Ethylene is a colorless gas with the chemical formula C₂H₄, featuring two carbon atoms connected by a double bond with four hydrogen atoms. As the simplest alkene and most produced organic compound worldwide, ethylene was first discovered in 1795 when Dutch scientists observed that gas leaking from pipes caused nearby carnations to wilt prematurely. This remarkable molecule serves dual roles as both the world’s most important petrochemical building block – used to manufacture polyethylene plastics, antifreeze, and countless other products – and as a natural plant hormone that regulates fruit ripening, flower blooming, and leaf dropping. With its sweet, faintly musky odor and ability to form explosive mixtures with air, ethylene production exceeds 170 million tons annually, making it the organic chemical industry’s foundation and a key economic indicator tracked by analysts worldwide.

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

20 Fun Facts About Ethylene

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

1. One rotten apple really does spoil the barrel – overripe fruit releases ethylene that triggers ripening in nearby produce at just 0.1 ppm.
2. Ethylene’s carbon–carbon double bond is exactly 1.34 Angstroms long and completely rigid, preventing rotation and creating distinct molecular sides.
3. Ancient Egyptians unknowingly used ethylene by gashing figs to stimulate ripening, as wounded plants produce the gas.
4. The gas was used as a surgical anesthetic from 1923-1960, requiring 80% concentration but causing less nausea than chloroform.
5. Commercial banana shipments use ethylene scrubbers and release controlled amounts at distribution centers to time perfect ripeness.
6. Ethylene burns with a luminous flame producing 1,411°C, hot enough to weld aluminum but too sooty for steel cutting.
7. Plants under attack release ethylene to trigger defense mechanisms in neighbors – essentially screaming a chemical warning.
8. The molecule absorbs UV light at 165 nanometers so strongly it’s used to calibrate vacuum ultraviolet spectrometers.
9. Pineapple field workers in the 1920s noticed fruit near smoking areas ripened faster, leading to ethylene’s agricultural discovery.
10. Climacteric fruits (bananas, tomatoes, avocados) respond to ethylene, while non-climacteric ones (grapes, citrus) don’t.
11. The compound polymerizes so readily that commercial supplies contain 100 ppm acetylene to prevent spontaneous plastic formation.
12. NASA life-support systems must remove ethylene because just 50 ppb causes abnormal growth in space-grown plants.
13. Ethylene forms an explosive silver compound (Ag₂C₂H₄) that detonates when dry, discovered accidentally in 1899.
14. The petrochemical industry measures economic health by the ethylene-to-propylene price ratio, called the “EP spread.”
15. Triple-response in plants – stunted growth, stem thickening, and horizontal growth – occurs at just 0.01 ppm ethylene.
16. Modern apple storage facilities maintain 0.005 ppm ethylene and 2% oxygen to keep fruit fresh for 12 months.
17. The molecule lies perfectly flat with all six atoms in one plane, rotating as a unit 10¹² times per second.
18. Flooding causes plant roots to produce ethylene, triggering aerenchyma (air channels) formation for oxygen transport.
19. Ethylene oxide, made from ethylene, sterilizes 50% of medical supplies but is 700 times more toxic than its parent.
20. The compound exists in interstellar space and Jupiter’s atmosphere, suggesting simple organic chemistry occurs throughout the universe.

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