for that obviously we needed halogen so br2 and then we need the alcohol and we can do that through the form of water so those are the reagents we need for hydro halogenation fantastic now if we look at seven here all right seven we're adding two bromines to the double bond all right so just plain old halogenation here and we know that halogenation happens in the anti-fashion so that's exactly what's occurring here we're adding two halogens in an anti-fashion and halogenation is pretty easy whatever halogen you're adding you need two of them obviously right so br2 for this example all right now if we look at eight what's happening at eight well we have a double bond and then suddenly we don't have a double bond that means what we're adding here are two hydrogens so this is hydrogenation right and all you need for this is molecular hydrogen h2 but it can't work on its own you need some sort of catalyst as well platinum is commonly used you can also use something like palladium or nickel that would work as well fantastic now if we look at nine all right if we look at nine what we have here is we've added an alcohol group all right to the least substituted side and then a hydrogen on the other side so we're adding alcohol to the least substituted side and then hydrogen to the more substituted side this is hydroboration oxidation all right so hydroboration oxidation that's how we add water to the double bond all right and so the reagents for this are bh3 with thf all right then some h2o2 and sodium hydroxide now if we look at 10 all right if we look at 10 we've added an alcohol and a hydrogen again but now the alcohol is in the more substituted position all right so this is just going to be a normal acid catalyzed hydration here that would work for this reaction and it's really easy because all you need is a strong acid of any sorts so acid catalyzed hydration all right and obviously you need a strong acid fantastic now this last part here all right 11 and 12. let's look at 11 and 12 here 11 and 12 sorry okay we're starting off with a ring structure that has this one methyl group and what we want to do is add a bromine to the more substituted position so it's going to be that position which is tertiary when when uh dehydrogenated so we want to add essentially that's besides the point actually we just want to add a halogen to this position all right and we know that we can do this we know we can do this as possible all right and there's really two ways to do this but we're going to cover one right now all right to add halogen right to just a normal unreactive alkane what you can do is treat it with br2 and light right so you can do this through a radical reaction actually now another way you can do this is also just to treat it with nbs and that will also add a halogen at that position either or and usually something to remember from synth like especially from multi-synthesis multi-path a multi-step synthesis pathways i'm sorry when you get down to doing a synthesis pathway sometimes there's going to be more than one way to accomplish the same thing all right and you just have to be able to figure out what you want to use because there is more than one way to get usually from precursor to end material all right now these are two ways we can have done that all right now 12 our last and final step all right we're taking we're taking this alkyl halide now right alkyl halide and we want to form a double bond okay we want to form a double bond so now what we have to do is is an elimination reaction all right and something that will accomplish this elimination reaction is something like for example sodium ethoxide will accomplish this all right and so this is how you you can work through one-step synthesis we've done all of this together already in great detail when we covered chapter eight addition reactions of alkenes and we've also covered in chapter seven how to work with substitution and elimination reactions all right so this is a really good stepping stone if the idea of more than one step synthesis is a little scary at first start off with just practicing one step synthesis all right take for example i'm gonna scroll up take this graph for example study it and when you feel confident block out all of these and see if you by yourself can figure out what reagents you need to do all of these one step synthesis and do it the same for this do it the same for additional reactions of alkenes and do it for addition reactions of alkynes practice these one-step synthesis first a lot more than one time all right constantly and then when you feel like you've really gotten a good grasp of the reagents and what they do then you can confidently move into more multi-step synthesis pathways all right because multi-step synthesis pathways require creativity and they require that you have all the tools in your toolbox to be able to to do them and the tools in your toolbox are all of these sets of reagents that you should know all right so it's okay if you don't feel like you can just jump into multi-step synthesis yet i mean this is all new material all right you've probably never seen any of this organic chemistry material until you started this class so obviously it takes a while to digest all of these reagents so practice one-step synthesis first all right and then when confident enough jump into multi-step synthesis all right so this was our first example of one step now we're gonna move into more step synthesis problems all right and this this these two problems here that we're gonna do um require functional group transformations i wanted to label it like that um we're going to learn how to get from starting material precursor to end product we're going to do these problems together now we're gonna talk through them and hopefully all right you'll be able to see me implement some of those techniques we discussed in the in the first few minutes of this lecture and you can see me uh put them to play for actual synthesis problems okay so let's talk about this all right we we're gonna first begin by analyzing what we're given for the starting material and for the end product so we're going to take a good look at these all right our starting material here has a 1 2 3 4 carbon chain all right our end product here also has a one two three four carbon chain so we're not necessarily growing our carbon chain here but what you do notice is there is a difference in one thing that's very clear in our starting material we have a double bond here all right and at our end product we actually have a triple bond there okay so we want to move from double bond to triple bond all right so this movement of pi bonds right we're not necessarily moving location of the pi bond but we're transforming our our our pi bond we're transforming our functional groups if you will all right is going to require a few steps it's not going to be straight from double bond to triple bond what we can do here is add some functional groups to this double bond all right and try to transform it from what we know of a a fung of having uh maybe leaving groups into a triple bond one way we can do this is let's take our double bond that looks like this all right and let's transform it into let's do an addition reaction where we add halogens to both sides of that double bond all right so let's use br2 to go ahead and add bromine to both sides of this double bond like so now what we have are these two halogens all right right next to each other all right now if you remember when we cover triple bonds whenever you have either vicinial or geminal halogens right when you have either two halogens on the same carbon or two halogens only one carbon away you can take advantage of that and convert it into a triple bond all right through the use of excess na nh2 and water we covered this is one of the first things we've covered in chapter nine when we started talking about addition reactions of alkenes how to prepare triple bonds well if you have two leaving groups like two halogens either on the same carbon or one carbon away we can remove them right some sort of double elimination reaction if you will to form a triple bond and these are the reagents you need to accomplish that all right and so then what we form is that triple bond now what you could have done here another technique of how to approach this problem all right and we can erase these reagents just for one second all right another way that would have been just as good if not better to do is you could have started with your end product and you're like triple bond how do i prepare a triple bond all right well we've covered this right you know you've covered how to prepare triple bonds well we'll need two leaving groups that are either vicinial or geminal all right and that will lead you to a structure that looks like this where instead of the triple bond there are once two leaving groups two halogens and then you can ask well how did i get those two halogens there with my from my starting material oh i know how to do this i can halogenate my double bond and you would end up with the same result this way as well so you can work from the start to the end or you can work from the end to the start whatever makes more sense to you all right fantastic now let's do b all right let's do b now we're going to take a good look at b all right we're starting off with this ring structure that has uh one carbon and a bromine so we're starting off with an alkyl halide all right where the bromine is added to this carbon right here all right and we want to end up with um a structure where the bromine is at the same location as this methyl group so what we are doing here is moving that functional group we're moving the bromine all right now the best way to do this all right is probably to do an elimination reaction first all right and then do an addition reaction to get there right because one good way of moving functional groups as well as moving pi bonds like we've talked about is to take advantage of alternating elimination and addition reactions so going back and forth to move things to different positions so that's what we're gonna try out here all right we're gonna start off with this alkyl halide where the bromine is here all right and we want to move it so first step is we're gonna do an elimination reaction we can use something like dbu or tert-butoxide whatever and that's just going to do an elimination reaction at this position obviously because here's our leaving group it'll come in steal a hydrogen here hydrogen dumps its electrons to form a double bond bromine leaves and boom now we have a double bond here all right now what we can do is do an addition reaction to this double bond all right where we add our hydrogen here and add our bromine here to lose the double bond now we're adding the hydrogen to the least substituted position and the bromine to the more substituted position so this hydro halogenation has to occur through mark addition so all we need for that is just hbr and that will add the bromine here and break the double bond and that's how you get this final product all right so far so good we started with one step synthesis now we're doing uh functional group transformations where we're moving uh leaving groups we're moving pi bonds taking advantage of alternating elimination addition reactions and these are pretty easy these are two-step synthesis pathways all right so we're slowly building our comfort and our um techniques to be able to do harder and harder synthesis problems all right let's keep doing this all right let's keep practicing we're gonna do here again same thing let's develop synthesis pathways for these two reactions now these reactions involve changes in carbon structure all right so we want to keep that in mind so we're starting off here with a triple bond so just two carbons here and we're ending off with one two three four five carbons all right so we're starting with two carbons ending up with five carbons now let's take a look further at our end product we still preserve this triple bond all right we're still preserving the triple bond we don't want to lose the triple bond ultimately but we're adding to one side is a methyl group and we're adding this ethyl group to the other side of the triple bond well it's a good thing that in chapter 9 we covered how to add variable groups r groups alkyl groups two different sides of the triple bond we know how to work with this and so if we start off with a triple bond all right we can treat it with nanh2 and then treat it with whatever alkyl group we want to add to it so if we want to add that ethyl group all right we're just going to add ethyl iodide for example with some halogen all right and that's going to take this triple bond and add that ethyl group to it fantastic well we're going to have to do this one more time because we want to add a methyl group to the other side so again same technique nanh2 and then the group we want to add methyl iodide all right and that takes our triple bond now and adds a methyl group to the end so whenever you have these terminal alkynes all right alkynes right you can add alkyl groups to size to the sides of this triple bond simply by using nanh2 and then the r group you want to add whether it's methyl ethyl butyl whatever it may be iodide all right and that's how you want to work this problem fantastic all right now let's do b together as well all right what do we have as our starting material we have this alkyl halide to start off with right we have this benzene with this carbon bromine attached to it fantastic what do we want to end off with well we want to end off with this terminal alkyne terminal kind this terminal triple bond okay and also notice this is one carbon this is one two three carbons right so we're obviously building our carbon structure here fantastic so again the starting material benzyl bromide different than the end product we have okay so we're going to have to install two carbons here okay now this is an alkylation process and it actually can be achieved in just one step all right all you have to think about here is all right what if our starting material that looks like this all right br hey this looks like something like an r group attached to a halogen right something like this all right so what we can treat it with is the triple bond that we want to attach it to a terminal one all right plus some sodium in there as a result what this is going to do is it's going to react this here like a a little bit of a substitution reaction all right and we're going to get to replace that bromine all right with this triple bond here all right one step synthesis here all right fantastic let's just keep doing more and more okay just to get comfortable let's do this all right let's look at what we're starting off with this is a one two three four five carbon chain fantastic it's a five carbon chain what are we ending up with one two three four five six seven eight okay so we've really grown this carbon chain now it's a good thing it's a good thing we're starting off with a terminal alkene right because we can add things to this triple bond all right and what we want to add is three more carbons to that triple bond so we can get eight carbon chain then we can worry about converting the triple bond to a double bond all right so then our first step has to be to grow that carbon chain all right because we need it to be eight not five so we're going to do the same technique we just saw all right nanh2 and then whatever we want to add all right a three carbon chain one two three attached to iodide all right so this is the group we want to add to this terminal side of the triple bond what do we get as a result well we get something that looks like this fantastic one two three sorry i missed i almost missed the carbon there perfect one two three all right cool now what you notice here let's erase this really quickly use a different color all right now to this double bond we have one two three carbons on one side and one two three carbons on the other side let's look at this triple bond we have one two three carbons on one side one two three three carbons on the other side fantastic so we don't have to worry about shifting anything now all we need is to convert the triple bond to a double bond we know exactly how to do this and we know how to do it to the point where this triple bond gets converted to a double bond that is obviously cis okay not trans but we need it to be cis both of the groups on the same side of the double bond okay we covered this in chapter nine to convert a triple bond to a double bond in the cis conformation what we need is molecular hydrogen but we can't use our normal platinum catalyst it's not going to give us cis conformation we have to use a unique catalyst called lindlar's catalyst right we've covered this this is going to take this triple bond convert it to a double bond specifically in cis conformation and that's how we get our end product now i'm going to let you attempt c since i haven't given you any homework yet take an attempt at c all right tell me what you think in the comments below the set of reagents we would need to produce this end product from this precursor all right now we're still going to keep doing a few more all right practice makes perfect and that's exactly what you should be doing especially if you've got into this chapter at this point highly recommend that you keep consistently doing synthesis problems even if it's just one or two problems from your textbook every day all right do one or two problems check it with the solutions manual if you don't have a solutions manual damn just email me and i'll check it for you okay just make sure you consistently do practice problems all right so let's keep doing some more let's look at this here's our starting material a good old triple bond all right and we want to end up with this molecule where there is an alcohol group and a bromine that we didn't have to begin with and also absolutely no pi bonds okay so quick thing we have one two carbons here we have one two three four carbons here okay so before we even worry about these added groups these bromine and alcohol since we're starting with it with a with a triple bonded terminal triple bond let's take advantage of it and add that extra two carbons we need that should be the first step since we are lucky enough to start off with a triple bond all right so we've done this enough times we use nanh2 all right and we're going to add two carbons all right here's two carbons and iodide so ethyl iodide all right what is this going to do it's going to add two carbons to one side of this double bond a triple bond i'm so sorry now what we can do is well we want to lose this triple bond and then we want to add bromine and alcohol so what we can do is we know how to do we know how to add an alcohol and a halogen right hydrohalogenation on a double bond so what we can do is convert this triple bond to a double bond all right we can do this we can again just use h2o and lindler's catalyst we don't have to worry about cis or trans here right because it's terminal so it's just going to give us boom just a normal alkene now we know how to treat this alkene all right with halogen right br2 and water so we can add that alcohol group all right and ta-da we have added our bromine and alcohol through the hydrohalogenation of this alkene all right so this synthesis pathway was just a little more involved right so you see how we're building up our confidence to do this we did one step then we did a few two-step and now this is three steps all right we're getting there slowly but surely all right let's do one more we'll do bt we'll do a c together and i'll leave e for you to figure out all right so let's do c together let's do it in a different color all right what are we starting off with well we're starting off with this carbon chain that has two bromines on the same carbon here and two methyls on this carbon all right what we want to end up with is a carbonyl here okay fantastic now let's think all right so our product is this methyl ketone all right we've seen this methyl ketone before we know how to make this methyl ketone from a triple bond all right so if we had something like a triple bond like this that looked exactly had the same carbon structure as our starting material but without the bromines there no but instead a triple bond there if we had this we know how to get to a methyl ketone we saw this in chapter nine all right it's just kind of like a acid catalyzed hydration all right doing an acid catalyzed hydration of this triple bond will give us a methyl ketone okay but now the question is well how do we get from this to a triple bond well guess what that's how we prepare triple bonds whenever we have two leaving groups like two bromines either on the same carbon or one carbon apart we can take advantage of that to form the triple bond so that's exactly what we're going to do we're going to start off all right we're going to start off with what we're given perfect we have two leaving groups all right that means we can take advantage of our alkene preparation methods we just need excess nh2 and water this will do those two elimination steps we need to get a triple bond there and now that we have this triple bond like we just said we know how to get a methyl ketone from this all right we need acid catalyzed hydration that meaning that means we need sulfuric acid water and this mercury sulfate complex and we can take that triple bond or right and convert it into this methyl ketone and that is the synthesis pathway for obtaining that all right i'm going to leave e for you to accomplish we've done so many synthesis problems together now one step two step three step we've really built up our confidence while refreshing our memory of all the reagents we've learned so far in our o chem journey i hope this was helpful i hope you continue to do practice problems if you have any questions or if you need motivation or whatever else feel free to reach out to me i like to make myself available to you because i really want you to succeed in this course uh but other than that good luck happy studying have a beautiful day