Dimethyl disulfide (DMDS) is an organic

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the molecular formula . It is a flammable liquid with an unpleasant,

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to central and south Asia, str ...

-like odor resembling that of "leaking gas". The compound is colorless, although impure samples often appear yellowish.

Occurrence and synthesis

Dimethyl disulfide is widespread in nature. It is emitted by bacteria, fungi, plants, and animals. Along with

dimethyl sulfide Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula . It is the simplest thioether and has a characteristic disagreeable odor. It is a flammable liquid that boils at . It is a component of the smell produc ...

and dimethyl trisulfide, it has been confirmed as volatile compounds given off by the fly-attracting plant known as dead-horse arum (''Helicodiceros muscivorus''). These flies are attracted to the

odor An odor (American English) or odour ( Commonwealth English; see spelling differences) is a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive ...

resembling that of fetid meat, and thus help pollinate this plant. The

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

has possibly detected evidence of DMDS in the atmosphere of the

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

K2-18b. DMDS can be produced by the oxidation of

methanethiol Methanethiol (also known as methyl mercaptan) is an organosulfur compound with the chemical formula . It is a colorless gas with a distinctive putrid smell. In small amounts, it is pervasive in nature and found in certain foods, such as some n ...

, e.g. with

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

: :

Chemical reactions

Important reactions include chlorination giving methanesulfenyl chloride (), methanesulfinyl chloride (), and methanesulfonyl chloride () as well as oxidation with

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

peracetic acid Peracetic acid (also known as peroxyacetic acid, or Percidine) is an organic compound with the formula CH3CO3H. This peroxy acid is a colorless liquid with a characteristic acrid odor reminiscent of acetic acid. It can be highly corrosive. Perac ...

giving the

thiosulfinate In organosulfur chemistry, thiosulfinate is a functional group consisting of the linkage (R refers to organic substituents). Thiolsulfinates are also named as alkanethiosulfinic (or arenethiosulfinic) acid esters. They are the first of the seri ...

compound, methyl methanethiosulfinate ().

Uses

DMDS is used as a food additive in onion, garlic, cheese, meats, soups, savory flavors, and fruit flavors. Industrially, DMDS is used in oil refineries as a sulfiding agent. It is also an effective soil fumigant in agriculture, registered in many states in the U.S. as well as globally. In this capacity, It is an important alternative in replacing

methyl bromide Bromomethane, commonly known as methyl bromide, is an organobromine compound with chemical formula, formula Carbon, CHydrogen, H3Bromine, Br. This colorless, odorless, nonflammable gas is Bromine cycle, produced both industrially and biologically ...

, which is being phased out. However, it is less effective than the former. This pesticide is marketed as "Paladin" by

Arkema Arkema S.A. is a Public company, publicly listed, multi-national manufacturer of specialty materials, headquartered in La Défense, near Paris, France. It has three specialty materials segments (or divisions); Adhesive, adhesives, advanced mater ...

Industrial use

DMDS is used to prepare catalysts for

hydrodesulfurization Hydrodesulfurization (HDS), also called hydrotreatment or hydrotreating, is a catalytic chemical process widely used to desulfurization, remove sulfur (S) from natural gas and from oil refinery, refined petroleum products, such as gasoline, g ...

, because of its high sulfur content and low decomposition temperature. Refineries use it instead of other sulfur spiking agents for catalyst sulfiding because it has more sulfur per pound than

(DMS) or di-''tert''-butyl polysulfide (TBPS). Once injected to a hydrotreater or hydrocracker, It decomposes to form H₂S. The H₂S reacts with the metal oxides on the catalyst, converting them to the active metal sulfide form. DMDS also works as an effective product for operators in the petrochemicals industry who must protect their steam-cracking coils against the formation of coke and carbon monoxide. DMDS is utilized in the preparation of 4-(methylthio)phenol which is used in the production of various pesticides. DMDS and chlorine are reacted with borontrifluoride phenoxide to produce 4-(methylthio)phenol.

Thiophene Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its reacti ...

and DMDS are blended with combustible hydrocarbon fuel gas to impart a gassy odor to the fuel gas.

References

{{Authority control Organic disulfides Foul-smelling chemicals Methyl compounds