CHM 121 LECTURE - MONDAY

[00:00:08]and mute your source.

[00:00:20]Thank you very much. 258 I'm looking at the Q here. I'm not seeing questions. Instead, it's people that are that are putting in their names.

[00:00:51]So, I guess Okay.

[00:01:04]Well, since I can't see any questions here.

[00:01:12][clears throat] Last class I asked you.

[00:01:17]We're concluding on the reactions of caroxilic acids.

[00:01:22]Here I brought some of them back cuz I know you will not read uh in spite of the time.

[00:01:31]So under reactions of caroxilic acids you have this equation here where we're converting we're reacting the caroxilic acid in this case acetic acid with phosphorus pentacchloride.

[00:01:52]Phosphorus pentacolide is used to convert Os to Cl. Simplistically put, so here you have an acid going to an acid chloride in the presence of PC5.

[00:02:13]This acid chloride is one of the compounds we call acid caroxyic acid derivative.

[00:02:23]That means that you can directly up those compounds from the acid. And this is one of the most reactive variants of a caroxilic acid.

[00:02:41]Most caroxilic acids on their own are not very reactive. So if you want them to be reactive, usually we convert them to an acid chloride for example. So that acid chloride is a derivative.

[00:02:58]Okay. So another compound you can use is tan chloride S O C L2.

[00:03:08]It will remove the O and leave a CL there with evolution of sulfur dioxide and HCl.

[00:03:20]Okay.

[00:03:21]So they are called asi halides.

[00:03:32]Asi helides for the CO double bond R the helide X in these equations represented by chlorine.

[00:03:46]Then you can also have the formation of amides which is also an a caroxilic acid derivative.

[00:03:54]Here you see the reaction of the acid with ammonia.

[00:03:59]Okay. So an ammide you remove the O and you replace it with NH2.

[00:04:10]Okay. Now what you have here the salt.

[00:04:15]So there should be a charge on top of this plus.

[00:04:23]Okay. And strictly speaking is an intermediate.

[00:04:32]Okay.

[00:04:34]So you can get a salt by reacting an acid with ammonia. you get that ammonium salt and then if water is given off it now gives you the caroxymide.

[00:04:52]The caroxymide is a caroxyic acid derivative.

[00:04:57]Okay.

[00:04:58]So I'm only bringing this up because it will they will lead us into what we are supposed to talk about today.

[00:05:09]and hydride.

[00:05:11]Caroxilic acid and hydide that's like bringing two acids together and removing a molecule of water.

[00:05:19]Okay. So simp simp illustrated by this equation.

[00:05:25]You see you have two acids here. Acetic acid in the presence of dphosphorus penttoxide you will get your anhydide.

[00:05:41]You can see that it has two carbon with oxygen in the middle and water is given off.

[00:05:49]So you will notice that most of the reactions for converting caroxyic acid to the caroxilic acid derivatives are condensation reactions.

[00:06:04]Again look at this formation of esester.

[00:06:07]Eers are caroxilic acid derivatives.

[00:06:12]This involves the reaction of the acid with an alcohol.

[00:06:17]here represented by methanol and you see you get an esther.

[00:06:24]Formation of esester can also be called eststerification.

[00:06:31]And sometimes we say thatifications reactions are the neutralization reactions of organic chemistry. If you remember your neutralization reactions in secondary school where you bring an acid and a base and it to give you a salt and water.

[00:06:52]So in organic chemistry your acid now becomes your organic acid.

[00:07:00]Your base that you learned in secondary school here is the alcohol.

[00:07:07]The salt is the esester and of course water is given off.

[00:07:14]Remember any reaction that gives out water is called a condensation reaction.

[00:07:23]Okay, that's how I started. But now the the the definition is that any reaction that forms a product with the elimination of a small molecule.

[00:07:35]So that's definition of um condensation reaction has been enlarged a little bit. So it's now small molecules like ammonia, water, carbon dioxide, HCl and so on and so forth.

[00:07:55]So last but not least, this is also an asterification reaction, but I want you to take special note of this because you are using a dazom.

[00:08:08]Now the name of this compound has no bearing with the IOPAC.

[00:08:14]Okay.

[00:08:20]So that if you don't if you don't know it now, you might not be able to recognize it.

[00:08:33]One, two, three.

[00:08:40]No, something is missing.

[00:08:44]No, that will have a charge. This doesn't have a charge. So you see dazo is is ent triple bond and but this one is where's my mac this one is uh there is there is where my wanted to draw CH2.

[00:09:54]Okay. Well, let me remove that there.

[00:09:56]So, that's C H double bond N double bond N. There should be a charge here.

[00:10:25]Okay. So, but I mean those of you that didn't get a chance to look at this probably will not appreciate what's going on here.

[00:10:43]But we talked about asterification as being between an acid and an alcohol.

[00:10:50]Now you're seeing it with an a dazo compound.

[00:10:56]and then it's going to give you an esther.

[00:11:03]So you can see that this equation is not complete. What happened to the nitrogen?

[00:11:12]So I want you to go and look at this equation again at your own leisure.

[00:11:19]So I want to talk about caroxyic acid derivatives.

[00:11:26]And this chart here shows us here is a simple formula for the acid derivative.

[00:11:40]Okay. And basically what happens is that the O here that we're used to for the acid is converted to different things.

[00:11:55]Once it's converted, whatever it converted to, you now call it an acid derivative or caroxyic acid derivative.

[00:12:08]So that if you look at this chart, you can see here different ways of preparing this that we're going to be looking at. The first one, if you use a greener reagent, you're going to here first of all form a ketone.

[00:12:36]This This is a ketone.

[00:12:42]We've already dealt with ketones.

[00:12:45]Okay. Then if you add excess or a second molecule of green reagent, you now form an alcohol.

[00:12:56]Okay.

[00:12:58]And the alcohol from here you can see here will be a tertiary alcohol.

[00:13:05]Okay. Now this is not neither of this this or this neither of this is an acid derivative.

[00:13:15]Okay, it's only appearing here to show you what can happen to an acid derivative.

[00:13:26]So this part of the equation that we just looked at are things we will discuss under reactions of acid derivatives.

[00:13:40]Excuse me.

[00:13:44]>> Okay.

[00:13:48]So I guess another way of these arrows might be misleading in the sense that here if you take this if you take this acid derivative that we're calling now It's um most likely what you have here is the acid derivative that is the most reactive like I said earlier which is the Sihaline.

[00:14:32]Okay, because it's with this now that you can make all these other ones.

[00:14:41]You It's difficult to convert an acid this caroxilic acid to an to an esther or an amide or an anhydide on its own because they are not very reactive. So you first of all have to form the acid halide where here now Y will represent C L or Br and so on and so forth.

[00:15:20]Okay, but we're not going to dwell too much on this because of our time constraints. But what you're taking away from this is if you add alcohol, which is the RO to an acid derivative, you're going to get an esther.

[00:15:54]So maybe an [clears throat] easier way is to call this in yellow activated acid to then give you the acid derivatives here. This is just a summary of what we're going to look at. But I guess I'm trying to introduce you to it before the main stuff for those who might find it easier to understand it this way.

[00:16:20]Now if you use ammonia you get caroxilamide or amide and that process is aminolysis.

[00:16:34]When you use alcohol is alcoholis.

[00:16:40]Okay. And what are you doing? you are converting activated caroxyic acid to the caroxilic acid derivatives and like I said theoretically what you're doing is that you're moving from this acid to the derivatives that you [clears throat] have seen here theoretically but this on its own is not very reactive. So you have to first of all convert this to maybe a CL or a Br.

[00:17:16]That's a headlight before you now start either adding alcohol or ammonia to be able to get what you need.

[00:17:36]This last one is uh acid hydraysis.

[00:17:41]It will give you an alihide which you can further reduce.

[00:17:52]Oh sorry that's H minus sorry not hydrarolysis that's that's reduction.

[00:18:03]Okay. So, if you take note, there's a difference between H+ and H minus.

[00:18:17]H+ is a proton, H minus is a hydride.

[00:18:23]And they represent different things.

[00:18:28]Okay. So, [clears throat] that's a summary of what we want to talk about.

[00:18:33]caroxyic acid derivatives.

[00:18:37]Now that you have that, let's see whether it will make sense the other way around as we've been doing it. So first of all, quickly how do you name these compounds?

[00:18:51]Basically all we've been doing before you find the long chain yada yada yada. Okay, but now we're going to look at how to name them as quickly as possible to make sure that we understand, but you will still have to go and do some work on your own. So here you can see the general formula for this is general formula for caroxilic acid.

[00:19:29]Then general formula for acid helide or caroxilic acid helide where the O is removed and substituted with a halogen here exemplified by chlorine and bromine.

[00:19:43]Okay, those are the more common ones as I'm sure you are aware. Then acid and hydide.

[00:19:52]That's the one where you use two acid molecules. You remove water and then you have the functional group of carbon oxygen double bond. Two of them with oxygen in the middle.

[00:20:07]That's how you know a caroxilic acid and hydride.

[00:20:13]Okay. Then you have the esester where simplistically you remove the H you put an or aromatic group okay you have the amite you remove the O you put NH2 that's one we we arrived at by reacting acid with ammonia you can also have thio esters tio esters are instead of oxygen you have sulfur.

[00:20:47]Tho represents sulfur.

[00:20:51]Then you can have SI phosphates.

[00:20:55]Okay, phosphates are common in nucleic acids and of course you know the phosphoric acid.

[00:21:08]Okay, so these are examples of caroxilic acid derivatives.

[00:21:16]Let's start with okay before that generally to form caroxyic acid derivatives they undergo what you describe as nucleophilic substitution.

[00:21:31]If you recall when we were talking about carbon, we said they have a propensity to deoize the pi electron where the oxygen now has a delta negative and the carbon now has a delta positive because this carbon is electron deficient by virtue of this oxygen pulling most of the electron to itself.

[00:21:58]The carbon will always be happy to receive a nucleophile.

[00:22:03]A nucleophile like I've said before is nucleus loving or positive center loving. So because this carbon has a positive center because it's electron deficient, the nucleophile will be happy to go there. And this is basically what all acid conversions to acid derivatives is based on.

[00:22:31]So the halite will now go off as this comes back.

[00:22:42]Where's as this now comes back also you can you can put in the middle here you have O minus here you have R here you have your Y and then of course you have your Nu the nucleophile that has come and as this comes back to form a double bond here this is a good living group it goes off and that's how come you have this and then of course you can see your wire that has gone off. So that's the general mechanism for reaction of carbon and that's how acid derivatives are formed.

[00:23:34]Okay, let's now look at specific examples. We start with the acid halid. Remember the halides are the reactive version of caroxilic acids.

[00:23:49]Okay. So how do you name them?

[00:23:54]We already said for caroxilic acid you're going to obviously have oic acid or caroxilic acid at the end.

[00:24:03]So to name acid and hydride you remove the C acid at the end and you put your Y L.

[00:24:14]So and then whatever hogen is. So in a way you if you remember the way we converted uh N is equal to 1 CH4 is methane.

[00:24:34]You remove one hydrogen there becomes CH3.

[00:24:38]You remove A and E here becomes methile.

[00:24:45]This is when you dealt with hydrocarbons from the nature. Okay. So for caroxilic acid helides whatever caroxilic acid is coming from you remove the ic acid of the caroxilic acid you put y l and then you write the h hallogen that is replacing the o there as a halide.

[00:25:13]So for instance here you have acetile chloride and you have why is that not sorry acetic chloride if you look at this you can cast your mind back here instead of this if you have oh there it will be asset ic acid.

[00:25:45]Okay. But remember acetic acid is common name. It's not pack.

[00:25:51]Okay.

[00:25:52]So just happens that this works. So that's why we're putting it here. But don't confuse it. The correct pack name will be itanoic.

[00:26:05]Where's Okay, the correct name for this compound if it had oxygen here and hydrogen would have been ethaninoic acid. So you take the ic acid, you remove it, you put Y L and then what has replaced it there is a chloro group or a chlorine group. So you have chloride.

[00:26:42]Okay. So the one in red is IOPAC. The one in black is common. It just happens that in this case the common name which usually will not follow rules. This one is following it.

[00:26:59]But do not confuse it.

[00:27:09]The next example that's benzo bromide and then cycllohexane carbonile chloride. What I would say to you first of all if it's confusing you the first thing you do remove this one first or if you see it and you asked to name this compound remove this first and imagine that is O once imagine that is O name it as a caroxilic acid once you've succeeded in doing that then remove the ic acid of the caroxilic acid put Y L and then now remove the O that you put here and check what is there chlorine that is there so chloride if you had named this this would have been cylohexen caroxyic acid okay remove the ic acid you put y l and then it is a chlorine atom that has replaced the O. So it's a chloride.

[00:28:28]It appears quite straightforward, but if you mess with it, it will mess with you. If you don't accord it importance, it will desert you in the exam. If it deserts you in the exam, there's no way you are passing.

[00:28:45]So use these ones to practice.

[00:28:54]Okay.

[00:28:57]Now acid and hydrides. We already said that acid and hydrides are the acid derivatives that have carbon two carbon oxygen double bonds. Then in between them you have oxygen. And then here you have your R. And on this other side you have your R prime. That's the acid and hydride.

[00:29:25]Now how do you name it? Just remove the acid and put an hydride or you add an hydride after the acid.

[00:29:41]So you look at this for instance like the way we did uh the way we did ethers the way a little bit of the way we did ketones.

[00:29:56]You come here, you divide the compound by virtue of the oxygen.

[00:30:07]On this side you have acetic acid or eaninoic acid. On this side you have benzoic acid.

[00:30:17]Okay. So here now this is the common name acetic benzoic and hydride.

[00:30:31]There is no rocket science to this one here.

[00:30:36]You have seen how it's done.

[00:30:45]Now um like I said if if you were doing citric acid is common name if it is IOPAC which is what we are talking about here.

[00:31:03]Okay.

[00:31:05]And I keep emphasizing it because uh acetic acid is not aliopac but in this acid derivatives you find that acetic obeys most of the rules of so but if you make the mistake of thinking is like that and then you get to other forms of acid like citric or uh lactic.

[00:31:39]The other one is dicaroxilic.

[00:31:43]So please don't get carried away with the aesthetic that is all over the place.

[00:31:51]Now look at this one here. This is the opac way of naming the compound we're looking at.

[00:32:01]And notice that now in this case the benzo comes before the tanoic.

[00:32:10]And also notice that here you have an you have acid.

[00:32:15]Okay. And hydride.

[00:32:19]So that's theopac nl. You divide the compound at the oxygen that holds the two carbon together.

[00:32:31]You name the right and the left.

[00:32:36]You now remove the acids from the names of the right and the left.

[00:32:41]Combine them alphabetically and then have acid and hydride at the end of it.

[00:32:52]So they are both going to be Zoic. Zoic or IC will end both of them. So there's no priority.

[00:33:05]If you cast your mind back to when we were doing the EAS, you usually give priority to the the uh the a longer chain.

[00:33:23]I hope you still remember all that.

[00:33:31]So that's for acid and hydride.

[00:33:38]Look at uh okay look at this for example this number three see it has been drawn this way this one is easy but look at this other one which is another way that it can be written for you in a test or in an exam and when it's written like this many of those before usually have problems if there is a CL somewhere and they tend to confuse the CL with carbon.

[00:34:15]I hope you won't be one of those people.

[00:34:20]So look at these ones, use them to practice.

[00:34:26]But so for example, if we do this one here, you come, you break this here.

[00:34:35]This one has one carbon here, one carbon here. When you have two carbon atoms is so that means that this is itaninoic acid.

[00:34:46]If you can't do it as fast as I I'm doing it, don't worry yourself. I've been doing this for long.

[00:34:52]Okay?

[00:34:54]So, you take your own time. Is here you have 1 2 3 4 5 6 n is equal to 6 is hexane. So that means that this will be hexanoic acid.

[00:35:11]Hexanoic acid.

[00:35:14]Okay. Now you're going to combine them to name this.

[00:35:19]E is before H. So it will be ethanino ethaninoic hexanoic acid and hydride.

[00:35:35]Okay.

[00:35:37]So understand you know usually in class you when the lecturer the lecturer will give you easy examples and then in the exam you see very hard ones. It will not be hard if you understand the principle that is being enumerated. It is when you don't understand it or you you seek to cram that when you might have issues.

[00:36:07]So you see those ones and again remember that the way we deal with compounds that are linear or straight chain like this is not the same as how we deal with ones there's a cyclic compound be it aromatic or nonaromatic.

[00:36:28]So that this one for instance when you divide it you're going to have a cylohexane caroxyic acid.

[00:36:41]I think we did example of this when we're dealing with caroxilic acids this compound here.

[00:36:50]So if we didn't but I mean I think we did but if you can't find your own Google is always your friend.

[00:37:02]It's good you come across these compounds when you are studying and name them and understand them than meeting them for the first time in a test or in an exam.

[00:37:16]They usually not very friendly when you are meeting them then cuz they will say you want to use them. So meet them and make friends with them before test or exam.

[00:37:29]Okay. Amites.

[00:37:33]How do you do amites?

[00:37:35]Caroxilic acid. You remove the X Y L I C acid and you put amide here.

[00:37:50]All these ones go off and you have this.

[00:38:05]Sometimes obviously it's better to show them.

[00:38:10]So if you look at this again two carbon atom asatomide theopac name is eanomide.

[00:38:24]Okay if you come across this is an is a caroxyic acid derivative. You've seen that. So mentally you just assume that O that is here.

[00:38:37]If it is O that is there. N is equal to 2. N is equal to 2 is ethane.

[00:38:46]And if you remember the rule for acids you remove the E, you put oic acid. So you remove E from ethane. You put oic becomes ethaninoic. So when this is O here is itaninoic. So you write that itaninoic acid.

[00:39:10]I'm just giving you example of how you name.

[00:39:14]Okay? Because you are just learning.

[00:39:16]It's easier you do them step by step so that you don't get confused or you don't forget anything. That's why I suggest it's a suggestion. You can choose not to. If you can already look at it and know what it is, then you don't need to be using my suggestion. But if you don't know, my suggestion is once you come and you identify that caroxyic acid derivative, you convert it to the caroxilic acid first. That will give you the parent caroxilic acid. Then you name that caroxilic acid.

[00:39:49]Once you've named that caroxilic acid, then you now come back to what you were asked to name. So if the NH2 there is O, it's going to be it's going to be eanoic acid. So if you remove if you now remove the O and it's back to the NH2, which is what you're supposed to be looking at, you now remove your OI here.

[00:40:24]You remove your OIC acid.

[00:40:28]You replace it with amide amide.

[00:40:36]So it becomes eanomide.

[00:40:44]That's the Iopac. The acetamide I cannot stress this enough is common. That's not the IOPAC. So in an exam if you see both if you go and choose a certain mind the computer will mark it wrong for you.

[00:40:57]Don't say you haven't been warned except if the question is common name but nobody will let me not say nobody will ask you cuz I don't know these are examples you will look at okay to be able to esters Esther just like similar Similar to amite you remove the O I mean you remove the in this case now you remove ic acid in the case of amide you remove the OIC.

[00:41:40]Okay in the case of esters you remove the ic acid and you replace it with a T.

[00:41:50]Okay.

[00:41:52]Every other thing stays the same.

[00:41:59]So that's nomencle.

[00:42:01]Now let's look at some reactions quickly. We said that for acid derivatives the halides or the acid halide is usually the most reactive and that's the first place to go to if you want to convert to other caroxilic acid derivatives.

[00:42:21]So here you see an example. The first example we saw when we were looking at reactions of caroxilic acids was with phosphorus pentacchloride.

[00:42:32]This one is tan chloride.

[00:42:36]That's the common name ti chloride.

[00:42:41]Iopac name sulfur oxy chloride but is a reagent is not a compound. So styl chloride we call it. So you know it as tyl chloride as well S O C2 it will convert acid to an acid chloride.

[00:43:02]Then you can see here instead of using phosphorus penttoxide we're using phosphorus tri bromide ether to give us the same acid halide in this case an acid bromide.

[00:43:21]Okay.

[00:43:23]So this basically explains the reaction which is what we've talked about before.

[00:43:35]This is the preparation for acid and hydride.

[00:43:40]You heat two molecules of the acid and it will give off water and give you acid and hydride.

[00:43:50]How do you prepare esters?

[00:43:52]There are different ways. You've seen some of them when we're talking when we're talking about uh alcohols. So some when we're talking about caroxilic acids.

[00:44:03]So here now to make the esester there are different roots. The first one here you convert the uh the acid to acid chloride or acid halite.

[00:44:22]Then you use an alcohol in the presence of a base.

[00:44:30]That will now give you your esester.

[00:44:33]That's one method. Another method here is you react your caroxyic acid with alcohol the presence of an acid you get your esester.

[00:44:47]Okay, that's acid. Uh, this one you use a base with your aide I mean your ailide.

[00:45:13]So first of all you use the base.

[00:45:17]It will convert your O here to O N A+.

[00:45:22]Then you use this.

[00:45:27]It will take the [clears throat] R here.

[00:45:30]Knock off the Na+ and put that R there.

[00:45:33]Then the Na will go and react with the X on the other side.

[00:45:38]So those are three ways of making esters.

[00:45:44]Obviously you know that esters are very important not the human ones. Well the human ones are also important. Yeah.

[00:45:53]But esters are sweet smelling and they are used for different things. So then you can see the rules here.

[00:46:03]If you make the acid chloride before you form the esester, it will apply to all of them. This one you can only do it with simple alcohols. So, primary alcohols, some secondary alcohols.

[00:46:19]The third method only primary alkaalites. That's for the second step there that you need to do.

[00:46:29]But those are all different ways of making esters.

[00:46:35]And here is a real example that you can look at at your convenience.

[00:46:41]How do you make amides? We said at the beginning you use ammonia.

[00:46:45]So that is that there.

[00:46:50]Why this one going back? Well, we're trying to hurry up. This one is pushing us back.

[00:46:58]Okay. This is okay. So, amid we've already seen you use ammonia, it will give you this is called a primary amide.

[00:47:16]If he has two hydrogen atoms, yeah, it's primary. If he has one, secondary. If he has none, it's tertiary. So emit can also have primary, secondary and tertiary just like alcohols.

[00:47:31]Okay.

[00:47:33]So so you either use ammonia or use an amine.

[00:47:43]We didn't get to look at the means again.

[00:47:47]So I will just send you the slides. You can read those ones. They're very easy.

[00:47:52]Okay. So here you have an example of a primary amine.

[00:48:01]This is a secondary amine.

[00:48:05]This is ammonia.

[00:48:07]All of them will give you an amide. But notice that you cannot use a tertiary amine.

[00:48:18]Tertiary A mean is R R prime R R prime N or if we write it the way as you will find we write a means as R NH2.

[00:48:34]Okay. So if the two hydrogen atoms are substituted into N R prime R prime prime that's the correct way okay not this one so that you don't get confused so you cannot use this is a tertiary amine you cannot use a tertiary amine on a caroxilic acid to get an amide because you need at least one hydrogen atom, replaceable hydrogen atom for that equation to form.

[00:49:24]But having said that, you can have a tertiary amide.

[00:49:28]You can have a tertiary amide like you're seeing here.

[00:49:38]Okay, that's how you make amides and the process is called aminoysis. We already said that.

[00:49:50]So this is an example that you can look at and hopefully this is another example where you're using ammonia here.

[00:50:06]So this is a chart that shows you the degree of reactivity.

[00:50:15]If you move from blue to pink, you get more reactive. If you move in the opposite direction, you get less reactive. So this chart compares the caroxilic acid derivatives.

[00:50:31]And you can see that at the top the most reactive is the acid haly represented by an acid chloride.

[00:50:41]And if you recall we said that that is the most reactive way. If you want to convert a caroxilic acid to a caroxilic acid derivative, you first of all convert to the caroxilic acid halide because it's the most reactive.

[00:51:02]The halide is a a good living group.

[00:51:06]Once a nucleophile comes and attacks the carbon that is bonded to the oxygen, the halides will happily leave.

[00:51:16]The next one is the acid and hydide. You can see it there. Then before you have the the tha then the esester and at the bottom is the amite.

[00:51:28]Okay. So it is the most reactive. I mean it is the least reactive but the most stable.

[00:51:38]So you can find questions where you asked for instance which is the most stable caroxilic acid derivative or you are given a list of caroxilic acid derivatives and you're asked to arrange in ascending order or descending order of reactivity or you can also get ascending order or descending order of stability or you can get ascending order descending order of instability.

[00:52:10]So first of all you have to understand the question then you'll be able to arrange. So here now what you see arranged is if you're going like this if you're going like this where's my arrow? You're going like this.

[00:52:29]So you're going to say, if we call this 1 2 3 4 5, you're going to say one less than two, less than three, less than four, and so on and so forth.

[00:52:46]If one is less than two, what are you talking about? You're talking about what are you talking about? If you say one is less than two. So this one now is this is less than this. That means this is greater. So you're moving in ascending order. Ascending.

[00:53:12]So again try not to let ascending and descending confuse you because that is the plan of the examiner to use that to confuse you. So first of all mentally whenever you come across it mentally first of all establish does this question want me to put the smallest one first or the biggest one first.

[00:53:34]If it is the biggest one first you are descending. If it is the smallest one first you are ascending.

[00:53:41]So now if you are ascending that means you're moving from lowest to highest like in this case. Now if you're moving from least reactive to most reactive you are ascending. But if you're moving from most reactive to least reactive you're descending.

[00:54:04]So you see those kind of questions test different they test at least two things.

[00:54:08]your knowledge of the English language of proportion and then the real chemistry of whether the halide is more active or less active and so on and so forth.

[00:54:24]Okay, so those are the things you should you should take note of. Um, like I said, I didn't get a chance to to teach uh a means.

[00:54:42]Ask your class reps for the for the slides.

[00:54:46]If you've understood all the ones we've talked about, then the ains will be easy for you to follow in terms of nomenclature, in terms of reaction. Some of them you've already seen.

[00:54:59]here.

[00:55:01]If you have any questions, I'm going to leave this the chat open. So once you once you you click on the link, you can get to the chat and you can put a question there.

[00:55:17]Now the plan is to do a general revision and a test at the end if time permits.

[00:55:28]If whether time permits or not you will do a test. It is the revision that anyway the school already has a revision week. So that means that that is also possible.

[00:55:39]So from Wednesday uh professor fashion will most likely be taking you in another part aspect of the chemistry in organic.

[00:55:52]So fortunately or unfortunately whichever one applies to you this will be the last time we'll be interacting on this forum and like I said if you have any questions put them all you wait till the revision.

[00:56:15]So, um, I don't usually get questions.

[00:56:21]I was going to say any questions, but I'm sure there will be none.

[00:56:28]But let me check anyway.

[00:56:33]Maybe I'll be surprised this time.

[00:56:37]Uh, no, I don't see any.

[00:56:43]I don't see any Q&A here. Our time is up anyway. Okay. So, all the best.

[00:56:53]Um, I'm sure you already know, you would have justified it, your or if you've seen past questions, your exam is going to be multiple choice. Your test also will be multiple choice.

[00:57:09]So, do your best. Try and study it.

[00:57:12]That's why you're here. If you study, you will pass.

[00:57:17]It's all in your hands. Have a good morning.