Methyl chloride is a colorless gas with the chemical formula CH₃Cl, consisting of a methyl group bonded to a chlorine atom. Also known as chloromethane, this sweet-smelling compound was first synthesized in 1835 by French chemists Jean-Baptiste Dumas and Eugene Peligot and later became one of the most widely used refrigerants until its ozone-depleting properties were discovered. As the most abundant chlorine-containing gas in the atmosphere, with both natural and industrial sources, methyl chloride serves as a crucial methylating agent in producing silicones, pharmaceuticals, and agricultural chemicals. Despite being phased out as a refrigerant under the Montreal Protocol, this versatile yet toxic compound remains industrially important, with global production exceeding 5 million tons annually, while nature continues to produce even larger quantities through oceanic phytoplankton, forest fires, and salt marsh vegetation.

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

20 Fun Facts About Methyl Chloride

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

1. Methyl chloride is produced by ocean phytoplankton at 5 million tons annually, dwarfing human industrial production.
2. The gas liquefies at -24°C (-11°F), meaning it can be liquid in a freezer but gas at room temperature.
3. Wood-eating fungi produce methyl chloride to help break down lignin, contributing 150,000 tons yearly to atmospheric levels.
4. The compound was used in early refrigerators until 1929 when leaks killed over 100 people in a Cleveland hospital.
5. Methyl chloride’s dipole moment of 1.87 Debye makes it polar enough to dissolve in water but still mostly hydrophobic.
6. Salt marshes emit CH₃Cl when seawater chloride reacts with plant matter, creating a distinct coastal smell.
7. The molecule tumbles through space 10¹¹ times per second, creating characteristic microwave emissions at 13.8 GHz.
8. Silicone production consumes 70% of industrial methyl chloride, converting it to methylchlorosilanes for polymers.
9. The gas has an autoignition temperature of 632°C, spontaneously exploding in air when heated above this point.
10. Antarctic ice cores show methyl chloride levels varied naturally by 30% over the past 160,000 years.
11. The compound crosses the blood-brain barrier easily, causing “chloromethane intoxication” with symptoms like alcohol.
12. Potato plants release methyl chloride when attacked by insects, possibly as a chemical defense signal.
13. Industrial workers called it “sweet death” because its pleasant smell masked dangerous exposure levels above 50 ppm.
14. Methyl chloride forms explosive peroxides when contaminated with oxygen, requiring inhibitors during storage.
15. The C-Cl bond vibrates at exactly 732 cm⁻¹, allowing infrared cameras to detect leaks from 100 meters away.
16. Volcanic eruptions inject 20,000-50,000 tons of CH₃Cl into the stratosphere, temporarily increasing ozone depletion.
17. The compound reacts with aluminum powder violently enough to be studied as a potential rocket propellant.
18. Biomass burning in the Amazon produces methyl chloride plumes detectable by satellite across the Atlantic.
19. The gas was pumped into grain silos as a fumigant until workers developed peripheral neuropathy from chronic exposure.
20. Deep-sea hydrothermal vents produce methyl chloride at 400°C when seawater chloride meets volcanic methane.

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