Dimethyl sulfide

Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. Dimethyl sulfide is a 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 contamination in malt production and brewing. It is a breakdown product of dimethylsulfoniopropionate (DMSP), and is also produced by the bacterial metabolism of methanethiol.

Dimethyl sulfide
Skeletal formula of dimethyl sulfide with all implicit hydrogens shown
Spacefill model of dimethyl sulfide
Names
Preferred IUPAC name
(Methylsulfanyl)methane[1]
Other names
(Methylthio)methane[1]
Dimethyl sulfide[1]
Identifiers
3D model (JSmol)
3DMet B00138
1696847
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.770
EC Number 200-846-2
KEGG
MeSH dimethyl+sulfide
RTECS number PV5075000
UNII
UN number 1164
Properties
C2H6S
Molar mass 62.13 g·mol−1
Appearance Colourless liquid
Odor Cabbage, sulfurous
Density 0.846 g cm−3
Melting point −98 °C; −145 °F; 175 K
Boiling point 35 to 41 °C; 95 to 106 °F; 308 to 314 K
log P 0.977
Vapor pressure 53.7 kPa (at 20 °C)
−44.9⋅10−6 cm3/mol
1.435
Thermochemistry
−66.9–63.9 kJ⋅mol−1
−2.1818–2.1812 MJ⋅mol−1
Hazards
Safety data sheet osha.gov
GHS pictograms GHS02: Flammable GHS05: Corrosive GHS07: Harmful
GHS signal word DANGER
H225, H315, H318, H335
P210, P261, P280, P305+351+338
Flash point −36 °C (−33 °F; 237 K)
206 °C (403 °F; 479 K)
Explosive limits 19.7%
Related compounds
Dimethyl ether (dimethyl oxide)
Dimethyl selenide
Dimethyl telluride
Related compounds
Dimethyl ether
Dimethyl sulfoxide
Dimethyl sulfone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Natural occurrence

DMS originates primarily from DMSP, a major secondary metabolite in some marine algae.[2] DMS is the most abundant biological sulfur compound emitted to the atmosphere.[3][4] 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.[5]

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.[6] 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.[7][8] The CLAW hypothesis suggests that in this manner DMS may play a role in planetary homeostasis.[9]

Marine phytoplankton also produce dimethyl sulfide,[10] and DMS is also produced by bacterial cleavage of extracellular DMSP.[11] DMS has been characterized as the "smell of the sea",[12] though it would be more accurate to say that DMS is a component of the smell of the sea, others being chemical derivatives of DMS, such as oxides, and yet others being algal pheromones such as dictyopterenes.[13]

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

Dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide have been found among the volatiles given off by the fly-attracting plant known as dead-horse arum (Helicodiceros muscivorus). Those compounds are components of an odor like rotting meat, which attracts various pollinators that feed on carrion, such as many species of flies.[14]

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]

At pathologically dangerous concentrations, this is known as dimethylsulfidemia. This condition is associated with blood borne halitosis and dimethylsulfiduria.[17][18][19]

In people with chronic liver disease (cirrhosis), high levels of dimethyl sulfide may be present the breath, leading to an unpleasant smell (fetor hepaticus).

Smell

Dimethyl sulfide has a characteristic smell commonly described as cabbage-like. It becomes highly disagreeable at even quite low concentrations. Some reports claim that DMS has a low olfactory threshold that varies from 0.02 to 0.1 ppm between different persons, but 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.[20] Dimethyl sulfide is also available as a food additive to impart a savory flavor; in such use, its concentration is low. Beetroot,[21] asparagus,[22] cabbage, corn and seafoods produce dimethyl sulfide when cooked.

Dimethyl sulfide is also produced by marine planktonic micro-organisms such as the coccolithophores and so is one of the main components responsible for the characteristic odor of sea water aerosols.

Preparation

In industry dimethyl sulfide is produced by treating hydrogen sulfide with excess methanol over an aluminium oxide catalyst.[23]

Industrial uses

Dimethyl sulfide has been used in petroleum refining to pre-sulfide hydrodesulfurization catalysts, although other disulfides or polysulfides are preferred and easier to handle. It is used 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.[24]

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

See also

References

  1. ^ a b c "CHAPTER P-6. Applications to Specific Classes of Compounds". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 706. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4.
  2. ^ Stefels, J.; Steinke, M.; Turner, S.; Malin, S.; Belviso, A. (2007). "Environmental constraints on the production and removal of the climatically active gas dimethylsulphide (DMS) and implications for ecosystem modelling". Biogeochemistry. 83 (1–3): 245–275. doi:10.1007/s10533-007-9091-5.
  3. ^ Kappler, Ulrike; Schäfer, Hendrik (2014). "Chapter 11. Transformations of Dimethylsulfide". In Peter M.H. Kroneck and Martha E. Sosa Torres (ed.). The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment. Metal Ions in Life Sciences. 14. Springer. pp. 279–313. doi:10.1007/978-94-017-9269-1_11. ISBN 978-94-017-9268-4. PMID 25416398.
  4. ^ Simpson, D.; Winiwarter, W.; Börjesson, G.; Cinderby, S.; Ferreiro, A.; Guenther, A.; Hewitt, C. N.; Janson, R.; Khalil, M. A. K.; Owen, S.; Pierce, T. E.; Puxbaum, H.; Shearer, M.; Skiba, U.; Steinbrecher, R.; Tarrasón, L.; Öquist, M. G. (1999). "Inventorying emissions from nature in Europe". Journal of Geophysical Research. 104 (D7): 8113–8152. Bibcode:1999JGR...104.8113S. doi:10.1029/98JD02747.
  5. ^ Glindemann, D.; Novak, J.; Witherspoon, J. (2006). "Dimethyl Sulfoxide (DMSO) Waste Residues and Municipal Waste Water Odor by Dimethyl Sulfide (DMS): the North-East WPCP Plant of Philadelphia". Environmental Science and Technology. 40 (1): 202–207. Bibcode:2006EnST...40..202G. doi:10.1021/es051312a. PMID 16433352.
  6. ^ Lucas, D. D.; Prinn, R. G. (2005). "Parametric sensitivity and uncertainty analysis of dimethylsulfide oxidation in the clear-sky remote marine boundary layer". Atmospheric Chemistry and Physics. 5 (6): 1505–1525. doi:10.5194/acp-5-1505-2005.
  7. ^ Malin, G.; Turner, S. M.; Liss, P. S. (1992). "Sulfur: The plankton/climate connection". Journal of Phycology. 28 (5): 590–597. doi:10.1111/j.0022-3646.1992.00590.x.
  8. ^ Gunson, J.R.; Spall, S.A.; Anderson, T.R.; Jones, A.; Totterdell, I.J.; Woodage, M.J. (1 April 2006). "Climate sensitivity to ocean dimethylsulphide emissions". Geophysical Research Letters. 33 (7): L07701. Bibcode:2006GeoRL..33.7701G. doi:10.1029/2005GL024982.
  9. ^ Charlson, R. J.; Lovelock, J. E.; Andreae, M. O.; Warren, S. G. (1987). "Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate". Nature. 326 (6114): 655–661. Bibcode:1987Natur.326..655C. doi:10.1038/326655a0.
  10. ^ "The Climate Gas You've Never Heard Of". Oceanus Magazine.
  11. ^ Ledyard, KM; Dacey, JWH (1994). "Dimethylsulfide production from dimethylsulfoniopropionate by a marine bacterium". Marine Ecology Progress Series. 110: 95–103. Bibcode:1994MEPS..110...95L. doi:10.3354/meps110095.
  12. ^ "Cloning the smell of the seaside". University of East Anglia. 2 February 2007.
  13. ^ Itoh, T.; Inoue, H.; Emoto, S. (2000). "Synthesis of Dictyopterene A: Optically Active Tributylstannylcyclopropane as a Chiral Synthon". Bulletin of the Chemical Society of Japan. 73 (2): 409–416. doi:10.1246/bcsj.73.409. ISSN 1348-0634.
  14. ^ Stensmyr, M. C.; Urru, I.; Collu, I.; Celander, M.; Hansson, B. S.; Angioy, A.-M. (2002). "Rotting Smell of Dead-Horse Arum Florets". Nature. 420 (6916): 625–626. Bibcode:2002Natur.420..625S. doi:10.1038/420625a. PMID 12478279.
  15. ^ Gahl, WA; Bernardini, I; Finkelstein, JD; Tangerman, A; Martin, JJ; Blom, HJ; Mullen, KD; Mudd, SH (February 1988). "Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency". The Journal of Clinical Investigation. 81 (2): 390–7. doi:10.1172/JCI113331. PMC 329581. PMID 3339126.
  16. ^ Tangerman, A (15 October 2009). "Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices". Journal of Chromatography B. 877 (28): 3366–77. doi:10.1016/j.jchromb.2009.05.026. PMID 19505855.
  17. ^ Tangerman, A; Winkel, E. G. (September 2007). "Intra- and extra-oral halitosis: finding of a new form of extra-oral blood-borne halitosis caused by dimethyl sulphide". J. Clin. Periodontol. 34 (9): 748–55. doi:10.1111/j.1600-051X.2007.01116.x. PMID 17716310.
  18. ^ Tangerman, A; Winkel, EG (March 2008). "The portable gas chromatograph OralChroma™: a method of choice to detect oral and extra-oral halitosis". Journal of Breath Research. 2 (1): 017010. doi:10.1088/1752-7155/2/1/017010. PMID 21386154.
  19. ^ Tangerman, A; Winkel, EG (2 March 2010). "Extra-oral halitosis: an overview". Journal of Breath Research. 4 (1): 017003. Bibcode:2010JBR.....4a7003T. doi:10.1088/1752-7155/4/1/017003. PMID 21386205.
  20. ^ Morton, T. H. (2000). "Archiving Odors". In Bhushan, N.; Rosenfeld, S. (eds.). Of Molecules and Mind. Oxford: Oxford University Press. pp. 205–216.
  21. ^ Parliment, T. H.; Kolor, M. G.; Maing, I. Y. (1977). "Identification of the Major Volatile Components of Cooked Beets". Journal of Food Science. 42 (6): 1592–1593. doi:10.1111/j.1365-2621.1977.tb08434.x.
  22. ^ Ulrich, Detlef; Hoberg, Edelgard; Bittner, Thomas; Engewald, Werner; Meilchen, Kathrin (2001). "Contribution of volatile compounds to the flavor of cooked asparagus". Eur Food Res Technol. 213 (3): 200–204=. doi:10.1007/s002170100349.
  23. ^ Roy, Kathrin-Maria (15 June 2000). Thiols and Organic Sulfides. Ullmann's Encyclopedia of Industrial Chemistry. p. 8. doi:10.1002/14356007.a26_767. ISBN 978-3-527-30673-2.
  24. ^ "Locations". Gaylord Chemicals.

External links

Borane dimethylsulfide

Borane dimethylsulfide (BMS) is a complexed borane reagent that is used for hydroborations and reductions. The advantages of BMS over other borane reagents, such as borane-tetrahydrofuran, are its increased stability and higher solubility. BMS is commercially available at much higher concentrations than its tetrahydrofuran counterpart (10 M neat) and does not require sodium borohydride as a stabilizer, which could result in undesired side reactions. In contrast, borane.THF requires sodium borohydride to inhibit reduction of THF to tributyl borate. BMS is soluble in most aprotic solvents.

CLAW hypothesis

The CLAW hypothesis proposes a negative feedback loop that operates between ocean ecosystems and the Earth's climate. The hypothesis specifically proposes that particular phytoplankton that produce dimethyl sulfide are responsive to variations in climate forcing, and that these responses act to stabilise the temperature of the Earth's atmosphere. The CLAW hypothesis was originally proposed by Robert Jay Charlson, James Lovelock, Meinrat Andreae and Stephen G. Warren, and takes its acronym from the first letter of their surnames.

Chloro(dimethyl sulfide)gold(I)

Chloro(dimethyl sulfide)gold(I) is a coordination complex of gold. It is a white solid. This compound is a common entry point into gold chemistry.

Chloro(tetrahydrothiophene)gold(I)

Chloro(tetrahydrothiophene)gold(I), abbreviated (tht)AuCl, is a coordination complex of gold. Like the dimethyl sulfide analog, this compound is used as a convenient entry point to gold chemistry. The tetrahydrothiophene ligand is labile and is readily substituted with other stronger ligands.

Corey–Kim oxidation

The Corey–Kim oxidation is an oxidation reaction used to synthesise aldehydes and ketones from primary and secondary alcohols. It is named for American chemist and Nobel Laureate Elias James Corey and Korean-American chemist Choung Un Kim.

Although the Corey–Kim oxidation possesses the distinctive advantage over Swern oxidation of allowing an operation above –25 °C, it is not so commonly used due to issues with selectivity in substrates susceptible to chlorination by N-chlorosuccinimide.

Dimethyl-sulfide monooxygenase

Dimethyl-sulfide monooxygenase (EC 1.14.13.131, dimethylsulfide monooxygenase) is an enzyme with systematic name dimethyl sulfide,NADH:oxygen oxidoreductase. This enzyme catalyses the following chemical reaction

dimethyl sulfide + O2 + NADH + H+ methanethiol + formaldehyde + NAD+ + H2O

Dimethyl-sulfide monooxygenase has lower activity with diethyl sulfide and other short-chain alkyl methyl sulfides.

Dimethylpropiothetin dethiomethylase

In enzymology, a dimethylpropiothetin dethiomethylase (EC 4.4.1.3) is an enzyme that catalyzes the chemical reaction

S,S-dimethyl-beta-propiothetin dimethyl sulfide + acrylate

Hence, this enzyme has one substrate, S,S-dimethyl-beta-propiothetin, and two products, dimethyl sulfide and acrylate.

This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is S,S-dimethyl-beta-propiothetin dimethyl-sulfide-lyase (acrylate-forming). Other names in common use include desulfhydrase, and S,S-dimethyl-beta-propiothetin dimethyl-sulfide-lyase.

Fetor hepaticus

Fetor hepaticus or foetor hepaticus (see spelling differences), also known as breath of the dead or hepatic foetor, is a condition seen in portal hypertension where portosystemic shunting allows thiols to pass directly into the lungs. It is a late sign in liver failure and is one of the clinical features of hepatic encephalopathy. Other possible causes are the presence of ammonia and ketones in the breath. The breath has a sweet, fecal smell to it and also described as having the odour of freshly mown hay.

The compound dimethyl sulfide has been associated with it, raising the possibility of an objective noninvasive measure of liver failure. Furthermore, the volatile dimethyl sulfide is thought by some researchers to be the main contributor to the odor of fetor hepaticus. A secondary form of trimethylaminuria is also associated with liver failure, and it has been suggested that that trimethylamine is also a contributor to the odor of fetor hepaticus.Foetor hepaticus is sometimes (often?) associated with an acid - base disorder such as diabetic ketoacidosis or isopropyl alcohol intoxication.

Gaylord Chemical Corporation

The company headquarters of Gaylord Chemical Company LLC are located in the New Orleans suburb of Slidell, Louisiana, USA. Gaylord's original manufacturing facility located in Bogalusa, Louisiana was shut down and demolished in 2010, when the company relocated its operations to Tuscaloosa, Alabama, USA. The company has manufactured dimethyl sulfoxide (DMSO) and dimethyl sulfide (DMS) continuously since the early 1960s.

Prior to its acquisition by its management team in 2007 Gaylord operated as a wholly owned subsidiary of Temple-Inland Inc. (NYSE: TIN). After the ownership transition was complete it continued to operate from its Slidell office, which had been established in the late 1980s. Gaylord announced expanded DMSO production capacity in Tuscaloosa, Alabama, which came on-line in 2010.Prior to being a subsidiary of Temple-Inland, Gaylord Chemical was a division of Gaylord Container Corporation, the successor (1986–2002) of the brown paper division of Crown Zellerbach (1928–86).

Halimeter

A Halimeter is an instrument for measurement of the level of volatile sulfur compounds (VSCs) in the mouth.

Halimeter was introduced in the early 1990s as an adjunct method for determining halitosis (bad breath, oral malodor) levels, alongside human assessment of odor levels (the latter is considered the gold standard). The instrument measures parts per billion levels of hydrogen sulfide and, to a lesser extent, methyl mercaptan, two gases which were previously shown to be associated with bad breath using gas chromatograph by Dr. Joseph Tonzetich in the late 1960s.

The Halimeter is manufactured by Interscan Corp. in California, and based on their earlier model 1170 portable sulfide monitor. This was the model used in the two original studies. These studies, conducted for the first time by Dr. Mel Rosenberg, showed a significant correlation between monitor levels and oral malodor scores. The small size, simplicity of use, and price (relative to gas chromatograph) of the Halimeter made it popular among dentists seeking to diagnose and treat bad breath, as well as scientific researchers. Much of the published research on bad breath over the past dozen years has employed this instrument. The electrochemical sensor is sensitive to alcohol vapors, and requires recalibration over time. The Halimeter has been the only VSC monitor for the diagnosis of halitosis for years, but now that its patent has expired, it faces competition from other sulfur monitors recently introduced into the marketplace.

More recently, the portable gas chromatograph, "OralChroma" has been recommended in the diagnosis of halitosis, as the Halimeter does not detect dimethyl sulfide, which is thought by some to be elevated in extraoral causes of halitosis. The OralChroma detects dimethyl sulfide in a semi objective manner, and hence is able to differentiate between oral malodor (intraoral halitosis) and extra-oral halitosis. The halimeter is therefore not indicated if extra-oral halitosis is suspected (its use will only be able to rule out intra-oral halitosis), but is useful for diagnosis and clinical monitoring of intra-oral halitosis.

Methanomethylovorans

In taxonomy, Methanomethylovorans is a genus of microorganisms with the family Methanosarcinaceae. This genus was first described in 1999. The species within it generally live in freshwater environments, including rice paddies, freshwater sediments and contaminated soil. They produce methane from methanol, methylamines, dimethyl sulfide and methanethiol. With the exception of M. thermophila, which has an optimal growth temperature of 50 °C, these species are mesophiles and do not tend to grow at temperatures above 40 °C.

Methanomethylovorans hollandica

Methanomethylovorans hollandica is a species of methylotrophic methanogen able to grow on dimethyl sulfide and methanethiol. It is the type species of its genus. It is obligately anaerobic. It was the first strictly anaerobic archeaon isolated from freshwater sediments in which dimethyl sulfide is the sole source of carbon. It is not a halophile. It can use methyl compounds as substrates, but it cannot use carbon dioxide or acetate. Because dimethyl sulfide has implications with respect to global warming, this organism may be of considerable importance.

Organic Lake

Organic Lake is a lake in the Vestfold Hills in eastern Antarctica. It was formed 6,000 years ago when sea levels were higher; it is isolated, rather shallow (7.5m), meromictic, a few hundred meters in diameter and has extremely salty water. It has the highest recorded concentration of dimethyl sulfide in any natural body of water.In 2011, a new species of virophage (a satellite virus that impairs the ability of its co-infective host virus to replicate) was discovered in Organic Lake, the Organic Lake virophage. It is a parasite of 'Organic Lake phycodnavirus', a large virus that infects algae and belongs to the nucleocytoplasmic large DNA viruses (NCLDV), but in fact may rather be a member of an extended family Mimiviridae (aka Megaviridae) than of the family Phycodnaviridae.

Sea air

Air at or by the sea has traditionally been thought to offer health benefits associated with its unique odor, which Victorians attributed to ozone. More recently, it has been determined that the chemical responsible for much of the odor is dimethyl sulfide, released by microbes.Salts generally do not dissolve in air, but can be carried by sea spray in the form of particulate matter.

In modern times, the quality of this air is now degraded by pollution from shipping which burns high sulphur fuel in its engines and so generates large quantities of sulphate aerosols.

Sulfate aerosol

The term sulfate aerosols is used for a suspension of fine solid particles of a sulfate or tiny droplets of a solution of a sulfate or of sulfuric acid (hydrogen sulfate). They are produced by chemical reactions in the atmosphere from gaseous precursors (with the exception of sea salt sulfate and gypsum dust particles). The two main sulfuric acid precursors are sulfur dioxide (SO2) from anthropogenic sources and volcanoes, and dimethyl sulfide (DMS) from biogenic sources, especially marine plankton. These aerosols can cause a cooling effect on earth.

However the UNFCCC has noted that sulfate aerosols remain in the atmosphere for only a short amount of time in comparison to well-mixed greenhouse gases, and therefore their cooling is localized and temporary. Other side effects of sulfate aerosols in the environment include poor air quality.

Sulfide

Sulfide (British English sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. Sulfide also refers to chemical compounds large families of inorganic and organic compounds, e.g. lead sulfide and dimethyl sulfide. Hydrogen sulfide (H2S) and bisulfide (SH−) are the conjugate acids of sulfide.

Swern oxidation

The Swern oxidation, named after Daniel Swern, is a chemical reaction whereby a primary or secondary alcohol is oxidized to an aldehyde or ketone using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic base, such as triethylamine. The reaction is known for its mild character and wide tolerance of functional groups.

The by-products are dimethyl sulfide (Me2S), carbon monoxide (CO), carbon dioxide (CO2) and—when triethylamine is used as base—triethylammonium chloride (Et3NHCl). Of the volatile by-products, dimethyl sulfide has a strong, pervasive odour and carbon monoxide is acutely toxic, so the reaction and the work-up needs to be performed in a fume hood. Dimethyl sulfide is a volatile liquid (B.P. 37 °C) with an unpleasant odour at high concentrations.

Thioether S-methyltransferase

In enzymology, a thioether S-methyltransferase (EC 2.1.1.96) is an enzyme that catalyzes the chemical reaction

S-adenosyl-L-methionine + dimethyl sulfide S-adenosyl-L-homocysteine + trimethylsulfonium

Thus, the two substrates of this enzyme are S-adenosyl methionine and dimethyl sulfide, whereas its two products are S-adenosylhomocysteine and trimethylsulfonium.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:dimethyl-sulfide S-methyltransferase. Other names in common use include S-adenosyl-L-methionine:thioether S-methyltransferase, and thioether methyltransferase.

Wine fault

A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to be of issue. In fact, depending on perception, these concentrations may impart positive characters to the wine. However, when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing (or that the winemaker wants the wine to express). Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.There are many causes for the perception in wine faults, including poor hygiene at the winery, excessive or insufficient exposure of the wine to oxygen, excessive or insufficient exposure of the wine to sulphur, overextended maceration of the wine either pre- or post-fermentation, faulty fining, filtering and stabilization of the wine, the use of dirty oak barrels, over-extended barrel aging and the use of poor quality corks. Outside of the winery, other factors within the control of the retailer or end user of the wine can contribute to the perception of flaws in the wine. These include poor storage of the wine that exposes it to excessive heat and temperature fluctuations as well as the use of dirty stemware during wine tasting that can introduce materials or aromas to what was previously a clean and fault-free wine.

Languages

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.