Chemistry Reference
In-Depth Information
UNSATURATED HYDROCARBONS
A
CETYLENES
(
ALKYNES
):
• Contain only carbon and hydrogen
• Contain the group , i.e., carbon atoms joined by three bonds
• The three bonds are called a triple bond, and the compound is
unsaturated because it contains fewer hydrogen atoms than the
corresponding paraffin, which is considered saturated (with hydro-
gen)
-
CC
≡
−
•
HC CH
≡
HC C CH
3
≡
-
acetylene methyl acetylene
ethyne propyne
• General formula is C
n
H
2
n
−2
Acetylenes contain at least one triple bond. The triple bond is even more
reactive than a double bond and, therefore, acetylene is used industrially to
make other compounds used in rubber and plastics. Acetylene burns in oxy-
gen to produce a very hot flame used for welding and metal cutting (oxy-
acetylene torch).
Although the current source of acetylene is petroleum, it can be manufac-
tured from calcium carbide, a product of the reaction of limestone and coke
(carbon). During World War II, Germany, having a shortage of petroleum, used
the latter technology to develop a chemical industry based on acetylene.
