Organic Chemistry of ALKANES

1. Organic Chemistry – the
chemistry of CARBON…
Vitamin C
Glucose
Ethanol

2. Nomenclature – where do we
start ????
Methane CH4
Ethane C2H6
Propane C3H8
Pentane C5H12
Butane C4H10
Decane C10H22
Nonane C9H20
Octane C8H18
Heptane C7H16
Hexane C6H14
The bad news is … you MUST memorize these.

3. Methane --
Remember, the
methane molecule is
3D with each
hydrogen spaced at a
maximum angle of
109 degrees around a
central carbon atom.
**Methane is small, fast moving, and nonpolar.
**It is a GAS at room temperature because its
molecules are NOT attracted together. Van der
Waals forces are not strong enough.

4. Ethane --
H H
H C C H
H H
I have drawn it 2D,
but remember it IS
3 dimensional.
**Also small, fast, and nonpolar.
**Gas at room temperature due to small VDWaals forces.

5. Propane--
H H H
H C C C H
H H H
Again, its really 3D.
**Yes, this is the propane
many people heat their
homes with. Small, fast,
nonpolar, low VDWaals
forces make it a gas at
room temperature.
**To make propane
condense to a liquid
you must decrease
the temp. to –43 F at
normal atmospheric
pressure !!!

6. Butane--
H H H H
H C C C C H
H H H H
**Getting larger,
still fast moving,
nonpolar, and 3D,
but Van der Waals
forces increasing.
**Gas at room temperature, but turns to liquid at 31
degrees Farenheit !! (due to VDWaals force of
attraction.)
Your lighter will not work if left in a
COLD car on a winter night.
WHY???

7. Butane Lighters If you go to the local store and buy a disposable
butane lighter with a clear case (so that you can see the liquid
butane inside), what you are seeing is liquid butane stored in a
high-pressure container. Butane boils at 31 degrees F at normal
atmospheric pressure (14.7 PSI). By keeping butane
pressurized in a container, it remains liquid at room temperature.
If you took a cup of butane and put it on your kitchen counter, it
would boil, and the temperature of the boiling liquid would be 31
F. The boiling point of butane, by the way, also explains why
butane lighters don't work very well on cold winter days. If it is 10
degrees Fahrenheit outside, the butane is well below its boiling
point, so it cannot vaporize. Keeping the lighter warm in your
pocket is what allows it to work in the winter.
Chemistry in action…

8. Pentane –Decane and up…
A. You can probably guess what they look like.
B. All are 3D.
C. All are nonpolar, but getting large enough so that
Van der Waals forces of attraction BETWEEN
molecules make them all LIQUIDS.
D. As size increases, boiling point increases due to
VdWaals.

9. BIOCHEMISTRY
Each glucose, when
hooked together form
long chains. This is
how sugar is stored in
your body (muscles).
LONG LONG
chain sugar.