Download CARBON CHEMISTRY AND FUNCTIONAL GROUPS

CARBON CHEMISTRY AND
FUNCTIONAL GROUPS
BEGINS
Hi there boys and girls. I’m Mr. Heat Miser and I will
be your instructor for this lesson. I’m going to be
honest with you right away and warn you that I am
very hot headed so you better listen carefully!
Observe the CARBON TETRAHEDRON. In this model
carbon is shown in red at the center. There are four
bonds projecting out of that carbon (tetra means
four) and each bond is an equal distance away from
each other in three dimensions.
The blue balls could represent various element
substitutions that form single bonds with the carbon.
We are not concerned at this moment with the blue
representation, only the shape of the overall carbon
tetrahedron.
The bonds are equidistant as the angle
remains the same between any of the
bonds in three dimensions(109.50). It is
like a small tripod with a camera on the
top. No matter how it is oriented, it
remains the same
Now one of the main reasons that I took this job to introduce
Carbon or Organic chemistry to you is my personal interest
(obsession) with heat release and the fact that hydrocarbons are
just so darn flammable!
Well down to business. Carbon is essential to living things and thus the study of carbon
is the study of organic chemistry. The Carbohydrates, Proteins, Fats and Nucleic acids all
have carbon as a key element.
Carbon can also create very large molecules by sharing its covalent electrons with other
carbons which results in long chains or branched chains as we shall see later.
Lets start with a very simple hydrocarbon. This is methane and
remember that for each shared pair of electrons we create one single
bond. Here they are represented by the line connecting the hydrogen
to the carbon in my drawing. Now once again, I must remind you that
this method of drawing is okay on paper but really represents the
carbon tetrahedron model shape as shown below.
The three dimensional model of the methane molecule shows the
black carbon atom in the center and four white hydrogen atoms
surrounding it.
Carbons can combine with other molecules to form chemical
families.
Just like in families, children share a last name , chemical
families share something called a functional group. This
gives all the chemicals within the family very similar
characteristics. I’ll give examples later.
NOTE these are all
non-polar (symmetry)
Since the children, however, are not identical, they can be
identified by their first names. This variable or “R” group
attaches to the functional groups to make the overall
molecules have slightly different properties. Lets examine
these names given to the first four members of the
hydrocarbon group.
VARIABLE “R” group MOLECULAR FORMULA
ADD HYDROGEN HYDROCARBON
Meth – 1 carbon
METHANE
Eth – 2 carbons
ETHANE
Prop- 3 carbons
PROPANE
But -4 carbons
BUTANE
FAMILY ENDS WITH ANE
MOLECULAR FORM
You probably appreciate the chemistry of hydrocarbons a little
more now that you know what they look like.
My first little hydrocarbon, methane. is also called natural
gas and is commonly used to keep your house warm in the
winter and to heat your hot water tank so you can take a warm
shower. Just think what your life would be like without him!
He may be small, but just look at the explosion he caused here!
METHANE + OXYGEN PRODUCTS?
When methane or any other hydrocarbon burns, they
combust in the presence of oxygen gas into --- let me see--PRODUCTS ARE: CARBON DIOXIDE + WATER + ENERGY!!!!!
Shown below is the balanced chemical equation for the
combustion of methane
2 CH3OH + 3 O2 → 2 CO2 + 4 H2O
DID YOU KNOW?
Methane is classified as a greenhouse gas when
released unburned.
More cows (even the Chinese now want to eat
burgers) means more methane gas released by the
cow intestines!
The methane gas used to heat your house naturally has no smell. The
smell has been added and is a type of mercaptan that smells of
sulphur to alert you in case of a gas leak. Mercaptan is a thiol
Biomass can be decomposed by microorganisms and turned into methane
gas which can be trapped and converted into a usable energy form.
GREEN ENERGY – HOW ABOUT THAT ALL YOU HOT SHOT POLITICIANS!
VARIABLE NAME
Now there are various functional groups and many different
chemical families. The next functional group I would like to
examine is the hydroxyl group in the alcohol family. I like this
family, they are all quite flammable. In addition they have an
added advantage over the hydrocarbons, they all mix with
water (polar), so I can control their flames with simple
dilution! A 50/50 alcohol water mixture burns nicely!
HYDROXYL GROUP
TYPE OF ALCOHOL
FACTS
ADDED OH
METH
METHANOL
Toxic sweet alcohol
antifreeze fuel
solvent (wood alcohol)
ETH
ETHANOL
Toxic but can be
detoxified by liver
cells –drinking
alcohol
PROP
PROPANOL
Toxic
BUT
BUTANOL
Toxic
Now take a look at these structures
These two are both examples of
propanol. They share the same
chemical formula C3H7OH . They
however, are different in their
structural formula and as a result
actually have different
properties. They are called
ISOMERS
If you see the word iso in
front of a chemical name it
means it is an isomer as
shown above.
I have an interesting problem
for you. If both of these mirror
images of me are possible, are
both actually identical or are
they different?
Now try this. Two isomers (lactic
acid) shown are mirror images of
each other and are called
stereoisomers. Can they be
superimposed on each other to
show that they are identical or not?
Enantiomers are stereoisomers that are non-superimposable mirror images.
These molecules are DIFFERENT!! JUST LIKE THE ABOVE PICTURES OF ME.
Stereoisomers differ only in their 3D structure
Chiral describes a molecule that is different from its mirror image;
enantiomers are chiral
The physical and chemical characteristics of enantiomers, however, are the
same. JUST LIKE THE IMAGES OF ME WOULD DO EXACTLY THE SAME THING,
THEY ONLY LOOK DIFFERENT!
D=dexter (means right) and L=laevus (means left) GLUCOSE VERSIONS D-glucose and
L-glucose are enantiomers
DID YOU KNOW?
Many biological molecules contain chiral carbons, creating
two possible stereoisomers. Two isomers for each amino
acid exist, the D and L forms, but only the L-form is found
in living things. Why? It remains a mystery!!
Sinistral on left
In nature there are numerous examples for the rule that right
is rarely the same as left. One example is the tetrahedral
structure of the carbon atom. Another is the coiling of a
snail's shell.
What makes a snail's seashell special, is the fact, that it is
asymmetrically coiled to one direction, either left or right.
The whorls of a snail's seashell (mollusca) rise to a visible tip the apex. Almost all seashells found have a clockwise rotation
if looked at from the top whether found in the northern or
southern hemisphere. Scientists have determined it is
connected to genetics, and the rare opposite swirl is called
sinistral and is considered quite valuable. but is there more to
it than that???? Why don’t you do a little shell analysis ?
Enough of this fooling around. Back to my
discussion of isomers. Sometimes you can have
stereoisomers that are not mirror images of each
other. These are called DIASTEREOMERS.
Diastereomers are not enantiomers. They have
different chemical and physical properties.
The prefix “en” means
“in” and the prefix “di”
means “two”
These two sugars taste
different and are called
diastereomers, a type of
stereoisomer. Look
hard to draw. Well
you’ll be drawing these
soon!
FAMILY
STRUCTURE
FUNCTIONAL GROUP EXAMPLES
Amine
Amino
Neurotransmitters
Carboxylic acid
carboxyl
vinegar
Amino Acid
Amino + carboxyl
Building block of
protein
Aldehyde
carbonyl
Formaldehyde
Ketone
carbonyl
Acetone solvent
Ester
carbonyl
Fragrant odour
Ether
Alcohol
19th century anesthetic
hydroxyl
sulphide
Sterilizing agent
Hydrogen sulphide
biomass rotten egg smell
Disulphide
Thiol
two cysteines bonded
sulfhydryl
Phosphate
Phosphodiester
Cysteine
ATP or G3P
phosphate
DNA
I’m
watching
you. You
better
learn
somethin
g from
this chart
because
this
material
will be
continual
ly
discussed
thoughout the
course!
Did you know ?
Looks like another boring molecule huh?
CH2O2
Ant stings are caused by the venom formic acid meth + carboxylic acid
The name “formic” comes from the Latin word
for ant, formica, referring to its early isolation
by the distillation of ant bodies.
I am very sceptical about your learning techniques. It’s my
guess that you know a lot more about useless information (like
High School Musical) than you know about the chart I just
showed you. I think it’s time to shake up your brain and set it
straight about something that is actually important!!
I want you to try to figure out the chemical family shown
before the words arrive on the screen. Start now!
Ether
Amine
Disulphide
Aldehyde
Phosphate
Carboxylic acid
Ketone
Amino acid
Ester
Lets try some more questions. This
time I want you to actually name the
chemicals.
Butanol
Methane
Butane
Ethanol
Propane
Methanol
Ethane
Butanol
Looks like you teenagers actually learned something
today!!
My job is done.
End