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in this video we're going to focus on
naming cycloalkanes so let's begin with
this one here we have a three carbon
cyclo alkane you can see the three
carbons at the edges and we know that
three carbons is associated with the
name propane for an alkane so this is
called cyclopropane anytime you have a
ring of carbon atoms you need to add the
prefix cyclo so with that in mind what
is the name of this particular cyclo
alkane so here we have four carbons and
four carbons is associated with butane
so this is called cyclo butane
now there's two other common shapes that
you need to be familiar with this is
called cyclopentane since it's a ring
with five carbons and the one that looks
like a hexagon this is known as cyclo
hexane now go ahead and take a minute
and draw cyclo heptane and cyclooctane
so this is how you draw a cyclohexane
you can start by putting two lines
that's cyclo pectin and four cyclooctane
this is probably the most easiest way to
draw it it has eight sides and that's
how you draw cyclooctane
now let's say if we have a six carbon
ring with two carbons outside of it what
is the name of this particular cycle
alkane how can we name it so as a
substituent this group is known as an
ethyl group since it contains two
carbons keep in mind for one carbon it's
associated with the word methane as a
substituent it's known as methyl ethyl
is two carbons propane 3 butane 4
pentane 5 hexane 6 heptane is for 7
octane is associated with 8 9 9 decane
10 to make sure you know the first 10
names of the common alkanes the name for
this compound is called ethyl
cyclohexane you just got to put these
two together and since you only have one
substituent you don't have to say 1
ethyl cyclohexane because it's
automatically on carbon 1 you need at
least 2 substituents to begin putting
numbers on it
what about this one how can we name this
particular alkane so this is a methyl
group since it only has one carbon and
here we have an ethyl group now when you
have multiple groups you want to put it
in alphabetical order e comes before M
so we want to put ethyl first before
methyl and if possible you want a number
in order and increase in order so we're
going to assign ethyl carbon 1 and
carbon 2 is going to be associated with
methyl we have five carbons in the ring
so we know it's a cyclopentane ring so
this is going to be called one ethyl -
two - methyl cyclo pentene you will
always need a - to separate a number and
a letter and if you have two numbers you
can separate them by a comma try this
one
go ahead and name this particular
compound by the way for each of these
examples feel free to pause the video as
you work on it so there's four carbon
atoms in the ring so the parent name is
called cyclo butane and we have a methyl
on carbon one and on carbon 3 so this is
going to be called 1 comma 3 use a comma
to separate the numbers - and dimethyl
since we have two methyl substituents
cyclo butane so that's the name for this
particular compound let's move on to our
next example
go ahead and name this compound so we
need to identify the longest chain the
longest chain is not the ring it is the
straight chain that we see here the ring
has six carbons but the chain above has
seven so that's going to be the parent
name which is associated with the word
heptane so what do we call this as a
substituent we know the parent name for
a six carbon ring is cyclohexane but as
a substituent is called cyclohexyl with
a yl so the name for this compound is
three cyclohexyl heptane
what is the name of that compound how
can we name it so we have a wedge and a
dash because one side is one chlorine
atom is in the front and the others in
the back this is the trans isomer and we
have a chlorine atom on carbon one and
two and the six carbon atoms in total in
a ring so we have a cyclohexane ring so
this is going to be called trance one
two dichloro
cyclohexane so if that's the case how
can we name this particular compound
since both bromine atoms are on the
wedge we have the sis isomer and we have
a total of five carbons in the ring so
this is going to be called sis one to
dye bromo cyclopentane
now what about this one
go ahead and name this particular cyclo
alkane so we have bromine group a bromo
group on carbon one and an ethyl group
on carbon three now because B comes
before E we want to put the one with the
B we want to say one bromo three advil
as opposed to one fo three bromo we need
to alphabetize it and if possible put it
in increase in order so to name it it's
going to be one bromo - three Ethel
cyclohexane so not only were we able to
put it in alphabetical order but we are
able to put the numbers in increase in
order which is preferable now let's move
on to by cyclic compounds
so let's say if we have a bicyclic
compound that is a compound with two
rings if it looks like that how can we
name it now the first thing you need to
be able to do is identify the bridgehead
carbons which are here now how many
carbons are between the bridgehead
carbons on the left side notice that we
only have two on the right side there's
only two carbons here and on top between
the two bridgehead carbons there's only
one so to name it it's going to be
called a bi cyclo into sin in order 2 to
1 and then add the total number of
carbons that we have which is going to
be the sum of these three numbers plus
the two bridgehead carbons which is 7 so
by Cyclone two-to-one heptane let's try
another example
go ahead and name this one so on the
left side there are two carbons on the
right side we have three and on top we
have one so to name it it's going to be
by cyclo 3 2 1 in descending order 3
plus 2 plus 1 is 6 and if you add the
two bridgehead carbons that's 8 + 8 is
associated with octane since we have a
total of 8 carbons so it's by cyclo 3 2
1
Achtung as you can see it's not very
difficult to name by cyclic compounds
but let's try one final example go ahead
and name this one notice that on the
left side we have two carbons we have
two on the right and in the top portion
between the two bridgehead carbons we
have two as well so this is going to be
called by cyclo 2 2 2 Achtung
