in this video we're going to talk about the nomenclature of alkane compounds in our previous video we have talked about what is alkane so alkanes are type of hydrocarbon which is carbon-carbon single bonds there's nowhere in the structure you can find carbon-carbon double bonds or carbon-carbon triple bonds all right so here is the the system that usually all chemists use to name the hydrocarbon alkane according to the international union of your applied chemistry system every chemical compound's name should have three parts prefix patterns and suffix prefix usually indicates the position number and type of branches and type of each functional presence in the compounds parents indicates the length of the longest carbon chain or ring and suffix always indicates what type of hydrocarbons that you are going to name for it whether it's an alkane or alkyne or any other functional group presence in that particular compound it could be alcohol could be carboxylic acid or ketone or lti so before we start naming the compound we first need to know what are the prefixes name that used for base name of alkene chain if you have number of carbon atoms once usually the prefix is met if you have two number of carbon atoms two then we call eight three carbon atoms equal probe four carbons butte five carbons paint six carbon hex seven carbon heft eight carbons hot nine carbons none and ten carbons take so you must need to memorize these prefixes otherwise you wouldn't be able to name uh organic compounds so usually when you have a structure and if you count the number of carbon atoms and based on the number of carbon atoms so these are the prefixes that we're going to be using if you have one again it's a myth it probably paint hex heft heart none and take and again please memorize these prefixes to name elkin compound there are certain rules you must need to follow first is though you need to find the longest continuous carbon chain and use it to determine the base name and towards the end you can add the suffix in and then number the chain from end closest to your branch if the compound has branch has some substituents on the main base chain and if there are two substituents appearing at the equal distance then use the next one name branches as alkyl group locate each branch by preceding its name with the carbon number on the chain and then list branches alphabetically do not count normal or secondary or tertiary count iso and write the name in the following water first substitute number of the first alpha vertical substituents then substituent's name of the first alphabetical substituent use prefixes to indicate whether you have multiple identical substituents usually prefix diatribe tetra to indicate you have 2 3 4 and so on number of identical substituents and repeat the repeat for other substituents finally you name the main chain so these are the five rules you must need to follow in order to name an alkene compounds so it looks daunting to you but if i show you some example and if i solve some problems with you it will be much it will look easier to you then so let's get started so let's here we have a substrate then we would like to name it the first rule is find the longest continuous carbon chain and use it to determine the base name and add the subjects in if you count the number of carbon atoms you can see you have one two three four five six seven you have seven carbon atoms seven carbon atoms the prefix we usually call hept and this is alkane because all here all the carbon-carbon single bonds we have this alkane so we will add the suffix n so it will be heptane so the longest carbon chain here the again is the seven carbons we call heptane we are not done yet because we have a substituents on carbon number four again the substituents on the middle carbon so if you go from these directions you can see one two three four we come from this direction one two three four this isn't at equal at the middle carbon so now how do you call this substituents again usually this is the alkyl substituents i'll kill branch uh branches so we have a way to name those type of substituents uh if we have one carbon substituents we call it methane so that's a kind of alkane usually this type of substrate if you look at it very carefully this type of alkanes they have one less hydrogen atom if they have one less hydrogen atom from their alkane structure then we usually call them alkyl we add the word l at the end so let's take a look here the ch4 that's the alkene structure as we call methane again if you use the rule c and h2 and plus two you can say this is ch4 right so this is methane one carbon alkane we call methane again here is the seven carbon alkyl heptane if you have two carbonyl chemical ethane propane butanes that way it goes now when this method this alkene acting as a substituent that time then it will turn into ch3 and according to this number two rule alkene will turn into alkyl so methane will turn into metal so we added yl at the end we removed the n then we added yl at the end so ch for acting as a methyl so we can at the ch for methane acting as the substituent we call methyl so the name of this ch3 would be methyl then we can again look at the number of carbon one less hydrogens so if we have one carbon chain as a substituent we can methyl because that's coming from methane if you have two carbon substituents it's coming from ethane we call ethyl if you have three carbon substituents we call in propyl if you have four carbon does of the straight chain four carbon we call n-butyl against a chain propyl group here and we have isopropyl like this and we have t butyl tertiary butyl group like this so you just need to remember those type of uh the name for these alkyl groups so again now to end the name of this one we have a substituents on carbon number four so according to the rule uh in the previous slide that you learned you need to indicate the position of this substituent then the name of the substituent the position is on carbon number four and the name of this one is methyl then the compound name would be for methyl heptane and that's all you have to do let's take a look another scenario if you have a substituent where you will have one or more hydrogen atoms are replaced by other groups in that case what you have to do you must need to indicate the location of the carbon atoms where those replacements are made so in in in doing that for doing that you need to number the chain in the direction that give the smaller number for the location of branches for example if you have let's say this substrate and you like to name it and it you can see here this carbon is substituted with methyl group so now the the rule is you have to indicate the position of this methyl group keeping in mind that you have to give this substituents this branch is the smaller number that means if you start numbering this ring have these compounds one two three four five so this name would be like two methyls this methyl carbon carbon number two you can one carbon substituents with methyl so two methyl and this is five carbon longest continuous carbon chain is five carbon we call pentane so it is two methyl pentane and if somebody says no i would like to name it this way one two three four five so then it would be 4-methylpentane would that be a correct name so if you do that way for methylpentane then this will not be the correct name because it's not obeying this rule it's a number in the direction that give the smaller number for the location of the branches next scenario here if you have two or more substituents on the s on on the on the carbon chain and how do you name it for example if you have this substrate here how do you name these compounds so again we have the two one two three four five six carbon longest continuous carbon chain we call hexane and we have two methyl group here on carbon number two and carbon number three those two are the same those two are identical substituents on carbon number two and three so we must need to indicate the location first and we also have to use diatribe tetrapentahexa to indicate how many of the same kind of substituents presents on that molecule on that chain so since we have two methyl groups then we can say two comma three again you have to write two that's indicating you have methyl group on carbon number two and three indicating here you have methyl group on carbon number three so two comma three dimethyl hexane would be the name if you have this one again you have two methyl group on the same carbon so then you have to say three comma three so that means three carbon number three has one methyl group and the same carbon has also the another methyl group this is why we got three comma three dimethyl hexane so if you have two of them we usually call dye all right you can see here we use this prefixes die to indicate that we have two of them but how about if you have a different type of substituents other than the alkyl group then in that case you also have to mention the location of those substituents and you must need to arrange them based on their alphabetical letter for example if you look at this substrate here you have a four carbon chain here so this is one two three four we know it's a butane and it has two substituents br and no2 how do you call those substituents if you have halogens we usually call them by hollow like if you have fluorine we call fluoro if you have chlorine we call chloro if you have bromine group then we call them call it as bromo group iodine iodo group no2 nitro this is car ch double bonds used to equal vinyl nh2 equal amino group again you must need to memorize our list these names here on this chart on this table so again if you have bromine here we call two bromo again b comes before n so we have to say two bromo and then no2 we call nitro so 3-nitrobutane that's the name of these compounds similarly if you have this substrate we know chlorine comes before fluorine so numbering from these one two three four that way chlorine will get the lower number um so you can see here chlorine is on carbon number one we call one chloro3 fluorobutane so this is how we have to name it all right that take us to our next lecture problem here give the ips the name of the following compounds so if you want you can pause this video and give a try on your own then check the answer the answer i'm going to show you now so the answer for this question is 2 comma 2 for trimethylhexane so if you look at here you have one two three four five six six carbons we call hexane and you have substituents on carbon number two and carbon number two has two methyl group and carbon number four has one methyl group so two comma two that means the carbon number two has two methyl group carbon number four has one methyl group so two comma two comma four then trimethyl because we have three methyl group hexane now i'm going to show you how to write structural formula from the given name so far we have learned if you are given a structure you should be able to name them but if you are given a name how do you write the structural formula let's start with this example here draw the structural formula uh for ethyl two methyl hexane so if you want to do that you need to look at the base name first it says hexane hexane how many carbons six carbons so first draw and number the base chain carbon cell skeletons we have six carbon here so we have to write all the six carbons um let us together and we also have to number one two three four five six the second thing you add the carbon skeleton of each substituents on appropriate main chain this is two methyls a carbon number has methyl groupings one carbon substituents four ethyl so carbon number four has two ethyl group and then you add required hydrogens to make each carbon four bonds so this carbon needs three hydrogens to have four bonds this carbon is one hydrogens this carbon is three hydrogen so if you fill with hydrogen then you will have the structural formula for four ethyl two methyl hexane so that take us to our next learning check questions here right the structural formula of three ethyl two comma two dimethyl pentane so again if you if you want you can pause this video and try to answer these questions on your own you first look at here pentane that means five carbons so you have to draw a number the base 10 carbon skeleton those are five carbons and then what you have to do add the carbon skeleton of each substituent and appropriate main chain carbon this is three ethyl so ethyl group one carbon number three and two comma two dimethyl dimethyl so you have carbon number two is two methyl so this is the carbon skeleton of the substituents and finally you add required hydrogens to make each carbon four bonds so you will have the structural formula for three ethyl two comma two dimensional pentane so that take us for next next lecture problem is here it says provide each counterpart so we have the name given three bromo two chlorhexane and we need to write the structural formula for that again if you want you can pause the video and you can try to answer this question on your own and then you can check your answer with the answer i'm going to show you now so we have hexane so that should be six carbon and then it says three bromo two chloro so if you start numbering from left to right so carbon number two will get chlorine and carbon number three will get bromine so this would is the structure this is the structure of three bromo two chlorohexane the next one here we have the structure we would like to name it if we count the number of carbon so this is carbon one two three four five six seven seven carbons we call heptane and we have substituents on carbon number one and carbon number two carbon number one has two iodine group so you can say one comma one diido and carbon number two is a methyl group so this is two methyl one one one comma one diiodo heptane so that's the name of this compound then two methyl one nitrobutane again we have butane this is a four carbon that's the butane and this is two methyl one nitro if you count this is one as carbon two then you can have a methyl group on carbon number two and nitro group on carbon number one similarly if you would like to name this compound here you see one two three four five six seven carbon so you should have heptane then you have carbon two has amino group carbon three has a ethyl group and carbon this one six has a nitro group so it's a two amino three ethyl six nitro heptane and that's the name of the structure that's all for this video