[Music] hello my name is chris harris and i'm from alley chemistry and welcome to this video on hydroxy compounds so this is topic 32 for the cie specification so this is the cambridge internationals so if you're studying the cie specification then you're in exactly the right place because we're going to go through all the different things that you need to know for this topic um i have produced the full range of year one and year two and cie topics that's from topic one to topic 37 and they're all available in alloy chemistry youtube channel all i ask is that you hit the subscribe button just to show your support for this project that'll be absolutely amazing um also these are slides that they are available to purchase from my test shop um they're in the link for that is in the description box below and they're great for revision um great for kind of writing notes print them out put them in your file and keep them on your phone um but they're great for that and i've bundled them all up as well so you can you can buy them at discount um for year one and year two so go and have a look on there there's loads of information on there okay so like i said the cie topics actually um the cia topics actually kind of merge into each other so you'll find that this topic in particular um what kind of blends into the um blends into the previous one where we looked at um topics 30 and 31 and so you'll probably see a little bit of kind of an overlap that's typical kind of how the cie kind of work it which is which is fine because it bridges between other topics this obviously links more heavily with that one than it does with the year one topic with the same title what i do encourage you to do though is to make sure you look at um here the year one topic first about hydroxy compounds and what that means because we're gonna look at that but also uh make sure you you look at topic 30 and 31 because i'm going to be talking a lot about um earrings and aromatic compounds in this so have a look at that if you're not too sure and what um what an earring is or if you've never heard of a benzene before benzene ring or anything like that so um let's look at these chlorides first so this topic is going to look at the oh group basically so the oah group is kind of the center of attention in this topic so we'll look at various different reactions involving that so one of them um is the reaction of alcohols which contains the oh group with acyl chlorides um and we need to understand what's actually produced with these so the first thing an acid chloride just to introduce it is basically just a bit like a carboxylic acid and but instead of in a which it's got a cl on the bottom there now these are incredibly reactive molecules they have a very strong delta positive delta negative here obviously the oxygen is electronegative and so is chlorine so it leaves this poor carbon in the middle pretty exposed it doesn't really have a lot of electrons of its own because they're being kind of torn away by these two electronegative groups so what this means is you've got a delta positive very strong delta positive charge here that is highly reactive now in this case it'll react with an alcohol because that's what we're going to be looking at with this topic um and when you react an acid chloride with an alcohol then we form an ester okay in this case it's methyl ethanoids because you've got a methyl group here so your neomestas backwards it's got a methyl group here and then you've got your two carbons which makes it ethanoate so it's methyl ethanoid so this is what's produced and then we produce hcl really vigorous reaction highly reactive um definitely you must be done the fume cupboard because you produce hydrogen chloride gas which is toxic highly acidic you don't want to be breathing this at all so it's a very vigorous reaction that produces um a lot of hydrogen chloride gas which is obviously acidic so just make sure you're aware of that okay so another um molecule with an alcohol group attached to it are phenols um now you a lot of this video is going to be focusing around phenols and and the reactions of them but phenols have a hydroxyl group that's your oh attached to a benzene ring so there's your phenol there so nice and straight forward um and two methyl phenol is there is an example and here's another one this is salicylic acid so basically the um carbon with the oh group is carbon one that's what we say and then we number from this group here so in this case this is obviously on the second carbon so that's carbon one that's carbon two so that's two methylphenol and that's how we name it so these are called phenols now phenols are actually um have kind of unique properties in their own right um phenols are actually acidic and they're more acidic than water and ethanol for that reason so phenols they have this oh group that's attached to them and like with any acid acids are proton donors so they can lose that proton much more readily and than they can with alcohols um and also and water as well and this is because the o minus group that's left behind when it's left when the proton has been removed um is kind of incorporated with the delocalized ring electron ring structure in the benzene and this actually increases stability now if what's been left behind is more stable than another molecule then it's more likely to lose that proton so looking at the orbitals here so the electrons in the p orbital of the oxygen what happens here is they actually overlap with the delocalized ring structure that exists within the benzene um the benzene ring and because they overlap they're effectively they're partially delocalized into this pi system and that brings about a lot of stability so this is why this bond here is effectively weaker than normal and so therefore phenols can lose that hydrogen um you know quite quite readily in this case so um and that means that actually um you know phenols that you say are more acidic than says like ethanol which doesn't have that benzene ring structure to kind of fall back on and form a stable compound so um it's less likely to donate that proton and so therefore phenols i'm sorry um ethanol so alcohols to your aliphatic alcohols your straight chains or your chin molecules are less acidic okay and um like i say they do partially dissociate which means they are weak acids they don't it's not classed as a strong acid where they donate loads of protons it still wants to try and keep a hold of that and so therefore it does exist it does exist in equilibrium um and you can see you've got your phenol here and it will exist in equilibrium with a phenoxide ion so that's obviously there the o minus and the electrons will kind of stabilize itself within this benzene structure and you've got your h plus ions as well that are produced and obviously it's this that makes it um that makes it acidic so phenols because they're acidic they can actually react like any other acid with um bases and um and an alkali should i say so they can react with these to form a salt plus water just like any other acid-base reaction so we've got your phenol reaction with sodium hydroxide it forms the salt of sodium phenoxide which is this here plus water so this is a neutralization reaction so it doesn't change anything it's exactly the same so just be just be aware of that okay phenols will also react with sodium so this is especially acid plus methyl and acids plus acid plus metal gives salt plus hydrogen okay no difference so these are quite you know standard reactions really so um here's your phenol here reacting with sodium metal and that's going to form sodium phenoxide and we've got the two there because we need two of them sodium phenoxide and hydrogen gas is produced um so they react with sodium to form this salt um and obviously you get some gas that's been produced as well so um just the same as any other acid metal reaction okay so no difference here so again a lot of chemistry here is applying basic principles such as acid plus bisque of salt plus water acid plus metal will form salt plus hydrogen and acid plus carbonates will form salts plus water plus carbon dioxide so these kind of basic kind of generic reactions you can adopt them to loads of different reactions and it it just makes it a bit easier you see a lot of this stuff is okay you haven't seen phenol before and you have probably never heard of sodium phenoxides before but the principles of the reactions are the same right across the board okay so like i said the oh group on the benzene ring or the phenol that can affect reactivity with electrophiles okay so the benzene we've seen this in the in the previous topic to do with um to do with topic 30 in particular but the benzene has carbons that have the same electron density and so reactivity is identical for each carbon so there's no difference there now you'll remember from the previous topics to topic 30 that the oh group in phenol what it does it distorts that electron density in the ring so it does affect the reactivity of carbon atoms in that ring as well in other words um it's easier to add a group onto phenol than it is onto benzene because the electron cloud has been distorted because there's no age group that's attached to it and actually um electron donating groups such as for example phenol um they do donate electrons into the benzene ring and there are other groups that you will have seen in topic 30 and this is why i encourage you to watch that first because there is a bit of overlap here um they actually push electrons into the benzene ring and it means that um carbons 2 4 and 6 are more susceptible to attack than any other point in that benzene ring and this obviously goes um with phenols so it means obviously any electrophiles remember anything to do with the benzene ring we have electrophilic substitution we don't have addition reactions um like your traditional alkenes for example but um reactions with phenols will encourage um electrophiles to attack positions two four and six on the benzene ring are more likely to attack in these positions okay so phenols can actually react with um bromine water as well so they wrap with bromine water as phenols are actually more reactive than benzene so you can see why phenols are quite popular in terms of for chemists um in terms of um you know forming new products because they're just easier to react if you try and get benzene to react with anything it just it's just not interested unless you produce a really positive like a strongly positive um like say carbo cation or positively charged particle to add into a benzene phenol doesn't need that and phenol is a bit more reactive it's just easier to use um so phenols like to say they will react with with bromine much more readily than um than benzene does and we observe a brown um decolorization of bromine water so the oh um in phenol is an electron donating group and so substitution is likely like to happen at two four and six on the benzene ring and so therefore the product when we add bromine water um is therefore two four six tri bromophenol okay so we get the substitution triple substitution here so we've got bromine bromine bromine and we form this product here okay so that's why we get these positions here and not not on these carbons here so not on carbons three or five relatively straightforward not too bad so effectively a test for alkenes remember is is using bromine water and it decolorizes it and it can be the same with phenol except we're not adding to a double bond it's a substitution reaction okay no halogen carriers needed for this either so um so that's good um 246 tribromophenol as well um it smells of antiseptic um it's insoluble in water as well so it doesn't dissolve um in any way okay so you might have heard of um you might have seen in the shop actually just to kind of feed off this um as a chemical or at such a medicine called tcp which is um normally what you would use if you had a sore throat you might gargle tcp um and it basically helps to kind of kill bacteria in the throat um so tcp stands for trichlorophenol um effectively instead of using bromine we use chlorine instead um but it's got if you've ever smelled tcp it's got a very antiseptic smell um and you'll find a lot of um halogen based phenols will have that similar smell um so yeah so if you ever wanted to kind of see what it smells like go and buy a bottle of tcp so it's available in supermarkets it's quite readily available so be where medicines are okay so um phenols they can also react with dilute nitric acid as well um so they react with dilute nitric acid to produce nitrophenols and phenols again are more reactive than benzene so we don't need aggressive electrophiles to attack the benzene ring um so we use if we use concentrated nitric acid we can get multiple nitration of the um of the benzene ring so oh again is a donating group as we've seen before um substitution will occur at carbons two and four as you can see here so we've got nitrophenol two nitrophenol and four nitrophenyl as as an example there okay so we get two isomers are produced two nitrophenol and four nitrophenol okay so the position like say a functional groups in a benzene ring can affect reactivity with electrophiles so let's have a look we're going to predict the reaction between phenol and chloroethane using alcl3 as a catalyst um you know if you wanted to you don't really need that but it could be used so um oh it's a donating group we're more likely to get substitution at carbons two four and six um so here we're going to predict the reaction between nitrobenzene and chloroethane okay so there we are so nitrobenzene is an electron withdrawing group so it pulls electrons away and so you're more likely to get substitutions at carbons three and five so just making sure that you understand you know where we normally get substitution for for alcohol so for example phenols that's gonna be carbons two four and six if you've got a phenol group in there if you've got a nitrate group a nitrile group then you're going to get it at three and five instead okay and just finally looking at the reaction with diazonium salts so ease or dies are made via a coupling reaction and by making a diazonium salt first and then we can couple that with um with phenol so um this is quite an interesting one because um obviously dyes are used um is or diesel we say or dyes are used obviously to make fabrics they make pigments to go on paints they can be used to make obviously color fabrics um to color anything that you've got so it's it's a very obviously dyes have moved on quite a lot obviously the pigmentation and the manufacturing of dye's stuff um has advanced quite significantly since this but one the basic dies is is an easel dye um and basically it's used by um so it's made by using phenol as one of the ingredients and um we make a diazonium salt so it's a coupling reagent so if we add phenol to sodium hydroxide to make sodium phenoxide so that's the first thing that we do and then the um benzene diazonium chloride is then added and the reaction vessel is sat in a ice bath an ice bath so the phenol is actually a coupling agent um it has a really high electron density as some of the electrons obviously from the oxygen and the oh group they integrate into that ring and it makes um carbons 2 4 and 6 susceptible to attack from the electrophile okay which is the diazonium ion so let's have a look so the iso died produced precipitates out quickly and we get this orange precipitate formed so the reaction you can see here there's your alcohol so your phenol sorry which does have the hydroxy group on there so your phenol this reacts with your um benzene diazonium chloride this is what this chemical is here okay and then what will form um and then we react that with bit of sodium hydroxide as well and produce that and it's actually a coupling agent so what it's doing is it's allowing this reaction to occur on the other side so you see there's your alcohol your phenol there substitution can happen at the far end here and it can basically add and couple onto this nitro um compound here and that's exactly what we've done so it's kind of the phenol has been spun around it's reacted at the back end of the ring as you can see on here and then obviously forms your is or die and this is your orange precipitate and this is um obviously this is the reaction that this is obviously a dye this this bit here this is how you make it you produce water and sodium chloride so what you need to know really here is the fact that alcohol sorry alcohol phenols phenols can react with benzene diazonium chloride which is this here to produce an is or die and this is called a coupling reaction um or coupling agent because um we're effectively coupling the two benzene rings together um using the chemistry of phenols to do this so you just need to be aware of this reaction here and the fact that that is obviously made to um these are made for dye stuffs so we can use them on fabrics and other other other uses as well so that's it and that's everything you need to know for the hydroxy compounds um like i said there's a lot of overlap with the previous topic which is topic 30 but obviously it mainly looks at the chemistry of phenols mainly like says a full range of videos for topic um topics one two thirty seven so that's year one and year two cie chemistry on allery chemistry youtube channel please hit the subscribe button to show your support um that'll be massively appreciated also like say these slides are available to purchase from a test shop i've bundled them up into year one and year two to try and um try and make it easier for you so you've got the full range of slides you can print them off put them in your file add notes to them etc great value for money just click on the link in the description box below and but that's it that's everything you need to know for topic 32 that's it bye bye