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IUPAC Nomenclature of Organic Chemistry



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hi friends in this video I'm going to

make our upse naming of organic

compounds really easy for you

questions on naming of organic compounds

always comes in exams so I'm going to

share some tips and tricks of how to

write the IU pack name I hope after this

video you will find the IU pack name as

easy as writing your own name and if you

like this video do share it out with

your friends and don't forget to try the

quiz and the top three questions on this

topic links are given below the video

there are some important rules that we

need to follow for IUPAC naming I'll

show you the rules with the help of some

examples I recommend you to sit with a

pen and paper so let's go ahead and do

this are you PSE naming together let's

start with this simple example so what

do we have here

to name this compound you need to first

find the longest continuous carbon chain

which is this two carbons here now go

ahead and number it forward and backward

now why do we do the backward numbering

we'll discuss that later in the video as

you can see this compound has two

carbons so what is its name going to be

remember there's a table if there's one

carbon then the name starts with met two

carbons the name starts with Earth three

carbons it'll start with prop four

carbons

buuuut and so on so the name of this

compound will start with Earth and what

type of bonds are there in this

hydrocarbon so you need to look at the

bonds between the carbon atoms and as

you can see there's only a single bond

here so this hydrocarbon is an alkane so

the name will be eat-in so that is the

IU pack name of this compound it's Ethan

so what

we have to do look for the longest

carbon continuous carbon chain number

eight forward and backwards and find the

name based on it it was earth and since

there are only single bonds

it's an alkane so it's going to be

eat-in now let's go ahead and take a

look at this example so let's apply the

same rules we are going to find the

longest continuous carbon chain which

are these three carbons and we'll number

it forward and backwards so three

carbons means the name is going to start

with that's right

prompt and is this a propane no because

there's a double bond here so there's a

single bond between these two carbon

atoms but there's a double bond between

these two carbon atoms so it's an alkene

so the name is going to be drop-in and

if we had a triple bond here instead of

a double bond what will the name be

that's right

it would have been prop I mean okay so

what we learnt here is that you need to

look at the longest continuous carbon

chain look at the number of carbon atoms

once you've numbered it forward and

backward find the name based on the

number of carbon atoms and also the type

of bond for these hydrocarbons let's

take a look at this example what will be

the IUPAC name of this compound again

let's find the longest continuous carbon

chain which is this one and let's number

it forward and backwards so it's a five

carbon chain and we are going to do the

forward and backward numbering so five

carbon means the name is going to start

with pent right and since there are only

single single bonds between the carbon

atoms this is an alkane so what is the

name it's

to be pentane right so this is a simple

one but now let's say the five carbon

atoms are arranged in a cyclic structure

something like this

and to fill in the let's fill in the

hydrogen's so that carbon has all the

four bonds satisfied so one two and two

hydrogen's same way here so what will be

the name of this cyclic compound so the

cyclic compound the name starts with the

word cyclo so remember it's going to be

cyclo not psycho and since there are

five carbon atoms here again it's going

to be cyclo pentene paint because five

carbon atoms and only single bonds so

it's a cyclo pentene now let's take a

look at this compound so this also has

five carbon atoms but remember we need

to find the longest continuous carbon

chain so it's going to be this one you

can't go up like this and come down so

let's number the longest continuous

carbon chain and as you can see there

are four carbon atoms here so if we

ignore this attachment of ch3 for a

moment what's the name going to be four

carbon means it's going to be Butte and

since there are only single bond between

the carbon atoms

it's a butane so that's simple now let's

look at this ch3 so ch3 as you may know

is an alkyne because the definition of

alcohol is it's an alkane minus one

hydrogen so if this had been ch4

but we've removed the hydrogen so we

have ch3 so if it was a ch4 the name

would have been methane one carbon atom

right but this will be now called me

time right because it's an alkyne and

the alkyl name comes in the prefix

so you have to put it over here in the

beginning of this name so we have

basically a meat aisle butane here but

now this methyl could have been here or

it could have been here or here so we

also need to give its position and the

position is based on this numbering that

we have done so what number should we

give it it's on number 2 or 3 but you

need to choose the smallest number so

it's going to be 2 methyl butene okay so

that's the name of this compound but

let's say we had another ch3 over here

so can you guess what it'd be the name

here so let's work it out again first

the trick is ignore these attachments so

it's basically a butane and we have two

methyls in here so that's going to be a

diamond time and we also need to specify

the positions of the methyl groups so

here you can't say I can't choose 2 & 2

because I want to choose the smallest

number you either have to go with the

top the forward numbering or the

backward numbering so it's going to be 2

comma 3 or if you use the backward

numbering it will be 2 comma 3 so both

the numbers are same we chose we have to

choose the smallest number so it's same

anyways so we are going to write it's 2

comma 3 dimethyl butane now note some

important points here between the number

and the letter there's always a dash as

you can see here or here so between the

number and a letter and if you have two

numbers like here there's a comma in

there can you see the comma so this one

would be 2 comma 3 dimethyl beauty

that's the are you pack name of this

compound now let's take a look at this

compound so what's interesting here is

that there is a chlorine in here but

again first ignore the chlorine and look

at the law

this continuous carbon chain so let's go

edit number it forward and backward and

we have one two three four five carbons

and I am going to number it backwards

also so if you know chlorine what is the

basic name here it's five carbon so

that's a pent and as you can see there

are only single bonds here so it's a

pentane now this chlorine is a halogen

and so that's our functional group here

so we have the halogen functional group

and remember for halogens and for the al

Kyle's that we had done the name goes in

the prefix so it's going to be a chloro

pentane not chlorine pentane it's chloro

painting so that's the way are you

pick-ups a name is done and we also need

to give the position so what position of

chloro should i give you is it going to

be five Torro

no it's one chloro because we choose the

nearest number the smallest number here

but there's no need to actually write

one chloro here because the number one

is not necessary so simply the name is

going to be chloro pentane but if the

chlorine was here then the name would

have been too - chloro pentane right now

let's take a look at another example

so let's say again we have five carbons

here

and we have a chlorine in here a

chlorine in here and let's say bromine

in here I'm not drawing all the other

hydrogen's so again we'll number our

carbon chain forward and backwards so

it's five carbon we ignore this for a

moment so that's a simple way to do it

so you'll have a pent and only single

bonds pentane now again we have some

halogens in here so there are two

chloros and a bromo right now there's

another rule that comes in here when you

have a bromo and and a chloro you need

to go in alphabetical order so B comes

before C you shouldn't consider the

dichloro the D is not important we are

comparing bromo and chloro so the name

bromo will come here first so there's a

bromo and there's a plural sorry

dichloro right so there's a bromo and

dichloro but we also need to get the

numbering and remember we need to choose

the smaller numbers so we won't go for

this scheme we'll go for the backward

scheme so you can see that there's a 1

comma 2 dichloro and a 3 bromo so I'm

going to rewrite this name again as so

let's cancel this out it's going to be 1

comma sorry it's going to be 3 bromo

right so the bromo is at position number

3 and after that we have 1 comma 2

dichloro correct and 19 so note these

things carefully that between the number

and the letter you can see there's a

dash between the numbers there's comma

and there's a number and a letter here

so again a dash and we went

alphabetical order bromo be came before

plural so you can see it's a three bromo

one comma two dichloro pentane

all right let's try the next one here so

what's the name gonna be

again let's number the longest

continuous carbon chain so we have four

carbons here so the name will definitely

have Butte in it and there's a double

bond so is this compounds name going to

be beauty

no because the double bond is not at the

first position or over here if you

counted the one from here so we also

need to give the position of the double

bond so how do we do that the double

bond is between two and three so we'll

choose the smaller number and say the

double bond is at position two

so the name is going to be Butte to in

because we are giving the position of

the double bond sometimes you may see

this compound written as 2 butene also

but usually this is the recommended

style where we give the number in the

middle here so it's 2 in Butte two in

okay now let's try this compound

so here what do we have we have a five

carbon chain and there are some

interesting triple bonds here so you can

see that there are two triple bonds so

is this going to be a pen tine no

because they're two bonds

so first the names going to start with

pent because there are five carbon atoms

here and it's a die ein because they're

two triple bonds so I'm going to write

that here it's a pent die I'm but I need

to specify the position of

triple bonds so what's the position

going to be we can say the triple bond

is between two and three and four and

five

but that's using the bigger numbers so

let's go for the smaller numbers so

we'll start counting from here so the

triple bond is between one and two and

three and four so we will use this

position numbers because we are saying

the triple bond is at position 1 and

position 3 so the name is going to be

paint 1 comma 3 III and again between

the letter and the number there's a dash

and between two numbers there's a comma

in here alright let's name this guy now

now what's interesting here is there's

the H functional group so this is an

alcohol but again to simplify things we

are going to ignore which and look at

the longest carbon chain here so let's

number it here forward and backwards so

they have four carbons so basically the

name is going to be a butte it's going

to start with butte and if the alcohol

wasn't there the name would have been

butane but you know that alcohol and

other functional groups that we are

going to talk about their name comes in

the suffix the prefix was for al Kyle's

and the halogens so this alcohol name

will come in the suffix and the name

isn't ends with oil now when you add oil

you need to remove the e so this oil

gets added to the name and the name

basically becomes butanol so remember

the is removed and we attach the suffix

om and what is the position of butanol

it's at position 4 but we'll choose the

number 1 here because that's the

smallest number so it's basically butan

1 all or basically butanol because we

don't have to write the number 1 now

let's say the H was at a different

position so let's say we had something

like this

and the witch was here and rest of

course our hydrogens so what will be the

name of this compound again we number

our longest carbon chain right so this

will be Butte it will start with Butte

and the name would have been butanol but

the position of H is on two because will

not take three that's the larger number

so it's basically a butan two all or

sometimes you might find it written as 2

butanol but usually this is the

preferred way of numbering it butan 2

all now let's try to name these two

compounds earlier we had seen the

alcohol functional group here also

there's a functional group so do you

know the name of this functional group

which has C double bond o NH that's

right

it's called aldehydes

and what is the functional group on this

compound this is a functional group and

it's called ketone so both the

functional groups have C double bond o

on them so what's the main difference

here the aldehyde group is always at the

end so either on this carbon or it could

have been here okay because it ends with

an H but the ketone group is interesting

because the ketone group must have at

least one carbon on both the sides

so that's an important difference to

remember because the functional group

decides the property of the compound and

of course its name so let's try to name

this guy so again we'll apply the rule

and look at the longest carbon chain and

one important point to remember is even

the functional group carbon needs to be

included in the counting okay so it's

five carbons including this one and

we'll also reverse number it so this

functional group wasn't there it would

have been a pentane right the compound

would have been five carbon paint and

only single bonds are there if we

ignored the functional group so it would

have been pentane but the rule is to

delete the e and add the suffix in the

name for this function group and it's an

aldehyde so we add the al to it so what

will be the name of this compound then

terminal and it's at position one the

smallest number so it's basically Penton

one eye or simply fentanyl okay is that

clear now let's take a look at this

compound so here we have three carbons

and will include the carbon of the

functional group so it's a three carbon

chain so the name will be propane right

if

ignore the functional group but again

the rule is will remove the letter e and

add for the ketone we need to add own so

what's the name going to be

proper known now you might be thinking

we need to include the number also right

because the functional group is at

position two so you might be thinking

the name will be proper to own or to

proper known but know the name is simply

proper known why because one propanone

or three properly known is not possible

because if I move this ketone group to

this side or this side if it becomes on

the end carbon what will you become

it'll be an aldehyde so only possibility

with three carbon is to propanone so we

simply write it as proper known now

let's take a look at this example I have

written this in the condensed form

because the whole structure with the

hydrogen's is not expanded here again

you should look for the functional group

and can you see it it's COOH so this is

a carboxylic acid I'm just going to

write simply acid here and again let's

count all the carbons in our longest

carbon chain so we have five carbons and

remember we need to include the carbon

in the functional group also and let's

reverse number eight here okay so if we

ignore the functional group the name

would have been pent because five

carbons and all have single bonds

between the carbons so it would have

been pentane right but this functional

groups name will come in the suffix and

for acid it's going to be the suffix is

going to be weak acid that gets added so

we are going to delete the e and add

weak acid here

so what is the name of this compound

it's going to be pentanoic acid right

and we don't have to give the position

of this functional group because it's at

position 1 so it's Penton 1 oak acid or

simply pentanoic acid now let's say we

have a chlorine over here so I'm going

to remove one edge and let's add a

chlorine in here so what is the name of

this compound B so it's basically a

pentanoic acid and the halogen comes in

the prefix so it would be a chloro

pentanoic acid but we need to do the

numbering right so what number should we

choose if we look at the smallest number

we will think of writing as 2-chloro

pentanoic acid but that's the wrong

answer

let me explain you why because in this

compound can you see that there are two

functional groups an acid and a halogen

and then there's an important priority

order that we need to follow so let me

write down the priority list here so

what is the priority list that you need

to know so we have on the top priority

we have the assets so that's co h then

we have aldehydes followed by ketones

then alcohols then you have the triple

bond double bond okay and then you have

the halogens so things like chloro bromo

right and then you have the alkynes

so things like methyl ethyl so these are

the highest priority so this is our

priority list here and the top ones are

at higher priority than though and this

one is at the lowest priority and easy

to remember is this one has the most

atoms one two three four so that's the

top priority here

this has three this has two and this one

doesn't have carbon and you know in

organic chemistry carbon is the king

so that's alcohol then you have the

triple and double bond followed by this

functional group of halogens and then

the al-qaeda's and remember these guys

were added as prefix in the name so the

prefix fellows come down at the priority

list and all of these affect the suffix

of the name so you can note down this

important priority list and the

numbering will be based on that so let's

apply this for our compound here so we

have acid and a halogen so according to

our priority list acid gets the top

priority so he wants position number one

right so we need to follow this

numbering scheme not this one

and the halogen is at position 4 so

basically what is this compound it's a 4

chloro Penton 1 auric acid right so we

can simply write that us instead of a

2-chloro it's going to be a 4 chloro

pent an but i won't write one because

it's not needed so it will just be for

chloro pentanoic acid so this is an

important thing we've learned that when

there are multiple functional groups we

need to apply a priority list to

determine the numbering here here's

another example for you why don't you

pause the video and try writing the IU

pack name yourself for this one so what

is the answer you got is it to Ethel

and three metal

one two three four five six hexane so is

this your answer actually this answer is

wrong so what is the right answer here

let's take a closer look so if you look

carefully this is not the longest

continuous carbon chain why because this

one has six carbons but if you go like

this then can you see there'll be two

three four five six seven carbons so the

longest continuous carbon chain is this

one so it's easier if we expand this one

and write it as right so just expanded

the a tile there for you and let's

number our longest carbon chain here so

four five six seven and again backwards

one two three four five six seven right

so this is not basically your hexane

it's a heptane right and what are the

attachments in front of this name

because you can see the attachments or

the substituent's we have here are two

ch3 s right so that's basically and you

know CH 3 is the alkyl group so it's a

dimethyl so we have a dimethyl in front

of the name here

the prefix part and what are its

positions it's at position 1 2 3 & 4 if

we number this way so 3 & 4 here and if

we go this way it said 4 & 5 so again we

will choose the smallest number which is

3 & 4 so the name is going to be 3 comma

4 dimethyl heptane so that's our correct

answer here ok let's try this one now

here we have folk

and can you see the functional group

here what is the functional group that's

right

it's a ketone because you have C double

bond o and carbon on both sides right so

let's number our longest carbon chain 1

2 3 4 and reverse 1 2 3 4 ok so if you

ignore the functional group it would

have been a butane right but there's a

functional group in there so I'm going

to delete the e and you know in ketone

the own gets added so it becomes a

butanone and what is the position of the

functional group it's at position 2

so that would make it a butan 2 own

right but there's something interesting

here if you write this name it's

probably fine but strictly speaking if

you look here if I shift the double bond

over here then what will the main be

it's not going to be butane 3 on again

now we will take the smaller name a

smaller number I mean so it's again

going to be butan 2 own so just like

propanone 4 4 carbons also only one

ketone is possible which is butan to own

or simply butanone so this is the best

answer here that the name is just butyl

because you can't have the double bond

all at carbon 1 or 4 because then it

will become an aldehyde it will be at

the end carbons and if you put it at 2

or 3 it doesn't matter the name is the

same butan to own or simply butanone and

here's our final example for this one I

want you to write the IU pack name

yourself so do let me know your answer

by putting it in the comments below I

hope the IU pack naming is crystal clear

to you now here is

Marie of the rules that we learnt the

first thing is to find the longest

continuous carbon chain and remember to

number it forwards and backwards then

you should check for functional groups

whether they are double bonds or triple

bonds present in the compound and add

the name as the prefix or the suffix and

remember to use the priority list that

we talked about the alphabetical order

and using the smallest number to give

the position numbers so go ahead and use

all these rules and find the answer for

this compound and do let me know your

answer by putting it in the comments

below and if you found this video useful

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chai academy.com for the quiz and the

top three questions on this video I'll

put the links in the description below

thanks for watching