CHM 121 LECTURE - FRIDAY

[00:00:27]Good morning all. Um, welcome to another class.

[00:00:41]Very cloudy out there.

[00:00:45]So, it's a good thing we have this facility here.

[00:00:51]And let me see 8:00 and there just 40 of you.

[00:01:00]Uh Eluma E mechanical engineering say good morning and then mute yourself.

[00:01:18]I don't have time to waste this morning.

[00:01:19]Someone say good morning for sound check please.

[00:01:24]>> Good morning sir.

[00:01:27]Thank you. Thank you very much. Now you can mute yourself.

[00:01:34]Thank you.

[00:01:42]Okay.

[00:01:46]So, Eluma doesn't want to tell me good morning.

[00:01:55]Oh, he did and I didn't hear.

[00:02:02]Where is that stuff?

[00:02:06]Okay. So in the last class we started our discussion.

[00:02:15]Uh good morning Nu. We started our discussion on carboniz. Does anybody have any question on what we've done so far?

[00:02:31]No question. At least the chat section is sanitized there.

[00:02:39]Okay, if there are no questions, we're going to go ahead.

[00:02:46]Uh I don't know why people are not here.

[00:02:56]I'm going to take special attendance today. just 51 of you.

[00:03:05]So others who are not here are not here.

[00:03:09]Anyway, um we have little time. So let's get right to brass task.

[00:03:21]So we introduced ourselves to carbonize alihides and ketones.

[00:03:28]We looked at how they are named.

[00:03:32]looked at industrial methods of preparation and lab methods of preparation.

[00:03:41]We did notice that a lot of the things we're seeing here, we saw in the reverse order when we were talking about alcohols because you can produce carbon from alcohols.

[00:04:01]You can also react carbonize with reducing agents to get alcohol.

[00:04:19]We've loo we looked at the physical properties terms of polarity in terms of melting and boiling points.

[00:04:31]We explained why that is so.

[00:04:37]Today we're going to talk about their reactions.

[00:04:46]meat cell biology and genetics.

[00:04:52]You have just shown that you don't come to class.

[00:05:00]Was that anyway? I don't have time for you guys.

[00:05:09]>> I'm not calling you. You're in trouble.

[00:05:11]That's why I'm calling you because you can't listen.

[00:05:15]So, how is it that you can even unmute your mic?

[00:05:20]I've even forgotten to to do that.

[00:05:31]Where's this?

[00:05:36]That's rather What's going on?

[00:05:42]Okay. So today we're going to be looking at reactions of wait has someone taking over zoom that I cannot phone.

[00:06:31]Just give me a minute. I'm trying to sort out trying to anyway reactions and of alhides and ketones just like there's something to bear in mind as we go into this discussion just like we said that the main issue about compounds is their functional groups.

[00:07:18]Okay, they determine practically what happens to those groups of compounds be they physical or chemical properties.

[00:07:30]Now we said that carbon here represent ketones have this main carbonized structure and this is what really what determines most of their reactions that carbon oxygen double bond.

[00:07:50]the fact that they have one sigma bond and one pi bond and the fact that the pi bond is more mobile. So double bonds and triple bonds are more mobile than single bonds. By mobility I mean that the electrons are freer to move. And then you know obviously several times you'd have seen this kind of stuff where you see an arrow moving from the double bond onto the oxygen.

[00:08:28]Okay? And you now get something like this.

[00:08:39]where this now becomes delta plus. Maybe I should use another marker for that.

[00:08:47]This becomes delta plus and this becomes delta minus.

[00:08:53]In some cases you will see it as plus here and minus here.

[00:09:03]Okay? And you see I've drawn a reversible arrow there to show you that it can move from one point to the other. So in a way you can describe this as two structures that are oscillating between one another.

[00:09:22]And this basically is the whole rationale. Once you understand this, you'll understand why carboniles behave the way they behave.

[00:09:35]I think someone got in here before me and messed up some things cuz I can't understand what is going on here and I don't have time to be.

[00:09:49]Please check your system and make sure you're not coming in here disturbing the class.

[00:10:08]That one can't even hear me. Okay, let's start by putting you in the waiting room.

[00:10:17]That means I have to go and check that.

[00:10:23]Someone has changed my settings.

[00:10:31]Anyway, so if you have this at the back of your mind, then you will be able to understand most of the reactions that we're going to be talking about subsequently.

[00:10:48]So the fact that that carbon can take a positive sign which is what we call it which is what we call a carbonium or a carocation.

[00:11:01]It therefore makes it willing to receive electrons from nucleophiles.

[00:11:08]Okay. Nucleophiles are nucleus loving.

[00:11:12]Nucleus is usually positively charged.

[00:11:15]So for something to be nucleus loving that thing in itself has to be negatively charged.

[00:11:22]Okay. So when it's negatively charged that substrate in itself is called a nucleophile. Because it's negatively charged it will be seeking a positive center. So it is called a nucleophile.

[00:11:35]The opposite is also the case. If it is positively charged and it's sticking a negative center that entity that is positively charged is called an electrofile electron loving. Okay. So how best to remember it? If you check the entity whatever charge it has it is going to be seeking the opposite charge. If it's seeking that opposite charge it likes that opposite charge. So if the opposite charge is seeking is a negative charge then electrons are negative. So it will be an electrofile. If what is seeking is a positive center or a positive charge then it's going to have to be an electron.

[00:12:26]Okay? Or it's going to be a negative charge on itself because opposites attract. And so that entity that is seeking the positive charge is a nucleophile.

[00:12:39]I hope you understand that. So now the reaction itself you now call it you now describe the reaction based on the entity that is receiving. So for instance carbonid we say they under go nucleophilicate reaction because the carbon becomes a positive center and anything coming in to react with it has to be a nucleophile.

[00:13:10]So the reaction is nucleophilic.

[00:13:14]Again, I hope you understand that. But don't worry. I mean, as you as you move higher, it will be easier to comprehend.

[00:13:24]So, chemical properties, the carbonile functional group is one of the most reactive groups in organic chemistry.

[00:13:30]I've just explained to you why. Many important reactions of alihides are consequent upon the high polarity of the carbonile bond which leaves the carbon atom electron deficient and susceptible to attack.

[00:13:44]All this I just said so just reading this the English part. So if you didn't understand the simple explanation, if you read this hopefully you'll be able to and if none of them helps, Google is your friend. And if that one doesn't help then or your lower at least one of them must help. You must understand one of them. So most reactions of alihads and ketones are addition reactions leading to the formation of alcohols. Again, addition reactions as the names implies are reactions that add to the reactant.

[00:14:21]Okay? If the reactant was one and then the product becomes two, it is an additional reaction because you have added to it. If the reaction was if the reactant was two and then the product becomes one.

[00:14:42]Okay. No, no, that's that's not a good example.

[00:14:46]Um, no, no, that's not a good example because matter is neither created nor nor destroyed. But in this case, the names what is on the team is actually what is inside the team in terms of these names.

[00:15:01]So when you see addition reaction, it is an addition. When you see substitution reaction, it is substitution.

[00:15:10]Okay, I was saying it's a bad example.

[00:15:12]But now I remember you at least you've been taught elimination reaction. So that example can still work. So if you if the reactant is one, the product becomes two. That's addition. If the reactant is two, the product becomes one. That's elimination.

[00:15:29]If the reactant is two, the product is two, but there's an exchange. That's a substitution reaction.

[00:15:37]Okay? And then you have a third one a fourth one rather um peryclic reaction but don't worry about that for the time being.

[00:15:49]Okay. So I think substitution addition elimination.

[00:15:56]Uh so you can see here the structure I drew for you at the beginning. So again if you look at that that should be self-explanatory. Now let's look at the first example of a nucleophilic addition using hydrogen cyanide.

[00:16:22]Okay. So hydrogen cyanide is some of you might have come across it. It's something that you find in manhot escalant that's cava and that's one of the reasons why you see cava is soaked for a long time before it's processed in making gary or starch or any other kind of food.

[00:16:49]The soaking for this is to help the water remove the cyanide in the cava.

[00:17:01]That's why it's dangerous to drink uh unprocessed gary or eat unprocessed cava.

[00:17:12]Okay, that's for the food that is common to us. But here in chemistry you can hydrogen cyanide can add across a carbonile compound to form what is called a cyanohed.

[00:17:30]Okay. So again if you look at what we're saying here basically this goes here.

[00:17:43]This will break up into Na + CN minus.

[00:17:49]This CN minus is a nucleophile because it's negatively charged. It will be looking for a positive center. So that charge can come here to this carbon cuz this carbon has become delta plus and this oxygen has become delta minus.

[00:18:07]Okay. Once it goes there, they form a bond.

[00:18:15]Okay. And then that this Oxygen here that was negatively charged will pick up a proton from this dilute HC you know dilute H2SO4 we in water will become H + 2 SO minus 2 here to balance the equation. So if you put this reversible it will give you this. So one proton from here will now react with this oxygen to form O. And that's how come this is here.

[00:18:53]This CN is the one that came in here and every other thing is the same. Okay. So there's no magic there.

[00:19:06]Okay. So this is an intermediate if you like.

[00:19:10]Sometimes you see in textbooks that this will be put in a square bracket to show that it's an intermediate.

[00:19:18]But depending on the com on the carbon sometimes it can be isolatable. So it's an isolatable intermediate and when that happens it's called is an eternal cyanohydrron. Tano obviously because you have two carbon atoms here but that name can be misleading because it has that's why if you take all this that's it part okay then the cyano hydrine is this but this whole this whole entity is called cyanohydrine this particular one is eanoscino hydrine because the alcohol alcohol that is forming it is eternal.

[00:20:10]Okay? And you get it as the intermediate when you react a carbon with a hydide.

[00:20:24]So obviously here you see that we're using that we're using uh sodium cyanide in the presence of dilute sulfuric acid that is what is going to generate the hydrogen cyanide in means something at that point in time. So when you say you generate a compound in CO2 it means that it is produced at that point you don't bring it from somewhere else.

[00:20:56]So here now what you're bringing is sodium cyanide and H2S04. So when you bring them then they will together form hydrogen cyanide.

[00:21:10]Okay. Hydrogen site is gous by the way but in solution because this is dilute H2SO4 it won't be able to escape so it will stay in the reaction medium there to give you what you want.

[00:21:32]Okay. So that's the cyanohydrine first step. Then if you subject the hydrant to acid hydraysis or rather hydration you expose it to hydration in the presence of acid then you get a hydroxy caroxilic acid.

[00:22:02]So this one will be Hydroxy pentaninoic acid. I hope should be you should be able to look at this and understand why this is two hydroxy caroxyic acid. So we'll talk about caroxilic acid but you can see here you have a two functional groups on that compound. This is the compound I'm talking about in case you're not paying attention.

[00:22:30]You have two functional groups there, an alcohol and a caroxilic acid that we're going to talk about shortly.

[00:22:41]Okay, the alcohol has less priority than the acid. So the acid takes precedence and you name the compound based on the acid.

[00:22:57]Okay, here it has the longest chain. The longest chain there is three. That's why it's propanoic and the hydroxy is on carbon 2.

[00:23:09]Okay. So that is one reaction.

[00:23:15]This is the mechanism.

[00:23:18]Reaction two with greenard reagent. You remember what greenard reagent is?

[00:23:26]That is it. RMX is the general formula for that.

[00:23:32]Okay. Again, uh RMX when it breaks down OS. Okay.

[00:23:47]breaks down as R minus Mgx plus.

[00:23:58]Okay. So one way to remember this is you remember that wherever a hogen is because it's highly electrogative it will take a negative sign and wherever a metal is because it's highly electropositive it will take a positive sign.

[00:24:17]Okay. But wherever a metal and hogen are in the same compound with an organic compound, that organic compound is the one that now takes the negative sign while the while the hogen and the metal take the positive sign.

[00:24:40]So in other words, wherever in organic chemistry you see a metal with a halogen, normally when that hogen is with the organic compound alone, the hogen will take a negative sign because it's usually more electro negative than the organic part of the compound. But when a metal is now in between that halogen will now take a positive sign. Okay, that's another easy way to remember what goes on here. So now when you remember that the organic part of the greenard reagent will take the negative sign and then you remember that the carbon part of the carbonile will take the positive sign. Then that will explain to you how the reaction occurs. that R of the greenard reagent that takes the negative sign will attack the carbon of the carbon that takes the positive sign and that's how the bond is formed.

[00:25:44]Okay. So if you look at this if you were to draw you see that this goes here leaving this as positive. So this r goes here and that's how come you have the R on this carbon directly and remember that when this arrow moves here this oxygen becomes negatively charged. Then the MX from the greenard which is positively charged will now go and form a bond with that oxygen and that's why you get this as the intermediate and then if you add water the water will knock off this.

[00:26:42]Okay, I don't know if that is there but let me show you this quickly. Where is my So here for this this water comes in as H+ O H minus.

[00:27:05]Okay. So momentally by uh mechanistically you can this is minus on the oxygen plus on the mgx.

[00:27:24]So if the if the minus on the oxygen goes to pick up this proton, the minus on the O H goes to pick up this Mgx positive center. And then you will have your product which is your alcohol plus if you want to complete the equation mg x that's what you have here.

[00:28:03]Okay. So that's the mechanism and then you can see an example here.

[00:28:15]Okay, this is a a phenile metal ketone using the using the um common name if you want to use if you want to use the the the park name I wonder can you why not wait to I'll go and start it's already 30 minutes gone I don't want to be rushing for time today okay so look at this compound there all the compounds you see in the equation please at your own leisure just for fun when you look at it see if you can give it its IOPAC name and it its common name as well as understanding the reaction okay it helps you it jos your memory and makes your naming of compounds better so I'll leave this one for you to try okay that's reacting with you see that is the greener reagent there where R is replaced repl by CH3 and X is replaced by CL chloride ion.

[00:29:48]You see forms that intermediate with the MX O Mgx and you see that the methile has gone to that carbon as well. So using this general equation here you should be able to understand this one.

[00:30:04]Okay. So here instead of showing the whole water molecule here is represented by just H+ because in this equation the other part of you see this this is not correct in the sense that because you have chloride here in this you should have chloride and not X there's no X here okay so it should be chloride that should be there to make that equation correct.

[00:30:42]And then here you can have if you put if you put H2O here instead of H+ then here you have to have plus Mg C O H.

[00:31:12]Okay, this Mg CH, the CL and the O are both bonded to the magnesium.

[00:31:24]So it's not as if it's not as if the magnesium is That is this Adams again.

[00:31:56]>> I remove you. No point. So, >> okay. So that's addition of greenard.

[00:32:05]Now we've called these two nucleophilic addition and I've explained to you why it is. Okay. But carbonites can also undergo what we call condensation reactions. Condensation reactions are reactions where two reactants come together to form a product with the elimination of a small molecule.

[00:32:27]The initial definition was with the elimination of water, hence the name condensation. Okay. But that's maybe that's that's the definition you got in the secondary school if you went to a good secondary school with a good secondary uh chemistry teacher. But you're now in the university. The definition is expanding a little. So it's not it's not just with the elimination of water. Now it's now elimination of a small molecule. And that small molecule can can be water or it can also be carbon dioxide or ammonia or hydrogen sulfide or hydrogen chloride. Those small molecules. So when two reactants come together to give a product and a small molecule is given off.

[00:33:13]It is called a condensation reaction.

[00:33:15]Carbonides can undergo condensation reactions with especially with ammonia. Okay. And this is used, you'll come across this in the lab because it's used as a way of testing several things as you will find out can be used to differentiate an alihide from a ketone.

[00:33:37]Can be used to form different kinds of compounds that have color. So that if they form you notice a color change in your reaction and then you can say okay this compound is there. Okay, so ammonia derivatives add to alihides and ketones to form derivatives that are important for the identification of alihides and ketones.

[00:34:03]Ammonia derivatives are also called amines. We're going to look at them as a group much later. Okay. But here suffice for us to know that it's ammonia that we are using as the nucleophile in this in this reactions and I'm sure you all know what ammonia is. Very very bad smell those of you who have come across it in the lab.

[00:34:32]So the product contains I'm on bullet point two there. The product contains a carbon nitrogen double bond resulting from elimination of a molecule of water from the initial addition product.

[00:34:46]Okay. So here up to the the addition reaction is up to is the first stage but after that you see that water is lost. So the second stage is where the reaction is named after that is the condensation reaction.

[00:35:06]Okay. So you look at an example here. If you take ammonia which is NH3, you remove one hydrogen and you substitute an organic group becomes an ammonia derivative. Okay? And like I said, they are called amines.

[00:35:21]We're going to learn just like alcohols, you have primary, secondary, and tertiary amines.

[00:35:28]So if you add this amine or ammonia derivative whichever one you prefer to a carbon you are going to get here this amino alcohol and then if you remove water you now get this an amine.

[00:35:59]So this one carbon with nitrogen double bond. Excuse me. It's called an amine.

[00:36:09]Okay, let's quickly look at the mechanism. Like I said, it's similar to what we've talked about so far.

[00:36:18]So nitrogen has as I'm sure some of you or if not all of you are aware a lone pair of electrons.

[00:36:26]Okay, someone is mic is on. Please mute yourself before I get to you.

[00:36:35]Lone pair as as is the practice pi electron will move to the oxygen. So this lone pair will come to this carbon that has become delta positive by virtue of this moving here.

[00:36:50]Okay.

[00:36:53]Now when it moves there uh I think maybe I should first of all draw here. So before you get to this you are going to get Uh let me use this.

[00:37:14]We're going to get a situation like this or no let me say that carbon this oxygen will be minus.

[00:37:31]Okay. I want to draw the way it is so that you will see what exactly is happening. Then this R is here.

[00:37:39]this N H came in here. Okay. And when it's coming here, there is H another H and then R. Okay. Now, because it has given off his lone pair to form this bond, this bond here, the nitrogen will have a positive center on top of it. Okay?

[00:38:05]showing that this lone pair is no longer under the control of the nucleus of nitrogen but rather is now under the control of nitrogen and carbon because they have formed a bond a dative coalent bond. Okay. So they are sharing that uh uh lone pair the nitrogen has donated the lone pair into to the uh to the carbon but sorry it's not dative it's is not dative it's coalent not dative carbon doesn't have any empty orital okay so that bond now forms that way and so that this doesn't confuse you let me remove this okay that's from there we move to where we are there's hydrogen here.

[00:39:12]Okay. So now what then happens is that one of these bonds.

[00:39:21]Let's let's use this one that's on top here because the nitrogen has formed the bond and is now positively charged but it's not happy about it. So it wants to go back. So what will happen is that the bond between this hydrogen and this nitrogen will break. So you have an arrow between that pointing here. Once it breaks this hydrogen will now go off as H+.

[00:39:49]Once it becomes H+ this nitrogen now has only one hydrogen and R which is what you're seeing here.

[00:39:59]Okay. And then this hydrogen here that is now H+ will now be attracted by this oxygen that is minus. And that's how come you have your O here.

[00:40:14]No magic about that. Sorry, I cannot repeat that because I'm in a hurry.

[00:40:20]If you got it, fine. If you didn't, please look later at the recording. Hopefully to be clear enough there cuz you can always play that back if there's something you did not hear or something you did not understand. Okay, so that's the mechanism.

[00:40:41]Then here once it has formed this how does it lose water again uh very simple okay no let me not say very simple so that you don't abuse me because you are just learning it it's very simple to me because I've learned it but I'm sure when you learn it you will agree that it's very simple so here. If you take this and you break it up, it's going to be N H here and R or R prime to be more accurate. Then let's draw another bond. This carbon. Okay, here is CH3.

[00:41:29]Here is CH3.

[00:41:32]Now here you have your O.

[00:41:40]Okay.

[00:41:43]So what happens is uh simplistically just for you to understand this bond between this hydrogen and nitrogen here if he breaks in such a way or something as what happened.

[00:42:11]Okay.

[00:42:14]Oh, H. Yep.

[00:42:18]So, if this bond breaks in such a way that it goes here.

[00:42:26]Okay.

[00:42:32]In moving here, this is a good living group here under this scenario. Okay.

[00:42:41]Oh normally is not a good living group but under this scenario this is mechanistic. If we write the full reagent you will see that there's a reagent in here that would compel this nitrogen to let go of that hydrogen as a proton and then form a double bond here and then this goes off. But what I'm showing you here is the mechanism.

[00:43:04]Okay. And the mechanism is that the bond between the nitrogen and the hydrogen breaks to go and form a double bond between the carbon and the nitrogen. And then for that to happen because carbon can only have four bonds, this O has to go off.

[00:43:23]Okay, thing is already cleaning itself.

[00:43:26]So when that happens, you now get your product here.

[00:43:34]The carbon nitrogen becomes a double bond. The H that left from here that left from this nitrogen as H+ will now combine with the O that left from here as O H minus and then you have your water that is leaving and that's why it's called a condensation reaction because water is given off.

[00:44:01]Okay.

[00:44:04]So that's the condensation reaction general. Now come specifically if you represent the remember the uh N H2 R that we said the amine.

[00:44:23]Okay.

[00:44:26]Where the R is equal to O.

[00:44:32]It forms the compound is called a hydroxyamine.

[00:44:37]Okay.

[00:44:39]So if you react a carbon with a hydroxyamine, you're going to get an oxy. By the way, remember I said to you here that this carbon where you have a carbon double bond nitrogen like you do here that functionality is called an amine amine.

[00:45:09]Okay? So you remove the A in the amine, replace you replace it with I becomes amine.

[00:45:23]We haven't dealt with the means. I thought we should deal with carbon before we talk about those ones, but we will. Okay. So here when the R is O the compound is hydroxyamine and when it reacts with the carbon is going to give you an oxy.

[00:45:48]Okay the same mechanism.

[00:45:51]So remember that here in this equation here we came away with NR as a general and in this reaction we have replaced the R with O and that's why we're coming away with O at the end there. Okay and is oxy.

[00:46:11]The next one instead of O if we have another NH2 NH2 that's called a hydroine. So when a hydroine reacts with a carbon maybe the slides telling us that we're moving too through too slowly.

[00:46:41]We've done all this now it has it's taking us back all this. Okay.

[00:46:54]Okay. Sorry about that. Okay. So with hydroine you get hydro zone. The same mechanism. If you go and understand it there you will pheni hydroine again you are replacing the R with a benzene ring that has NH.

[00:47:16]The benzene ring is represented here with PH as I'm sure you'd have seen before and it's called so that compound is called hydroine.

[00:47:32]Okay, I was going to draw it but I think it's drawn here. Okay, it's drawn here.

[00:47:42]Okay, that's a bigger one, but I can show you this so that it doesn't look strange to you.

[00:47:51]You have a phenile ring here. You have NH.

[00:48:01]That NH is connected with another N H2 there.

[00:48:14]Okay, that's a pheni hydra zim.

[00:48:24]That looks strange to you. You can also draw it like this.

[00:48:29]You can also draw it like this. NH2 here, NH here. You can put the NH here and put the bond or you can just write it NH and H2 that's the fin hydroine so that you won't say you've never seen it before in case your test or exam hall will not be the best place to be seeing things for the first time.

[00:49:03]Okay. So now a fin hydroine that you react with a carbonile will give you a pheni hydro zone. Okay, just like hydroine will give you hydro zone, the dihydroine will give you the nihydro zone.

[00:49:27]And then you see the first one is example with acetone which is who is this person just 10 minutes more don't let me face you today that some of you have already started doing ara Jessica mute yourself honorable if I hear another pin from Okay. So the first example is with an acetone which is a ketone.

[00:50:05]You see what it gives you. And like I showed you the the transformation or the reaction is happening at the carbon.

[00:50:15]Every other thing remains the same.

[00:50:18]Now this equation that you see here you would do you do it you do it in the lab.

[00:50:27]as a as one of the reactions that you do to differentiate an alihide from ketone. I keep forgetting this. I keep forgetting this.

[00:50:39]This is reaction of uh carboniles with sodium hypoiodates.

[00:50:49]So please for your own assignment go look it up and see the reaction and understand it. Okay. Sodium hypoiodates it's sodium instead of sodium iodates you now have more than one iodine uh atom in there. Okay. So look look at it. is finding because this is this has commercial use.

[00:51:22]So that's the assignment I'm giving you because that equation there is not clear.

[00:51:28]Okay. So how do we use this to distinguish between alihides and ketones?

[00:51:37]Oxidation reaction is used to differentiate between the alihides and ketones.

[00:51:41]You know that this is an oxidation reaction because simplistically you see it's addition oxidation reaction is the addition of oxygen or removal of hydrogen and you can see that all these reactions that we've been doing the hydrogen is removed in a manner of speaking.

[00:52:02]So that's why it's an oxidation reaction or if you go and look at the uh number of electrons you can also define it in terms of increase or decrease in oxidation number if you remember that from oh wait this is a year one uh you did you did uh yeah you did redux reaction in your first semester so that shouldn't If you forgotten, please go read it up.

[00:52:35]If you forgotten what oxidation and reduction uh bullet point two, alihides are easily oxidized while ketones are not. See that is the first main difference.

[00:52:49]Adihides are easily oxidized. Ketones are not. So when you now get an unknown and you oxidize the one that is easily oxidized will give an indication that that must be a ketone.

[00:53:05]I mean that that must be an alihide. I beg your pardon.

[00:53:09]Alihides are easily oxidized using mild oxidizing agents which cannot oxidize the tones. So because alihides are easily oxidized. If you take an oxidizing agent that is not very strong then it will affect the alihide but it will not affect the ketone.

[00:53:29]So note the word there easily oxidized doesn't mean that ketones cannot be oxidized. They can be under under very strainous conditions.

[00:53:43]But if you use a mild oxidizing agent then you know that only the alihide will respond. The ketone will remain unreactive and that's why we oxidation or rather mild oxidizing agents are used to differentiate between alihides and ketones. So in a laboratory experiment where you do test observation inference can be given two or more unknown compounds and you asked to subject those compounds to mild oxidation reactions to be able to tell you whether it is an alihide oxyone and then eventually you do what we call the confirmatory test.

[00:54:34]We also do all those things with alcohols as well. If you want to differentiate between a primary and a secondary alcohol.

[00:54:43]Okay. So if we look at the oxidation here, alihides are readily oxidized by acidified potassium permaganate or potassium dromate.

[00:54:55]Okay. And when you do that, the alihides will give you caroxilic acid.

[00:55:01]But the aromatic alihides are not readily oxidized.

[00:55:07]Okay. So again in a test or in an exam you can be given a carbonite compound and either simplified K M4 or K2 CR.

[00:55:23]No, I think it's easier to call it potassium dromate instead of calling it K2. So anyone that suits you potassium permaganate is the first one. The second one is potassium dromate.

[00:55:36]So you can be given any of those. And then on the other side you be asked what is the product. Okay. So if you remember this then you will never choose if there's a ketone as one of the options you automatically know that that is not the answer because ketones are not oxidized by these reagents.

[00:56:01]Okay. And then here also you're learning that if the alihide is aromatic then it is more difficult to oxidize it compared to the alihide that is alifhatic.

[00:56:21]Okay I hope you know the difference between aromatic and alifhatic.

[00:56:25]So proxidize the benzalihide. benzel alihide will be an aromatic alihide. Okay. And that you are seeing it there in the the structure that is being shown there. That one by your left hand side is a benzile alihide.

[00:56:44]Okay, that has a common name.

[00:56:50]What is theopac name?

[00:56:55]something for you to look up because I know I didn't teach you that. So look it up so that you will know it.

[00:57:02]You are seeing the structure here. An examiner can ask you cuz you have seen the structure and you've been asked to look it up.

[00:57:11]So to oxidize benzel alihide it is better to use alkaline potassium peranganate.

[00:57:18]Again know the difference if you use acidified potassium permaganate.

[00:57:23]So usually in an equation you will see it as this K M4 comma H+ or SL H+ that shows you that that's acidified potassium command or you will see or you will see the acid maybe HCl okay you know obviously if you see the acid then there's really no No deceiving you there because you immediately know that HCl is acid.

[00:57:59]Now the alkaline potassium peranganates you will see it as O minus or you will see it as N AOH plus this or you see it as KOH plus this.

[00:58:15]If you see any of those things, you know that you're looking at alkaline potassium permaganate and then you will know that compared to the acidified one, the alkaline potassium permaganate is a better oxidizing agent with aromatic alihides.

[00:58:34]Okay, with ketones nothing happens with alihides it will give you caroxyic acid.

[00:58:49]Okay.

[00:58:55]So the other toy there explains what's going on.

[00:59:01]You can also benzalihide can also undergo light catalyze auto oxidation to benzoic acid.

[00:59:12]Okay. So now you have two ways of forming benzoic acid from benzaldihide.

[00:59:20]Either you are using alkaline potassium permaganate or you are using light. Light is represented by HV there.

[00:59:31]Okay. And the O in a square is used to represent oxidation. That's to show you that that reaction is an oxidation reaction.

[00:59:43]Okay. So basically the light activates the oxygen in the atmosphere and then or in the atmosphere of the benzaldihide and I'm sure some of you will know okay well this is your one of the ways cancer is caused in the body is by radicals formation of radicals.

[01:00:08]Okay.

[01:00:10]So the the radicals are uh compounds that have single electrons.

[01:00:20]Okay. And they are formed by what you call homolytic fusion.

[01:00:26]So you know the way a compound breaks by electron moving to one side that's usually called a heterolytic fish.

[01:00:36]Okay? where one becomes positively charged and the other one becomes negatively charged.

[01:00:41]But you have situations where and in that case it means that the electron that that compound was sharing or electron from one of the compounds has moved to the other one when you're talking about ionic bonding which I'm sure you've been taught. But you have situation where instead of the electron moving to one atom the two atoms involved in that bond share the electrons equally. So one takes one and the other one takes one.

[01:01:11]So that instead of the two electrons moving to one element or to one atom they share it one one one equally.

[01:01:22]So when they do that the entities that they form are called radicals and radicals are also very very reactive. So that's why in the body for instance when they are there they will react with the other cells. Remember that cells are chemicals. They are atoms.

[01:01:44]Cells are made up of atoms. So once you have a radical react with the cell and then to make the cell go crazy what the biologist will call uh mitosis to now start reproducing producing more and that's basically how how cancer grows.

[01:02:07]Okay. So you see that all these things you can relate.

[01:02:11]So that's that oxidation.

[01:02:13]Then here we said that alihides are readily oxidized by mild oxidizing agents. On this next slide now you see an example of a not so mild oxidizing agent. Hot acidified potassium peranganates.

[01:02:37]Again something you should note here it is just acidified potassium permaganate or potassium dromate. Okay it is mild.

[01:02:46]When is just acidified but when it's hot acidified it is no longer mild then it can oxidize ketones.

[01:02:59]Okay. But in this case when when that reaction occurs what you find is that the ketone is broken into two.

[01:03:11]Okay. So the ketone is broken into two at the carbonile and then you now have two acids forming.

[01:03:23]So again note that when you have acidified potassium permaganate or dromate it will convert the alihide to an acid. Nothing is broken.

[01:03:35]Okay. When the alihide is aromatic you are better off with the alkaline potassium peranganate.

[01:03:44]It will still give you the acid. Or you can use light catalyzed auto oxidation. It will give you acid. But when you use hot acidified potassium peranganate or dromate on ketone give you one acid instead he now gives you two acids.

[01:04:20]So usually we take the ketone and you know that ketone has two substance one on the right of the carbonile one on the left of the carbonide. Okay. So it will break it at that carbon to form two acids.

[01:04:39]Then one of the acids will have will lose one carbon.

[01:04:53]Okay. So, um let's look at this general example. Now, this is for ketone.

[01:05:06]So what happens is that simplistically to understand it if you come to where this carbon is you divide it.

[01:05:18]Okay. So you have one acid on this side then another acid on this side.

[01:05:26]So that this one of the carbon atoms here on this side is what you use to form the acid.

[01:05:35]So if you are now looking at the total structure, you find out that this when it forms the two here, there will be one less uh carbon atom.

[01:05:50]Let's see if if there's an example on the slide.

[01:05:54]If there's no example.

[01:05:59]Oh, there's no example. Okay. So, um, let me give you one.

[01:06:09]I think that time is fast. Oh, look at that. No, no, no, no. Sorry about that.

[01:06:14]That time is up. So, please look that up and see this one again is modeled up.

[01:06:21]So, you have to look this one up as well.

[01:06:25]Ah, there are still reactions here.

[01:06:30]Wow. Okay.

[01:06:34]We will continue on Monday.

[01:06:39]Okay. So that means here on Monday we will start we look at here we look at a good example. Then you look at silver mirror test and get the equation for me.

[01:06:53]Here we'll continue from here.

[01:06:58]on Monday I think so that we don't rush I've sent you this slide so you have the opportunity to look at it over the weekend oh wait there just four remaining okay so please look at the rest we're really running out of time if you have any questions we'll take them on Monday because on Monday we'll go to another topic.

[01:07:31]Okay, they're just about four slides. So you should be able to handle that.

[01:07:39]Okay. Um sorry I have to rush you but is how it is now. Do we have any questions?

[01:07:50]Okay, there's one even though time is gone.

[01:07:55]Oh, okay. Maybe it's not a question.

[01:07:59]Uh, it's okay.

[01:08:03]I don't know. I think I allowed you back in. I can't remember. Um, you see, I've forgotten. I removed you, put you in the waiting room because you were disturbing the class. Now I forgot. So, please try not to disturb the class. or if I remove you from here and I forget just go to the to the YouTube channel and listen from there you guys can be see all these ones now that I've written their names here I think maybe what I'll be doing is anyway since there's no question there like I said to you if you put questions here I will not see them Okay. So remember what I've told you. Read the remaining slides. You're not in a university. And these remaining equations are very important. That's why I wanted to do them. But time is really against us. So look at them and come with questions in the next class.

[01:09:05]So we'll entertain the questions maybe for the first five or 10 minutes depending on what you have and then we'll go to the next topic.

[01:09:16]Temples fugit like they say.

[01:09:20]Have a good morning and enjoy your weekend.

[01:09:35]Okay, these ones are just they're just coming and putting their names.

[01:09:41]I'm sorry for you.

[01:09:44]You forget that this is Time stamp.