Propylene is a colorless gas with the chemical formula C₃H₆, featuring three carbon atoms with a double bond between two of them and six hydrogen atoms. Also known as propene, this fundamental building block of the petrochemical industry was first identified in 1850 by German chemist August Wilhelm von Hofmann during petroleum cracking experiments. As the second most important petrochemical feedstock after ethylene, propylene serves as the raw material for polypropylene plastics found in everything from yogurt containers to car bumpers, as well as countless other chemicals including antifreeze, synthetic rubber, and detergents. With its characteristic sweet petroleum-like odor and ability to polymerize into one of the world’s most versatile plastics, propylene production exceeds 100 million tons annually, making it a critical indicator of global industrial activity and economic health.

Find a review of the 50 most important industrial gases here.

20 Fun Facts About Propylene

Beyond the basics above, what else should we know about Propylene? Check out the 20 fun facts below!

1. Propylene’s double bond makes it 100,000 times more reactive than propane despite differing by just two hydrogen atoms.
2. The molecule exists in a single plane with the double bond preventing rotation, creating distinct “sides” to the molecule.
3. Polypropylene plastic from propylene is the only plastic that floats in water, making it perfect for dishwasher-safe containers.
4. The gas liquefies at -47.6°C, requiring cryogenic handling unlike easily liquefied propane at room temperature.
5. Propylene burns with a sooty yellow flame producing 30% more smoke than propane due to higher carbon content.
6. Catalytic cracking of crude oil produces propylene as a byproduct worth more than the gasoline in many refineries.
7. The compound polymerizes explosively at 425°C without inhibitors, forming solid plastic that clogs industrial equipment.
8. China consumes 35% of global propylene, converting it into face masks – producing 200 billion masks in 2020 alone.
9. Propylene oxide from this gas makes polyurethane foam, with one car containing 30 pounds of propylene-derived materials.
10. The molecule vibrates at 3,090 cm⁻¹ for C-H stretching and 1,645 cm⁻¹ for C=C stretching, its infrared fingerprint.
11. Banana ripening rooms use 100 ppm propylene as a safer alternative to ethylene for commercial fruit treatment.
12. The gas forms explosive peroxides when stored with oxygen, requiring butylated hydroxy-toluene inhibitors for safety.
13. Propylene prices correlate 0.85 with oil prices, making it a traded commodity future on global exchanges.
14. Isopropyl alcohol (rubbing alcohol) production consumes 2 million tons of propylene annually via hydration reactions.
15. The double bond angle is exactly 121.3° while single bond angles are 116.6°, creating an asymmetric shape.
16. PDH (propane dehydrogenation) plants convert cheap propane to valuable propylene, reversing nature with catalysts.
17. Propylene snow exists on Titan alongside methane and ethane precipitation in the moon’s complex weather system.
18. The compound serves as a refrigerant (R-1270) with zero ozone depletion but high flammability limiting use.
19. Medical-grade polypropylene from propylene is biocompatible, used in hernia mesh and surgical sutures.
20. Honeybees detect propylene at 2 ppb concentration, using it to locate damaged flowers that emit the gas.

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