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76-423: The municipal unit Gorgopotamos is subdivided into the following communities (constituent villages in brackets): The village Gorgopotamos grew around an acetylene plant that operated between 1907 and 1945. The village of Eleftherochori is situated at 800 m above sea level on the slope of Kallidromo . The village of Damasta features the natural spring known as Psoroneri. The Gorgopotamos bridge, built in 1905, put

152-567: A carbon arc . Since the 1950s, acetylene has mainly been manufactured by the partial combustion of methane in the US, much of the EU, and many other countries: It is a recovered side product in production of ethylene by cracking of hydrocarbons . Approximately 400,000 tonnes were produced by this method in 1983. Its presence in ethylene is usually undesirable because of its explosive character and its ability to poison Ziegler–Natta catalysts . It

228-574: A coal deposit, while enhanced coal bed methane recovery is a method of recovering methane from non-mineable coal seams). It is associated with other hydrocarbon fuels, and sometimes accompanied by helium and nitrogen . Methane is produced at shallow levels (low pressure) by anaerobic decay of organic matter and reworked methane from deep under the Earth's surface. In general, the sediments that generate natural gas are buried deeper and at higher temperatures than those that contain oil . Methane

304-458: A hydrogen halide molecule and a methyl radical ( •CH 3 ). The methyl radical then reacts with a molecule of the halogen to form a molecule of the halomethane, with a new halogen atom as byproduct. Similar reactions can occur on the halogenated product, leading to replacement of additional hydrogen atoms by halogen atoms with dihalomethane , trihalomethane , and ultimately, tetrahalomethane structures, depending upon reaction conditions and

380-401: A mass spectrometer to measure the isotopic ratio of carbon-14 to carbon-12. Acetylene combustion produces a strong, bright light and the ubiquity of carbide lamps drove much acetylene commercialization in the early 20th century. Common applications included coastal lighthouses , street lights , and automobile and mining headlamps . In most of these applications, direct combustion

456-402: A feedstock for a variety of polyethylene plastics. Halogens add to the triple bond. Acetylene is not especially toxic, but when generated from calcium carbide , it can contain toxic impurities such as traces of phosphine and arsine , which gives it a distinct garlic -like smell. It is also highly flammable, as are most light hydrocarbons, hence its use in welding. Its most singular hazard

532-516: A group of British SOE officers, which included C.M. Woodhouse , blew up the railroad bridge over the Gorgopotamos river on November 25, 1942 as part of Operation Harling and cut off the enemy-controlled route between Thessaloniki and Athens . The blast ruined two of the six piers of the bridge. In an act of reprisals, the German occupation forces executed 16 Greek locals. The area around

608-423: A melting point. The triple point on the phase diagram corresponds to the melting point (−80.8 °C) at the minimal pressure at which liquid acetylene can exist (1.27 atm). At temperatures below the triple point, solid acetylene can change directly to the vapour (gas) by sublimation . The sublimation point at atmospheric pressure is −84.0 °C. At room temperature, the solubility of acetylene in acetone

684-463: A moon of Saturn . Natural acetylene is believed to form from catalytic decomposition of long-chain hydrocarbons at temperatures of 1,700 K (1,430 °C; 2,600 °F) and above. Since such temperatures are highly unlikely on such a small distant body, this discovery is potentially suggestive of catalytic reactions within that moon, making it a promising site to search for prebiotic chemistry. In vinylation reactions, H−X compounds add across

760-534: A more convenient, liquid fuel, is challenging because the reaction typically progresses all the way to carbon dioxide and water even with an insufficient supply of oxygen . The enzyme methane monooxygenase produces methanol from methane, but cannot be used for industrial-scale reactions. Some homogeneously catalyzed systems and heterogeneous systems have been developed, but all have significant drawbacks. These generally operate by generating protected products which are shielded from overoxidation. Examples include

836-400: A requirement for pure methane can easily be fulfilled by steel gas bottle from standard gas suppliers. Methane is the major component of natural gas, about 87% by volume. The major source of methane is extraction from geological deposits known as natural gas fields , with coal seam gas extraction becoming a major source (see coal bed methane extraction , a method for extracting methane from

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912-482: A residue of what is now known as potassium carbide , (K 2 C 2 ), which reacted with water to release the new gas. It was rediscovered in 1860 by French chemist Marcellin Berthelot , who coined the name acétylène . Berthelot's empirical formula for acetylene (C 4 H 2 ), as well as the alternative name " quadricarbure d'hydrogène " (hydrogen quadricarbide), were incorrect because many chemists at that time used

988-399: A resource that is otherwise difficult to transport for its weight, ash content, low calorific value and propensity to spontaneous combustion during storage and transport. A number of similar plants exist around the world, although mostly these plants are targeted towards the production of long chain alkanes for use as gasoline , diesel , or feedstock to other processes. Power to methane

1064-408: A suitable substrate for bacteria, provided an adequate source is available. A number of bacteria living on acetylene have been identified. The enzyme acetylene hydratase catalyzes the hydration of acetylene to give acetaldehyde : Acetylene is a moderately common chemical in the universe, often associated with the atmospheres of gas giants . One curious discovery of acetylene is on Enceladus ,

1140-465: Is unsaturated because its two carbon atoms are bonded together in a triple bond . The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°. Acetylene was discovered in 1836 by Edmund Davy , who identified it as a "new carburet of hydrogen". It was an accidental discovery while attempting to isolate potassium metal. By heating potassium carbonate with carbon at very high temperatures, he produced

1216-399: Is 27.9 g per kg. For the same amount of dimethylformamide (DMF), the solubility is 51 g. At 20.26 bar, the solubility increases to 689.0 and 628.0 g for acetone and DMF, respectively. These solvents are used in pressurized gas cylinders. Approximately 20% of acetylene is supplied by the industrial gases industry for oxyacetylene gas welding and cutting due to the high temperature of

1292-402: Is a chemical compound with the chemical formula CH 4 (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride , the simplest alkane , and the main constituent of natural gas . The abundance of methane on Earth makes it an economically attractive fuel , although capturing and storing it is difficult because it is a gas at standard temperature and pressure . In

1368-454: Is a fire hazard , and so acetylene has been replaced, first by incandescent lighting and many years later by low-power/high-lumen LEDs. Nevertheless, acetylene lamps remain in limited use in remote or otherwise inaccessible areas and in countries with a weak or unreliable central electric grid . The energy richness of the C≡C triple bond and the rather high solubility of acetylene in water make it

1444-406: Is a halogen : fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). This mechanism for this process is called free radical halogenation . It is initiated when UV light or some other radical initiator (like peroxides ) produces a halogen atom . A two-step chain reaction ensues in which the halogen atom abstracts a hydrogen atom from a methane molecule, resulting in the formation of

1520-454: Is a major precursor to vinyl chloride . Prior to the widespread use of petrochemicals, coal-derived acetylene was a building block for several industrial chemicals. Thus acetylene can be hydrated to give acetaldehyde , which in turn can be oxidized to acetic acid. Processes leading to acrylates were also commercialized. Almost all of these processes became obsolete with the availability of petroleum-derived ethylene and propylene. In 1881,

1596-542: Is a technology that uses electrical power to produce hydrogen from water by electrolysis and uses the Sabatier reaction to combine hydrogen with carbon dioxide to produce methane. Methane can be produced by protonation of methyl lithium or a methyl Grignard reagent such as methylmagnesium chloride . It can also be made from anhydrous sodium acetate and dry sodium hydroxide , mixed and heated above 300 °C (with sodium carbonate as byproduct). In practice,

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1672-558: Is abiotic. Abiotic means that methane is created from inorganic compounds, without biological activity, either through magmatic processes or via water-rock reactions that occur at low temperatures and pressures, like serpentinization . Most of Earth's methane is biogenic and is produced by methanogenesis , a form of anaerobic respiration only known to be conducted by some members of the domain Archaea . Methanogens occur in landfills and soils , ruminants (for example, cattle ),

1748-416: Is associated with its intrinsic instability, especially when it is pressurized: under certain conditions acetylene can react in an exothermic addition-type reaction to form a number of products, typically benzene and/or vinylacetylene , possibly in addition to carbon and hydrogen . Consequently, acetylene, if initiated by intense heat or a shockwave, can decompose explosively if the absolute pressure of

1824-421: Is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H . The lowest-energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this energy level is a triply degenerate set of MOs that involve overlap of the 2p orbitals on carbon with various linear combinations of

1900-428: Is easier to store than hydrogen due to its higher boiling point and density, as well as its lack of hydrogen embrittlement . The lower molecular weight of the exhaust also increases the fraction of the heat energy which is in the form of kinetic energy available for propulsion, increasing the specific impulse of the rocket. Compared to liquid hydrogen , the specific energy of methane is lower but this disadvantage

1976-409: Is increasing the amount of methane released from wetlands due to increased temperatures and altered rainfall patterns. This phenomeon is called wetland methane feedback . Rice cultivation generates as much as 12% of total global methane emissions due to the long-term flooding of rice fields. Ruminants, such as cattle, belch methane, accounting for about 22% of the U.S. annual methane emissions to

2052-446: Is lower than that of any other hydrocarbon, but the ratio of the heat of combustion (891 kJ/mol) to the molecular mass (16.0 g/mol, of which 12.0 g/mol is carbon) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit (55.7 kJ/g) than other complex hydrocarbons. In many areas with a dense enough population, methane is piped into homes and businesses for heating , cooking, and industrial uses. In this context it

2128-463: Is mostly composed of methane, is used to produce hydrogen gas on an industrial scale. Steam methane reforming (SMR), or simply known as steam reforming, is the standard industrial method of producing commercial bulk hydrogen gas. More than 50 million metric tons are produced annually worldwide (2013), principally from the SMR of natural gas. Much of this hydrogen is used in petroleum refineries , in

2204-512: Is obtained by the reaction of CO with water via the water-gas shift reaction : This reaction is mildly exothermic (produces heat, Δ H r = −41 kJ/mol). Methane is also subjected to free-radical chlorination in the production of chloromethanes, although methanol is a more typical precursor. Hydrogen can also be produced via the direct decomposition of methane, also known as methane pyrolysis , which, unlike steam reforming, produces no greenhouse gases (GHG). The heat needed for

2280-433: Is offset by methane's greater density and temperature range, allowing for smaller and lighter tankage for a given fuel mass. Liquid methane has a temperature range (91–112 K) nearly compatible with liquid oxygen (54–90 K). The fuel currently sees use in operational launch vehicles such as Zhuque-2 and Vulcan as well as in-development launchers such as Starship , Neutron , and Terran R . Natural gas , which

2356-419: Is selectively hydrogenated into ethylene, usually using Pd – Ag catalysts. The heaviest alkanes in petroleum and natural gas are cracked into lighter molecules which are dehydrogenated at high temperature: This last reaction is implemented in the process of anaerobic decomposition of methane by microwave plasma. The first acetylene produced was by Edmund Davy in 1836, via postassium carbide. Acetylene

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2432-503: Is then scattered back out. The familiar smell of natural gas as used in homes is achieved by the addition of an odorant , usually blends containing tert -butylthiol , as a safety measure. Methane has a boiling point of −161.5  °C at a pressure of one atmosphere . As a gas, it is flammable over a range of concentrations (5.4%–17%) in air at standard pressure . Solid methane exists in several modifications . Presently nine are known. Cooling methane at normal pressure results in

2508-435: Is under the seafloor in the form of methane clathrates . When methane reaches the surface and the atmosphere , it is known as atmospheric methane . The Earth's atmospheric methane concentration has increased by about 160% since 1750, with the overwhelming percentage caused by human activity. It accounted for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases , according to

2584-403: Is usually known as natural gas , which is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot . Liquefied natural gas (LNG) is predominantly methane ( CH 4 ) converted into liquid form for ease of storage or transport. Refined liquid methane as well as LNG is used as a rocket fuel , when combined with liquid oxygen , as in

2660-552: The Catalytica system , copper zeolites , and iron zeolites stabilizing the alpha-oxygen active site. One group of bacteria catalyze methane oxidation with nitrite as the oxidant in the absence of oxygen , giving rise to the so-called anaerobic oxidation of methane . Like other hydrocarbons , methane is an extremely weak acid . Its p K a in DMSO is estimated to be 56. It cannot be deprotonated in solution, but

2736-599: The Sabatier process . Methane is also a side product of the hydrogenation of carbon monoxide in the Fischer–Tropsch process , which is practiced on a large scale to produce longer-chain molecules than methane. An example of large-scale coal-to-methane gasification is the Great Plains Synfuels plant, started in 1984 in Beulah, North Dakota as a way to develop abundant local resources of low-grade lignite ,

2812-481: The TQ-12 , BE-4 , Raptor , and YF-215 engines. Due to the similarities between methane and LNG such engines are commonly grouped together under the term methalox . As a liquid rocket propellant, a methane/ liquid oxygen combination offers the advantage over kerosene / liquid oxygen combination, or kerolox, of producing small exhaust molecules, reducing coking or deposition of soot on engine components. Methane

2888-634: The conjugate base is known in forms such as methyllithium . A variety of positive ions derived from methane have been observed, mostly as unstable species in low-pressure gas mixtures. These include methenium or methyl cation CH + 3 , methane cation CH + 4 , and methanium or protonated methane CH + 5 . Some of these have been detected in outer space . Methanium can also be produced as diluted solutions from methane with superacids . Cations with higher charge, such as CH 2+ 6 and CH 3+ 7 , have been studied theoretically and conjectured to be stable. Despite

2964-497: The strength of its C–H bonds, there is intense interest in catalysts that facilitate C–H bond activation in methane (and other lower numbered alkanes ). Methane's heat of combustion is 55.5 MJ/kg. Combustion of methane is a multiple step reaction summarized as follows: Peters four-step chemistry is a systematically reduced four-step chemistry that explains the burning of methane. Given appropriate conditions, methane reacts with halogen radicals as follows: where X

3040-500: The 1s orbitals on hydrogen. The resulting "three-over-one" bonding scheme is consistent with photoelectron spectroscopic measurements. Methane is an odorless, colourless and transparent gas. It does absorb visible light, especially at the red end of the spectrum, due to overtone bands , but the effect is only noticeable if the light path is very long. This is what gives Uranus and Neptune their blue or bluish-green colors, as light passes through their atmospheres containing methane and

3116-430: The 2021 Intergovernmental Panel on Climate Change report. Strong, rapid and sustained reductions in methane emissions could limit near-term warming and improve air quality by reducing global surface ozone. Methane has also been detected on other planets, including Mars , which has implications for astrobiology research. Methane is a tetrahedral molecule with four equivalent C–H bonds . Its electronic structure

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3192-416: The Earth's atmosphere methane is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas . Methane is an organic compound , and among the simplest of organic compounds. Methane is also a hydrocarbon . Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane

3268-635: The Gorgopotamos village on the map for the strategic purpose the bridge played during World War II. The Engineer who originally designed and built the infamous Gorgopotamos bridge was Agostino Tacconi, later Αυγουστίνος Τακωνης (Takonis) who migrated from Palermo Italy to Greece to supply Greece with his Engineering skills. At the time Greece was recruiting from other nations to fill a significant skills shortage. The name of Gorgopotamos became famous during World War II , when 150 Greek partisans, following plans drawn by E. C. W. "Eddie" Myers and assisted by

3344-522: The Russian chemist Mikhail Kucherov described the hydration of acetylene to acetaldehyde using catalysts such as mercury(II) bromide . Before the advent of the Wacker process , this reaction was conducted on an industrial scale. The polymerization of acetylene with Ziegler–Natta catalysts produces polyacetylene films. Polyacetylene, a chain of CH centres with alternating single and double bonds,

3420-681: The US, National Electric Code (NEC) requires consideration for hazardous areas including those where acetylene may be released during accidents or leaks. Consideration may include electrical classification and use of listed Group A electrical components in US. Further information on determining the areas requiring special consideration is in NFPA 497. In Europe, ATEX also requires consideration for hazardous areas where flammable gases may be released during accidents or leaks. Methane Methane ( US : / ˈ m ɛ θ eɪ n / METH -ayn , UK : / ˈ m iː θ eɪ n / MEE -thayn )

3496-426: The atmosphere. One study reported that the livestock sector in general (primarily cattle, chickens, and pigs) produces 37% of all human-induced methane. A 2013 study estimated that livestock accounted for 44% of human-induced methane and about 15% of human-induced greenhouse gas emissions. Many efforts are underway to reduce livestock methane production, such as medical treatments and dietary adjustments, and to trap

3572-679: The breakup of organic matter at elevated temperatures and pressures in deep sedimentary strata . Most methane in sedimentary basins is thermogenic; therefore, thermogenic methane is the most important source of natural gas. Thermogenic methane components are typically considered to be relic (from an earlier time). Generally, formation of thermogenic methane (at depth) can occur through organic matter breakup, or organic synthesis. Both ways can involve microorganisms ( methanogenesis ), but may also occur inorganically. The processes involved can also consume methane, with and without microorganisms. The more important source of methane at depth (crystalline bedrock)

3648-480: The bridge has been designated a national monument. After World War II and the Greek Civil War , the bridge of Gorgopotamos was partially rebuilt, the damaged piers being replaced with steel pylons. The community is served by Gorgopotamos railway station , with Regional services to Leianokladi and Athens . Acetylene Acetylene ( systematic name : ethyne ) is the chemical compound with

3724-547: The by-product. Copper acetylide is used as the catalyst. In addition to ethynylation, acetylene reacts with carbon monoxide , acetylene reacts to give acrylic acid , or acrylic esters. Metal catalysts are required. These derivatives form products such as acrylic fibers , glasses , paints , resins , and polymers . Except in China, use of acetylene as a chemical feedstock has declined by 70% from 1965 to 2007 owing to cost and environmental considerations. In China, acetylene

3800-612: The chosen catalyst. Dozens of catalysts have been tested, including unsupported and supported metal catalysts, carbonaceous and metal-carbon catalysts. The reaction is moderately endothermic as shown in the reaction equation below. As a refrigerant , methane has the ASHRAE designation R-50 . Methane can be generated through geological, biological or industrial routes. The two main routes for geological methane generation are (i) organic (thermally generated, or thermogenic) and (ii) inorganic ( abiotic ). Thermogenic methane occurs due to

3876-588: The cold gas, the gas at ambient temperature is lighter than air. Gas pipelines distribute large amounts of natural gas, of which methane is the principal component. Methane is used as a fuel for ovens, homes, water heaters, kilns, automobiles, turbines, etc. As the major constituent of natural gas , methane is important for electricity generation by burning it as a fuel in a gas turbine or steam generator . Compared to other hydrocarbon fuels , methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion

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3952-441: The early 21st century, China, Japan, and Eastern Europe produced acetylene primarily by this method. The use of this technology has since declined worldwide with the notable exception of China, with its emphasis on coal-based chemical industry, as of 2013. Otherwise oil has increasingly supplanted coal as the chief source of reduced carbon. Calcium carbide production requires high temperatures, ~2000 °C, necessitating

4028-421: The flame. Combustion of acetylene with oxygen produces a flame of over 3,600 K (3,330 °C; 6,020 °F), releasing 11.8  kJ /g. Oxygen with acetylene is the hottest burning common gas mixture. Acetylene is the third-hottest natural chemical flame after dicyanoacetylene 's 5,260 K (4,990 °C; 9,010 °F) and cyanogen at 4,798 K (4,525 °C; 8,177 °F). Oxy-acetylene welding

4104-491: The formation of methane I. This substance crystallizes in the cubic system ( space group Fm 3 m). The positions of the hydrogen atoms are not fixed in methane I, i.e. methane molecules may rotate freely. Therefore, it is a plastic crystal . The primary chemical reactions of methane are combustion , steam reforming to syngas , and halogenation . In general, methane reactions are difficult to control. Partial oxidation of methane to methanol ( C H 3 O H ),

4180-432: The formula L n M−C 2 R , are also common. Copper(I) acetylide and silver acetylide can be formed in aqueous solutions with ease due to a favorable solubility equilibrium . Acetylene has a p K a of 25, acetylene can be deprotonated by a superbase to form an acetylide : Various organometallic and inorganic reagents are effective. Acetylene can be semihydrogenated to ethylene , providing

4256-421: The formula C 2 H 2 and structure H−C≡C−H . It is a hydrocarbon and the simplest alkyne . This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine . As an alkyne, acetylene

4332-465: The gas exceeds about 200 kilopascals (29 psi). Most regulators and pressure gauges on equipment report gauge pressure , and the safe limit for acetylene therefore is 101 kPa gage , or 15 psig. It is therefore supplied and stored dissolved in acetone or dimethylformamide (DMF), contained in a gas cylinder with a porous filling , which renders it safe to transport and use, given proper handling. Acetylene cylinders should be used in

4408-434: The gas to use its combustion energy. Most of the subseafloor is anoxic because oxygen is removed by aerobic microorganisms within the first few centimeters of the sediment . Below the oxygen-replete seafloor, methanogens produce methane that is either used by other organisms or becomes trapped in gas hydrates . These other organisms that utilize methane for energy are known as methanotrophs ('methane-eating'), and are

4484-449: The guts of termites, and the anoxic sediments below the seafloor and the bottom of lakes. This multistep process is used by these microorganisms for energy. The net reaction of methanogenesis is: The final step in the process is catalyzed by the enzyme methyl coenzyme M reductase (MCR). Wetlands are the largest natural sources of methane to the atmosphere, accounting for approximately 20 - 30% of atmospheric methane. Climate change

4560-401: The halogen-to-methane ratio. This reaction is commonly used with chlorine to produce dichloromethane and chloroform via chloromethane . Carbon tetrachloride can be made with excess chlorine. Methane may be transported as a refrigerated liquid (liquefied natural gas, or LNG ). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of

4636-436: The loosening of corroded nuts and bolts, and other applications. Bell Canada cable-repair technicians still use portable acetylene-fuelled torch kits as a soldering tool for sealing lead sleeve splices in manholes and in some aerial locations. Oxyacetylene welding may also be used in areas where electricity is not readily accessible. Oxyacetylene cutting is used in many metal fabrication shops. For use in welding and cutting,

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4712-482: The main reason why little methane generated at depth reaches the sea surface. Consortia of Archaea and Bacteria have been found to oxidize methane via anaerobic oxidation of methane (AOM); the organisms responsible for this are anaerobic methanotrophic Archaea (ANME) and sulfate-reducing bacteria (SRB). Given its cheap abundance in natural gas, there is little incentive to produce methane industrially. Methane can be produced by hydrogenating carbon dioxide through

4788-457: The production of chemicals and in food processing. Very large quantities of hydrogen are used in the industrial synthesis of ammonia . At high temperatures (700–1100 °C) and in the presence of a metal -based catalyst ( nickel ), steam reacts with methane to yield a mixture of CO and H 2 , known as "water gas" or " syngas ": This reaction is strongly endothermic (consumes heat, Δ H r = 206 kJ/mol). Additional hydrogen

4864-469: The reaction can also be GHG emission free, e.g. from concentrated sunlight, renewable electricity, or burning some of the produced hydrogen. If the methane is from biogas then the process can be a carbon sink . Temperatures in excess of 1200 °C are required to break the bonds of methane to produce hydrogen gas and solid carbon. However, through the use of a suitable catalyst the reaction temperature can be reduced to between 550-900 °C depending on

4940-435: The synthesis of vinyl formate . Acetylene and its derivatives (2-butyne, diphenylacetylene, etc.) form complexes with transition metals . Its bonding to the metal is somewhat similar to that of ethylene complexes. These complexes are intermediates in many catalytic reactions such as alkyne trimerisation to benzene, tetramerization to cyclooctatetraene , and carbonylation to hydroquinone : Metal acetylides , species of

5016-423: The triple bond. Alcohols and phenols add to acetylene to give vinyl ethers . Thiols give vinyl thioethers. Similarly, vinylpyrrolidone and vinylcarbazole are produced industrially by vinylation of 2-pyrrolidone and carbazole . The hydration of acetylene is a vinylation reaction, but the resulting vinyl alcohol isomerizes to acetaldehyde . The reaction is catalyzed by mercury salts. This reaction once

5092-404: The two sp hybrid orbital overlap to form a strong σ valence bond between the carbons, while on each of the other two ends hydrogen atoms attach also by σ bonds. The two unchanged 2p orbitals form a pair of weaker π bonds . Since acetylene is a linear symmetrical molecule , it possesses the D ∞h point group . At atmospheric pressure, acetylene cannot exist as a liquid and does not have

5168-737: The upright position to avoid withdrawing acetone during use. Information on safe storage of acetylene in upright cylinders is provided by the OSHA, Compressed Gas Association, United States Mine Safety and Health Administration (MSHA), EIGA, and other agencies. Copper catalyses the decomposition of acetylene, and as a result acetylene should not be transported in copper pipes. Cylinders should be stored in an area segregated from oxidizers to avoid exacerbated reaction in case of fire/leakage. Acetylene cylinders should not be stored in confined spaces, enclosed vehicles, garages, and buildings, to avoid unintended leakage leading to explosive atmosphere. In

5244-403: The use of an electric arc furnace . In the US, this process was an important part of the late-19th century revolution in chemistry enabled by the massive hydroelectric power project at Niagara Falls . In terms of valence bond theory , in each carbon atom the 2s orbital hybridizes with one 2p orbital thus forming an sp hybrid. The other two 2p orbitals remain unhybridized. The two ends of

5320-532: The working pressures must be controlled by a regulator, since above 15 psi (100 kPa), if subjected to a shockwave (caused, for example, by a flashback ), acetylene decomposes explosively into hydrogen and carbon . Acetylene is useful for many processes, but few are conducted on a commercial scale. One of the major chemical applications is ethynylation of formaldehyde. Acetylene adds to aldehydes and ketones to form α-ethynyl alcohols: The reaction gives butynediol , with propargyl alcohol as

5396-407: The wrong atomic mass for carbon (6 instead of 12). Berthelot was able to prepare this gas by passing vapours of organic compounds (methanol, ethanol, etc.) through a red hot tube and collecting the effluent . He also found that acetylene was formed by sparking electricity through mixed cyanogen and hydrogen gases. Berthelot later obtained acetylene directly by passing hydrogen between the poles of

5472-558: Was a popular welding process in previous decades. The development and advantages of arc-based welding processes have made oxy-fuel welding nearly extinct for many applications. Acetylene usage for welding has dropped significantly. On the other hand, oxy-acetylene welding equipment is quite versatile – not only because the torch is preferred for some sorts of iron or steel welding (as in certain artistic applications), but also because it lends itself easily to brazing, braze-welding, metal heating (for annealing or tempering, bending or forming),

5548-529: Was experimentally used as an inhalation anesthetic . Acetylene is sometimes used for carburization (that is, hardening) of steel when the object is too large to fit into a furnace. Acetylene is used to volatilize carbon in radiocarbon dating . The carbonaceous material in an archeological sample is treated with lithium metal in a small specialized research furnace to form lithium carbide (also known as lithium acetylide). The carbide can then be reacted with water, as usual, to form acetylene gas to feed into

5624-458: Was historically produced by hydrolysis (reaction with water) of calcium carbide: This reaction was discovered by Friedrich Wöhler in 1862, but a suitable commercial scale production method which allowed acetylene to be put into wider scale use was not found until 1892 by the Canadian inventor Thomas Willson while searching for a viable commercial production method for aluminum. As late as

5700-517: Was one of the first discovered organic semiconductors . Its reaction with iodine produces a highly electrically conducting material. Although such materials are not useful, these discoveries led to the developments of organic semiconductors , as recognized by the Nobel Prize in Chemistry in 2000 to Alan J. Heeger , Alan G MacDiarmid , and Hideki Shirakawa . In the 1920s, pure acetylene

5776-515: Was the dominant technology for acetaldehyde production, but it has been displaced by the Wacker process , which affords acetaldehyde by oxidation of ethylene , a cheaper feedstock. A similar situation applies to the conversion of acetylene to the valuable vinyl chloride by hydrochlorination vs the oxychlorination of ethylene. Vinyl acetate is used instead of acetylene for some vinylations, which are more accurately described as transvinylations . Higher esters of vinyl acetate have been used in

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