Misplaced Pages

#560439

77-432: Selenium dioxide Tellurium dioxide Polonium dioxide Sulfur dioxide ( IUPAC -recommended spelling) or sulphur dioxide (traditional Commonwealth English ) is the chemical compound with the formula S O 2 . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and

154-399: A Lewis acids in its η-SO 2 (S-bonded pyramidal) bonding mode with metals and in its 1:1 adducts with Lewis bases such as dimethylacetamide and trimethyl amine . When bonding to Lewis bases the acid parameters of SO 2 are E A = 0.51 and E A = 1.56. The overarching, dominant use of sulfur dioxide is in the production of sulfuric acid . Sulfur dioxide is an intermediate in

231-418: A dichromate solution, turning the solution from orange to green (Cr (aq)). It can also reduce ferric ions to ferrous. Sulfur dioxide can react with certain 1,3- dienes in a cheletropic reaction to form cyclic sulfones . This reaction is exploited on an industrial scale for the synthesis of sulfolane , which is an important solvent in the petrochemical industry . Sulfur dioxide can bind to metal ions as

308-437: A ligand to form metal sulfur dioxide complexes , typically where the transition metal is in oxidation state 0 or +1. Many different bonding modes (geometries) are recognized, but in most cases, the ligand is monodentate, attached to the metal through sulfur, which can be either planar and pyramidal η . As a η-SO 2 (S-bonded planar) ligand sulfur dioxide functions as a Lewis base using the lone pair on S. SO 2 functions as

385-477: A byproduct in the manufacture of calcium silicate cement; CaSO 4 is heated with coke and sand in this process: Until the 1970s commercial quantities of sulfuric acid and cement were produced by this process in Whitehaven , England. Upon being mixed with shale or marl , and roasted, the sulfate liberated sulfur dioxide gas, used in sulfuric acid production, the reaction also produced calcium silicate,

462-429: A deep ruby red colour. Selenium dioxide is the active ingredient in some cold-bluing solutions. It was also used as a toner in photographic developing . Selenium is an essential element , but ingestion of more than 5 mg/day leads to nonspecific symptoms . Hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula H 2 S . It is a colorless chalcogen-hydride gas , and

539-472: A few weeks. Long-term, low-level exposure may result in fatigue , loss of appetite, headaches , irritability, poor memory, and dizziness . Chronic exposure to low level H 2 S (around 2 ppm ) has been implicated in increased miscarriage and reproductive health issues among Russian and Finnish wood pulp workers, but the reports have not (as of 1995) been replicated. Short-term, high-level exposure can induce immediate collapse, with loss of breathing and

616-620: A high heat of evaporation , sulfur dioxide is a candidate material for refrigerants. Before the development of chlorofluorocarbons , sulfur dioxide was used as a refrigerant in home refrigerators . Sulfur dioxide content in naturally-released geothermal gasses is measured by the Icelandic Meteorological Office as an indicator of possible volcanic activity. In the United States, the Center for Science in

693-857: A high probability of death. If death does not occur, high exposure to hydrogen sulfide can lead to cortical pseudolaminar necrosis , degeneration of the basal ganglia and cerebral edema . Although respiratory paralysis may be immediate, it can also be delayed up to 72 hours. Inhalation of H 2 S resulted in about 7 workplace deaths per year in the U.S. (2011–2017 data), second only to carbon monoxide (17 deaths per year) for workplace chemical inhalation deaths. Treatment involves immediate inhalation of amyl nitrite , injections of sodium nitrite , or administration of 4-dimethylaminophenol in combination with inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm , and in some cases hyperbaric oxygen therapy (HBOT). HBOT has clinical and anecdotal support. Hydrogen sulfide

770-445: A key agent in the warming of early Mars , with estimates of concentrations in the lower atmosphere as high as 100 ppm, though it only exists in trace amounts. On both Venus and Mars, as on Earth, its primary source is thought to be volcanic. The atmosphere of Io , a natural satellite of Jupiter , is 90% sulfur dioxide and trace amounts are thought to also exist in the atmosphere of Jupiter . The James Webb Space Telescope has observed

847-680: A negative inotropic effect on cardiac output function, thus effectively lowering blood pressure and myocardial oxygen consumption. The vasodilating and bronchodilating effects of sulfur dioxide are mediated via ATP-dependent calcium channels and L-type ("dihydropyridine") calcium channels. Endogenous sulfur dioxide is also a potent antiinflammatory, antioxidant and cytoprotective agent. It lowers blood pressure and slows hypertensive remodeling of blood vessels, especially thickening of their intima. It also regulates lipid metabolism. Endogenous sulfur dioxide also diminishes myocardial damage, caused by isoproterenol adrenergic hyperstimulation, and strengthens

SECTION 10

#1732772426561

924-426: A phenomenon that leads to the browning of the wine and a loss of cultivar specific flavors. Its antimicrobial action also helps minimize volatile acidity. Wines containing sulfur dioxide are typically labeled with "containing sulfites ". Sulfur dioxide exists in wine in free and bound forms, and the combinations are referred to as total SO 2 . Binding, for instance to the carbonyl group of acetaldehyde , varies with

1001-451: A precursor in cement production. On a laboratory scale, the action of hot concentrated sulfuric acid on copper turnings produces sulfur dioxide. Tin also reacts with concentrated sulfuric acid but it produces tin(II) sulfate which can later be pyrolyzed at 360 °C into tin dioxide and dry sulfur dioxide. The reverse reaction occurs upon acidification: Sulfites results by the action of aqueous base on sulfur dioxide: Sulfur dioxide

1078-447: A presence of a catalyst under atmospheric pressure around 1200 °C into hydrogen and sulfur. Hydrogen sulfide reacts with metal ions to form metal sulfides, which are insoluble, often dark colored solids. Lead(II) acetate paper is used to detect hydrogen sulfide because it readily converts to lead(II) sulfide , which is black. Treating metal sulfides with strong acid or electrolysis often liberates hydrogen sulfide. Hydrogen sulfide

1155-505: A reagent for allylic oxidation , a reaction that entails the following conversion This can be described more generally as; where R, R', R" may be alkyl or aryl substituents. Selenium dioxide can also be used to synthesize 1,2,3-selenadiazoles from acylated hydrazone derivatives. Selenium dioxide imparts a red colour to glass . It is used in small quantities to counteract the colour due to iron impurities and so to create (apparently) colourless glass. In larger quantities, it gives

1232-400: A result of the action of sulfate-reducing bacteria . Hydrogen sulfide is produced by the human body in small quantities through bacterial breakdown in the intestinal tract of proteins containing sulfur; it therefore contributes to the characteristic odor of flatulence. It is also produced in the mouth ( halitosis ). A portion of global H 2 S emissions are due to human activity. By far

1309-464: A waste product. Water heaters can aid the conversion of sulfate in water to hydrogen sulfide gas. This is due to providing a warm environment sustainable for sulfur bacteria and maintaining the reaction which interacts between sulfate in the water and the water heater anode, which is usually made from magnesium metal. H 2 S in the body acts as a gaseous signaling molecule with implications for health and in diseases. Hydrogen sulfide

1386-485: Is stinkdamp . Hydrogen sulfide is a highly toxic and flammable gas ( flammable range : 4.3–46%). It can poison several systems in the body, although the nervous system is most affected. The toxicity of H 2 S is comparable with that of carbon monoxide . It binds with iron in the mitochondrial cytochrome enzymes , thus preventing cellular respiration . Its toxic properties were described in detail in 1843 by Justus von Liebig . Even before hydrogen sulfide

1463-458: Is a mild but useful reducing agent . It is oxidized by halogens to give the sulfuryl halides, such as sulfuryl chloride : Sulfur dioxide is the oxidising agent in the Claus process , which is conducted on a large scale in oil refineries . Here, sulfur dioxide is reduced by hydrogen sulfide to give elemental sulfur: The sequential oxidation of sulfur dioxide followed by its hydration is used in

1540-445: Is a one-dimensional polymer , the chain consisting of alternating selenium and oxygen atoms. Each Se atom is pyramidal and bears a terminal oxide group. The bridging Se-O bond lengths are 179 pm and the terminal Se-O distance is 162 pm. The relative stereochemistry at Se alternates along the polymer chain ( syndiotactic ). In the gas phase selenium dioxide is present as dimers and other oligomeric species, at higher temperatures it

1617-466: Is a one-dimensional chain, TeO 2 is a cross-linked polymer. SeO 2 is considered an acidic oxide : it dissolves in water to form selenous acid . Often the terms selenous acid and selenium dioxide are used interchangeably. It reacts with base to form selenite salts containing the SeO 3 anion. For example, reaction with sodium hydroxide produces sodium selenite : Selenium dioxide

SECTION 20

#1732772426561

1694-522: Is active as an antimicrobial and antioxidant, and this is also the form which may be perceived as a pungent odor at high levels. Wines with total SO 2 concentrations below 10 ppm do not require "contains sulfites" on the label by US and EU laws. The upper limit of total SO 2 allowed in wine in the US is 350 ppm; in the EU it is 160 ppm for red wines and 210 ppm for white and rosé wines. In low concentrations, SO 2

1771-433: Is also known to increase the levels of glutathione, which acts to reduce or disrupt ROS levels in cells. The field of H 2 S biology has advanced from environmental toxicology to investigate the roles of endogenously produced H 2 S in physiological conditions and in various pathophysiological states. H 2 S has been implicated in cancer and Down syndrome and vascular disease. It inhibits Complex IV of

1848-503: Is also produced by roasting pyrite and other sulfide ores in air. Sulfur dioxide is the product of the burning of sulfur or of burning materials that contain sulfur: To aid combustion, liquified sulfur (140–150 °C (284–302 °F) is sprayed through an atomizing nozzle to generate fine drops of sulfur with a large surface area. The reaction is exothermic , and the combustion produces temperatures of 1,000–1,600 °C (1,830–2,910 °F). The significant amount of heat produced

1925-399: Is also responsible for tarnishing on various metals including copper and silver ; the chemical responsible for black toning found on silver coins is silver sulfide ( Ag 2 S ), which is produced when the silver on the surface of the coin reacts with atmospheric hydrogen sulfide. Coins that have been subject to toning by hydrogen sulfide and other sulfur-containing compounds may have

2002-408: Is an important reagent in organic synthesis . Oxidation of paraldehyde (acetaldehyde trimer) with SeO 2 gives glyoxal and the oxidation of cyclohexanone gives 1,2-cyclohexanedione . The selenium starting material is reduced to selenium, and precipitates as a red amorphous solid which can easily be filtered off. This type of reaction is called a Riley oxidation . It is also renowned as

2079-549: Is called E 220 when used in this way in Europe. As a preservative, it maintains the colorful appearance of the fruit and prevents rotting . Historically, molasses was "sulfured" as a preservative and also to lighten its color. Treatment of dried fruit was usually done outdoors, by igniting sublimed sulfur and burning in an enclosed space with the fruits. Fruits may be sulfured by dipping them into an either sodium bisulfite , sodium sulfite or sodium metabisulfite . Sulfur dioxide

2156-405: Is commonly known as anaerobic digestion , which is done by sulfate-reducing microorganisms . It also occurs in volcanic gases , natural gas deposits, and sometimes in well-drawn water. Hydrogen sulfide is slightly denser than air. A mixture of H 2 S and air can be explosive. In general, hydrogen sulfide acts as a reducing agent , as indicated by its ability to reduce sulfur dioxide in

2233-420: Is harmless. Hence, low levels of hydrogen sulfide may be tolerated indefinitely. Exposure to lower concentrations can result in eye irritation, a sore throat and cough , nausea, shortness of breath, and fluid in the lungs . These effects are believed to be due to hydrogen sulfide combining with alkali present in moist surface tissues to form sodium sulfide , a caustic . These symptoms usually subside in

2310-456: Is inhaled or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the human body produces small amounts of this sulfide and its mineral salts, and uses it as a signalling molecule . Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers; this process

2387-409: Is involved in vasodilation in animals, as well as in increasing seed germination and stress responses in plants. Hydrogen sulfide signaling is moderated by reactive oxygen species (ROS) and reactive nitrogen species (RNS). H 2 S has been shown to interact with NO resulting in several different cellular effects, as well as the formation of another signal called nitrosothiol. Hydrogen sulfide

Sulfur dioxide - Misplaced Pages Continue

2464-404: Is monomeric. The monomeric form adopts a bent structure very similar to that of sulfur dioxide with a bond length of 161 pm. The dimeric form has been isolated in a low temperature argon matrix and vibrational spectra indicate that it has a centrosymmetric chair form. Dissolution of SeO 2 in selenium oxydichloride give the trimer [Se(O)O] 3 . Monomeric SeO 2 is a polar molecule, with

2541-435: Is mostly undetectable in wine, but at free SO 2 concentrations over 50 ppm, SO 2 becomes evident in the smell and taste of wine. SO 2 is also a very important compound in winery sanitation. Wineries and equipment must be kept clean, and because bleach cannot be used in a winery due to the risk of cork taint , a mixture of SO 2 , water, and citric acid is commonly used to clean and sanitize equipment. Ozone (O 3 )

2618-418: Is natural gas with a high content of H 2 S . It can also be produced by treating hydrogen with molten elemental sulfur at about 450 °C. Hydrocarbons can serve as a source of hydrogen in this process. The very favorable thermodynamics for the hydrogenation of sulfur implies that the dehydrogenation (or cracking ) of hydrogen sulfide would require very high temperatures. A standard lab preparation

2695-437: Is not soluble in water. The sulfide anion S is not formed in aqueous solution. At pressures above 90 GPa ( gigapascal ), hydrogen sulfide becomes a metallic conductor of electricity. When cooled below a critical temperature this high-pressure phase exhibits superconductivity . The critical temperature increases with pressure, ranging from 23 K at 100 GPa to 150 K at 200 GPa. If hydrogen sulfide

2772-414: Is now used extensively for sanitizing in wineries due to its efficacy, and because it does not affect the wine or most equipment. Sulfur dioxide is also a good reductant . In the presence of water, sulfur dioxide is able to decolorize substances. Specifically, it is a useful reducing bleach for papers and delicate materials such as clothes. This bleaching effect normally does not last very long. Oxygen in

2849-430: Is often used as a low-temperature solvent/diluent for superacids like magic acid (FSO 3 H/SbF 5 ), allowing for highly reactive species like tert -butyl cation to be observed spectroscopically at low temperature (though tertiary carbocations do react with SO 2 above about −30 °C, and even less reactive solvents like SO 2 ClF must be used at these higher temperatures). Being easily condensed and possessing

2926-423: Is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs . Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide . When it

3003-402: Is prepared by oxidation of selenium by burning in air or by reaction with nitric acid or hydrogen peroxide , but perhaps the most convenient preparation is by the dehydration of selenous acid . The natural form of selenium dioxide, downeyite, is a very rare mineral. It is only found at a small number of burning coal banks , where it forms around vents created from escaping gasses. SeO 2

3080-469: Is pressurized at higher temperatures, then cooled, the critical temperature reaches 203 K (−70 °C), the highest accepted superconducting critical temperature as of 2015. By substituting a small part of sulfur with phosphorus and using even higher pressures, it has been predicted that it may be possible to raise the critical temperature to above 0 °C (273 K) and achieve room-temperature superconductivity . Hydrogen sulfide decomposes without

3157-454: Is primarily produced for sulfuric acid manufacture (see contact process , but other processes predated that at least since 16th century). In the United States in 1979, 23.6 million metric tons (26 million U.S. short tons) of sulfur dioxide were used in this way, compared with 150,000 metric tons (165,347 U.S. short tons) used for other purposes. Most sulfur dioxide is produced by the combustion of elemental sulfur . Some sulfur dioxide

Sulfur dioxide - Misplaced Pages Continue

3234-498: Is recovered by steam generation that can subsequently be converted to electricity. The combustion of hydrogen sulfide and organosulfur compounds proceeds similarly. For example: The roasting of sulfide ores such as pyrite , sphalerite , and cinnabar (mercury sulfide) also releases SO 2 : A combination of these reactions is responsible for the largest source of sulfur dioxide, volcanic eruptions. These events can release millions of tons of SO 2 . Sulfur dioxide can also be

3311-845: Is to treat ferrous sulfide with a strong acid in a Kipp generator : For use in qualitative inorganic analysis , thioacetamide is used to generate H 2 S : Many metal and nonmetal sulfides, e.g. aluminium sulfide , phosphorus pentasulfide , silicon disulfide liberate hydrogen sulfide upon exposure to water: This gas is also produced by heating sulfur with solid organic compounds and by reducing sulfurated organic compounds with hydrogen. It can also be produced by mixing ammonium thiocyanate to concentrated sulphuric acid and adding water to it. Hydrogen sulfide can be generated in cells via enzymatic or non-enzymatic pathways. Three enzymes catalyze formation of H 2 S : cystathionine γ-lyase (CSE), cystathionine β-synthetase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST). CBS and CSE are

3388-529: Is typically removed by amine gas treating technologies. In such processes, the hydrogen sulfide is first converted to an ammonium salt, whereas the natural gas is unaffected. The bisulfide anion is subsequently regenerated by heating of the amine sulfide solution. Hydrogen sulfide generated in this process is typically converted to elemental sulfur using the Claus Process . The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures

3465-645: The Bakken formation crude, possibly due to oil field practices, and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements". Besides living near gas and oil drilling operations, ordinary citizens can be exposed to hydrogen sulfide by being near waste water treatment facilities, landfills and farms with manure storage. Exposure occurs through breathing contaminated air or drinking contaminated water. In municipal waste landfill sites ,

3542-550: The Claus process . Hydrogen sulfide burns in oxygen with a blue flame to form sulfur dioxide ( SO 2 ) and water : If an excess of oxygen is present, sulfur trioxide ( SO 3 ) is formed, which quickly hydrates to sulfuric acid : It is slightly soluble in water and acts as a weak acid ( p K a  = 6.9 in 0.01–0.1 mol/litre solutions at 18 °C), giving the hydrosulfide ion HS . Hydrogen sulfide and its solutions are colorless. When exposed to air, it slowly oxidizes to form elemental sulfur, which

3619-616: The proliferation rate of endothelial smooth muscle cells in blood vessels, via lowering the MAPK activity and activating adenylyl cyclase and protein kinase A . Smooth muscle cell proliferation is one of important mechanisms of hypertensive remodeling of blood vessels and their stenosis , so it is an important pathogenetic mechanism in arterial hypertension and atherosclerosis. Endogenous sulfur dioxide in low concentrations causes endothelium-dependent vasodilation . In higher concentrations it causes endothelium-independent vasodilation and has

3696-506: The pulmonary stretch receptors and abolishes the Hering–Breuer inflation reflex . It is considered that endogenous sulfur dioxide plays a significant physiological role in regulating cardiac and blood vessel function, and aberrant or deficient sulfur dioxide metabolism can contribute to several different cardiovascular diseases, such as arterial hypertension , atherosclerosis , pulmonary arterial hypertension , and stenocardia . It

3773-514: The Kraft process), tanneries and sewerage . H 2 S arises from virtually anywhere where elemental sulfur comes in contact with organic material, especially at high temperatures. Depending on environmental conditions, it is responsible for deterioration of material through the action of some sulfur oxidizing microorganisms. It is called biogenic sulfide corrosion . In 2011 it was reported that increased concentrations of H 2 S were observed in

3850-696: The Public Interest lists the two food preservatives, sulfur dioxide and sodium bisulfite , as being safe for human consumption except for certain asthmatic individuals who may be sensitive to them, especially in large amounts. Symptoms of sensitivity to sulfiting agents, including sulfur dioxide, manifest as potentially life-threatening trouble breathing within minutes of ingestion. Sulphites may also cause symptoms in non-asthmatic individuals, namely dermatitis , urticaria , flushing , hypotension , abdominal pain and diarrhea, and even life-threatening anaphylaxis . Selenium dioxide Solid SeO 2

3927-448: The atmosphere at about 15 ppb . On other planets, sulfur dioxide can be found in various concentrations, the most significant being the atmosphere of Venus , where it is the third-most abundant atmospheric gas at 150 ppm. There, it reacts with water to form clouds of Sulfurous acid (SO2 + H2O ⇌ HSO−3+ H+), and is a key component of the planet's global atmospheric sulfur cycle and contributes to global warming . It has been implicated as

SECTION 50

#1732772426561

4004-444: The atmosphere reoxidizes the reduced dyes, restoring the color. In municipal wastewater treatment, sulfur dioxide is used to treat chlorinated wastewater prior to release. Sulfur dioxide reduces free and combined chlorine to chloride . Sulfur dioxide is fairly soluble in water, and by both IR and Raman spectroscopy; the hypothetical sulfurous acid , H 2 SO 3 , is not present to any extent. However, such solutions do show spectra of

4081-408: The bonding in terms of resonance between two resonance structures. The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke d orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1. Sulfur dioxide is found on Earth and exists in very small concentrations in

4158-540: The burial of organic material rapidly leads to the production of anaerobic digestion within the waste mass and, with the humid atmosphere and relatively high temperature that accompanies biodegradation , biogas is produced as soon as the air within the waste mass has been reduced. If there is a source of sulfate bearing material, such as plasterboard or natural gypsum (calcium sulfate dihydrate), under anaerobic conditions sulfate reducing bacteria converts this to hydrogen sulfide. These bacteria cannot survive in air but

4235-416: The burning of sulfur - bearing fossil fuels. Sulfur dioxide is somewhat toxic to humans, although only when inhaled in relatively large quantities for a period of several minutes or more. It was known to medieval alchemists as "volatile spirit of sulfur". SO 2 is a bent molecule with C 2v symmetry point group . A valence bond theory approach considering just s and p orbitals would describe

4312-590: The corresponding metal sulfides. Oxidic ores are sometimes treated with hydrogen sulfide to give the corresponding metal sulfides which are more readily purified by flotation . Metal parts are sometimes passivated with hydrogen sulfide. Catalysts used in hydrodesulfurization are routinely activated with hydrogen sulfide. Hydrogen sulfide was a reagent in the qualitative inorganic analysis of metal ions. In these analyses, heavy metal (and nonmetal ) ions (e.g., Pb(II), Cu(II), Hg(II), As(III)) are precipitated from solution upon exposure to H 2 S . The components of

4389-519: The cysteine catabolic pathway. Dietary amino acids, such as methionine and cysteine serve as the primary substrates for the transulfuration pathways and in the production of hydrogen sulfide. Hydrogen sulfide can also be derived from proteins such as ferredoxins and Rieske proteins . Sulfate-reducing (resp. sulfur-reducing ) bacteria generate usable energy under low-oxygen conditions by using sulfates (resp. elemental sulfur) to oxidize organic compounds or hydrogen; this produces hydrogen sulfide as

4466-404: The dipole moment of 2.62 D pointed from the midpoint of the two oxygen atoms to the selenium atom. The solid sublimes readily. At very low concentrations the vapour has a revolting odour, resembling decayed horseradishes. At higher concentrations the vapour has an odour resembling horseradish sauce and can burn the nose and throat on inhalation. Whereas SO 2 tends to be molecular and SeO 2

4543-771: The hydrogen sulfite ion, HSO 3 , by reaction with water, and it is in fact the actual reducing agent present: In the beginning of the 20th century sulfur dioxide was used in Buenos Aires as a fumigant to kill rats that carried the Yersinia pestis bacterium, which causes bubonic plague. The application was successful, and the application of this method was extended to other areas in South America. In Buenos Aires, where these apparatuses were known as Sulfurozador , but later also in Rio de Janeiro, New Orleans and San Francisco,

4620-409: The largest industrial source of H 2 S is petroleum refineries : The hydrodesulfurization process liberates sulfur from petroleum by the action of hydrogen. The resulting H 2 S is converted to elemental sulfur by partial combustion via the Claus process , which is a major source of elemental sulfur. Other anthropogenic sources of hydrogen sulfide include coke ovens, paper mills (using

4697-420: The main proponents of H 2 S biogenesis, which follows the trans-sulfuration pathway. These enzymes have been identified in a breadth of biological cells and tissues, and their activity is induced by a number of disease states. These enzymes are characterized by the transfer of a sulfur atom from methionine to serine to form a cysteine molecule. 3-MST also contributes to hydrogen sulfide production by way of

SECTION 60

#1732772426561

4774-579: The mitochondrial electron transport chain, which effectively reduces ATP generation and biochemical activity within cells. Hydrogen sulfide is mainly consumed as a precursor to elemental sulfur. This conversion, called the Claus process , involves partial oxidation to sulfur dioxide. The latter reacts with hydrogen sulfide to give elemental sulfur. The conversion is catalyzed by alumina. Many fundamental organosulfur compounds are produced using hydrogen sulfide. These include methanethiol , ethanethiol , and thioglycolic acid . Hydrosulfides can be used in

4851-474: The moist, warm, anaerobic conditions of buried waste that contains a high source of carbon – in inert landfills, paper and glue used in the fabrication of products such as plasterboard can provide a rich source of carbon – is an excellent environment for the formation of hydrogen sulfide. In industrial anaerobic digestion processes, such as waste water treatment or the digestion of organic waste from agriculture , hydrogen sulfide can be formed from

4928-419: The myocardial antioxidant defense reserve. Sulfur dioxide is a versatile inert solvent widely used for dissolving highly oxidizing salts. It is also used occasionally as a source of the sulfonyl group in organic synthesis . Treatment of aryl diazonium salts with sulfur dioxide and cuprous chloride yields the corresponding aryl sulfonyl chloride, for example: As a result of its very low Lewis basicity , it

5005-471: The presence of sulfur dioxide on the exoplanet WASP-39b , where it is formed through photochemistry in the planet's atmosphere. As an ice, it is thought to exist in abundance on the Galilean moons —as subliming ice or frost on the trailing hemisphere of Io , and in the crust and mantle of Europa , Ganymede , and Callisto , possibly also in liquid form and readily reacting with water. Sulfur dioxide

5082-480: The production of thiophenol . Upon combining with alkali metal bases, hydrogen sulfide converts to alkali hydrosulfides such as sodium hydrosulfide and sodium sulfide : Sodium sulfides are used in the paper making industry. Specifically, salts of SH break bonds between lignin and cellulose components of pulp in the Kraft process . As indicated above, many metal ions react with hydrogen sulfide to give

5159-539: The production of sulfuric acid, being converted to sulfur trioxide , and then to oleum , which is made into sulfuric acid. Sulfur dioxide for this purpose is made when sulfur combines with oxygen. The method of converting sulfur dioxide to sulfuric acid is called the contact process . Several million tons are produced annually for this purpose. Sulfur dioxide is sometimes used as a preservative for dried apricots, dried figs, and other dried fruits, owing to its antimicrobial properties and ability to prevent oxidation , and

5236-399: The production of sulfuric acid. Sulfur dioxide dissolves in water to give " sulfurous acid ", which cannot be isolated and is instead an acidic solution of bisulfite , and possibly sulfite , ions. Sulfur dioxide is one of the few common acidic yet reducing gases. It turns moist litmus pink (being acidic), then white (due to its bleaching effect). It may be identified by bubbling it through

5313-435: The reduction of sulfate and the degradation of amino acids and proteins within organic compounds. Sulfates are relatively non-inhibitory to methane forming bacteria but can be reduced to H 2 S by sulfate reducing bacteria , of which there are several genera. A number of processes have been designed to remove hydrogen sulfide from drinking water . Hydrogen sulfide is commonly found in raw natural gas and biogas. It

5390-729: The resulting solid are then identified by their reactivity. Hydrogen sulfide is used to separate deuterium oxide, or heavy water , from normal water via the Girdler sulfide process . A suspended animation-like state has been induced in rodents with the use of hydrogen sulfide, resulting in hypothermia with a concomitant reduction in metabolic rate. Oxygen demand was also reduced, thereby protecting against hypoxia . In addition, hydrogen sulfide has been shown to reduce inflammation in various situations. Volcanoes and some hot springs (as well as cold springs ) emit some H 2 S . Hydrogen sulfide can be present naturally in well water, often as

5467-638: The sense of smell, creating temporary anosmia , so victims may be unaware of its presence until it is too late. Safe handling procedures are provided by its safety data sheet (SDS) . Since hydrogen sulfide occurs naturally in the body, the environment, and the gut, enzymes exist to metabolize it. At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm. Metabolism causes oxidation to sulfate, which

5544-424: The sulfur dioxide treatment machines were brought into the streets to enable extensive disinfection campaigns, with effective results. Sulfur dioxide or its conjugate base bisulfite is produced biologically as an intermediate in both sulfate-reducing organisms and in sulfur-oxidizing bacteria, as well. The role of sulfur dioxide in mammalian biology is not yet well understood. Sulfur dioxide blocks nerve signals from

5621-460: The toning add to the numismatic value of a coin based on aesthetics, as the toning may produce thin-film interference , resulting in the coin taking on an attractive coloration. Coins can also be intentionally treated with hydrogen sulfide to induce toning, though artificial toning can be distinguished from natural toning, and is generally criticised among collectors. Hydrogen sulfide is most commonly obtained by its separation from sour gas , which

5698-422: The wine in question. The free form exists in equilibrium between molecular SO 2 (as a dissolved gas) and bisulfite ion, which is in turn in equilibrium with sulfite ion. These equilibria depend on the pH of the wine. Lower pH shifts the equilibrium towards molecular (gaseous) SO 2 , which is the active form, while at higher pH more SO 2 is found in the inactive sulfite and bisulfite forms. The molecular SO 2

5775-462: Was discovered, Italian physician Bernardino Ramazzini hypothesized in his 1713 book De Morbis Artificum Diatriba that occupational diseases of sewer-workers and blackening of coins in their clothes may be caused by an unknown invisible volatile acid (moreover, in late 18th century toxic gas emanation from Paris sewers became a problem for the citizens and authorities). Although very pungent at first (it smells like rotten eggs ), it quickly deadens

5852-523: Was first used in winemaking by the Romans, when they discovered that burning sulfur candles inside empty wine vessels keeps them fresh and free from vinegar smell. It is still an important compound in winemaking, and is measured in parts per million ( ppm ) in wine. It is present even in so-called unsulfurated wine at concentrations of up to 10 mg/L. It serves as an antibiotic and antioxidant , protecting wine from spoilage by bacteria and oxidation –

5929-571: Was shown that in children with pulmonary arterial hypertension due to congenital heart diseases the level of homocysteine is higher and the level of endogenous sulfur dioxide is lower than in normal control children. Moreover, these biochemical parameters strongly correlated to the severity of pulmonary arterial hypertension. Authors considered homocysteine to be one of useful biochemical markers of disease severity and sulfur dioxide metabolism to be one of potential therapeutic targets in those patients. Endogenous sulfur dioxide also has been shown to lower

#560439