[Music] [Music] hello my name is Chris Harris I'm from a Lurie chemistry and welcome to this video on OSI our carbonyl compounds so this video is dedicated specifically to OSHA a so if your study in this example ordered a level chemistry then L all the content here is completely relevant to you nothing more and nothing less so what I asked you to do is just subscribe to my channel because all of this is free it's not just this video but there are loads of other videos for the full range of the OCR content that you need to know for your exam and so please subscribe and there's no cost for it that's that would be massively helpful to show you support and these powerpoints if you like your own private copy of these powerpoints then they're all available to purchase on the link in the subscribers in the subscribers box in the description box below all of our information is there so just click on that like say these videos are designed to as revision so you may have looked at this already in school or college or you may be studying it on your own as an independent candidate so therefore the information here may be quite new to you but it still informs you of all the information that you that you need for it it is one thing knowing the content you've got to be able to do your exam practice as well and so just make sure that you're practicing thoroughly with exam papers and if you're unsure on the technique that you need to adopt and I have done videos on exam technique on Alawis chemistry YouTube channel so just go and have a look there and remember to subscribe did I say that already right okay so like I say this matches the specification directly to OSHA a so it contains reactions of carbonyl compounds and characteristic text tests for carbonyl compounds as well so the test you can do so is quite a short topic but the some mechanisms in here that you need to know of course okay so let's start with aldehydes and ketones so all the housing ketones have the carbonyl functional group which is C double bond o the different screen and aldehyde in a ketone is the position of the carbonyl group which is the C double bond o group so aldehydes they have the carbonyl group on the end and they always have an ending of owl so ethanol ethanol methanol propanol etc etc so here's an example this is propanol so you can see propanol has two carbons in it so we call it probe and because it has the carbonyl group @ly on the end carbon and we call this propanol this one is ethanol so it has three carbons the first one this second one has two carbons and so this is called ethanol which is ch3cho seen see how it's written out as a displayed formula and there's a structural formula as well where's ketones they have the carbonyl group on an inner carbon and they all end in own so for example this one's called propanone and this one is called Penton two own so with ketones you have to be able to name them properly so you can see here that we've got a ketone in the second carbon here so this is pent Antoine but you've got five carbons hence why it's called pent so make sure you familiar with how they look and the naming of them as well okay so aldehydes they can be readily oxidized however ketones can't be oxidized so all the hides are oxidized to carboxylic acids and and we use an oxidizing agent to be able to do that so for example here's your aldehyde here it's been oxidized and you notice that we're using the oxidation symbol you can see here so we're using that to symbolize an oxidizing agents it's just o in a square bracket and then we form our carboxylic acid there at the end ketones are not oxidized at all so they so they also is just a cross so they can't be oxidized also if you add an oxidizing agent to a ketone and you don't get any any further reaction with that one okay so tollens reagent this can be used to distinguish between aldehydes and ketones so tollens reagent is a is a nice is a nice colorful colorful reagent to use to test it but the tollens reagent has to be made first to be able to distinguish between an aldehyde and a ketone so you tollens is a it you get this nice silvery color that comes out it comes out at the end that's really good so anyway what we're going to make first is silver nitrate solution so that's colorless so we not make it we pour it into the test tube I don't know how you would how you but you wouldn't want to make it you can actually buy it and so silver nitrate solution you add that into your test tube then we have a few drops of sodium hydroxide and we form a pill brown precipitate that forms so we add that until we see that precipitate and then we add a few drops of dilute ammonia to that until that precipitate dissolves and then what we've made there in our test tube is tollens reagent so then what we do is we are dialdehyde or ketone depending on obviously what we're testing to the tollens reagent and we place it in a hot water bath as you can see as you can see on there and we don't use a Bunsen burner because i'll hides and ketones are flammable and the last thing you want to do is to have a test tube with an aldehyde akita in there with the naked flame underneath and you end up with fire coming out the top of your test tube and you end up with all sorts of also as a problem so so use a water bath and it's a lot safer to use a water bath so tolerance contains this complex so it's AG nh3 - so remember what a complex looks like so you've got your silver in the middle and your ammonia ligands around the side this is a different complex because it's a linear one you've only got two ligands around here for this one and it's added some warm it's added warm and and we add it to all the hides and if there's no other hide present we get a silver mirror it's also known as a silver mirror test and and if we get ketones we've got ketones in there then we get no precipitate at all so we don't see any visible change if there's a ketone so this test is really good for distinguishing the difference between aldehydes and ketones so Brady's reagent or two for dye night trophy now hydrazine try and say that one quick or two for DNP it can be used to distinguish between are the Hyde's and ketones so Brady's reagents is dissolved the Zowie make its Brady agent is dissolved in concentrated sulfuric acid and method on okay so would dissolve them in that and then it's out to the substance under test depending what we're testing here if a carbonyl group exists then a bright orange precipitate is formed and only reacts with seed or Bondo's in other hides and ketones not in carboxylic acids so they actually this statement the statement here is not to distinguish between aldehydes and ketones that should be to distinguish between carbon aisle carbonyl groups but only in our hides and ketones and it's this bright orange substance and it's a derivative of a carbonyl compound and different carbonyl compounds produce different derivatives so it depends on what you're reacting it with and so they have different melting points and they can be identified against a library of no melting point so what we can do is we could take that and put it into a device that measures melting points and we can distinguish what type of substance we may have worked if it's an aldehyde if it's keto on depending on what what the aldehyde is okay so when we're saying and distinguishing between that it's about trying to identify what these compounds are what the aldehyde is and what the ketone is so are those in ketones they can be reduced to form primary and secondary alcohols so reducing agents such as sodium borohydride and or also known as sodium tetraborate sodium sodium tetrahydrate bora-bora it is a three if I could spit that out it is dissolved in methanol and water is easy just a sodium borohydride dissolve the method on and what and can reduce aldehydes and ketones okay so it's common to represent reducing agents as H in the square brackets so just like we've seen oxidizing agents are represented in a square bracket which is oh okay we represent reducing agents as H and this is then used to reduce your substances so for example here we've got an aldehyde here so this is this is propanol which is here we react it with our reducing agent and then we form our alcohol now you might think well why do we use a two here why do we have to H and the reason is because we need to lots of reducing agent to produce two hydrogen's to make it into the alcohol so we need one hydrogen to go here which is this bit here and we need one hydrogen to attach onto the oxygen which goes here so that's why we need to H so make sure these are balanced ketones are reduced to secondary alcohols exactly the same so we've got two hydrogens there so one hydrogen goes onto the oxygen and one hydrogen goes down there as you can see so um the mechanism showing how hydride ions so h minus ions are produced by the reducing agent how that reduces aldehydes and ketones to primary and secondary alcohols respectively so the mechanism is the same for all the highs and ketones there's no difference here so here we've got the H minus sign so that H minus sign comes from the reducing agent that way that we're doing sorry that we're using so we've got h minus lone pair of electrons they go into that Delta positive carbon there and then that then has a knock-on effect that in terms of break in that double bond which is there so it breaks that double bond and the electrons jump onto the oxygen there so remember from year one chemistry you need to know how to use curly arrows and mechanisms and it's very important so in other words the arrows must short direction of electron travel so it goes from the lone pair here into the carbon it breaks that double bond and then onto the oxygen there so then we form this substance which is here and this is our intermediate we've got a lone pair on the oxygen that's the remaining because the electrons have jumped from one of the double bonds from the double bond here into the oxygen so it's now a single bond and then these electrons from here then go and attack the h plus iron that comes from an acid or water that was added to the reducing agent at the start so remember it's about trying to make sure that we've got enough h+ ions in there to allow this step to to occur and then finally we form our products which is our primary alcohol in this case because we've used an aldehyde but like say the mechanism is the same for ketones as well ketones obviously just secondary second foot the form secondary alcohols okay so let's have a look at the interaction between potassium cyanide and a carbonyl group so tarsem cyanide reacts with the carbonyl group to form hydroxy nitriles so the reaction occurs by a nucleophilic addition and so this means a nucleophile which is your CN minus sign normally would get that from some like potassium cyanide or hydrogen cyanide but I didn't sign that's quite difficult to use but that's where it comes from and it attacks the carbonyl group adds on and makes the hydroxy nitro and all the hydroxy nitrile is is just a compound that has a hydroxy group which is Oh 8 and the nitrile group which is CN so potassium cyanide is used to produce the CN minus ions potassium cyanide is easier to use because it's easier to handle it's safer to use and you can dissolve it and quite readily in this case we dissolve it in acidic solution and it produces the following ions so we've produced our k+ and CN minus signs here so those are k+ and as you CN minus ions that are produced so here the CN minus signs comes from potassium cyanide and is a nucleophile so remember a nucleophile means nucleus loving so itself will have a lone pair of electrons so you can see here I've got a lone pair of electrons here and these if you think about your mechanism these will then move on to the Delta positive carbon which will then break that double bond so let's have a look so there we go okay so the positively charged carbon the positively charged carbon is attacked by the cyanide and the lone pair of electrons are donated from the CN minus sign as you can see and then immediately the two electrons from the double bond transfers to the oxygen so that's the first step that we've got to do so very similar to what we've seen before with other reactions of carbonyl compounds so they say we can use hydrogen cyanide but it's easier to it's easier to use potassium cyanide but we've got to dissolve it and in in acid for potassium cyanide but we don't need to do it for hydrogen cyanide because it already has a supply of h+ ions okay so as the potassium cyanide m' is used as a potassium cyanide used Sarris acidified then we have a ready supply of h+ ions because we've acidified it so same reaction happens already with the oxygen that's got the lone pair of electrons that reacts with the h plus iron and then what we form is our hydroxy nitrile which is formed there as you can see so the mechanism is very similar to the other reactions that you may have seen so the overall generic equation for an aldehyde is you've got your aldehyde here which is our CH o adding your potassium cyanide and the h plus signs is because we've dissolved it in acid and that forms our aldehyde sorry a hydroxy nitrile which is here and K plus so a hydroxy Nitro will be on the terminal carbon if it's reacting with an aldehyde now with a ketone it's exactly the same except we form our hydroxy nitrile in a middle carbon instead and but the reaction is very similar and if we use an unsymmetrical ketone or an aldehyde so apart from methanol then what we do is you get in a mixture of enantiomers are produced and and this is seen in the optical isomerism topic and that you would have seen or that you may have seen already okay so when we use potassium cyanide and we need to assess the risks when using it and you need to be aware of some of these risks when using a potassium cyanide because as you you may know cyanide is not particularly good for you so potassium cyanide is an irritant it's very dangerous if it's ingested or hit or inhaled but it's gotta be better than hydrogen cyanide which is a gas and it's much more difficult to control that's why we prefer to use potassium cyanide and when it reacts with moisture and it can form a hydrogen cyanide gas we've got to keep it dry and to reduce the risks we need to do the following so we need to take some precautions using personal protective equipment so PPE and using lab equipment to help protectors as well so for example we need to wear gloves when we're handling chemicals like this and we need to wear safety goggles at all times that'll be the case for anything any type of reaction and you wear a lab coat that just prevents contamination on your clothing so it's to protect your protective clothing and ideally we'd use a fume cupboard to prevent exposure to toxic fumes now this is only relevant if there's moisture if it's in a quite a damp area and you're getting hydrogen cyanide you don't want to breathe in hydrogen cyanide it is horrendously acidic and it's toxic so that's not a good idea to breathe that in okay and that's it so a nice short topic on carbon are compounds and like I say there's a full range of OCR videos or vision videos available on a Lurie chemistry and YouTube channel so just go and have a look on there please subscribe to all for free your subscription is is more than enough and just to show you support for the channel and these powerpoints are available to download as well so if you can purchase them click on the link in the comments box and but that's it okay bye bye