Overview

Propylene (PRO-puh-leen) is a colorless gas with a slightly sweet odor that burns with a yellow, sooty flame. It ranks sixth among all chemicals produced in the United States and second (after ethylene) among all organics. Its primary use is in the manufacture of polypropylene, one of the most popular polymers produced in the world.

Key Facts

Other Names:

Propene; methylethylene; methylethene

Formula:

CH₂=CHCH₃

Elements:

Carbon, hydrogen

Compound Type:

Alkene; unsaturated hydrocarbon (organic)

State:

Gas

Molecular Weight:

42.08 g/mol

Melting Point:

−185.24°C (−301.43°F)

Boiling Point:

−47.69°C (−53.84°F)

Solubility:

Slightly soluble in water; very soluble in ethyl alcohol and ether

How It Is Made

Propylene is prepared commercially by the thermal or catalytic cracking of hydrocarbons. The term cracking refers to a process by which large hydrocarbons—organic compounds that contain only carbon and hydrogen—are broken down into smaller hydrocarbons. Cracking can be accomplished either by...