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in this video we're going to focus on
naming ketones
so let's start with our first example
let's say if you have a ketone that
looks like this
what's the name of this particular
ketone
well let's count the longest chain
there's only three carbons
and three carbons is associated with
propane
just to review methane is for one carbon
two carbons is ethane an alkane with
three carbons is propane
butane is four pentane is five hexane
six peptane for seven octane for eight
nine eight for nine decaying for ten
now
if you put the carbonyl group let's say
at the end
it's no longer a ketone this becomes an
aldehyde
so for a three carbon chain
to have a ketone it has to be in the
middle
so therefore you don't have to say it's
two propanone this is simply
propanone
the common name for this particular
ketone is called acetone
now let's say if
you have a ketone that looks like this
what's the name of this particular
ketone
now it helps to draw the structure
so we have a ch3 attached to a carbon
that has a carbonyl group
that's connected to two ch2s
in a straight chain attached to another
ch3
so as you can see we have a total of
five carbon atoms
so five carbon atoms is associated with
pentane
but instead of saying pentane
we're going to replace the
e and add omni so it's pentanone and the
ketone is on carbon 2.
it could be on carbon 2 on carbon 3. so
this time we got to specify that it's on
carbon 2 so it's called 2-pentanone
try this one
ch3
ch2 ch
br
ch2
ch2
co
ch3
so let's convert this into a line
structure notice that we have seven
carbon atoms
one two three
four
five six seven
on carbon two we have the carbonyl group
and
on carbon five not on four but on five
we have the bromine atom
over here this is a ch2 that's carbon
four
it already has four bonds so it has no
space for a bromine atom but on carbon 5
it's a ch
since carbon can only form four bonds it
has a space for the bromine atom
now let's go ahead and name this
particular ketone
feel free to pause the video
and try this example
now we need to count from right to left
and not left to right because
we want the ketone functional group to
have
the lowest number so that's why we need
to count in that direction
the ketone has more priority than
the bromine atom
so this is going to be five bromo
and the ketones are carbon 2 so dash 2
dash
a 7 carbon chain is heptane but instead
of saying heptane we're going to say
it's heptanone
so that's how you can name
this particular organic compound
so now let's move on to our next example
so what if you have an aldehyde and a
ketone at the same time
what can we do to name this particular
example
you need to know that the aldehyde has
more priority than the ketone and the
aldehyde is always at the end the ketone
is somewhere in the middle of the chain
so instead of saying hexane the parent
name is going to be hexanal
since we have an aldehyde
and you don't have to say one hex now
because it's always at the end
now we do have a ketone on five a ketone
as a substituent
is known as oxo so this is five oxo
hexanol
let's try another example
go ahead and name
this compound
so which group has more priority
the
ketone or the carboxylic acid which one
has higher priority
the carboxylic acid is going to be part
of the parent name
it has uh more priority than the ketone
so we're going gonna have to assign the
carboxylic acid
a number of one
so the ketone group is on number four
and it's the uh substituent in this
molecule so this is gonna be four oxo
and instead of saying hexane it's going
to be hexanoic acid
since we have a carboxylic acid
and so that's how you can name
this
compound
now what about
some cyclic ketones let's say if we have
this particular keto
a five carbon ring is known as
cyclopentane
but with a ketone this is simply called
cyclo
pentanone
so now what if we have a ketone
and let's say
a methyl group attached to it
how can we name this particular ketone
the ketone is automatically assigned a
number of one
so this is going to be called 2-methyl
cyclohexanone because we have a 6-carb
ring
now what about this one
what's the name for this particular
ketone
should we count this way
or this way
now
either way we count it
we're going to have a 3
and a 4. if we count it the other way
the cl is going to be on carbon 3
br is going to be on carbon 4.
so the numbers are the same however b
comes before c so
let's assign bromine number three and
then cl number four
so it can not only be in alphabetical
order but an increase in order so to
name it
b comes c4c so it's gonna be three bromo
dash four dash chloro
cyclo
pentanone
let's try another example
consider this one
how can we name this particular ketone
so because there's two ketone functional
groups
this is going to be called a dione
now if the first one is assigned a
number of one the other one will be four
so this is going to be called one four
cyclo
not penta but hexa since there's six
carbons in the ring
so cyclohexane
and then diode
now what if we have a cyclic ketone
with an alkene
so in this particular example the ketone
is going to
have more priority than the
alkene so the alkenes on carbon two so
there's two ways in which we can name it
we could say it's two
cyclopentene
so the two is for the double bond and
then own
we know the ketones on carbon one or we
can say
it's cyclo
pent
two in
one own so this specifies where
everything is
it tells you that the ketone is on
carbon 1 the alkene is on carbon 2.
it's between 2 and 3 but you pick the
lower of the two numbers
how can we name this particular ketone
which one has more priority the alcohol
or the ketone
ketones have more priority than the
alcohol so
we're going to give the ketone the lower
number we're going to count it from left
to right
now the oh group as a substituent is
called hydroxy so this is 3
hydroxy
dash 2
pentanone
what about this example
so we have four carbons
the ketone has
higher priority than the amine
so this is going to be 3 amino
2
dash butanol since we have a 4 carbon
chain
try this example
so once again the ketone has
higher priority than the ether
and the alkyl halide
so we have to count from
left to right so that we can have a
three on a ketone as opposed to a four
so we have a five bromo and a two
methoxy this is called methoxy if you
see och2c3 that's ethoxy
so b comes before
m
so it's going to be 5 bromo
we need to alphabetize it
and then 2
methoxy
dash
dream
dash
hexamone since we have a six carbon
chain
and that's it for
that example
so here's the last example for
today
go ahead and try this one
so we need to identify the longest chain
and it's not six carbon atoms
it's actually eight carbons
so we have a methyl on four
and a methyl on five
so it's going to be four
five dimethyl since we have two of them
the ketones on carbon two so it's two
dash
octanone since we have an eight carbon
chain
so that is it for this video hopefully
you found it useful
and now you know how to name ketones so
thanks for watching
you
