Dimethyl sulfide

Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH₃)₂S. Dimethyl sulfide is a water-insoluble flammable liquid that boils at 37°C and has a characteristic disagreeable odor. It is a component of the smell produced from cooking of certain vegetables, notably corn, cabbage, beetroot and seafoods. It is also an indication of bacterial infection in malt production and brewing. It is a breakdown product of dimethylsulfoniopropionate (DMSP), and is also produced by the bacterial metabolism of methanethiol.

Natural sources and link with climate

DMS is the most abundant biological sulfur compound emitted to the atmosphere. Emission occurs over the oceans by phytoplankton. DMS is also produced naturally by bacterial transformation of dimethyl sulfoxide (DMSO) waste that is disposed of into sewers, where it can cause environmental odor problems..

DMS is oxidized in the marine atmosphere to various sulfur-containing compounds, such as sulfur dioxide, dimethyl sulfoxide (DMSO), dimethyl sulfone, methane sulfonic acid and sulfuric acid. Among these compounds, sulfuric acid has the potential to create new aerosols which act as cloud condensation nuclei. Through this interaction with cloud formation, the massive production of atmospheric DMS over the oceans may have a significant impact on the Earth's climate. The CLAW hypothesis suggests that in this manner DMS may play a role in planetary homeostasis.

Smell

Dimethyl sulfide has a characteristic cabbage-like smell that becomes highly disagreeble at higher concentrations. DMS has a low olfactory threshold that varies from 0.02 to 0.1 ppm between different persons. However, it is also available as a food additive to impart a savory flavor; in such use, its concentration is low. Beetroot, asparagus, cabbage, corn and seafoods produce dimethyl sulfide when cooked.

Marine phytoplankton also produces dimethyl sulfide. Andrew Johnston, of the University of East Anglia, has characterized DMS as being the "smell of the sea". It would be more accurate to say that DMS is a component of the "smell of the sea," another being pheromones of algae called dictyopterenes.

Dimethyl sulfide is also an odorant emitted by kraft pulping mills, and a byproduct of Swern oxidation.

Industrial uses

In industry it is used in petroleum refining and in petrochemical production processes to control the formation of coke and carbon monoxide. In addition it is used to control dusting in steel mills. It is also used in a range of organic syntheses, also being a side product of Swern oxidation. It also has a use as a food flavoring component. It can also be oxidized by natural or artificial means to dimethyl sulfoxide, (DMSO), which has several important solvent properties.

The largest single commercial producer of DMS in the world is Gaylord Chemical Corporation, which is a significant economic component of the paper industry of Bogalusa, Louisiana.

Safety

Dimethyl sulfide is flammable and an irritant. Dimethyl sulfide has an unpleasant odor at even extremely low concentrations.

See also

• Dimethyl telluride
• Swern oxidation

References

External links

• Brewing
• NOAA DMS flux
• Dimethylsulfide (DMS) in the Bering Sea and Adjacent Waters: In-situ and Satellite Observations
• DMS and Climate
• Industrial chemicals