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Organic Chemistry
Chemistry based on carbon and carbon compounds
Originally, all organic compounds came from plants or animals (hence the name organic
chemistry - chemistry from living sources). However, a great number of these can now be
synthesized in the laboratory.
The important thing to remember about organic chemistry is that it is based on the
chemistry of carbon. If we take a look at the electron arrangement of carbon, we find that there
are four electrons in the outer valence shell. This is the most important aspect of carbon - its four
valence electrons. Because the valence orbital is very close to the nucleus, there is a strong
tendency for carbon to make covalent bonds with other atoms. The number of covalent bonds
that carbon will make is always the same number - 4.
In the last unit, we described covalent bonds as being a shared pair of electrons. In our
Lewis Dot Diagrams, we drew in every valence electron to show the 'shared' nature of the bonds
as well as the 'lone pair' electrons that frequently occur. In this unit we will only be concerned with
drawing the covalent bonds between the two atoms and not with any other electrons. The bonds
will be drawn as
a '-' between two atoms. It is assumed that in the bond, one electron comes from each atom.
Types of Bonds
There are several types of covalent bonds that can exist between two adjacent
atoms. We will consider at this time only carbon to carbon bonds.
By far the vast majority of bonds between carbon atoms are single bonds - that is
one electron from each atom is shared between them. Compounds that contain only carbon to
carbon single bonds are called SATURATED compounds.
Because carbon needs a total of four bonds around it, it is possibly to make
carbon to carbon double and triple bonds. Each of these bonds requires more energy to make
them and therefore release more energy when they are broken. Compounds do not contain only
carbon to carbon single bonds but double and/or triple bonds as well are called UNSATURATED
compounds. There are specific types of compounds that contain several multiple bonds. These
are called POLYUNSATURATED compounds.
Hydrocarbons
In order to fill up the bonds in a carbon atom, it is most probable that the carbon
atom will share an electron with a hydrogen atom. In fact, there are several thousand compounds
that are composed of just carbon and hydrogen atoms. These are known as HYDROCARBONS.
Hydrocarbons are classified as to the type of carbon to carbon bonds they contain.
ALKANES
Alkanes are compounds that are saturated - that is they contain only carbon
to carbon single bonds. These compounds can exist in straight chains or in branched chains
(see below). For the present time, we will talk about the straight chains only. We will go
back to the branched chains at a later time.
Straight Chain
H H H H H H
| | | | | |
H-C-C-C-C-C-C-H
| | | | | |
H H H H H H
Branched Chain
H H H H H H H
| | | | | | |
H-C-C-C-C-C-C-C-H
| | | | | | |
note : the
H | H H | H H
branched
|
|
H-C-H H-C-H
not this
|
|
much longer
H
H
in branched
groups.
Naming Alkanes
Alkanes, like most other hydrocarbons are identified by the length of their
carbon chain as well as to what type of bonds they have in them (single, double or triple).
Because we are talking alkanes, they all contain only single bonds. This is shown in their name by
the last part of the name ending -ANE. All alkanes end in the suffix ane.
Now for the length of the carbon chain. The following list is brought to you by the
folks at IUPAC (International Union of Pure and Applied Chemistry - These are the bozos that
make up all the rules about naming compounds - remember elements 104 onward ?! You'll learn
to hate these people a little later.)
Number of C prefix
atoms in chain
1
meth
2
eth
3
prop (an o as in Oh No)
4
but (a u as in I.O.U.)
5
pent
6
hex
7
hept
8
oct
9
non (an o as in Oh No)
10
dec
The shortest chain we can possibly have in an alkane is one carbon atom. The
rest of the atoms surrounding the carbon are hydrogen atoms.
H
|
H-C-H
CH4 - methane
|
|
\- alkane
H
one carbon
Note : the molecule is not flat but is in three dimensions. Unfortunately, I can't
draw too well so I'll represent them as flat on the board. (At this point you may want to show a
model of methane to show its three dimensional shape.
The next chain is known as ethane.
H H
| |
H-C-C-H
C2H6 - ethane
| |
H H
H H H
| | |
H-C-C-C-H
| | |
H H H
C3H8
propane
H H H H
| | | |
H-C-C-C-C-H
| | | |
H H H H
C4H10
butane
H H H H H
| | | | |
H-C-C-C-C-C-H
| | | | |
H H H H H
C5H12
pentane
Assignment :
- draw the next 5 alkanes, name them, and see if you
can determine a formula to find out the relationship
between the number of carbon atoms and hydrogen atoms
in an alkane.
- go over homework
ALKANES
As we saw yesterday, there is a pattern to the number of carbon and hydrogen
atoms in an alkane molecule.
We can make what is known as a general formula for an alkane from this information - CnH2n+2
This means that if we know how many C atoms there are, we can easily determine the number of
H atoms as well (or vice versa).
Example :
How many C atoms are there in an alkane with 254 H atoms ?
Solution :
# H atoms = 2n + 2
254 = 2n + 2
252 = 2n
126 = n
Therefore there are 126 C atoms in this
alkane.
ALKENES
An alkene is a molecule with at least one carbon to carbon double bond in the
chain. In reality we can have more than one double bond (the presence of two are called a diene) but for the sake of simplicity, we will only consider one double bond.
The shortest carbon chain that has a C=C double bond we can have is 2 carbon
atoms long.
H
H
\
/
C= C
C2H4 - ethene (sometimes called
/
\
ethylene)
H
H
note suffix -ene
Next :
H
H H
NOTE : each C atom
| |
has exactly
C=C-C-H
C3H6 - propene
4 bonds
/
|
around it !
H
H
But we could have just as easily have drawn the double bond at the other end of the molecule.
\
H H
H
| | /
H-C-C=C
C3H6 - propene
|
\
H
H
Is this the same molecule ? The way to tell is to try to rotate the molecule in space (as molecules
often do) to see if the molecules can be superimposed on one and other. Try it ! You will see that
they are one and the same.
Next alkene is butene. This can be drawn three different ways as follows :
H
H H H
| | |
C=C-C-C-H
/
| |
H
H H
\
C4H8
H H H H
| | | |
H-C-C=C-C-H
|
|
H
H
C4H8
H H H
H
| | | /
H-C-C-C=C
| |
\
H H
H
C4H8
Are these the same molecules ? Again we can try and rotate them in space. When we do we see
that the first and the last are the same but there is no possible way to rotate either one to make
the middle molecule. It is clear that the middle molecule is different. In fact, if we check out the
physical and chemical properties, we see two completely different molecules. These types of
molecules that have the same empirical formula but different structural formula are called
ISOMERS. It is clear then that we must name these isomers differently. The way we go about it is
to number the carbons in the chain - starting from the end that the double bond is closest to.
H
H H H
\ 1|2|3|4
C=C-C-C-H
/
| |
H
H H
H H H H
|1|2|3|4
H-C-C=C-C-H
|
|
H
H
H H H
H
|4|3|2 /1
H-C-C-C=C
| |
\
H H
H
In the first and third molecules, the double bond is between the carbon atoms # 1 & 2. In the
middle one, it is between
# 2 & 3. We name these isomers by using the smallest number that the double bond is attached
to.
H
H H H
| | |
C=C-C-C-H
/
| |
H
H H
\
1-butene
H H H H
| | | |
H-C-C=C-C-H
|
|
H
H
2-butene
H H H
H
| | | /
H-C-C-C=C
| |
\
H H
H
1-butene
This naming method shows that the first and the last molecules are the same but the middle one
is different.
Any alkene that has more than three carbon atoms in the chain has more than one isomer.
Pentene :
H
H H H H
H H H H H
\ | | | |
| | | | |
C=C-C-C-C-H
H-C-C-C=C-C-H
/
| | |
| |
|
H
H H H
H H
H
C5H10
1-pentene
C5H10
2-pentene
General formula for alkenes : CnH2n There are twice as many hydrogen atoms as there are
carbon atoms in an alkene.
ALKYNES
Alkynes possess at least one C to C triple bond. As with alkenes, there can be
more than one isomer. In fact, all the rules that apply for alkenes also apply for alkynes.
H
|
H-C=C-H
H-C=C-C-H
C3H4 - propyne
|
C2H2
H
ethyne
(more commonly called acetylene)
H H
H H H H
| |
| | | |
H-C-C-C=C-C-C-C-C-H C8H14 - 3-octyne
| |
| | | |
H H
H H H H
General formula for alkynes : CnH2n-2
Example :
What is the molar mass of an alkyne having
256 H atoms ?
Solution :
2n-2 = 256
2n = 258
n = 129
formula is C129H256
molar mass is (129)(12.0) + (256)(1.0)
= 1804 g/mol
-Assignment - Organic Worksheet #1
- Go over organic worksheet #1
- Quiz on organic worksheet #1 tomorrow
ARENES
Carbon atoms can also form chains that go around in a circle like fashion. These
compounds are called arenes or aromatic compounds. Because they go in a circle, their names
have cyclo- as a prefix to them.
Cyclobutane
Cyclopentane
Cyclohexane
More examples:
Cyclopentene
Cyclohexene
ATTACHING GROUPS
Instead of always having hydrogen atoms as the atoms that are attached to the carbon
chain, a number of other substances can attach. As we said earlier, there are branched carbon
chains. The branches themselves can be saturated or unsaturated but again for the sake of
simplicity, we will consider only saturated carbon chains as attaching groups.
As we said earlier, the number of carbons in a chain are given special prefixes. When
these are attaching groups, a special suffix is given to this prefix (does that make any sense ?!?!)
For example a one carbon attaching group
H
|
H-C-H
|
is called methYL
sometimes written as CH3-
As with different isomers of alkenes and alkynes, different isomers of alkanes can exist if
attaching groups are at different positions on the carbon chain. Example
CH3
CH3
H | H H H H H H
| | | | | | | |
H-C-C-C-C-C-C-C-C-H
| | | | | | | |
H H H H H H H H
H H H H | H H H
| | | | | | | |
H-C-C-C-C-C-C-C-C-H
| | | | | | | |
H H H H H H H H
2-methyloctane
4-methyloctane
Systematic method of naming organic compounds :
Step 1 - Identify the family by the 'functional group'
(the thing that makes it this family - for
example the double bond in an alkene)
Step 2 - Identify the longest, uninterrupted, unbroken
chain of carbon atoms that contains the
functional group. NOTE : This does not have to
be a straight line. In fact the only reason
why we are drawing them straight is because it
is easier. In reality these are 'kinky'
molecules !!!
Step 3 - Number the carbon chain from one side to
another (see notes for how to number a carbon
chain.)
Step 4 - State what is attached and where it is
attached. Generally, we number from the
smallest to the largest as we read the name
from left to right. DON'T forget the position
of the functional group if there are different
isomers !!!
Step 5 - You're all done !!!
Rules for numbering the carbon chain :
The following rules have an order of priority. If Rule 1 does not make any
difference, or doesn't apply, go on to rule 2. If rule one does apply, stop immediately and number
the chain. Do not pass Go, do not proceed to rule 2 etc.
Rule 1 - Start numbering from the end which the
functional group is closest to.
Rule 2 - Start numbering from the end that an attaching
group is closest to.
Rule 3 - Which attaching group (if there two at the
same distance away from an end) is larger ?
Start from the largest end. For example, if a
C2H5- and CH3- are attached at the same
distance from an end of the chain, start
numbering from the end that the C2H5- is
closest to because it is longer than the CH3group.
Rule 4 - Try alphabetical order for attaching groups.
This will become more evident when we add more
attaching groups to the list.
Rule 5 - Try the next closest attaching groups as per
rules 2 and 3 and 4.
Rule 6 - (And the best rule of all as far as I am
concerned!) WHO CARES !!! If we have got down
this far, we have a symmetrical molecule. It
really won't make any difference as to which
end to start from.
More attaching groups :
FCl Br INH2 NO2 -
fluoro
chloro
bromo
iodo
amino
nitro
Examples :
H I H H H Br
| | | | | |
H – C – C – C – C – C – C - NH2
| | | | | |
H H H H H H
H H F H NO2
| | | | |
H–C=C–C–C–C–H
| | |
H H H
1-amino-1-bromo-5-iodohexane
H F F F H H H H
| | | | | | | |
H–C–C–C–C–C–C–C–C-H
| | | | | | | |
H H H H H H H H
2,3,4-trifluorooctane
We have to state where
all the fluoro's are and for
some reason we also must
include a 'tri' to show that
we have three of them. I know
it seems redundant, but I
didn't make the rules !
3-fluoro-5-nitro-1-pentene
H H I H
| | | |
H -C = C – C – C – C – H
|
| | |
H
H H CH 3
4-iodo-1-hexyne
Tricky ! Did you notice
that the last methyl
group was really a part
of the longest unbroken
uninterrupted chain of
carbon atoms.
Different types of isomers (Geometric Isomers)
When attaching groups form on either side of a double bond, we can not rotate
them in space to fit one over top of the other. We must then call them by different names.
Example :
H F F H
| | I |
H-C- C= C- C-H
|
l
H
H
H F
H
| |
|
H- C-C=C- C-H
|
l |
H
F H
Both of these are forms of 2,3-difluoro-2-butene but are slightly different. The
one on the left has both its F atoms on the 'up' side while the one on the right has one 'up' and
one 'down'. (If both are 'down' it is a rotated version of the one on the left.)
When both are 'up', we call that form of isomerism CISWhen one is 'up' and one is 'down', we call this TRANSH F F H
| | I |
H-C- C= C- C-H
|
l
H
H
cis-2,3-difluoro-2-butene
H F
H
| |
|
H- C-C=C- C-H
|
l |
H
F H
trans-2,3-difluoro-2-butene
Exercises:
1. Draw the shapes of the following molecules using CONDENSED structures:
a) cis-2-butene
b) 3-pentyne
c) cis-3-octene
d) 3-methyl-trans-2-pentene
2. Name the following molecules:
a) CH3-CH2
CH2CH3
\
/
C = C
/
\
H
H
b) H
CH2 CH2CH3
\
/
C = C
/
\
CH3
H
c)
d) H
CH2 CH2CH3CH3
\
/
C = C
/
\
CH3CH2
H
CH3
H
\
/
C = C
/
\
H
CH2CH2CH3
Aromatic Compounds:





Benzene, C6H6, is a very important molecule in organic chemistry.
Aromatic: because many molecules containing benzene ring have fragrant and pleasant
smell
The ring-like structure of benzene can be represented using RESONANCE STRUTURES.
The double bond of benzene is said to be “DELOCALIZED”. That is, the actual distribution of
electrons in the carbon-carbon bonds in Benzene are a mixture of the single and double
bond.
Bond Length Data:
C-C length in ethane
1.54 pm
C?C length in benzene
1.40 pm
C=C length in ethene
1.34 pm
Aromatic Compounds are molecules containing one or more benzene rings.
Examples:
Phenol
methylbenzene (toluene)
naphthalene
vanillin
Naming Aromatic compounds:
a) 1,3,5-trimethylbenzene
b) chlorobenzene
c) 1,4-dichlorobenzene
d) hexachlorobenzene
e) 1,3,5-trichlorobenzene
g) TriNitroToluene
f) Methyl benzene (commonly known as toluene)
h) 1,3-dimethyl benzene
Functional Groups:

Group of atoms that gives a molecule specific physical and chemical properties such as:

Making it acidic or basic, making it soluble in water or not, making it smell, etc.
1. Alcohols

Alcohols are defined as a carbon chain that has the functional group
attached to a carbon atom in the chain.
 The suffix on the alcohols
is
Examples :
H
H H
|
| |
H-C-OH
H-C- C-OH
|
| |
H
H H
methanol
ethanol
-OH (called hydroxyl)
ANOL.
H
|
H-C|
H
H H OH
|
|
|
C- C- C|
|
|
H H H
3-hexanol
H
|
C|
H
H
|
C-H
|
H
All the other rules about having other things attached to the carbon chain (instead of hydrogen
atoms) still apply.
H I F H H CH3 H H H Br
| | | | | | | | | |
H-C–C–C–C–C–C–C–C–C–C-H
| | | | | | | |
| |
H H H OH H H NH2 H H NO2
2-iodo-3-fluoro-6-methyl-7-amino-10-bromo-10-nitro-4-decanol
Properties of Alcohol:


The –O—H Group is polar, and makes the molecule dissolve in water.
The hydrocarbon section of the molecule is non-polar, which makes the molecule non-soluble
in water. For example:
Methanol is soluble in water, while pentanol is insoluble in water.

Boiling points of alcohols are higher than expected from their molar masses. The –O—H
group of alcohol undergo extensive hydrogen bonding between molecules which holds
them together. This intermolecular bonding is exhibited by a relatively high boiling point.
All alcohols are poisonous.

Exercise:
1. Draw the following molecules:
a) 1-butanol
b) 3-methyl-2-hexanol
c) 4,5-dimethyl-3-hexanol
d) 2-methyl-2-butanol
e) 3-methyl-1-pentanol
2. Name the following compounds:
a) CH3-CH-CH3
l
O-H
b) CH3-CH-CH2CH2CH3
l
O-H
CH3CH2CCH2CHCH3
l
l
OH CH3
2. Aldehydes
\




Aldehydes are compounds that have a
C=O group (called carboxyl)
/
attached to the beginning of the carbon chain. (Remember that we start numbering the
carbon chain from the end that the functional group is closest to.)
The functional group MUST be at an end of the chain or it will not be classified as an
aldehyde.
The suffix for this group of molecules is ANAL. Be careful of the spelling - the spelling is
very close to that of an alcohol, but the molecules are very different.
R - C= O
l
H
where R = some organic group
Examples :
H
|
H-C=O
H CH3 H H H F H H H
| |
|
| |
|
|
|
|
H – C – C – C – C – C – C – C – C – C =O
|
|
| | |
| |
|
methanal
H H H H H F H H
(formaldehyde)
8-methyl-nonanal
Ethanal
butanal
benzaldehyde
3. Ketones

Ketones are very similar to aldehydes in so far as they have the same functional group (C=O)
but it is NOT attached at the beginning of the carbon chain but somewhere in the middle
portion of the chain. Another difference is that we can get different isomers of a ketone but
not of an aldehyde. The functional group is sometimes written as
O
ll
R - C – R’
where the R's stand for the
rest of the carbon chain.

As far as the ending of the name of the compound is concerned, the suffix is ANONE.

The smallest chain of carbon atoms you can have in a ketone is 3 because in order for the
“=O” atom to be located in the middle portion of the chain, the chain must be longer than two
atoms long. This ketone
H
O
H
|
||
l
H--C----C --- C--H
|
|
H
H
Examples :
Butanone
propanone, is sometimes referred to as
acetone. (In an old system of naming
organic compounds, ACET- usually meant
two carbon atoms [e.g. acetic acid,
acetate ion, acetylene] but was
inconsistent, as we see here.)
2-pentanone
H H H H H O H
| |
| |
| || |
H – C – C – C – C – C – C – C –H
| |
|
| |
|
H H H H H
H
2-heptanone
3-pentanone
H H O H NH2
|
| || |
|
Cl – C – C – C – C – C – Cl
|
|
|
|
H H
H NH2
1,1-diamino-1,5-dichloro-3-pentanone
4. Carboxylic Acids
Carboxylic acids seem to be a combination of an alcohol and an aldehyde in that their functional
group has both a C=O and an -OH on the first carbon atom of the chain.
O
||
R – C – O-H
Suffix is ANOIC ACID. There are no different isomers as both attaching groups have to be on
the first carbon atom of the chain.
Examples :
Methanoic Acid (red ant venom):
H O
| ||
H–C–C–O–H
|
H
ethanoic acid
H F H H H H H O
| |
| |
|
| |
||
H – C – C – C – C – C – C – C – C - OH
| |
|
|
| |
|
H H H F H H H
5,7-difluoropentanoic acid
(sometimes called
acetic acid or
vinegar)
H H H O
l l
l
ll
H – C – C – C – C – OH
| |
|
|
H H H H
Butanoic Acid
(butyric acid, chemical due to the odour
of smelly feet)
Amino Acids:
 Carboxylic acid that contains an amine (-NH2) group at the 2 position.
 There are 20 essential amino acids that are 20 essential biological building blocks.
 The amine group (basic group) can react with an acid, while the carboxylic acid group can
react with a base.
CH3-CH-COOH
l
NH2


2-aminopropanoic acid (analine)
- has an acidic and basic part
- the amine group is basic, and the carboxylic acid is acidic
Soluble in water
Two amino acids link together to form a dipeptide:
H
O
l
ll
H – N – CH2 – C – OH

H
O
l
ll
H – N – CH2 – C – OH 
H
O H
O
l
ll
l
ll
H – N – CH2 – C – N – CH2 – C – OH + H2O
A series of amino acids can join together to form a polymer molecule (molecule made of
many smaller molecules) called polypeptide.
5. Amines:
 Organic Bases that have a “fishy” smell
 Reacts with acids
 Lewis Base: 2 lone pair of electrons, protons attach to this site.
- NH2
Group
examples:
CH3- NH2
methylamine
CH3CH2-NH2
ethylamine
6. Amides:
contains the following group:
examples:
CH3CONH2
CH3CH2CONH2
O
ll
- C – NH2
methylamide
ethylamide
Continuation of Organic Chemistry
All the groups of carbon compounds we have talked about to this point in time
involve chains of unbroken carbon atoms. The next two groups vary from that pattern in that they
have an oxygen atom in the middle of the chain somewhere. For simplicity sake, we will not
complicate these molecules by adding any attaching groups.
7. Ethers

Ethers consist of two carbon chains joined together by a single oxygen atom. There are two
ways that they can be named - both are permitted and both must be known. See the
examples below.

Ether are Non-polar compounds.
Examples :
H
H H
|
|
|
H–C–O–C–C-H
|
|
|
H
H H
methoxyethane (a derivative of ethane
with a meth chain
attached to an oxy
atom attached to chain.)
methylethyl ether
H H
H H
| |
|
|
H–C–C–O–C–C-H
|
|
|
|
H H
H H
ethoxyethane
OR
diethyl ether
(This is the ether we normally
think of as ether. It was used as an anaesthetic
hospital)
8. Esters

Esters are the result of the reaction of an alcohol with a carboxylic acid. It is important to see
which part of the molecule came from the alcohol and which from the acid. The reaction is
catalysed with acid.
methanol +
propanoic acid
--->
methyl propanoate
H
O H H
H
O H H
|
|| |
|
|
|| |
|
H – C – OH + HO – C – C – C - H ----> H – C – O – C – C – C – H
|
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H
H
H
H
H H H
+
water
+ HOH

The ending of an ester is ATE (or anoate). The part of the molecule that came from the acid
(the part of the molecule with the =O on it) is the one that has the anoate ending. The part of
the molecule that used to be an alcohol has the ending changed to YL and placed before the
acid's name.
Most esters possess distinctive aromas and flavors. Synthetically prepared esters are commonly
added to food products as artificial flavorings.
More examples :
1. Methanoic acid + propanol ------------ >
H
O H H H
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H–C–O–C–C–C–C-H
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|
H
H H H
methyl butyrate (apple)
or methyl butanoate
2. Ethanoic acid + butanol ------- ----->
H H
O H H H
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|
|
H–C–C–O–C–C–C–C-H
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|
H H
H H H
ethyl butyrate (pineapple)
or ethyl butanoate
4. Pentanol + butanoic acid
H H H H H
O H H H
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H–C–C–C–C–C–O–C–C–C–C–H
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H H H H H
H H H
pentyl butyrate (apricot)
Experiment 23-B
In the lab next day, 23-B, we will not be making any of the above esters because the acid used in
all of them, butanoic acid (also known as butyric acid) is VERY foul smelling. Imagine an entire
class losing their lunch simultaneously - this approaches the odor of butyric acid. It should be
noted that the odors do change significantly from the acid to the ester !!!
-
Set up lab 23-B (we will do the lab next class!!!)
Read: Chapter 23 of Heath
Read p. 233-239 of Hebden
Hebden: p. 240-244, Exercise # 37, 38, 39, 43, 44
Quiz on recognising functional groups next class before the lab.
Test in 3 classes!
- Lab 23-B - Preparation of Esters
Notes :
1) Use the alcohols and acids sparingly.
2) Remember to have students recap the containers
of reagents before they leave the area.
3) Have a beaker of water with a pipette in it
right beside the 18M H2SO4. Caution the
students about this acid. They should only use
a few drops as a catalyst.
4) Use ONLY hot plate to heat the test tubes. The
organic molecules are EXTREMELY flammable !!!
5) Before they smell the test tubes, they should
add water to them. This will dissolve any
H2SO4 remaining as well as enhance the odor.
6) Dispose of the chemicals by depositing them in
an organic waste container - not just the
normal waste container.
7) The odors they should recognize are as
follows :
Test tube A - I don't know. I can recognize it as
ethyl acetate but can't place it as anything
else. The lab manual states that has a
'rum-like' odor. If that is rum, I really
don't want to drink any of this !!!
Test tube B - I think this one is more of a rum
like odor.
Test tube C - A hint of orange or lemon. It's
amazing what the power of suggestion will do
- try it.
Test tube D - Very definitely wintergreen.
Test tube E - Banana.
- Assignment : Questions - 1,2
Follow up questions #2,3,4
(to be completed in class tomorrow)
- Quiz tomorrow on Organic worksheet #3
Polymers



As we said earlier, carbon atoms can join together in long chains. There are certain types of
molecules that are actually seemingly endless chains of repeating segments. These
molecules are called polymers.
Polymers are important in many aspects of our society. Plastics, vinyls and styrofoams are
common polymers.
To see the type of reaction and molecules formed, turn to page 695 - 697 in text book. Some
of the reactions are shown.
The basic repeating unit in a polymer is called MONOMER.
Addition Polymerization:
H
H
\
/
C=C
/
\
H
H
ethylene
H
H
/
\
+
/
H
C=C
\
H
ethylene
catalyst
-------- >
H H H
C- (connects to other
l l l
/
ethylene groups)
H- C - C – C = C
l l
l
\
H H H
H
polyethylene (thousands of monomer)
- One or more hydrogen can be replaced by groups such as –F, -Cl, -CH3, -COOCH3.
- Examples of different types of polyethylene: Teflon, Saran, Lucite, Plexiglass.
Condensation Polymerization:
Demonstrations :
A) 'Bakelite'
This is a type of Bakelite, first discovered
by accident by Bakeland. In this
demonstration, the product will not
completely harden until the next day, but an
interesting result can be shown in a few
minutes.
1) Pour equal amounts of saturated aniline
hydrochloride and 37% formaldehyde into a
small bottle. (The bottle will not be
saveable.)
2) Look at the solution. Nothing appears to be
happening. Say something to that effect.
3) Go on to demonstration #2.
4) When demonstration #2 is over, go back to
the small bottle. "Accidently" drop a
stirring rod from about 5 cm above the
surface of the chemicals. The rod will
bounce back up to your hands !
5) Next day, drop the stirring rod again. The
material will be hard as a rock.
B) 'Nylon'
1) Prepare a dilute solution of
1,6-diaminohexane in water. It might be
useful to add a little food colouring to the
solution - I suggest green (for a reason
which you will see when you do it for your
class)
2) Prepare a dilute solution of sebacyl
chloride in CCl4. Suggestion : prepare these
solutions in advance to save time.
3) Pour the water solution CAREFULLY on top of
the CCl4 solution. The reaction will take
place at the interface of the two solutions.
4) Carefully, place a paperclip (or some other
small, pointed object) into the solution and
snag the interface.
5) Pull the nylon up out of the beaker and
start rolling ! It will continue to
polymerize until it is either broken (by too
hard of pulling) or until one of the two
solutions runs out.
6) Before the solutions run out, stir the two
together. This will produce large globs of
nylon. (Do you see why I suggest green food
colouring yet ??)
7) Clean up by throwing nylon away. It should
be noted that the students should NOT play
with the nylon. It is not 'set' yet and
besides, the CCl4 is not a nice solvent.
8) As a further demonstration, you might want
to pour a SMALL amount of concentrated
1,6-diaminohexane into a SMALL amount of
sebacyl chloride. The result is rather
spectacular but I make two suggestions :
1) Do it in a fume hood !!!
2) Use a small, disposable jar !!!