hello everybody my name is iman and sad welcome back to my youtube channel today we're going to go ahead and cover chapter 12. now in chapter 12 we're going to be talking about the structure and properties of alcohols and phenols really focusing on the acidity of alcohols and phenols then we're going to talk about preparation methods as well as reactions of both alcohols and phenols and hopefully do a couple of synthesis problems at the end to put it all together but first an introduction to alcohols what is an alcohol you might ask well an alcohol or alcohols are compounds that possess a hydroxyl group so an o h group connected to a sp3 hybridized carbon atom and these are characterized by name with the ending o l now alcohols are more acidic than amines or alkanes but they're less acidic than hydrogen halides and if you remember we determine acidity by evaluating the conjugate base so if we take all of these functional groups here alkane amino amine group alcohol and alkyl halides if we take these groups and we deprotonate these molecules to obtain their conjugate bases the most stable molecules the molecules that can stable that negative charge better after deprotonation when they are protonated back again make four stronger acids if you guys remember we covered this in chapter three all right so the most stable molecules in their conjugate base form have the highest acidity which is why our alkyl halides are the most acidic followed by our alcohol groups than amines then alkanes all right so alkyl halides most acidic and then going down is less acidic all right now another question you might have that's important is well how do we deprotonate an alcohol well a strong base will do the job something like sodium hydride would work perfectly to deprotonate an alcohol something else that would also work is using a metal like lithium sodium potassium these metals react with the alcohol to liberate hydrogen gas producing the alkoxide ion which is the conjugate base of an alcohol all right now there are several factors that affect the acidity of alcohols when we're relatively comparing one thing is resonance the presence of resonance can lower the overall ph of the alcohol making it more acidic and again this essentially goes back to our areo rules if you remember okay if you have an alcohol all right if you have something like this all right this is an alcohol versus if you have something that that looks like this but there's some resonance here all right which one would be more acidic all right the one with resonance all right induction also plays a very important role the presence of electron withdrawing groups can increase acidity again this is a nice reminder of our area rules and we can do something very quickly here to demonstrate this so something like this just a normal alcohol versus uh versus well let me fix that up versus something like this cl clcl right if you compare just your normal alcohol versus your alcohol that has these electron withdrawing groups um nearby this is going to be more acidic because of those electron withdrawing groups and the inductive effect they play all right solvation not solution i wrote this wrong salvation all right also plays a role in acidity molecules that are easily solvated so molecules that are not sterically hindered display greater acidity relatively speaking so if we're comparing something like ethanol versus something like a butyl group like this all right ethanol is more easily solvated because it's not sterically hindering like the tert-butyl group therefore more acidic all right so something to keep in mind three rules that have an effect that factor into acidity or resonance induction and solvation effects now with this nice profile we've built up on alcohols we know how to identify them we know their acidity pka between 14 to 16. usually we know how to deprotonate an alcohol and we also talked about factors that affect the acidity of alcohols so we have this complete profile on alcohols let's jump into all the methods and techniques we can use to prepare alcohols so for substitution we can use either sn2 or sn1 to to to prepare alcohol so for substitutions alcohols can be prepared by substitution reactions in which a leaving group is going to be replaced by a hydroxyl group now a primary substrate will proceed through sn2 reaction so use a strong nucleophile like sodium hydroxide with a primary um alkyl halide through sn2 we're going to replace this chlorine with a alcohol group and there you go we've prepared an alcohol all right now if you have a tertiary substrate this is going to require sn1 conditions so you want to use a weak nucleophile like water right this is all going back to our substitution reactions from chapter seven just a friendly reminder here all right so tertiary with a weak nucleophile like water this will proceed through sn1 we're going to replace that chlorine with a hydroxyl group and again we've prepared an alcohol now something to remember with a secondary substrate neither sn2 or sn1 is particularly effective for preparing a secondary alcohol under sn1 conditions the reaction is going to be a little too slow with sn2 conditions we're actually going to favor elimination over substitution so preparing secondary substrates uh preparing secondary alcohols using substitution reactions is not the best way to go now for addition if you remember in chapter eight we covered three ways to add a hydrogen and an alcohol group to both sides of a double bond these three techniques were acid catalyzed hydration oxymercuration demercuration and hydroboration oxidation now if you remember for acid catalyzed hydration you're using something like dilute sulfuric acid and it's going to proceed through mark addition markovnikov edition that means the hydroxyl group the oh group the alcohol group is installed at the more substituted position hydrogen less substituted position it's a useful method if your substrate is not susceptible to carbocation rearrangement that is usually the caveat with acid catalyzed hydration you have to be aware that sometimes carbocation rearrangement is possible which usually means a mixture of products in the end which might not be good if you're doing if you're trying to prepare a particular product through a synthesis pathway all right so keep that in mind now um oxymercuration demer creation also this is the reagents for this you are doing this through mark addition now um this also has to be um this is also through mark addition it does not involve carbo cation rearrangement which is good so if you don't want a mixture of products you just want your mark addition product through um hydration then this would be a good pathway to take advantage of now hydroboration oxidation while still adding an alcohol group and a hydrogen to a double bond it occurs through anti-mark addition of water so your alcohol group will go to your least substituted position all right while you're hydrogen to the more substituted position so these are all important things to keep it in mind in regards to preparing alcohols using addition reaction all right with that being said let's do a few practice problems really quickly identify the reagents you would use to accomplish each of these following transformations this is going to be one step synthesis kind of problems all right so if we look at a we're replacing that bromine with alcohol this is pretty much the only thing that's changing now an important thing to note is that this is tertiary a tertiary substrate so what's going to be happening is we can replace the bromine to this alcohol group but it's going to occur through sn1 so we want a weak nucleophile so the reagent we would need to accomplish this is simply water water will convert that bromine to an alcohol group now if we look at b all right again we're converting this halogen to an alcohol group our substrate is primary so we're going to be doing this substitution through sn2 that means we can use a strong nucleophile like sodium hydroxide sodium hydroxide sorry all right now if we look at c all right what we're doing is we're starting off with this double bond and what we're going to be adding is an alcohol group to the more substituted position hydrogen to the least substituted position you can do this either through um acid catalyzed hydration or oxymercuration demarcation because you're not going to have to worry about carbocation rearrangement so either one of those pathways would work we'll just do something easy uh acid catalyzed hydration since we don't need to worry about carbocation rearrangement here because um you're going to form your more stable carbocation anyways to begin with so no need for rearrangement all right so you can do acid catalyzed with dilute h2so4 or you could do oxymerc d mark if that is what you would like fantastic let's continue now that we've done these practice problems with more alcohol preparation techniques another alcohol preparation technique is through reduction here we can start with something like a ketone or an aldehyde where there is a double bond right that carbonyl carbon double bonded to oxygen and what we can do is reduce it to a single bond where there is now a alcohol group instead so the conversion of a ketone or aldehyde to an alcohol is a reduction reaction so that means it requires a reducing agent we're going to cover three reducing agents now these are going to reappear a lot in ochem 2 so make sure you at least remember one to use for all your synthesis that you will be doing in ochem2 all right so with a starting ketone or aldehyde you can use hydrogenation in the presence of a metal catalyst such as platinum palladium or nickel to reduce this double bond to an alcohol group where there is also a hydrogen installed all right so this is this can be used as a reducing agent this only works under certain conditions so it's actually not as commonly used something else that can be used as a reducing agent is sodium borohydride sodium borohydride is a common reducing agent that can be used on ketones or aldehydes it functions as a source of hydride all right it functions as a source of hydride and the solvent functions as a source of hydrogen now in the mechanism what happens and we're going to zoom in here in the mechanism what happens in your first step is sodium borohydride is going to deliver hydride to um to the carbonyl group all right so sodium borohydride delivers a hydride to the carbonyl group this is followed by a proton transfer where the resulting alkoxide ion is protonated to form your alcohol for unsymmetrical ketones all right if you had an unsymmetrical ketone like something like this okay you're gonna get a mixture of stereoisomers as products so you'll get a mixture of stereo isomers as products so if this is your starting ketone and you're reducing it through sodium borohydride you're gonna get a mixture of stereoisomers as products so keep that in mind all right now last but not least my favorite lithium aluminum hydride is another common reducing agent it has a structure very similar to sodium borohydride it also is also a delivery agent of hydride but it's a much stronger reagent uh no it reacts violently with water and therefore a proteac solvent cannot be present with with lithium aluminum hydride in the reaction flask now for the ketone aldehyde when treated with lithium aluminum hydride follows kind of a similar mechanism in the first step your lithium aluminum hydride delivers hydride to the carbonyl and then as a final step you do a proton transfer where the resulting alkoxide ion is protonated to form that alcohol all right this is the simplified mechanism by the way again with an unsymmetrical ketone you are going to get a mixture of products a pair of stereoisomers is going to be obtained right because the hydride nucleophile is going to be able to attack here on either face of the carbonyl group all right so keep that in mind let's jump into some quick practice problems now that where we can display what we just learned okay so here's our starting aldehyde okay we're treating it with lithium aluminum hydride this is a reducing agent what that means is that this carbonyl is no longer going to be a carbonyl it's going to be an alcohol group and of course there's going to be the addition of an extra hydrogen to make sure your carbon is satisfying its octet rule all right so what our product is going to look like then all right we keep the same structure but now there's an alcohol here and of course an additional hydrogen this is your final product for a now for c here all right we're treating with sodium borohydride again a reducing reagent what's going to happen here all right and this is a ketone and it's unsymmetrical what's going to happen here is we're going to replace this with an alcohol group of course there'll be also an hydrogen attached here now it's an unsymmetrical ketone which means your products that you're going to obtain are going to be a pair of stereoisomers so we're going to draw out the structure of this as is all right looks something like this and there's going to be an added alcohol group here so it can be added to the face front face of this to produce this stereoisomer or your sodium borohydride can attack from the back to get this stereoisomer all right so your alcohol will be on a wedge and a dash and this is the pair of stereoisomers you're gonna obtain from this reaction fantastic one more preparation method lastly another way you can prepare alcohols is through grignard reagents now grignard reagent is formed by the reaction between an alkyl halide all right and magnesium what's going to happen is your magnesium is going to insert itself between the alkyl group and the halogen this is a grignard reagent all right it's characterized by the presence of a carbon magnesium bond carbon is more electronegative than magnesium so the carbon is going to withdraw electron density from magnesium via induction which gives it a partial negative charge and the magnesium a partial positive charge all right in fact the difference in electronegativity between carbon and magnesium is going to be so large that you can treat this bond as an ionic bond now carbon reagents are carbon nucleophiles and they're going to be capable of attacking a wide range of electrophiles including the carbonyl group of ketones or aldehydes so let's take a look at this mechanism if you're starting with a ketone or an aldehyde you can react this with a grignard reagent all right to obtain an alcohol product all right so how this is going to happen is your grignard reagent is going to act as a nucleophile it will attack your carbonyl and attach itself there so whatever your r group is in your grignard reagent will attach itself to your ketone or aldehyde in this reaction so if that r group is an ethyl group you're going to be adding an ethyl group if it's a phenyl group you're going to be adding a phenyl group so on and so forth okay so it attacks nucleophilic attack then you get a product like this where your your oxygen has a negative charge you've added an r group all right now we get a proton transfer this alkoxide ion is then protonated to form an alcohol and this is how you can prepare an alcohol through using grignard reagents now um do not mix with water okay this water comes in only after your grignard reagents because if it's just reacting with water it's going to deprotonate the water all right so just keep that in mind all right so let's do a couple of practice problems um to to make sure we understand how to do this show how you would use a grignard reaction to prepare each compound below so our ultimate goal is to prepare this alcohol all right how do we do this using grignard reagent well what we can do is we can take this and use it as a motivation use it as motivation as our starting ketone or aldehyde so i'm going to draw the same structure here all right with an alcohol group all right and uh with sorry a carbonyl i'm getting too ahead of myself all right with a carbonyl where over here i'm gonna put a hydrogen so we're starting off with an aldehyde why we're gonna play this methyl into it we're going to put this methyl into this molecule we're going to add it using our grignard reagent remember our grignard reagent has this magnesium halogen group we're just going to use bromine all the time just to say consistent plus an r group this r group can be anything that we want to add to the starting substrate we want to add to it a methyl group so that we ultimately get this molecule here fantastic and then of course the water comes in as a second step what's going to happen here then using this grignard reagent and this starting material okay what's going to happen is one we're going to add a methyl group here which is going to give us this carbon skeleton that we want all right and we're going to instead of this garbage carbonyl we're going to have an alcohol group all right this is the two things that are happening here we add a methyl group all right and we get an alcohol so the end product of this is now we have this methyl group all right our hydrogen is still there we can draw this if you don't if you want to see what it looks like and then our alcohol group here and look at that we started with this aldehyde and through grignard reagents we got the final product that we want fantastic let's do b okay again this is the final product we want all right we're going to use this as motivation as inspiration uh on what we want to start off with so we're going to keep the same structure as before and we're gonna right there where the alcohol is we're gonna have it a carbonyl so we're starting with this ketone something to notice is we want to add a methyl to this position here so the grignard reagent we're gonna use is going to be methyl because that's the group we want to attach all right with our magnesium bromide this is our grignard reagent and then water as a second step to get the alcohol what's going to happen here is we're going to add a methyl here and then through these other set of reagents we're going to convert this to an alcohol and what that's going to give us as a final product is an alcohol here right because our grignard reagent is going to convert that carbonyl to an alcohol but we also need to add whatever r group is there so that's going to be that methyl group and look at that we get the product that we wanted i'm going to let you try to figure out c and let me know what you get as an answer but with that we have covered all the ways that we can prepare alcohols now what we want to talk about are protection groups if there is an alcohol present in your molecule to begin with that you don't want to operate on but you want to operate on a different part of the same molecule what you can do without affecting the alcohol is you can temporarily replace that alcohol group with a protecting group react whatever other parts of this molecule you want it to and then convert back to alcohol so let's look at here we have this molecule it has an alcohol group and it has a bromine group we don't want anything to happen to the alcohol group we just want to work with this bromine to do a grignard reagent a grignard reaction what we can do is protect this alcohol group so convert it to something else all right proceed through grignard reaction to uh operate on this bromine to get an alcohol group there then what we can do is remove that protecting group and put back our alcohol if we never protect the alcohol whenever we're doing the grignard reaction it will do something to the alcohol we don't want so a good protecting group is going to be otms which is our trimethyl cilial ether all right it looks like this all right but but it's commonly written on a molecule as ot ms all right so the reagents you will need to replace the alcohol group to otms are this set of reagents tms chlorine all right and then et3n as your solvent so this set of reagents will convert your alcohol to an otms group all right then you can go ahead with your grignard reaction to convert that bromine to a alcohol group with two r groups attached then you can remove your otms you can remove your protecting groups using tbaf and replace it with that alcohol group all right fantastic so this is how you want to approach these kinds of problems if you're only operating on part of the molecule if there's another functional group that might react in the process that you do not want to change then you need to protect it to protect it you can replace it with another group for alcohols you can replace them with otms go about your reaction and then replace that protecting group back to your alcohol fantastic now for preparation methods of phenols there's really only one we want to talk about this is how it's how phenols are industrially prepared you start with a benzene you convert it to a cumin all right and then eventually this gets converted to a phenyl group and this is how phenol groups are industrially prepared all right now we want to do a few quick practice problems identify the reagents that you would use to achieve each of the following reactions or the following transformations all right we're going to look at a all right we want to convert this bromine to an alcohol group with two methyl groups all right but we don't want to touch this alcohol at all so our first step is to protect that alcohol all right so that's exactly what we're going to do we're going to protect this alcohol all right by converting it to otms how do we do this easy tms chlorine with et3 n all right what this will do is it'll convert that alcohol group to otms all right and here's our bromine now we want to convert this bromine to an alcohol group with two methyl groups okay so what we're gonna do is we're gonna first treat it with magnesium all right that magnesium is going to insert itself in between right here all right and then what we want to treat it with all right so when that happens when we treat it with magnesium what this is going to look like i'm going to show you really quickly is mgbr and so this now this now is our grignard reagent okay that means this is our magnesium bromine and the rest of this molecule is our r group okay so let's think about it like that this is our r group so if we want at the end of this to take a carbonyl convert it to an alcohol but still have those two methyl groups we want then to this carbonyl we need to have two methyl groups okay fantastic so this is the ketone that will react with this grignard reagent all right to form an alcohol and two methyl groups attached to this r group all right and of course you need to finish this off with water to be able to do that okay what that means is what we get is something that looks like this here's our otms group and then we have our alcohol and our two methyl groups now we can remove that protecting group using tbaf and bring back our alcohol all right and just like that we have accomplished this transformation so you see if you only want to operate in one region you need to protect the alcohol group go about your reaction and then finally replace the protecting group you put in with your alcohol group if you kept the alcohol group without protecting it whenever you treat it with magnesium and your ketone in your water your alcohol will have a side reaction and transform and we don't want that to happen all right fantastic so now we've talked about reactions of i mean preparations of uh alcohols and phenols now we want to talk about reactions so on to all the reactions with alcohols now with alcohols you can use sn1 reactions to replace the alcohol all right tertiary alcohols are going to be needed for this right because you're doing sn1 reactions all right and so ultimately you can replace this alcohol group back with a halogen if you want it we can also do sn2 reactions primary and secondary alcohols can react with things like socl2 and pyridine or pbr3 via sn2 reactions what these do is really awesome if you have an alcohol group and you react it with these reagents you replace the alcohol with a chlorine group if you have an alcohol group and you treat it with pbr3 you can replace the alcohol with bromine other ways of doing this is if you have a primary alcohol you can just treat it with hbr and this will also convert it to bromine or if you have an alcohol group um secondary alcohol you can convert it to a better leaving group ots will convert it to a tosylate group and then treat it with your halogen like bromine or chlorine and that will replace it as well now as you notice this proceeds through inversion of configuration so do these these will proceed with inversion of configuration now for the mechanism of treating alcohol with socl2 to get that chlorine here is the mechanism you're going to be uh your alcohol will attack your socl too it'll attach to the alcohol pyridine serves to depre deprotonate your alcohol all right and then this is finally going to be a good leaving group so when your chlorine comes into attack to replace this group can leave all right and as for treating alcohol with pbr3 to replace the alcohol with a bromine you just pretty much are using your bad leaving group alcohol to attach to this pbr3 which is now serving as a good leaving group so when your bromine comes to attack your alpha position this group can leave and your bromine can come in and replace it fantastic let's do some practice problems with this now what we're going to want to do is figure out the kinds of reagents we would need to go from substrate to final product we have an alcohol group to start off with we're ending with a bromine what we can do is just take advantage of pbr3 easy and what it will do is it will replace our alcohol group with bromine by making it out the alcohol first a good leaving group and then having bromine to come in and attack and replace of course again we told you it operates under inversion of configuration which is what we see here so perfect now for c all right we're trying to convert the secondary alcohol into a secondary alkyl chloride we can treat this with so cl2 and pyridine and what what will occur is this alcohol group gets converted to a better leaving group so when your chlorine minus comes into attack you have something that can leave and therefore you get your chlorine attached here again we told you this operates with inversion of configuration you see that here at play so perfect now with alcohols you can also do elimination reactions to form double bonds uh you can use concentrated acid for this for tertiary alcohols like this one right here you can treat it with concentrated acid it's going to proceed through e1 reaction to form a double bond we've covered this in chapter 7. also when more than one product is formed recall that elimination generally for generally favors the more substituted product as the major product all right so that's something that's very important to remember fantastic now alcohols can also go through oxidation reactions we will now see how we can convert an alcohol back into a ketone aldehyde so we've covered how to go from a ketone or aldehyde to an alcohol that was called a reduction reaction now we're going to learn how to go from an alcohol back to a ketone or aldehyde this is called an oxidation reaction okay we can convert an alcohol to a ketone or aldehyde in multiple ways there's three sets of reagents that will accomplish this you can use chromic acid all right to accomplish this reaction one note on chromic acid okay this is very important it will only work on a secondary alcohol a secondary alcohol can be converted to a ketone if you had a primary alcohol and you treated it with this set of reagents chromic acid reagents what will actually happen is you're going to form a carboxylic acid you would think you would form an aldehyde but it's actually the aldehyde is not isolated so when you treat a primary alcohol with chromic acid expect to get carboxylic acid but when you treat a secondary alcohol with chromic acid you're gonna get your ketone where you preserve your r groups and your alcohol gets converted to a carbonyl other ways to do this is using pcc alright this will also work it will work with also primary alcohols to give you aldehyde so this works with primary alcohols to give you aldehydes it will work with secondary alcohols to give you ketones dmso also does the same thing it will react with primary alcohols to give you aldehydes and then it will react with secondary alcohols to give you ketones this is actually has a name when you use dmso cocl2 it's called sworn oxidation all right so any one of these sets of reagents can potentially work to do the oxidation reaction of alcohols to get ketones or aldehydes and now what we're going to do is we're going to jump into a few practice problems before we do some synthesis questions to end this chapter excuse me predict the product for each of the following transformations we have this alcohol it's a tertiary alcohol we're going to be treating it with concentrated sulfuric acid that means we're going to be getting elimination we're going to or this is going to proceed through an elimination reaction what we're going to be getting are double bonds okay now there are two places that this can react if you remember this is going to be a friendly reminder of our chapter seven all right here's our our our our alpha position and there's two unique beta positions okay this position right here and this position by the way this is equivalent to this so we only need to worry about one okay that means we can get an elimination reaction that occurs here to get a double bond or an elimination reaction to form a double bond here so that means we're going to be getting two products from a okay one that will look like this and one that will look like this all right this is just chapter seven review okay reactions of alcohol groups through concentrated sulfuric acid is going to get us elimination products these two specifically now if you remember your major product here is going to be your more substituted alkene so this is going to be our major product fantastic let's do b now b we have this uh alcohol group secondary alcohol group we're reacting with t scl this is going to for take our alcohol all right and make it a tosylate group all right so what this is going to do is going to take our alcohol and make it a tosylate group now it's a good leaving group so when we react it with the second part sodium ethoxide we're going to get a elimination product all right we're going to get an elimination product that looks like this fantastic and this is gonna be our major product fantastic now let's do continue doing more practice problems okay here's a we have a secondary alcohol we're reacting it with chromic acid all right sodium chromate sulfuric acid and water okay what is going to happen here is we're going to convert our secondary alcohol into a ketone so wherever this alcohol group is now going to be converted to a carbonyl group and so our product is this and that is it all right now if we look at b this is a primary alcohol we're treating it with chromic acid what did we say happens when we treat a primary alcohol with chromic acid no we're not going to get an aldehyde like you would expect we're actually going to get a carboxylic acid all right and so we're gonna get a carboxylic acid fantastic all right now i'm going to leave c for you to attempt okay keep in mind that here's our alcohol group or can we're treating it with um this is our chromic acid kind of a derivative here what are we going to get let me know what you think in the comments below but now what we want to move in as a final note for this chapter is we're going to do a few synthesis problems just to put everything we've learned so far in ochem1 together with what we just learned in this chapter so we're going to go ahead we're going to do a let's make note of what's occurring what's changing between our starting material and end product all right in our starting material we have a triple bond there's actually one two carbons here but at the end what we have here is we still preserve these two carbons but now we've attached an alcohol group okay now we don't know a direct way of adding uh we don't know one direct way of going from a triple bond to a primary alcohol what we do know is we can take we can go from a double bond to an alcohol so here's our starting reagents all right here's our end product okay we don't know one direct way to go from this to this but what we do know is if we had a double bond there we know how to treat a double bond okay if we had a double bond where that triple bond was once all right we can easily do hydroboration oxidation to add the alcohol group to the least substituted position and hydrogen to the more substituted position so if only we were lucky to have a double bond here we know how to treat a double bond to get a primary alcohol easy hydroboration oxidation and the reagents you would need are bh3 and thf along with peroxides and sodium hydroxide this could take our double bond into that primary alcohol but we don't have a double bond so is there a way to convert our triple bond to a double bond the answer is yes all right we can just do a hydrogenation reaction and specifically we can add as a catalyst here lindler's catalyst fantastic and that means we get that double bond we can convert the triple bond to a double bond now we know how to work with a double bond to add the alcohol group we notice that the alcohol group needs to be added to the least substituted position so that means that the kind of hydration reaction we're looking for is hydroboration oxidation because that's the hydration reaction that will proceed through anti-mark addition and there you go we've developed the synthesis pathway to go from substrate to and product fantastic all right now i'm going to do one more for you all right and we'll leave the third one as if as one that you can attempt on your own time all right so b is the opposite sort of in in theory uh going from alcohol to triple bond so let's do that one together and i'll leave c for you to attempt okay so our goal is to take this primary alcohol convert it to a triple bond now what we can do here is work step by step all right we're starting with no double bonds at all no triple bonds just single bonds but we have an alcohol group that we can take advantage of to convert this primary alcohol to a double bond as a first step and one way that we can do this is through an elimination reaction using concentrated sulfuric acid and heat what this will do is it will take that alcohol group and it'll convert it to a double bond now there is another way to do this okay what you can do is you can convert the alcohol group to a good leaving group all right so i'm going to give you an alternative way to do this you can use tscl and pyridine to convert the alcohol group to a tosylate group good leaving group and then treat it with something like sodium methoxide to do the elimination reaction we saw an example of this up here somewhere so that would have taken advantage of something that we just recently covered or again you can use concentrated sulfuric acid either one of these ways will take your primary alcohol and convert it to a double bond i drew this incorrectly let me draw this better to a double bond like this so sorry right because we have three carbons this is our leaving group we formed the double bond here perfect now what we can do is we can try and take this to a triple bond but we can't go directly from double bond to triple bond what we can take advantage of is an addition reaction that we can then do an elimination reaction to again to get the triple bond okay so there needs to be an intermediate step here that we can then take to a triple bond all right that means we need to do an addition reaction here and then another elimination reaction here all right what can we do to this double bond that will help us take it to a triple bond well if we remember we can form triple bonds with dihalides so if there are two halogens present what we can do is then do an elimination reaction with those two halogens to get that triple bond so what we want to do to this double bond is add some halogens we're going to halogenate this double bond and we can use br2 what will happen then is we're going to add bromine to both sides of the double bond now we have a dihalide dihalides are perfect for triple bond preparations now that we have this dihalide what we can do is treat it with excess sodium amide and water sorry one two and water to take the day dihalide into a triple bond and this will this synthesis pathway will take us from our primary alcohol all the way to a triple bond attempt c and let me know what you get other than that we've completed chapter 12. i highly recommend you do more practice problems if you have questions reach out to me other than that good luck happy studying and have a beautiful