Nomenclature part 26

Added: 2026-05-13

[00:00:00]next we are going to start nomenclature of aromatic compounds aromatic the ball aroma aroma means which has got a characteristic smell the beans this compound has got some another smell not it science it is called elevated now this is also being called as Eddings this is also known as actually when I was when I started the chapter nomenclature that are detrimental you amines means is again same thing a bar has come from the word aromatic and E and E because you will find that erasing means we are having benzene so we have ultimately single and double bond single and double bond double bond is always what England so hence it is known as rings because e ne AR has come from the bottom aromatic and ene as you can see they are all technically single and double bond is their hands will call it as headings so I already compounds that otherwise also known as hairiness we can say that okay fine so in this way what if I decide we are going to study the nomenclature of this aromatic compounds that is it's very important nomenclature of aromatic compounds because already we have completed that is aliphatic and cyclic and finally we are coming to aromatic now I already compounds when it came into being pyramid when we came to know about the aromatic compounds different scientist gave different structures about this already cream that we are going to study when I teach you hydrocarbons when I will start the chapter I become this is nomenclature teaching you when I start the chapter of hydrocarbons hydrocarbons I've been teaching as benzene when I do Betsy sorry at that time I will tell you about the history of the I already compounds what are the structures given by the different scientists little bit sister what to tell you because otherwise you would understand from where we got this particular structure now this structure was given by KQ a scientist was there whose name was kick you he gave this particular structure all right he numbered it in this way that is one two three four five six I can write this or we can also write now this is equal X and you know that alright we can also write in this way we can also write in this way there is one two three four five six I told you by before we take this as the first position by default otherwise any anyone who can trigger so first carburetor anyone but before we take this as the first pattern now here what we can see is that you said that we can write the benzene structure in this way or in this way hick use it we can write the benzene ring either we can represent in this way or in this but this structure but it has got certain disadvantages now let me tell you before kick you look so many scientists was there which is ready that I will be telling you in hydrocarbons when I teach you hydrocarbons so that time I will say you that who are the scientists have hardest said about but their structure was discarded and the huge structure was being considered because it was the first scientist who said that pencil is two dimensional in nature two dimensional vincent's otherwise everybody said that benzene in three dimension which is absolutely wrong for that reason it was discarded all right there are other reasons also but that is one of the main reasons we consider they consider the benzene to be as three dimensional all of the scientists all right only he was the first person to Cuba the first scientist who gave the structure of benzene and he only consider the benzene has two dimensional in nature but what he did is that he they have two structures to you sequency structure one and structure to and in structure one and two he said that that we can put the double bond in the first and the second carbon atom also and we can put the double bond in the first in second and third also written putting and ultimately became a represent the structure in this way or we can represent the section this will both affect now cookie according to PQ history but later on whether analytic us we can say hydrocarbon progressed the people came to know more and more about it then we came to know what are the structure even packet you was having some drawbacks it was because I don't say that was completely discarded like the previous scientists but it has got some drawbacks till we use this particular structure to it see we are using it all right but it has got some drawbacks so what is the drawback it is in front of you only you can say that in the fall structure if you see then what I find is that the first carbon first and second carbon between the first and second party that is a double god and here between the first and second carbon there is a single bond so if a particular student is writing the reactions between the first and second carbon he will undergo addition reactions because the vimana said you know that there was one undergoes addition reactions multiples one double and triple bond under burst and he still reactions he has studied in the lower classes okay multiple bonds but if another student he is writing this structure and he is writing the reactions then he will do substitution reactions between the first since again carpenter well because single bond is the single god undergoes substitution rates and double and triple bond attackers addition reactions so if a person is writing if a student is acting with structure and he's doing addition reaction his fact if a student is said in this structure and he is doing substitution reaction he is also correct how it is possible that the same compound will give under they they give a decent reaction and the last solution reaction how it is possible it's not possible a decent solution both gives you different because this is saturated solution this is unsaturated how it is possible that in one structure it is been series unsaturated another structured means in is saturated no not pasta all right most the next thing is that you could not say anything about the stability of the Vincent Lee that whether this ring is a stable or not now stability having calculated by calculating the energy because remember it remember it what I am saying you energy is inversely proportional to stability for any compound in chemistry how do we compare the stability we compare the energy energy is less stability is more energy is more stable is less now how can we say that this is a very simple thing you see suppose a stone is there at the top of the hill how do we have the natural stone what a challenge MGH its maximum but when the same stone is at the bottom of the hill you can get the potential energy MGH now it is almost zero nil negligible so energy is what minimum so stability is one maximum because when the stone is at the top of the hill it has for every chances that it will roll down the hill by giving a slight push slightly push it it was going to roll down it has got every chances that means it is highly unstable in nature try to understand so he is highly unstable in nature because energies maximum what is the mg a try this maximum synergies maximum stability is minimum but when it's at the bottom of the hill when is at the bottom that may be at least minimum height is minimum so energy is also minimum MGH you can create with this minimum stability is maximum if you give a slight push to the stone or a little down the road up because it is this is already at the bottom of the hill it is going to slide from this position to that position it will slide it's not going to hold up as good a slight changes position that's it so what I find when Energy's minimum stabilities maximum always was this particular but it's the same thing powders when the compound is having minimum energy it has got maximum stability so if you could not calculate the energy of the benzene ring he could not calculate it he gave the structure he gave the structure two dimensional but he could not say anything about the stability of the benzene because he could not calculate the energy of the benzene or you could not see next is if you said that benzene undergoes addition reactions but later on he found it out experimentally that benzene neither undergoes addition reaction nor it undergoes substitution reaction it undergoes electrophilic substitution reaction a different type of reaction will be studying it and teaching it undergoes then so hence some of the still some more area which will be studying in that particular chapter hydrocarbons so hence what you find is that for that particular purpose this structure was not completely discarded all right but we came to some another structure which was given by a group of scientists and this structure is known as resonance none don't think resonance is the name of a scientist listen carefully I said a group of scientists all right this is a resonance structure we are putting a ring inside it instead of ultimately single and double bond we are putting a ring how do we come to mean all these things I said you had patience when I teach you the hydrocarbons chapter you will come to know how to begin this particular all right clear and say so this structure is known as a resonance structure of benzene it gives us all the information about the benzene ring it gives us the stability of the pencil ring it say undergoes electrophilic substitution reaction how benzene is stable it also explains about it sorry so hence this structure be considered to be as correct which is given by resonance and we consider what I said this is a resonance structure of benzene because this is a resonance structure of benzene which gives us all the informations or rather I should say what are the information KQ could not give it to us or the pic you'll give the information which was not correct that was provided by resonance all right and hence this structure is correct and we are having this structure today that is the resonance structure of benzene ring answer that say easy to write also here we have the competency ultimately single and double Gandhi I don't need to come to it just you make a excitement for every insect it is easy easy to be present so it is the benzene ring so hence we will be representing the benzene ring in this particular you can be present in this view also it is not wrong still we are using it quite a bit the mechanism of a actually be used if suddenly we don't be used to use this because it is easy for us to show the shifting of the bond you can come to know about it of the shifting of the bond you come to know when you will sleep there Mary will study the GOC GOC means general organic chemistry that's the to be is where it will study about the organic reaction mechanism at that time we will come to know okay lot of things are getting studied hence different for that reason I say that deep what you can say 100% to use chains there's a lot of things are they have to be learnt okay fine understood not so high this vrb I am using this particular structure the resonance structure of the benzene and tell you the different structures of benzene okay so just a brief idea I gave it to you that from where we got this structure and widely okay if I didn't leave you again any beach I'll tell you more about it in hydrocarbon chapter because this is nomenclature this is not my chapter now where I should speak about benzene in extra because I need to understand the naming first naming I'm studying about the mini so now as you can see this is your benzene ring now benzene has got two type of structures to type of structures one is nuclear derivatives another is your side chain derivatives for it listen carefully we have got two type of structures one is nuclear derivatives what I said nuclear derivatives nuclear nuclear derivatives another is your side chain derivatives side chain derivatives okay now side chain means what and you clearly spot then now listen carefully where the functional group is directly attached to the benzene ring directly like which is Ricky attached to the benzene ring you can see it is on as new behaviors metal function good whether it is co h whether it is co h whether it is CH o whether it is C oh whatever it is any functional group which is really attached to the benzene ring it is your kness nuclear develops but if the same functional group attached to the sidechain like suppose we are having ch2 words it is not an activity this voyage is not attached directly to the benzene ring it has it is attached to a side gene there is no us what sidechain derivatives hence it is called a side chain derivatives and the name is also being done differently or it naming is also done differently so how to name it in the next day we will