[Music] hello and welcome to this video on alcohols and this is for ocr-a my name is Chris Harris and I'm from a Lurie cheaters.com and let's say this video is just a revision video so it's just going to do a quick overview of the alcohol topic specifically for OCIE and besides I'm going to use here you can purchase just click on the link in the description box below this video and you'll be able to get hold of them there I'm great for things like revision on the move you can put them any tablet in your smartphone you can print them off write notes etc so pretty useful I think so yeah okay so like I say these are specifically for ocr-a and their Maps these specification points and from the syllabus that you can see here so useful if you do know sorry okay so let's have a look at an introduction to alcohols because we need to know what you want these things up so alcohols have the functional group Oh H that's a hydroxyl group and that's its homologous series and it's got the general formula cnh2n plus one oh hey CH okay so make sure you can use that formula as well they come in different types and the first one is a primary alcohol normally we give it a little one degree symbol and so that doesn't mean temperature that means primary and this is kind of obvious as opposed home so you've got your your R which is your alkyl group and this is r1 and you can see here this is primary because we've got an alcohol attached to a carbon which is attached to one of the carbon which makes it a primary alcohol which is this one here okay so this is an example could be beaut our model and you get secondly alcohols as well here's a secretary on so the alcohol is bonded to a carbon which is bonded to two other carbons this is a secondary alcohol so butan to all will be classed as a secondary and tertiary as you might have guessed it's basically an alcohol bonded to a carbon which is bonded to three of the carbon groups so an example will be to me style propound to of this example here these are the by the way these are these structural formulas of the of the example that we'll put on there okay so we need to know about some parts of these things in solubility is one of them okay so alcohols and so we've got these Oh H bond remember on alcohols and it's polar okay we have a delta negative on that oxygen which means the electrons are pulled towards this electronegative oxygen in the covalent bond that's attached to the carbon okay so because these alcohols are polar they actually interact with water molecules so these are your alcohols here these are these examples of methanol and this is water here now these will hydrogen bond with the water the lone pair on the oxygen on the alcohol will form a hydrogen bond with the hydrogen on the water that's because the Delta negative charge and the oxygen is attracted to the Delta positive on the hydrogen okay and this is a hydrogen bond so because these interactions are there this allows the alcohol to dissolve in water however this can only apply to suit a shorter chain alkanes because this bit doesn't dissolve in water it's not polar so the more of this bit you've got another is a hydrocarbon bit the less likely your alcohol will dissolve so things like methanol and ethanol and proton one all would dissolve as soon as you start getting into longer hydrocarbon chains they become insoluble so yes that's what basically since the longer the hydrocarbon chain the more insoluble it is this bit remember is nonpolar and it reduces the interaction that water can make with the alcohol because most of the molecule is nonpolar so it won't dissolve okay alcohols they can also hydrogen bond with each other that's pretty useful and an hydrogen bonding is the strongest type of intermolecular force remember they also have a higher boiling point and then molecules of a similar relative mass with no hydrogen bonding for example alkane so if we take the similar similar hydrogen similar mass of an alcohol and convert it to an alkane and alcohol will have a higher boiling point because its ability to hydrogen bond with each other whereas a standard alkane can only do your your temporary or your induced dipole dipole okay so make alcohols not as volatile really as alkanes okay so let's see how we can make a halo alkane from these okay so here are canes are made on also known as how the juno arcane they are made from alcohols virus substitution reaction okay so we take our hero alkene or halogen wark in basically these are made when an alcohol is reacted with a halide iron sauce so for example like a salt like sodium bromide and we add an acid catalyst which is sulfuric acid okay so let's have a look and here's your reaction here this is butan tool basically react that with a our salt which is sodium bromide we form 2-bromobutane you can see here obviously we have an acid catalyst sulfuric acid is used as you countless to help this go you form your hero arc in and notice it's just a straight swap alcohol for here lark in and we form sodium hydroxide this is alkaline so our pH should become more alkaline if we test that with a pH meter okay dehydration of alcohols so we can make alkenes from alcohols and this is pretty straightforward by just dehydrate them dehydration means the removal of water in case it's eliminating water from the comp reduce the alkie that's why we call them dehydration so the reaction involves the use of an acid catalyst so again sulfuric or phosphoric you could use basically you have your ethanol there you use your acid you form ethene from ethanol and you form water you literally all you're doing is just removing water from ethanol and you for me pizza whether it be straight forward alkenes are really and useful because we can use polymers we can make polymers from them and these used to make plastics so again it's a really useful reaction of making plastics and for non primary alcohol chains longer than three carbons okay you can get different positional isomers of alkenes and you may also get some easier as well so please check to see if your alkene that you've drawn does have easy if it does they may be asking you to name the isomer that's formed as it e is it an e alkene or is it as L arche so make sure you check up case really important you've got it just kind of making awareness of that okay so dehydration of non primary alcohols can lead to three different alkenes okay so let's have a look at this example so the double bonds can be formed either side of the carbon that did have the O H which is the hydroxyl group on gene C here we've got Butte and two all as our example okay now if we add sulfuric acid to this you can see that we get our double bond here on the left now we can get the double bond there remember there's the O H we get the double bond form there or we can get the double bond forming on the other side you can see the double bonds here on the end and here it is in the middle so we've got two different and isomers of each other these are positional isomers okay and just check for your M just check for your easy like I say so you can see this one won't display any easy ed because we've got two hydrogens on the same carbon so that one's fine but this one will okay so you get other two hydrogens on the same side which would make it Z you to E or you can have a formation where the hydrogen's now on the opposite side or the methyls and that would form EB to e okay so make sure you can differentiate check to see if your alkene does how easy if it does write them down so basically this reaction here produces three different alkenes buuuut one een which is that one I said butene which that one and EB two in which that one so for 3 different alkenes made okay so make sure you wear that okay and combustion about the holes so obviously they were fuel we could burn them and we can make electricity problem so they burn readily they have this lovely light blue flame when you burn and alcohols it's almost colorless depending on the length of the hydrocarbon chain of course so when burnt they react with oxygen they form carbon dioxide and water like other fuels do and because of burning them with oxygen obviously the alcohol is being oxidized so you can see here there's your ethanol then for example we ignite it reacts with oxygen forms carbon dioxide and water make sure it's balanced and look at your state symbols alcohols they can be oxidized by using a mild oxidized agent like potassium dichromate and this one actually is a bit more useful because we get the products produced from a mild oxidizing agent are we can use obviously carbon dioxide and water were pretty limited at what we can use them for so let's have a look so like I said it can be oxidized to aldehydes ketones and coverage so the acids by dichromate sources of mild oxidizing agents okay so alcohols are oxidized using potassium dichromate k2cr2o7 this is the mild oxidizing agent so it's reduced itself okay so this is what it's reduced from so it goes from dichromate which is orange the are 207 to - that's a diaper behind and it goes to greens the chromium iron cr3 plus you can see chromium has been reduced from here from plus seven plus three so it's a reduction okay so if it's reduced itself it's an oxidizing agent so we're going to color change okay so primary alcohols these can be oxidized to aldehydes and then they can go to carboxylic acids so if we have a look here there's your aldehyde there it has a carbonyl group C double bond o and the CH on the end carbon at CH 3 CH 2 CH o so ends in our aldehyde these can be oxidized further though to a carboxylic acid please end in O ik acid these have again a carboxylic acid II carbonyl group and the co h bonds as well at the end carbon this is the carpet or the acid secondary alcohols these can be oxidized to ketones so there's a ketone there ending on so have AC double bond again it's got a carbonyl group on the in a carbon ch3co ch3 so you can see primaries oxidized to aldehyde then carboxylic acids secondaries are oxidized to ketones and primaries can't be oxidized using potassium dichromate so the only way we can burn them is by is the only way we can oxidize them is by burning them okay so the oxidation about the hospital we need to know the kit that we use because this is the practical technique distillation and reflux is used in the oxidation of alcohols primary alcohol are oxidized but the products produced are dependent on the method that we use you got really careful this one okay Morgan knew is going to represent an oxidizing agent as Oh in a square bracket so let's have a look at this one this is a primary alcohol okay and these will produce an aldehyde then a carboxylic acid however it's really difficult just to get this aldehyde here when we're just heating it in a boiling tube so we have to use a special method for this so there's the alcohol going to oxidize it when you form your aldehyde so we have to remove the aldehyde soon as its forms if we don't it will react with more oxidizing agent and turn into a carboxylic acid so in order to remove it before it reacts further we use destination ok the aldehyde is quite lucky so as a lower boiling point the alcohol so the first bit soon as we get the vapor formed that must be the aldehyde and we extract that off so if we want to go further though if you want to form a carboxylic acid then we have to use reflux and we use an excess of an oxidizing agent so basically we heated up your aldehyde would form first cool and condense against the condenser drop back down react with more oxidizing agent and then turn into a carboxylic acid so this is why when we use it with just one this one over have to remove that first but this one we're not that bothered because we just want to produce a carboxylic acid so basically the reflux allows strong heating so in heated up from underneath without losing your volatile compounds they don't escape anywhere they condense and drop back down and and so allows them to react so reflexes are really useful for okay secondary alcohols are oxidized to ketones and it's really difficult to oxidize ketones further they don't go any further than that so we only produce one product again we're going to represent an oxidizing agent as oh in a square bracket so here's our secondary alcohol again we're going to use our reflux setup and we're going to oxidize and we're going to oxidize this using the oxidizing agent so secondary alcohols oxidize to a ketone which is this one here so this case this is pro con 2 all going to propanone and basically we can do that when we react it with acidified potassium dichromate which is our mild oxidizing agent which is represented with the square brackets oh and that's it that's your overview for alcohols for ocr-a and please support this channel by subscribing to it you get all the updates and the new videos that I put up we just click on the middle button you'll be able to subscribe and also just a reminder that if you want the copy of these slides you can purchase them just click on the link in the description box below this video right and that's it I'm off see ya bye