Hey everyone welcome to home school hope everybody are doing good and welcome back to class 11 chemistry we are with the chapter organic chemistry you all know that we have started IUPAC nomenclature we have already discussed naming of saturated hydrocarbons with heavy branches Naming of unsaturated hydrocarbons and naming of organic compounds with functional group. And this is our another session on the naming of cyclic compounds. So here cyclic compounds are two types. Allocyclic compounds we have, aromatic compounds we have. So first we will discuss about the nomenclature of allocyclic.
Alley cyclic compounds. Even this nomenclature is very very important. So try to understand it carefully. Watch the video till the end. Definitely every point on cyclic compounds will be covered.
Right? So every example is important. Fine.
The moment I say alley cyclic compound, what do you mean by them? It means that you must have seen such compounds, right? Say, a shape of a triangle.
a shape of a square, right? So a shape of a hexagon, are they shapes? No, they are organic compounds. And this is a bond line representation of few allencyclic compounds.
So what do you mean by this? Everywhere carbon is there, at every point carbon is there. And how many hydrogens are there with this carbon?
Two bonds are already there. It wants two more bond. That means there must have been two hydrogens.
So this is our CH2. This is our CH2. That means this is nothing but CH2, CH2, CH2. So three carbon atoms are connected in a cyclic way.
Right. And similarly, what do you mean by this compound? It is nothing but four carbons connected cyclically. Right?
And what do you mean by this? Here 6 carbons are connected in a cyclic way. Right? So here carbon atoms are connected in a cyclic way. Such compounds are called allicyclic compounds.
Right? So you know what? When you name cyclic compounds, we will use the prefix Here we have to use the prefix cyclo.
So the word cyclo is very very important for naming allicyclic compounds. So this is our rule number one that you need to remember right. For example how do you name this? Cyclo there must be a prefix cyclo and three carbon atoms so word root prop prop.
And all single bonds, so primary suffix A and E, right? So the name of this compound is cyclopropane. Similarly, this is cyclobutane, right? Four carbon atoms, so butane. All single bonds between carbons A and E.
Why did we write cyclo? Because they are connected in a cyclic way. Similarly, very famous compound, this is called cyclohexane.
Cyclohexane, right? So, these are some examples of early cyclic compounds. Remember, when you name them, you must definitely add a prefix cyclo before a word root.
Before your word root, cyclo word should come. So, that is a compulsory. rule that you must follow. And now let us see some variations and some rules along with examples.
Okay, so example number 2. In case if you have a compound something like this, this one. So what is this? Everywhere carbon, this is actually a branch CH3, right?
So this is a cyclohexane molecule, right? And there is a branch CH3. So what do you do? How do you name this particular compound?
See the carbon atom, this is carbon, everywhere carbon, this is CH2, here is CH2, here is one more CH2, here also CH2, everywhere CH2s are there, right? And the carbon which has got a branch, which has got a substituent group will get number one position, okay? Fine. So now, What is the name of this CH3?
Methyl. Which methyl? It is 1-methyl, isn't it?
1-methyl, prefix is over. Now, before writing a word root, what is the word that you must use? Cyclo. So, this is 1-methyl-cyclohexane, right? So, this is how you have to name whenever simple branches are there.
Now observe the third example. I will introduce two branches here. So suppose you have methyl group as one branch, another branch as ethyl group. This is ethyl group right?
So CH2, CH3. So now how do you give a name for this? Two branches are there.
So how do you number it? You see the name of this branch is Mithai. The name of this branch is Ethai. So alphabetically which comes first?
M comes first or E comes first? E comes first. So numbering is done alphabetically. Okay.
So this is our rule number 2 that we are learning. Right. So More than two branches when you have number.
Number alphabetically. Okay, so alphabetically here E comes first, isn't it? So carbon atom carrying ethyl group will get number 1, then this gets number 2, this gets number 3. Don't go this way, 1, 2, 3, no, you know this carbon containing branch also should get a least number, right?
So go this way, 1, 2, 3, 4, 5, 6. right so now you write the name it is one ethyl right three methyl three methyl then the word cyclo six carbons cyclically connected so cyclohexane right so this is how you have to name such compound and we have another example here observe this example number four very very important suppose If you have, sorry there are no double bonds inside, it's not benzene, okay fine. So if you have this compound, then how do you number this? Say obviously we can say that there are two methyl groups attached at same carbon and there is one ethyl group. okay at another carbon so how do you name this we know that these two are branches and this is a branch right this is a parent compound fine so now how do you number this Here we studied you know this was methyl this was ethyl.
I told number the carbon atoms alphabetically right. I mean according to alphabetical order of side chains or side groups or substituent groups. So ethyl E comes first. So ethyl group containing carbon had got number 1. But here this carbon is highly branched.
So when a particular carbon is highly branched, you know, highly branched carbon should get number 1. Okay, so highly branched carbon should be given preference. right so this is what you need to worry about and here this carbon gets number one now this is two this is three this is four five six this way you have to number right so this is our rule number three that we have studied okay fine so now how do you write the name here okay so this is ethyl Ethyl and this is both are methyl. So alphabetically E comes first. For writing a name ethyl only you should mention.
So it is 3-ethyl right hyphen 1,1-dimethyl 1,1-dimethyl cyclohexane is its name right. So this is how you have to name such compound. So whenever you have too many branches at one carbon, you know that carbon should be given preference. Though methyl alphabetically comes later than ethyl. Okay, so we have given number one position for carbon carrying methyl is because this carbon is highly branched.
There are two branches on this carbon. So that carbon should be given more preference. So that is the reason we have numbered one.
1 okay for that carbon. That is the most important example one must remember. So now let us learn many more rules with many examples.
Observe this compound cyclohexane and a functional group is there right OH is the functional group. Then this carbon itself gets number one position no doubt in that right. So how do you write its name? cyclohexane, okay, hyphen 1 all, okay, cyclohexane 1 all. And you know, in our previous video, we have discussed if any secondary suffix name is starting with A E I O U. Then previously if E is there that one we will vomit.
Right. So cyclohexane one all. So why did we remove this E? Because secondary suffix has started with O. So if any secondary suffix any functional groups name you are starting with A E I O U. Then previously if E is there that one we will vomit.
in a word root that one you have to remove you have to vomit okay so that is why we have removed e from this place right because it's an alcoholic group starting with ol o is one of the oval right so that's why we remove this e right okay so now look at this example you Double bond is there, functional group is there, right? So, more preference you have to give it for functional group only. So, functional group carrying carbon should get number 1 and this is 2, this is 3, 4, 5, 6. So, this is the way of giving numbers for carbon atoms.
So, now write the name. There is no branch, isn't it? So, directly we will start with cyclo. Hex, cyclohex, you see double bond is there. So, primary suffix is what?
En, which en? 2 en, 2 en. Then at first position functional group, 1 all, right? So, this is how you have to name this compound. And coming to one important compound, here I will be talking about rule number 4 in this case, right?
Here you see This is your side chain. So this is called as side chain. Right. Fine.
And this is normally apparent chain. Okay. You count the number of carbons in a side chain. 1, 2, 3, 4, 5, 6. 6 carbons are there.
So when number of carbons are more in a side chain, then that side chain is considered as parent chain. This is considered as substituent group. So hope my point has become clear.
See, if side chain has more number of carbons than a cyclic compound, okay, than a cyclic thing, then this is considered as main chain. This is considered as main chain. Let me write the point for you.
If this is actually a branch, let me call it as branch. If branch, if branch has more carbon atoms than cyclic one, then branch is considered as parent-child. Branch is considered, very very important, you have to note it down, considered as parent-child. Then ring. I will call instead of calling a cycle, I will call it as ring.
Ring is considered as substituent group. Okay. Is that clear?
Fine. Now this is my parent chain, main chain. Okay.
So now this is like a substituent group. Ring is substituent group. Say at first carbon, this ring is attached.
Okay. When I consider this as a substituent group, I will write its name as subgroup. cyclopentyl. It's a pentane. 5 carbon atoms are there in a ring, right?
I will call it as cyclopentyl. Okay. So, now how do I write its name? I will write it as 1 cyclopentyl. pentile, one cyclopentile and how many carbons in the main chain?
This I considered as main chain. Why? Because ring had only 5 carbons whereas your side chain has 6 carbons.
So I consider this as my parent chain and this as a substituent group. Okay. So how many carbons in a side chain?
It is 6 right? So hex, all single bonds there. So hexane.
So name of this compound is 1-cyclopentylhexane, right? Very, very important. See guys, in case, in case, observe this.
Yeah. If this is a compound, you know how to name this, right? Say this ring, ring has 6 carbons, ring has 6 carbons. Whereas your side chain has how many carbons?
1, 2, 3, right? So now this one is considered as branch or substituent group and ring is considered as main chain, right? So this one, how do you name? You will name it as, yeah, this carbon itself is number 1 because to this this branch is attached.
So, 1, 3 carbons in the sense propyl. So, the name of this compound is 1 propyl cyclohexane, cyclohexane, right? So, when the branch has less number of carbon atoms than the ring, then the branch is branch only, right? It is considered as substituent group and its name is written as a prefix. So why we have not considered this as a prefix writing group?
Why we have not considered this as a branch? Is because the carbon atoms are more than the ring. Then this is main thing and this becomes a side shell. Ring will become a substituent group.
That's the reason we have named it as one cyclopentyl hexane. Okay? And coming to next example, this is also very important.
And your ring. Ring has how many carbons? 5 carbons, right? 1, 2, 3, 4, 5. Side chain has how many carbons?
1. right one two three oh let me put star mark one two three and this carbon is a part of a ring not as a part of side chain be careful this carbon is a part of ring not as a part of side chain okay side chain has three carbons ring has five carbons then which is considered as parent chain Is this the ring or this side chain? Normally what is our concept? Side chain has less carbon atoms only no? Then definitely this is only parent chain we think.
But no if side chain has unsaturation. Now rule number 5 you try to remember. If side chain has unsaturation and saturation. Then, then it is a parent child. It is a parent child.
Okay, ring, ring will become a substituent group, ring will become a substituent group. Okay, so here also you have to be careful. If a side chain has more carbons than a ring or if a side chain has unsaturation or any functional group, then definitely that is your parent chain. Ring will become substituent group.
Okay, so how do you name this? How do you number this? See double bond containing carbon should get number one position. This is number two.
This is number three. So at third carbon, substituent group is attached, right? You should not give number one position for this carbon because double bonded carbons are always have more preference, right?
So one, two, three. So how do I name this? It is three. cyclopentyl, 3-cyclopentyl. Okay, so prefix is over.
Now, word root. Chain has 3 carbons. So, prop and what is the primary suffix? Double bond is there.
So, ene, which ene? 1-ene. So, this is the name of this compound.
Very, very important. And coming to our last compound. Okay, you see small branches only.
So here this is like methyl and this is also methyl and this is CH2, CH3, right? So these are small groups, branches, you consider them as branches. But the thing is how do you number this?
Okay, so numbering is done. with double bonded carbons. Double bonded carbon should get number 1 position.
So how do I number? I will number it from 1, 2, 3. Okay, why can't I number 1, 2, 3? It's because you know the heavily branched carbon again should get a least number. That's the reason I am going that side.
Okay, 1 anticlockwise I am numbering. 1, 2, 3, 4, 5, 6. Okay. So how do I write its name? It is 6-ethyl-3,3-dimethyl-cyclohex and primary suffix 1-ene.
1-ene. Okay. So this is the name of this compound.
Look at these examples guys. Very interesting. See here.
This compound, how do you name it? You see this branch, you see it's not called as a branch actually, right? This is COOH.
This is a functional group. This is a functional group. So, if a side chain has a functional group, then that itself is your parent chain. That itself is your parent chain. Then your ring will become substituent group, okay?
So, whenever you have unsaturation or whenever you have a functional group, see number of carbon atoms like 1, 1, 2, 3. Number of carbon atoms are lesser than the ring. Ring has 5 carbon atoms. But then if you have a functional group or if you have unsaturation then definitely you have to consider this side chain as your parent main chain. Then ring becomes substituent group. So how do you write the name here?
So definitely 1, 2, 3. When you consider this as your parent sign, functional group containing carbon, this itself is a functional group. So that carbon is number 1, this is number 2, this is number 3. And this is not number 4. This carbon actually belongs to a ring, not to this particular part. Careful there. Okay. So now how do I write its name?
This is nothing but. So 3 cyclopentile, 3 cyclopentile, right? Cyclopentile over. Now prefix is over, word root you have to mention.
1, 2, 3, 3 carbons. So it is prop, prop, air. right one oic acid propane one oic acid or propanoic acid directly without this one you can join and write it off not an issue okay fine coming to our second example so here co here carbon here carbon this like ch2 this is ch2 this is like ch2 and this is ch right okay So now this is a functional group ketone right. So let this carbon be number one carbon.
So this is our number two carbon. This will be our third carbon. This is fourth carbon. This is fifth carbon.
So now this is like a branch. So this is your branch. You will mention this as a substituent group.
So which meet so this is ethyl group isn't it. So we will write it as 3 ethyl prefix is over now word root. What is the word root? 5 carbons and it is cyclic, right? So, cyclopentane, cyclopentane 1-ONE.
CO group when it is there, if you have to mention it as a suffix, you will mention it as ONE, isn't it? So, the name is cyclopentane 3-ethyl cyclopentane ONE or CO group. without this one straight away you can call it as pentanon.
3-ethyl-cyclo-pentanon that is also fine. Okay. So now you look at this compound. This compound.
Double bond is there. Functional group is there. Ring is there.
Right. So now first you decide which can be a parent chain. Definitely this one because double bond is there, functional group is there. So this becomes your substituent group. You have to write its name as prefix, not as suffix, okay, not as word root.
Fine. So now once you select this as your parent chime, now the duty is to number this. So what way you will number?
Definitely this is the carbon having functional group that gets number 1. This is 2. This is 3. And here is a carbon which is 4. Right? Very good. So now we have to mention prefix now. Which is a prefix? This ring itself is a prefix.
It has 6 carbons. It's a cyclohexane thing. So it has got attached to first carbon.
So the name is 1-cyclohexyl-3. One cyclohexyl. Over.
Prefix is over. Now, word root. How many carbons in a? Yes, this is fourth carbon, right? So, 1, 2, 3, 4, 4 carbons.
So, it is bute, right? And there is a double bond. So, what is the primary suffix?
In, which in? 2 in, bute 2 in, again hyphen, 1 all, okay? So, functional group OH, its name is all, right?
So, the name is 1 cyclohexyl bute 2 in, 1 all is the answer. Very good. And now coming to these examples.
Very very important. So what is the name of this compound? This is cyclohexane right? And this is COOH carboxylic acid directly connected to ring. So how do you name it as?
You will write its name as cyclohexane carboxylic acid. Directly you will write it as. carboxylic acid say if you have written something like this cyclohexane one since first carbon this cooh is there one oic acid if you logically speaking this is also correct right cyclohexane one oic acid but this is the correct answer say for the competitive examinations when you have an options suppose if you have both options you have to tick for This one. So it is normally named as cyclohexane carboxylic acid. Okay.
Similarly, this compound is named as cyclohexane aldehyde group. No, it is called as carb aldehyde. Cyclohexane carb aldehyde. Right.
So now this is even this is COOH group. Elaborately I wrote. Right. so this is cyclopropane so write its name in the comment section so this is the homework question for you right so hope you have enjoyed these examples i have covered almost all the possible ways of cyclic compounds okay so practice them and work with more questions If you want to feel nomenclature easy, if you want to get perfection in nomenclature, only possible shortcut is to practice more and more and more examples. The more examples you practice, more new things you will come to know and more perfect you will get in a concept and ultimately you feel confident about this IUPAC nomenclature.
So I recommend you And I always tell organic chemistry is volatile. It can easily escape from your mind. If you want to avoid that, you should hold on in your mind by continuous, continuous revisions, consistent revisions.
Okay. So that is the only shortcut to practice organic chemistry and to feel organic chemistry easy. So that's all I wanted to tell you and in my next class I am coming with the nomenclature of cyclic itself but aromatic compounds.
Benzene and benzene like compounds we will discuss in my next class and that is also the most useful and wonderful video you will ever see. okay so do subscribe our channel and don't miss the next video definitely i'll i'll cover every possible point of aromatic compounds naming and along with that we will discuss some something about bicyclo compounds as well as spiro compounds okay so don't miss it out meet you all in the next video take care and keep learning keep watching thank you so much