Let's talk about naming acyl halides or acid halides so if the acid halide functional group
is the highest priority group in our list so it's higher than all of these groups and if it's the
highest one we're gonna name it with the suffix -oyl halides so pentanoyl halide, heptanoyl
halide the parent chain suffix goes to the acid halide now if there's a higher priority group
present such as an ester more common for an ester to be in the presence of an acid halide in a real
molecule okay well then that acid halide loses its priority and we would name the compound as
an ester having a halocarbonyl- group okay so this the acid halide subordinate prefix for the
group name is halocarbonyl and as always with these naming challenges we're gonna circle the
parent chain to make sure we don't make mistakes we're gonna write the names of the subordinate
groups number the chain and assemble the name checking for stereochem so let's have a look
at when the acid halide is the highest priority group so we're gonna identify the parent chain
and with our highest priority group the acid halide we can either take the chain or ring
but not both so we have to stop at 3 carbons and then we can't number through oxygen either
so there we would circle our parent chain so ultimately this is going to be a propanoyl
bromide okay a propanoyl bromide that's the parent chain it is substituted with
a cyclohexyl group and a methoxy group so as we diagram this we've numbered and
labeled our names or less likely to make mistakes so now we can add the
nonpriority groups in alphabetical order a 3-cyclohexyl and a 3-methoxy
propenoyl bromide well if there's more than one acid halide present then we would add since
we have only the parent chain here and no groups off of that parent chain we can just
number from either side 1-2-3-4 & 5 and so if we were naming this as a
carboxylic acid it would be a pentanedioic acid so we could name this then as a pentane
a pentane with an "e" to separate consonants there so I forgot that at first but we need
to separate those consonants pentanedioyl instead of -dioic and then dichloride because
there's two chlorines on either side so pentanedioyl dichloride. If we have a higher priority
group present such as the ester here the ester is going to be our parent chain and we've got
a couple options so I'm going to truncate the parent chain here to illustrate the name of our
group with a halocarbonyl so this is a chlorocarbonyl group that is on the parent chain of
an ester here with a methyl group attached to oxygen so as we talked about back when we named
esters we would want to name that first group the methyl attached to oxygen first as its own
word and then we have a propanoate but it is a 3-chlorocarbonylpropanoate okay
so methyl-3-(chlorocarbonyl)propanoate and so we can separate the systematically named
chlorocarbonyl group from the rest of the name with parentheses in order to make that
clear that it is its own chlorocarbonyl group that was systematically named we have another
option though so we can also choose to use the new this is the before 2013 recommendations we
can use the new recommendations by IUPAC to take the full length of the carbon to carbon
chain that's possible including the carbonyl of that acid chloride so it's at the end of the
parent chain we can get that fourth carbon in and so now we have a methylbutanoate instead
and instead of having a chlorocarbonyl group we would have a 4-oxo but chloro before oxo
4-chloro-4-oxobutanoate and so our group names are simplified by splitting up the chloro
and the oxo instead of chlorocarbonyl naming the carbonyl separately from chlorine those are
the new recommendations and there's no problem for my class to use either version of the name
methyl-4-chloro-4-oxobutanoate or the previous method that we looked at with the
3-chlorocarbonyl group either one's fine. If however this acid halide is not on the parent chain at all
so we can get two esters in make sure we remember those methyl groups I'm going to circle leaving
those methyl groups out so we can name those there's a methyl and there's a methyl and there
we have to name this a chlorocarbonyl group okay so that now it has to be named in that fashion
either way we can number 1-2-3-4 & 5 and so here as an ester we would name
this as a dimethyl two methyl groups out front separate word and this is a
3-(chlorocarbonyl)pentanedioate instead of pentanedioic
acid the esters a carboxylic acid derivative, pentanedioate.