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 which is the simplest

disulfide In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

. It is a flammable liquid with an unpleasant, garlic-like odor.

Occurrence

Dimethyl disulfide is a widespread natural odoriferous compound emitted from many sources such as bacteria, fungi, plants and animals. It is an oxidation product of methanethiol in air. Along with dimethyl sulfide 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 resembling that of fetid meat, and thus help pollinate this plant. 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. It is a natural substance found in the blood, brain and feces of animals (including humans ...

, e.g. with iodine: :

Chemical reactions

Important reactions include chlorination giving methanesulfenyl chloride (), methanesulfinyl chloride (), and

methanesulfonyl chloride Methanesulfonyl chloride (mesyl chloride) is an organosulfur compound with the formula . Using the organic pseudoelement symbol Ms for the methanesulfonyl (or mesyl) group –, it is frequently abbreviated MsCl in reaction schemes or equations. ...

() 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 viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

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

giving the

thiosulfinate In organosulfur chemistry, thiosulfinate is a functional group consisting of the linkage R-S(O)-S-R (R are organic substituents). Thiolsulfinates are also named as alkanethiosulfinic (or arenethiosulfinic) acid esters. They are the first member o ...

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. DMDS is also an effective soil fumigant in agriculture, registered in many states in the U.S. as well as globally. In this capacity, DMDS is an important alternative in replacing methyl bromide, which is being phased out, however less effective than the former. This pesticide is marketed as "Paladin" by Arkema.

Food use

DMDS is used to alpha substitute 2-methylfuran-acrolein to produce a food stuff used in concentrations from 0.02 ppm up to 50 ppm.

Industrial use

DMDS is a stable pale yellow liquid which works as an effective product fo
sulfiding hydroprocessing catalysts
because of its high sulfur content and low decomposition temperature. Most refineries utilize DMDS instead of other sulfur spiking agents for catalyst sulfiding because it has more sulfur per pound than dimethyl sulfide (DMS) o
di-tertiary-butyl polysulfide (TBPS).
re

/ref> Once injected to a hydrotreater or hydrocracker, DMDS 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 react ...

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

References

Reactor Resources LLC {{Authority control Organic disulfides Foul-smelling chemicals