Dimethylsulfide

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Dimethyl sulfide

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Identifiers
CAS number 75-18-3 YesY
PubChem 1068 YesY
ChemSpider 1039 YesY
UNII QS3J7O7L3U YesY
EC number 200-846-2
UN number 1164
KEGG C00580 YesY
MeSH dimethyl+sulfide
ChEBI CHEBI:17437 YesY
RTECS number PV5075000
Beilstein Reference 1696847
3DMet B00138
Jmol-3D images Image 1
Properties
Molecular formula C2H6S
Molar mass 62.13 g mol−1
Appearance Colourless liquid
Odor Cabbage, sulfurous
Density 0.846 g cm-3
Melting point

-98 °C, 175 K, -145 °F

Boiling point

35-41 °C, 308-314 K, 95-106 °F

log P 0.977
Vapor pressure 53.7 kPa (at 20 °C)
Refractive index (nD) 1.435
Thermochemistry
Std enthalpy of
formation
ΔfHo298
-66.9--63.9 kJ mol-1
Std enthalpy of
combustion
ΔcHo298
-2.1818--2.1812 MJ mol-1
Hazards
MSDS osha.gov
GHS pictograms
GHS signal word DANGER
GHS hazard statements H225, H315, H318, H335
GHS precautionary statements P210, P261, P280, P305+351+338
EU classification Xn
R-phrases R11, R22, R37/38, R41
S-phrases S7, S9, S16, S26, S29, S33, S36/39
Flash point -36 °C
Autoignition
temperature
206 °C
Explosive limits 19.7%
Related compounds
Related chalcogenides Dimethyl oxide (dimethyl ether)

Dimethyl selenide
Dimethyl telluride

Related compounds Dimethyl sulfoxide

Dimethyl sulfone

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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 (99 °F) and has a characteristic disagreeable odor. It is a component of the smell produced from cooking of certain vegetables, notably maize, 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 occurrence

DMS originates primarily from DMSP, a major secondary metabolite in some marine algae. DMS is the most abundant biological sulfur compound emitted to the atmosphere.[2] 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.[3]

DMS is oxidized in the marine atmosphere to various sulfur-containing compounds, such as sulfur dioxide, dimethyl sulfoxide (DMSO), dimethyl sulfone, methanesulfonic acid and sulfuric acid.[4] 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.[5] The CLAW hypothesis suggests that in this manner DMS may play a role in planetary homeostasis.[6]

Smell

Dimethyl sulfide is said to have a characteristic cabbage-like smell that becomes highly disagreeable at higher concentrations. While some report that DMS has a low olfactory threshold that varies from 0.02 to 0.1 ppm between different persons, it has been suggested that the odor attributed to dimethyl sulfide may in fact be due to di- and polysulfides and thiol impurities, since the odor of dimethyl sulfide is much less disagreeable after it is freshly washed with saturated aqueous mercuric chloride.[7] Dimethyl sulfide is also available as a food additive to impart a savory flavor; in such use, its concentration is low. Beetroot,[8] asparagus,[9] 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".[10] 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.[11]

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

Dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide have been confirmed as volatiles given off by the fly-attracting plant known as dead-horse arum (Helicodiceros muscivorus). The plant fools flies into pollinating it by emitting an odor like rotting meat, which is an attractive food source for flies.[12]

Preparation

In industry dimethyl sulfide is produced by treating hydrogen sulfide with excess methanol over an aluminum oxide catalyst.[13]

Industrial uses

Template:Ref improve section Dimethyl sulfide has been used in petroleum refining to presulfide hydrodesulfurization catalysts, although other disulfides or polysulfides are preferred and easier to handle. It is as a presulfiding agent to control the formation of coke and carbon monoxide in ethylene production. DMS is also used in a range of organic syntheses, including as a reducing agent in ozonolysis reactions. It also has a use as a food flavoring component. It can also be oxidized to dimethyl sulfoxide, (DMSO), which is an important industrial solvent.

The largest single commercial producer of DMS in the world is Gaylord Chemical Corporation, which until mid-2010 was a significant economic component of the paper industry of Bogalusa, Louisiana. The Bogalusa DMS plant operated continuously until this date, since its startup in 1961 by the now defunct Crown Zellerbach Corporation. The process technology practiced at the Bogalusa plant (alkylation of sulfur using Kraft lignin) is no longer in operation anywhere in the world. All DMS manufacturers currently use hydrocarbon-based feedstocks. Gaylord has no production of any kind at the old Louisiana site after opening its expanded DMS / Dimethyl sulfoxide operation in Tuscaloosa, Alabama in 2010.[14]

ChevronPhillips Chemical Company is another major manufacturer of DMS. CP Chem produces this material at their facilities in Borger, Texas, USA and Tesserndelo, Belgium.

Other uses

Dimethyl sulfide finds a niche use as a displaceable ligand in chloro(dimethyl sulfide)gold(I) and other coordination compounds. Dimethyl sulfide is also used in the ozonolysis of alkenes, reducing the intermediate trioxolane and oxidizing to DMSO.

alkene + ozone + DMS → aldehyde(1) + aldehyde(2) + DMSO

Safety

Dimethyl sulfide is highly flammable and irritant to eyes and skin. It is harmful if swallowed and has an unpleasant odor at even extremely low concentrations. Its ignition temperature is 205 °C.

Physiology of dimethyl sulfide

Dimethyl sulfide is normally present at very low levels in healthy people, namely < 7nM in blood, < 3 nM in urine and 0.13 - 0.65 nM on expired breath. [15] [16]

When dimethyl sulfide becomes pathologically increased, this is known as dimethylsulfidemia, which is associated with blood borne halitosis and dimethylsulfiduria.[17] [18] [19]

See also

References

External links

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