Chemistry Reference
In-Depth Information
UNSATURATED HYDROCARBONS
O
LEFINS
(
ALKENES
):
• Contain only carbon and hydrogen
•
Contain the group
, i.e., carbon atoms joined by two bonds
• The two bonds are called a
double bond
, and the compound is
unsaturated
because it contains less hydrogen atoms than the cor-
responding paraffin, which is considered
saturated
(with hydrogen)
• CH
2
=
C
C
CH
2
CH
2
=
CHCH
3
CH
2
=
CHCH
2
CH
3
ethylene
propylene
1-butylene
• General formula is C
n
H
2
n
One of the most important reactions in the chemical industry is the “crack-
ing” (removing hydrogen) of paraffins to form
olefins
. Olefins are essential
starting materials for many common products that we all use, particularly
plastics. The simplest olefin is ethylene, which can be
polymerized
(reacted
many times with itself ) to give
poly
ethylene used for bottles, dishware, film,
etc. The next higher olefin, propylene, can be polymerized to polypropylene
used in the manufacture of rugs, toys, kitchenware, and many other plastic
objects. Note that the names of olefins end in -
ene
, which denotes the
presence of a double bond in the compound.
