Nomenclature of Haloalkanes Video Lecture - Class 12

laya hear from labor sicom and in this
video I will show you how to name alkyl
halides but what is an alkyl halide an
alkyl halide or halo alkane comes from
the word alkyl meaning a carbon chain
and halide meaning a halogen halogen
reversed to group 7 on the periodic
table typically shown as X and
represents the atoms fluorine chlorine
bromine and iodine
the rules for naming alkyl halides are
just like the rules for naming organic
compounds where the halogen folds into
the prefix category or substituent e2
name a halogen in an organic compound
you drop the IND from the ending and add
the letter O for example for fluorine
you drop the ine add the letter O and
you get fluoro for chlorine you get
chloro for bromine you get bromo and for
iodine you get iota
let's start with this simple example we
start by identifying and highlighting
the parent chain and the numbering from
the side that gives you the lowest
number for the halogen in this case we
number from the right for a total of
four carbons which gives me a first name
of Bute only single bonds gives me a
last name of a and a halogen substituent
gives me the prefix of two bromo putting
the name together I get to bromo butane
now let's look at an example where you
have multiple halogens first I identify
and highlight my parent chain I can
choose the number from the right or the
left given that both halogens show up in
the middle I have a total of three
carbons for a first name of proq only
single bonds gives me a last name of a
the fact that I have two chlorine atoms
showing up on carbon number two I have
to write 2 comma 2 to show which carbon
both halogens show up at and then I have
to put the prefix die before chloro
again to signify that I have two
chlorine atoms putting the name together
I get 2 to dichloro propane when you
have a halogen and a carbon substituent
they have equal priority and so you
number in a way that gives you the total
lowest set of numbers that means both of
these examples are numbered from the
left so that for the first one I have a
2 bromo and three methyl but for the
second one I have a 2 methyl 3 bromo the
parent chain for both of these examples
have a total of 5 carbons and only
single bonds giving me a first name of
pent and the last name of a in the first
example I have bromine on carbon 2
giving me 2 bromo and methyl on carbon 3
giving me 3 methyl
for the second one I have methyl on
carbon 2 for 2 methyl and bromine on
carbon 3 for 3 bromo putting the name
together the prefixes are arranged in
alphabetical order regardless of their
number since B comes before M bromine is
going to be named first that means the
first molecule will be to bromo three
methyl pentane and the second molecule
will be three bromo
two methyl pentane but what happens when
you have both a carbon and a halogen at
the same position in this molecule
I can number from the left getting two
methyl or number from the right to get
to iota in this case you take
alphabetical order into account since I
comes before M we start numbering from
the right so that iota will come before
methyl since I have a total of six
carbons in my parent chain I have a
first name of hex having only single
bonds gives me a hiya Dyne having the
higher alphabetical priority gives me
two Yodo
methyl having the lower alphabetical
priority gives me five methyl for a
final name of two i odo 5-methyl hexane
now let's look at this example we have a
substituted cyclohexane so we start
numbering from the halogen and go
clockwise or counterclockwise since we
have no other substituents six carbons
gives me a first name of hex the ring
gives me a prefix of cyclo and only
single bonds gives me a last name of a
fluorine occurs on carbon one so we
would put one fluoro
however since fluorine is the only
substituent the number one will be
self-understood and does not have to be
included therefore instead of one floor
of cyclohexane i skipped the one and
simply call this molecule floor
cyclohexane
let's try a multi substituted
cyclohexane I start with my parent chain
of six carbons for a first name of hex
only single bonds for a last name of a
m-- and a ring for a prefix of cyclin
when it comes to numbering since I have
two halogens on one carbon and one
halogen on a second carbon I start
numbering from the carbon that has more
things or more substituents coming off
of it I have the option of going
clockwise or counterclockwise however if
I go counterclockwise my second halogen
gets a number five with going clockwise
my second halogen gets a three and so I
have to go clockwise since I have
multiple halogens the number one cannot
be assumed and so I have to put the
number for each two chlorines on carbon
one gives me a 1 comma one dichloro
when iodine on carbon 3 gives me 3 iota
when putting the name together we
alphabetize based on the halogen not
based on the word die since C comes
before I we have one one dichloro three
iota of cyclohexane
when a Python and a halogen compete for
priority the pie bond is going to get
the lower number in this case I
highlight my parent chain and start
numbering from the left since the double
bond is higher priority than the
chlorine I have four carbons for a first
name of Bute a PI bond starting at
carbon one for a last name of 1e since
chlorine occurs at carbon four
we have four - chloro for a final name
of four chloro 1-butene
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