2. So like stereotyping?
No, this is more to do with the placement of
certain molecules/atoms on a hydrocarbon
(always alkenes)
3. Ok so we know how carbon chains are labelled
And if not, this is a quick recap
On the 2nd and 3rd Carbon On the 6th Carbon atom There are 10
atom, there’s a Methyl there’s a Bromine group Carbon atoms in
group the chain
On the 4th carbon
atom, there is a
2,3-dimethyle-1-fluro-6-bromo-8-chloro-dec-4-ene double bond, which
means the
On the 1st Carbon hydocarbon is
there’s a Flourine
On the 8th Carbon unsaturated, turnin
group atom there’s a g it, into an alkene.
Cholrine group
H
H C H
H H H Br H H H H
F C C C C C C C C C C H
H H H H H Cl H H
H C H
H
Yes I made is unnecessarily
big, but ehh… you live and
learn I guess.
4. For now we’re just going to look at
geometric isomerism
So what it really is, is where Alkenes are considered to have groups on either side of their
double bond, and when this occurs. The groups can be in either E or Z (yeah german words, I
don’t get it either) isomerism, which we’ll get to.
This what we’re gonna
So looking at our earlier examplEH focus on.
H
H C H
H H H Br H H H H
F C C C C C C C C C C H
H H H H H Cl H H
H C H
H
5. H
H C H
H H H Br H H H H
F C C C C C C C C C C H
H H H H H Cl H H
H C H
H
C6H10F H H
H
C C = H
C C
C5H9BrCl
Notice how the 2 carbon atoms on either side
of the double bond, now appear to have 2
groups of atoms on each of them. This is how
stereoisomerism can work. However it can’t
work if….
C6H10F H It can’t happen since one of the
C C carbon atoms groups consist of the
H H same molecules within each group
So..
6. Here’s where E-Z Isomerism comes into play
C6H10F H
Would be classed as an E
C C Isomerism, as it’s heaviest
H
C5H9BrCl groups are across from one
another.
Name: E-2,3-dimethyle-1-fluro-6-bromo-8-chloro-dec-4-ene
We measure each groups
“heavyness” by calculating
their Mr value.
C6H10F C5H9BrCl Would be classed as Z
C C isomerism, as the
H H heaviest groups are next
to each other.
Name: Z-2,3-dimethyle-1-fluro-6-bromo-8-chloro-dec-4-ene
