Transcript for:
Cycloalkanes and Functional Group Nomenclature

in this video we're going to talk about the nomenclature of cycloalkane and the functional group so no inclusion of cycloalkane we usually use the cyclo or cycloprefix before the word alkane if you have three member cycloalkanes if it is we know is three carbon we call propane then we'll use the the prefix cyclo then it will turn into cyclopropane if you have four member ring then we call cyclobutane again four carbon we call butane and this is a cyclic ring and this is what we call cyclobutane uh if you have five member ring we call cyclopentane if you have six member ring we call cyclohexane again this is the skeletal structure of cyclopropane as you see here the angles represent the number of carbon atoms each angle here is ch2 so cdh2 ch2ch2 is a three-member ring again we name it as cyclopropane this is the skeletal structure of cyclobutane skeletal structure of cyclopentane and skeletal structural cyclic sense usually when we write the cycloalkane structure we write the skeletal structure of those cycloalkanes as you imagine that it can save you a lot of time and space if you use the skeletal structure to indicate your cycloalkane now if you have one substituent on the cycloalkane ring how do you name it so usually we use the ring as a parent hydrocarbons unless the alkyl substituent has more carbon atoms than ring carbons in that case the substituents will be the parent hydrocarbons so if you have only one substituent so there is no need to give it a number so for example if you have here this is the cyclic ring here five member cycling ring we call cyclopentane and we have one carbon substituent here so this is we know it's called methyl group so this is one substituent so we don't need to indicate the position of that methyl group on this chain on this ring so it would be methylcyclopentane the thing that i would like to point out here so here we have five member carbon ring which is which has five carbons which is more than the substituents carbon number but if you have carbon numbers which has more than five carbon atoms then you have to treat this ring as a substituent in that case that ring will be called a cyclopentyl group right so let's say you have six carbon atoms here and the substituents over here then it would be one pental hexane that's how you can name it but if you have substituents uh on which uh the number of carbons in the substituent less than uh is is is less than this one or a smaller than the ring carbon then we have to use the ring carbon as a parent hydrocarbon as you see here in this case methylcyclopentane if you have this one here again you have the cell two carbon substituents we have six carbon cyclic ring so we have to treat the six carbon cycle ring as if parent hydrocarbons we call cyclohexane and we have substituents to carbons we call ethyl so it is ethyl cyclohexane that's how we have to name a monosubstituted cycloalkane ring but if you if the monos if the cycloalkane ring has two substituents here is the rules you need to list them in alphabetical order and give number one to the first name group for example if you have cyclopentane as you see here is the five carbon rings and you have two substituents one is three carbon one is one carbon and one carbon we call methyl and three carbon nuclear propels so m comes before p so this is why we have to give carbon one two three four five so this is like one methyl two purple cyclopentane would be the name if you have this substitution this structure here you have a one carbon substituents and two carbon substituents again methyl and ethyl group and this is a cyclopentane ring then you start need to numbering from here one two three four five so you will have one ethyl three methyl cyclopentane again you have to now you have to start numbering the direction such way that all the substituents get the lower number so if you start numbering from this way your methyl group will get carbon number three but if you start numbering from this way your methyl group will get carbon number four so that will not be the valid name if if a ring has more than two substituents so here is the rule so list them in alphabetical order and when you are numbering the substituents so one substituent is given the position number one then you number either clockwise or counterclockwise such way that all the substituents should get the lowest numbers for example if you have these substituents here as you see in this structure here as you see we have three substituents on cyclopentane ring so now we have to start numbering here so we need to give carbon number one here then two that way carbon number one this two methyl group will get the lower number if we give this carbon one then this two methyl group will get carbon uh two switches which is higher than one so this is why you have to start numbering on this carbon then it will be one comma one two trimethylcyclopentane if you have this substrate here again we have three carbon substituents which is propyl methyl and ethyl when we are going to name it we have to arrange this one according to arrange this substituent's name according to the alpha particular letter but in order to number it then we have to number uh two ways so if you want to number from this one two three four as you see that way methyl can get carbon number two but if you start numbering from these directions like ethyl one two three four then methyl will get carbon number three which is higher number so you have to start numbering from here one two three four that way you will have one four ethyls a carbon number four has ethyl group two methyl one propyl cyclo hexane but if you number or in the opposite direction one two three four then it will be one ethyl three methyl four purple cyclohexane in that case the methyl will get carbon number um carbon number three so which means uh three is larger than two so this name is not the correct name that take us to our next lecture problem here name each of the following compounds so again if you like you can pause the video and try to answer this question on your own so we have here one substituent on this ring so this is six member cyclic ring we call cyclo hexane and you have here this have two carbon substituents we call ethyl group so one can say ethyl cyclohexane for this case here we have five member cycling ring we call cyclopentane that's the base name and we have two substituents methyl group and nitro group so then it would be one methyl two nitro cyclopentane again m comes before a now we have three carbon substituents cyclohexane rings six member ring nucleocyclohexane and we have to start numbering from this carbon one and two then we'll have one chloro a one bromo one chloro2 methyl cyclopentane again b comes before c c comes vapor amps we arranged the substituents here according to their alpha particular letter and we ended up with cyclohexane so this should be cyclohexane not cyclopentane that's a small mistake there now we're going to talk about the functional group functional group usually a group of atoms that show a characterized is influence on the properties of molecules that basically tells what would be the physical properties or what would be the chemical properties for that type of organic molecules so generally whatever the reaction that compound will perform or exhibits that are determined by what type of functional group presence in that structure and usually most of the time the the hydrocarbon chain are irrelevant to the reactions and in the textbook often it is indicated by general symbol r so for example if you have this molecule ch3ch2ch2oh whatever the physical properties and chemical properties that you are going to observe for these molecules is due to these group of atoms all which group we call that group of atoms as a functional group and this group here this hydrocarbon chain it those usually do not take part in any chemical reactions or are not very responsible for that much physical properties so in the textbook you probably would see these are written as r group r represents the alkyl group that are hydrocarbon chain part so there are several type of functional group presence in organic molecules and based on the functional group compound names are also classified accordingly if the carbon if it is a pure hydrocarbons all our carbon-carbon single bonds we usually call alkane and here is the example for butane you can see four carbonyl can we usually call butane three carbon alkyl propane five carbon pentane hexane heptane that's why we name the alkene group we also have learned cycloalkane where we have seen the carbon-carbon single bonds but it's a cyclical structure cervical cycloalkane an example here six carb six carbon cyclic alkyl cycloalkynical cyclohexane alkyl halide it looks like um alkane except they have at least one halogen atom in them so as you see here you have four carbons which is um the butane carbon here's the butane chain and we have chlorine atoms one of the hydrogen is replaced with chlorine we call butanyl chloride uh if we have so usually we name it uh by this il chloride or ill-bromide ill iodine so if you have three carbons chloride we call probe we can propanyl chloride ethyl chloride methyl chloride so that's how we usually name the alkyl halide so if we discard bromine then we call methyl bromide ethyl bromide butanol bromide so this type of thing uh this type of way that we name alkyl halide but if you have alcohol alcoholics look like alkane except they have always grow um so if you look at here you have one of the hydrogen is replaced with the oh groove here so and if we have four carbon alcohol we use the suffix all at the end so we remove the e and replace with all so this is butanol if you have three carbon alcohol we call propanol two carbon alcohol we call ethanol pentanol hexanol anytime you you hear about the all that means we're talking about the alcohol functional group then ethers ethers are usually when you see the the oxygen is bridging between two carbon atoms so we call ethers so for example here the diethyl ether this is the compound named diethyl ether because you have two ethyl group on two on on the two opposite side of the oxygen so we call diethyl ether aldehyde groups usually they have a carbonyl bonds and here is the structure this carbon oxygen double bonds we call carbonyl bonds and the carbonyl carbon bonded with an r group and this carbonyl carbon bonded with an hydrogen group to name those type of compound we use the suffix l so if you have let's say uh this group here two carbon aldehyde we call ethanol three carbonyl we can call it as propane l and butanol pentanal any time you see l l means we are we are talking about functional group aldehyde ketone again the carbonyl carbon bridging between two r groups so r could be alkyl group could be an oil group again if you see the difference between aldehyde and ketones so carbonyl group here is bonded with hydrogens and one r group but for ketone we have two r group uh bonded to the carbonyl carbon again carbonyl carbon means carbon oxygen double bond that is a type of carbonyl carbonyl carbon this here is some example if you have we have three carbon ketone we call propanone if you have four carbon uh ketone we can butanone again we use the subject owner then o n e at the end that means we're talking about ketone functional group so propanone beta noun pentanone hexanone heptanone that's how it goes then carboxylic acid carboxylic acid is here as you see you have a carbonyl carbon bonded with an r group and then carbonyl carbon bonded with o h group there is a little difference here so if you have only alcohol alcohol means there is no carbonyl carbon it is only the oh is directly bonded with the alkene carbons there's no carbonyl carbon means there's no carbon oxygen double bonds uh there but for carboxylic acid you have carbonyl carbon and o h and the other end you have r group so that's the carboxylic acid functional group and we usually use suffix oak acid at the end so if you have two carbon carboxylic acid we call ethanoic acid three carbon carboxylic acid we call propanoic acid five carbon carboxylic acid we call pentanoic acid that's how we name the carboxylic acid functional group ester usually here is the ester the carbonyl carbon they're bonded with or group and bonded with r group so that is the functional group for ester so again o r group r is not hydrogens r is an alkyl group or could be a rhoyl group again the carbonyl carbon bonded with r group and or group that is we call ester and here usually the subjects that we use to name this weight at the end oh it so methylmethanoid that's the name so usually name first is alkyl group here so this is methyl group here and then we named this in methylmethanide that's how we have to name it so methyl ethanoid then the next category is the amine so nitrogen atom is bonded with r groups um so nitrogen atom is bonded with r groups here is the amine this is the function because the nitrogen bonded with r groups if all the r's or hydrogen this is called ammonium but if all the one of the r is like alkyl group or aryl group then we usually call amine and so here is the functional group uh as the structure of one amine so you have alkyl group here ch3ch2 we call ethyl so we name the alkyl group and then we end the name with the word amine so ethyl amine at the ends so that's all all the functional groups again usually depending on the functional group we call them as amine or ester carboxylic acid or alcohol those type of compounds so that take us to our next lecture problem here is identify and name the functional group in the following compounds so here is the structure for ibrufin can you identify the functional group presence in this molecules if you want you can pause this video and try to answer this question on your own so i hope you have right answer so as you see here this carboxylic acid you have carbonyl group here then you have oh group and then you have r group this this r group here then usually this is the functional group of carboxylic acid here is the structure for aspirin could you find some uh could you find the functional group here and the aspirins here you can see you have a carboxylic acid this is the carbonyl carbon bonded with o h group and then carbonyl compounded with an r group here this whole r group so overall this is a carboxylate functional group and here is the ester function you have carbonyl carbon carbonyl carbon bonded with r group and carbonyl carbon also bonded with or group this is the whole thing or group so you have carboxylic acid and you have ester functional group in aspirin structure vanillin so could you find the functional group here yes so you can see the aldehyde here you have the carbonyl carbon bonded with an r group here this side and bonded with hydrogens here so when carbonyl carbon bonded with r group and hydrogens we call aldehyde functional group and then we have here ether so oxygen is bridging between two carbon atoms here is the carbon and here is the carbon so this is ether functional group and finally you can see you have o h group here this is alcohol now look at here this is alcohol and this is carboxylic acid so alcohol bonded directly to the carbonyl carbons so this is a carboxylic acid but there is no carbonyl cover this is or bonded with directly in our group so this is alkyl functional group finally we have diphenyl hydramine hydrochloride so what is the functional group can you find here we can see an ether group here's an oxygen bridging between two carbon and we can also see the nitrogen bonded with an r group so that's an amine functional group uh so this is how you have to identify what type of functional group presence in organic molecules and that's all for this video