You’re here because you’ve heard of ethyl mercaptan or its less-known name, ethanethiol. Maybe you are wondering what makes the LPG smell when there is a gas leak.

Gas Gas Cylinder Torch Camping  - JerzyGorecki / Pixabay
JerzyGorecki / Pixabay

Ethyl mercaptan or ethanethiol is the chemical compound with the formula CH3SH. The name is derived from its structure and the fact that it consists of an ethyl group bonded to a thiol.

you know the smell of ETHYl mercaptan

Ethyl mercaptan (or ethanethiol) is a colorless volatile liquid with the odor of rotting cabbage, that has been added to natural gas since the 1930s as a safety measure. During transportation through pipelines, it gives off an odor that is easily detected, alerting you to take appropriate action if there’s a leak. The most likely exposure route to humans and animals is inhalation, which can result in problems with breathing and damage to the central nervous system and other organs.

What is ethyl mercaptan or ethanethiol?

Ethanethiol, also known as ethyl mercaptan or ET, is an organic compound with the formula CH3SH. It is classified as a thiol and has a strong garlic like odor. Ethanethiol is produced on a large scale by treating ethylene with hydrogen sulfide gas with the use of a catalyst.

Ethyl mercaptan is a colorless liquid with a distinctive odor. It is added to natural gas to give it the characteristic odor which allows us to detect a gas leak. Without the aroma of ethyl mercaptan, we could be walking around unaware that there is a dangerous gas leak in our area. The additive is also added to pipelines carrying hydrocarbon gases like propane or butane to help detect leaks.

What is the chemistry of ethyl mercaptan?

Lewis electron dot diagram of ethyl mercaptan is shown above. As you can see there are two carbon atoms and a sulfur atom in this molecule. Free electrons of the sulfur atom are shown as dots in this diagram.

The above diagram shows the covalent bond structure of ethyl mercaptan. Note the two carbon atoms and the sulfur atom in this organosulfur compound.

Why is there so much confusion around this compound?

Until recently, this chemical was used as a material in plastic manufacturing and in the industry of insecticide production.

Because of its foul odor, it is now commonly used mixed with LPG to detect leaks. This chemical occurs naturally in the environment, with petroleum in very less amounts.

Uses of ethyl mercaptan or ethanethiol?

You’ll find ethanethiol in production of antioxidant agents, pesticides and plastic polymers.

Ethanethiol makes up for one of the most profoundly effective pesticides. This is due to its ability of attacking the nervous system and leading to respiratory muscle paralysis of a wide range of insects and mites.

Ethyl Mercaptan is the chemical that is added to natural gas in small quantities as a warning.


Hopefully, this post has helped you better understand regarding the compound its chemistry and its common uses. The purpose of this article is to inform anyone who has an interest in ethyl mercaptan, also known as ethanethiol, including natural gas utilities, pipeline operators and manufacturers that produce products containing ethyl mercaptan. Just as with any chemical used in our industry, safety is paramount. It is critical that anyone who works with ethyl mercaptan be aware of the product identity for this and other reasons.

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