Organic chemistry nomenclature and isomerism A2 Chemistry Unit 4 Lecture 7 part b - Bilingual Subtitles
For the nitrile groups, how to name these nitrile groups?
So we have three carbon atoms excluding the nitrile but when we name them we have to include
this also in a carbon chain and this is our first carbon always.
So there are four carbon that's why it is but they have a single bond.
But this time we light full A and E because this is not starting with a wobble.
The functional group suffix is not starting with a wobble.
And then for C triple bonded with N, we that as nitrile.
But it also contains, we contain another group, but we always give priority to nitrile come.
As we discussed, first is carboxylic acid, then it's derivative, then nitrile groups are there.
When we select the longest carbon chain in this example, 1, 2, 3 or 1, 2, 3, so both ways we have three carbon atoms.
1, 2, 3, 2nd position we have OH group and 2nd position we have hydroxy.
So, 2 are there.
So, whenever 2 branches are there, then you always name the branches according to their alphabetical order.
So, hydroxy is first, it is not about position, it can be the one which is And afterwards, we have a closer position to the functional group, but when we name the branches,
it is always according to alphabetical order.
So, it is two hydroxy two methyl, because second position we have hydroxy and second position we have methyl.
prop because of three carbon atoms a any because of single bond throughout the
carb between the carbon atoms in nitrile due to this functional group carbon triple bonded with n.
Then carboxylic acid derivatives such as like example estertoide form when carboxylic acid react with alcohol.
So, the part which is attached with oxygen is considered as a branch, and it is always coming from alcohol.
And the part which is attached with the main carbon 3 double bonded with O is considered as a chain.
So, one carbon in the branch that is
3 carbon in the chain prop, single bond N and due to the functional group it is, so it is methyl propinoid.
How to name acyl chlorides?
Because acyl chloride means C double bonded with O and C L is acyl chloride and the name should have oil chloride.
So 2 carbon at single bond A in and because function group, the suffix of the function group is starting with O.
So, we remove E and that is why it is oil chloride.
But if there are branches like when we select the carbon chain,
this is the chlorine so 1, 2 and 3 carbon, so this is a branch.
Second position, we have a branch that is why.
because of three carbon and and single bond and oil chloride.
So two methyl propane oil chloride Now C double bonded with O and CL C double bonded with O and CL and between them three carbon atoms are there because CH 3 in CH 2 in
a bracket 3 So, you have to include all of them.
So, pent because of five, why pent because one, two, three, four, and then five.
A and E,
why A and E,
because when we say die or try or tetra, we write the full and We do not remove E from A n.
It is pentane, diui and chloride because of this function load.
Mite, Mite means C double bonded with O and N.
Two carbon at single bond N and Mite.
But if, more carbon chains are attached like hydrogen are replaced by more alkyl groups carbon chains.
Then these carbon chains are considered as a branch but how you mention these carbon chains
you will use the term N like what N represent this N represent that this is a alkyl group attached directly to nitrogen.
So n, one carbon means there's a branch attached to nitrogen directly and this is a main chain.
So n, because one carbon in the branch so it is methyl and three carbon in the main chain so prop n.
Now, as you can see, there are two carbon chains are attached nitrogen and identical are there.
So, nn, because first branch is also attached to nitrogen, second is also so, nn, n, n.
And when you check the whole structure, like this is a main chain, so there is a branch to the main chain as well.
And there are two branches attached directly to nitrogen.
So n, n, and 2, why this 2?
Because 2, and 3.
So n, 2.
because three branches so that's why try methyl propane amide same in this case
so nn dimethyl propane amide but it can be like c2h5 then it will be you
will always name according to If it's like one of the group is ethyl, another one is methyl.
So, ethyl should be first and methyl should be afterwards.
So, it will be N ethyl, N methyl, and then propane amide.
Like, if I simply change it instead of it is 3 to h5.
Now, what happened the name will change the how the name will change because the one which is attached with the nitrogen is the branch.
So, n group is also a branch and ethyl is also a branch.
So, which one we should name first.
because we name according to the alphabetical order.
So, n is there, then n ethyl and then this is a main chain.
So, it prop single bond between them a and and a mind group is there that a mind group is there that's why we call a mind.
So, any trial, any trial a mind or n n ethyl methyl a mind.
Is it clear how to name a style chloride in a mites and what is a mind function group?
Then, isomers isomerism when compound have same molecular formula, but they have different structures, we call them is isomers.
It can be a structural isomerism.
It be chain isomerism, like structural isomerism is divided into chain isomerism, position, and function in rows.
And stereomerism is geometrical or optical.
So, when compound have same molecular formula, but different structure, we call that a structure isomerism and it can be chain.
So, in chain isomerism, what happened?
Thus, they have same molecular formula, but different carbon skeleton like arrangement of the carbon is different.
You can see 5 carbon in a straight chain, 4 in a straight, 1 is three in a straight and two of them are branched.
So all have the same molecular formula but they all have different names.
Three carb, five carbons, that's why it is pentane.
Second we have a branched to two methyl butane.
Second position, we have two branches, so two, two dye methyl.
propane.
Position isomerism means when the position of the functional group is different like example bromine is attached with the first carbon and bromine is attached to a
second carbon.
So, two different positions of the bromine, we call that as position isomerism.
But functional group isomerism means the two compounds have different functional group.
Same molecular formula, but different functional group.
Like example, when we write ethanol, ethanol, how many carbon, two carbon atoms are there.
6 hydrogen are there and 1 oxygen.
Another compound which is called ether,
it is called thing, but this is another organic compound, functional groups when oxygen is linking the carbon chain, that's called ether.
So it is the name of this compound is methoxy methane.
But you can see here,
when I count the number of the carbon atoms,
C2H6O and C2H6O, and What we call when two compounds have the same molecular formula, but different functional group.
We call that as functional group isomerism.
Same way, like example, cyclohexane, when we write cyclohexane, it is C6 and H12.
When we write the formula for hexane, C6, H12.
So, both have the same molecule of formula, but totally different functional group, one
is having all throughout the chain carbon, carbon single bond, where other one is having carbon, carbon double bond.
So, we call this as functional.
isomerism.
Then another type of isomerism which is known as stereoisomerism as you already studied this part like the geometrical isomerism.
So same structural formula for different arrangement of the atoms is there e and z in a s.
like cis and trans or E and Z, so C double bonded with C.
If the two function groups are attached,
The heavy groups vertically attach to the same side of the carbon and this arises only due to the presence of carbon-carbon double bond.
How it arises?
There geometrical isomerism, basically carbon can form 4 bond and how the formation of a bond can occur?
two of the bond it can form in the same plane,
one of the bond is into the plane and one of the bond is out of the plane.
But what happens if the carbon, carbon, double bond occur like these two are used to form a bond with.
So, now only possibility is left that either a molecule will be in or out and same thing
for other one, the molecule will be in or out.
So, when we check the heavy groups, if the heavy groups are on the same site, if then we call that as cis.
And if heavy groups are on the opposite side, we call that as trans.
So, for e or z, You can see here when we check like C double bonded with C.
So groups are attached to top and heavy groups are at the bottom.
So what is the name of this compound?
It is in terms of carbon number.
There are four carbon atoms.
but even in view to in it is further divided.
So, view in it can be cis view to in or trans view to in or z view to in or e view to in.
So, in this case because you can see the heavy groups are at the same site.
So, that is why.
And, if we change the position, this is also view to in, no difference in the name,
but heavy group one side it stop,
another side separate arrangement out of the page, so it is e view to e or it will be truss.
And we always give a priority to a group which is having greater mass,
but if identical groups are attached like example, if it was having like hydrogen.
then it will not have any geometrical isomer it will be same as normal like it is propene
this is not it cannot because we cannot here we can check like this one is heavy but for
other carbon we cannot say which one is heavier like because both are hydrogen.
So, it does not have geometrical isomer.
So, same thing for but one in there is no geometrical isomer for but two in it shows ENZ isomerism.
Is it clear this geometrical isomer?
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Then, what is optical isomer?
When two molecules are actually mirror images of each other, we that is optical isomer.
And, for optical isomer.
to be to have an optical isomer four different carbon should be like four different functional
groups should be attached and the carbon which is having these four functional groups that is known as a chiral carbon.
So, the difference, only difference optical isomers, they change the plane of the polarized light.
Polarized light means light which is having only one plane of vibration.
So, when we pass through a container example which is having only one
molecule and their optical eyes why we call them as optical isomer because what they do
they absorb the light and they rotate the light the plane polar light either clockwise or anti clockwise.
So, both possibilities are there when light enters, it can rotate clockwise or anticlockwise.
So, they are active to light or optics, that's why we call them as optical isomers.
And optical isomer only occur for the molecule in which the carbon is having four different non-functional groups as well.
that carbon is known as the chiral carbon.
So, the way to this optical y and z.
So, if I place a mirror in front of this, so what I will see a mirror image of this molecule, so this will be C, the z will be here.
y, x, and w.
So, these two are the optical isomers of each other.
The optical isomers cannot overlap on each other.
Like, if I move this and try to overlap I cannot overlap.
So for a compound to have an optical isomer the carbon should have four different functional growth.
So example you can see say you have so you have butane tool So,
in case of butane tool, now how to draw an optical isomer for butane tool, tool.
first thing you have to identify the chiral carbon.
So, how you identify chiral carbon, when you check the first carbon this cannot be chiral because three hydrogen are there.
The is that this carbon which is a chiral carbon should have different groups or different functional groups attached to it.
When you check the second carbon, two hydrogen are there.
When you check this carbon, look, you have OH, you have CH3, you have H and you will consider this as 1.
So, you have C2H4.
So, this shows that this carbon is a chiral carbon.
So, if want to draw the, first I will draw this carbon, so hydrogen is there, CH3 OH.
So, it's, it's, it's, it's, it's, it's, and C 2 H 5.
Now, if I want to draw an optical isomer.
So, what be the optical isomer of this.
So, we have this carbon the central carbon.
hydrogen arc, then CH3 closes, so it will be H3C opposite like, then this will be HO and then C5, C2H5 is there, so H5C2.
So these two are the mirror images of each other, which are also known as enantiomers.
Is it clear how to draw the optical isomer?
So, first thing is you have to find the chiral carbon and then draw that the four carbon like groups around that chiral carbon.
then draw the mirror image.
Is it clear?
Any doubt in this part?
And we have sometime when we have the racemic mixture means we have the both isomers in the same ratio like if we have
five molecules of the isomer which try to rotate the light
polarized light clockwise and 5 molecule for in the mixture which try to rotate the light clockwise.
If we have the same ratio we call that as a resume or a resume mixture and resume mixtures does not rotate the polarized lightwise.
because they like the two isomers cancel out each other.
So, there is no effect to the polarized light.
If there is a racemic mixture,
if one is more than the other,
yes, if it is a the one isomer which tries light clockwise is more, then it will rotate clockwise.
If anticlockwise more, it will rotate anticlockwise.
Any doubt till this point?
So, you can see the polarized light can be rotated clockwise or it can be rotated anti clockwise.
So, next class we will discuss the organic chemistry reactions of these aldehydes ketones and the separation techniques.
I'll end the session and share the recording with you.
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