Ethane

Ethane (/ˈɛθeɪn/ or /ˈiːθeɪn/) is an organic chemical compound with chemical formula C
2
H
6
. At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production.

Related compounds may be formed by replacing a hydrogen atom with another functional group; the ethane moiety is called an ethyl group. For example, an ethyl group linked to a hydroxyl group yields ethanol, the alcohol in beverages.

Ethane
Skeletal formula of ethane with all implicit hydrogens shown
Skeletal formula of ethane with all implicit carbons shown, and all explicit hydrogens added
Ball and stick model of ethane
Spacefill model of ethane
Names
Preferred IUPAC name
Ethane[1]
Systematic IUPAC name
Dicarbane (never recommended[1])
Identifiers
3D model (JSmol)
1730716
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.741
EC Number 200-814-8
212
MeSH Ethane
RTECS number KH3800000
UNII
UN number 1035
Properties
C2H6
Molar mass 30.070 g·mol−1
Appearance Colorless gas
Odor Odorless
Density
  • 1.3562 kg/m−3 (gas at 0 °C)[2]

544.0 kg/m−3 (liquid at -88,5 °C)
206 kg/m−3 (at critical point 305.322 K)

Melting point −182.8 °C; −296.9 °F; 90.4 K
Boiling point −88.5 °C; −127.4 °F; 184.6 K
56.8 mg L−1[3]
Vapor pressure 3.8453 MPa (at 21.1 °C)
19 nmol Pa−1 kg−1
Acidity (pKa) 50
Basicity (pKb) -36
Conjugate acid Ethanium
-37.37·10−6 cm3/mol
Thermochemistry
52.49 J K−1 mol−1
−84 kJ mol−1
−1561.0–−1560.4 kJ mol−1
Hazards
Safety data sheet See: data page
inchem.org
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H220, H280
P210, P410+403
NFPA 704
Flash point −135 °C (−211 °F; 138 K)
472 °C (882 °F; 745 K)
Explosive limits 2.9–13%
Related compounds
Related alkanes
Related compounds
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

History

Ethane was first synthesised in 1834 by Michael Faraday, applying electrolysis of a potassium acetate solution. He mistook the hydrocarbon product of this reaction for methane and did not investigate it further.[4] During the period 1847–1849, in an effort to vindicate the radical theory of organic chemistry, Hermann Kolbe and Edward Frankland produced ethane by the reductions of propionitrile (ethyl cyanide)[5] and ethyl iodide[6] with potassium metal, and, as did Faraday, by the electrolysis of aqueous acetates. They, however, mistook the product of the reactions for methyl radical rather than the dimer of methyl, ethane. This error was corrected in 1864 by Carl Schorlemmer, who showed that the product of all these reactions was in fact ethane.[7]

The name ethane is derived from the IUPAC nomenclature of organic chemistry. "Eth-" is derived from the German for potable alcohol (ethanol),[8] and "-ane" refers to the presence of a single bond between the carbon atoms.

Properties

At standard temperature and pressure, ethane is a colorless, odorless gas. It has a boiling point of −88.5 °C (−127.3 °F) and melting point of −182.8 °C (−297.0 °F). Solid ethane exists in several modifications.[9] On cooling under normal pressure, the first modification to appear is a plastic crystal, crystallizing in the cubic system. In this form, the positions of the hydrogen atoms are not fixed; the molecules may rotate freely around the long axis. Cooling this ethane below ca. 89.9 K (−183.2 °C; −297.8 °F) changes it to monoclinic metastable ethane II (space group P 21/n).[10] Ethane is only very sparingly soluble in water.

Chemistry

Ethane can be viewed as two methyl groups joined, that is, a dimer of methyl groups. In the laboratory, ethane may be conveniently synthesised by Kolbe electrolysis. In this technique, an aqueous solution of an acetate salt is electrolysed. At the anode, acetate is oxidized to produce carbon dioxide and methyl radicals, and the highly reactive methyl radicals combine to produce ethane:

CH3COO → CH3• + CO2 + e
CH3• + •CH3 → C2H6

Synthesis by oxidation of acetic anhydride by peroxides, is conceptually similar.

The chemistry of ethane involves chiefly free radical reactions. Ethane can react with the halogens, especially chlorine and bromine, by free radical halogenation. This reaction proceeds through the propagation of the ethyl radical:

C2H5• + Cl2C2H5Cl + Cl•
Cl• + C2H6 → C2H5• + HCl

Because halogenated ethanes can undergo further free radical halogenation, this process results in a mixture of several halogenated products. In the chemical industry, more selective chemical reactions are used for the production of any particular two-carbon haloalkane.

Combustion

The complete combustion of ethane releases 1559.7 kJ/mol, or 51.9 kJ/g, of heat, and produces carbon dioxide and water according to the chemical equation

2 C2H6 + 7 O2 → 4 CO2 + 6 H2O + 3120 kJ

Combustion may also occur without an excess of oxygen, forming a mix of amorphous carbon and carbon monoxide.

2 C2H6 + 3 O2 → 4 C + 6 H2O + energy
2 C2H6 + 5 O2 → 4 CO + 6 H2O + energy
2 C2H6 + 4 O2 → 2 C + 2 CO + 6 H2O + energy etc.

Combustion occurs by a complex series of free-radical reactions. Computer simulations of the chemical kinetics of ethane combustion have included hundreds of reactions. An important series of reaction in ethane combustion is the combination of an ethyl radical with oxygen, and the subsequent breakup of the resulting peroxide into ethoxy and hydroxyl radicals.

C2H5• + O2 → C2H5OO•
C2H5OO• + HR → C2H5OOH + •R
C2H5OOH → C2H5O• + •OH

The principal carbon-containing products of incomplete ethane combustion are single-carbon compounds such as carbon monoxide and formaldehyde. One important route by which the carbon-carbon bond in ethane is broken, to yield these single-carbon products, is the decomposition of the ethoxy radical into a methyl radical and formaldehyde, which can in turn undergo further oxidation.

C2H5O• → CH3• + CH2O

Some minor products in the incomplete combustion of ethane include acetaldehyde, methane, methanol, and ethanol. At higher temperatures, especially in the range 600–900 °C (1,112–1,652 °F), ethylene is a significant product. It arises through reactions such as this:

C2H5• + O2C2H4 + •OOH

Similar reactions (with agents other than oxygen as the hydrogen abstractor) are involved in the production of ethylene from ethane in steam cracking.

Ethane barrier

Ethane conformations and relative energies
Ethane (shown in Newman projection) barrier to rotation about the carbon-carbon bond. The curve is potential energy as a function of rotational angle. Energy barrier is 12 kJ/mol or about 2.9 kcal/mol.[11]

Rotating a molecular substructure about a twistable bond usually requires energy. The minimum energy to produce a 360-degree bond rotation is called the rotational barrier.

Ethane gives a classic, simple example of such a rotational barrier, sometimes called the "ethane barrier." Among the earliest experimental evidence of this barrier (see diagram at left) was obtained by modelling the entropy of ethane.[12] The three hydrogens at each end are free to pinwheel about the central carbon-carbon bond when provided with sufficient energy to overcome the barrier. The physical origin of the barrier is still not completely settled,[13] although the overlap (exchange) repulsion[14] between the hydrogen atoms on opposing ends of the molecule is perhaps the strongest candidate, with the stabilizing effect of hyperconjugation on the staggered conformation contributing to the phenomenon.[15] However, theoretical methods that use an appropriate starting point (orthogonal orbitals) find that hyperconjugation is the most important factor in the origin of the ethane rotation barrier.[16][17]

As far back as 1890–1891, chemists suggested that ethane molecules preferred the staggered conformation with the two ends of the molecule askew from each other.[18][19][20][21]

Production

After methane, ethane is the second-largest component of natural gas. Natural gas from different gas fields varies in ethane content from less than 1% to more than 6% by volume. Prior to the 1960s, ethane and larger molecules were typically not separated from the methane component of natural gas, but simply burnt along with the methane as a fuel. Today, ethane is an important petrochemical feedstock and is separated from the other components of natural gas in most well-developed gas fields. Ethane can also be separated from petroleum gas, a mixture of gaseous hydrocarbons produced as a byproduct of petroleum refining. Economics of building and running processing plants can change, however. If the relative value of sending the unprocessed natural gas to a consumer exceeds the value of extracting ethane, ethane extraction might not be run, which could cause operational issues managing the changing quality of the gas in downstream systems.

Ethane is most efficiently separated from methane by liquefying it at cryogenic temperatures. Various refrigeration strategies exist: the most economical process presently in wide use employs a turboexpander, and can recover more than 90% of the ethane in natural gas. In this process, chilled gas is expanded through a turbine, reducing the temperature to about −100 °C (−148 °F). At this low temperature, gaseous methane can be separated from the liquefied ethane and heavier hydrocarbons by distillation. Further distillation then separates ethane from the propane and heavier hydrocarbons.

Uses

The chief use of ethane is the production of ethene (ethylene) by steam cracking. When diluted with steam and briefly heated to very high temperatures (900 °C or more), heavy hydrocarbons break down into lighter hydrocarbons, and saturated hydrocarbons become unsaturated. Ethane is favored for ethene production because the steam cracking of ethane is fairly selective for ethene, while the steam cracking of heavier hydrocarbons yields a product mixture poorer in ethene and richer in heavier alkenes (olefins), such as propene (propylene) and butadiene, and in aromatic hydrocarbons.

Experimentally, ethane is under investigation as a feedstock for other commodity chemicals. Oxidative chlorination of ethane has long appeared to be a potentially more economical route to vinyl chloride than ethene chlorination. Many processes for producing this reaction have been patented, but poor selectivity for vinyl chloride and corrosive reaction conditions (specifically, a reaction mixture containing hydrochloric acid at temperatures greater than 500 °C) have discouraged the commercialization of most of them. Presently, INEOS operates a 1000 t/a (tonnes per annum) ethane-to-vinyl chloride pilot plant at Wilhelmshaven in Germany.

Similarly, the Saudi Arabian firm SABIC has announced construction of a 30,000 tonnes per annum plant to produce acetic acid by ethane oxidation at Yanbu. The economic viability of this process may rely on the low cost of ethane near Saudi oil fields, and it may not be competitive with methanol carbonylation elsewhere in the world.

Ethane can be used as a refrigerant in cryogenic refrigeration systems. On a much smaller scale, in scientific research, liquid ethane is used to vitrify water-rich samples for electron microscopy (cryo-electron microscopy). A thin film of water, quickly immersed in liquid ethane at −150 °C or colder, freezes too quickly for water to crystallize. With slower freezing methods, ice crystals can disrupt soft structures, damaging the samples.

Health and safety

At room temperature, ethane is a flammable gas. When mixed with air at 3.0%–12.5% by volume, it forms an explosive mixture.

Some additional precautions are necessary where ethane is stored as a cryogenic liquid. Direct contact with liquid ethane can result in severe frostbite. Until they warm to room temperature, the vapors from liquid ethane are heavier than air and can flow along the floor or ground, gathering in low places; if the vapors encounter an ignition source, the chemical reaction can flash back to the source of ethane from which they evaporated.

Ethane can displace oxygen and become an asphyxiation hazard. Ethane poses no known acute or chronic toxicological risk. It is not a carcinogen.[22]

Atmospheric and extraterrestrial ethane

Titan North Pole Lakes PIA08630
A photograph of Titan's northern latitudes. The dark features appear to be hydrocarbon lakes, but further images will be needed to see if the dark spots remain the same (as they would if they were lakes)

Ethane occurs as a trace gas in the Earth's atmosphere, currently having a concentration at sea level of 0.5 ppb,[23] though its preindustrial concentration is likely to have been only around 0.25 part per billion since a significant proportion of the ethane in today’s atmosphere may have originated as fossil fuels. Global ethane quantities have varied over time, likely due to flaring at natural gas fields.[24] Global ethane emission rates declined from 1984 to 2010,[24] though increased shale gas production at the Bakken Formation in the U.S. has arrested the decline by half.[25] [26]

Although ethane is a greenhouse gas, it is much less abundant than methane, has a lifetime of only a few months vis-à-vis over a decade,[27] and is also less efficient at absorbing radiation relative to mass. It has been detected as a trace component in the atmospheres of all four giant planets, and in the atmosphere of Saturn's moon Titan.[28]

Atmospheric ethane results from the Sun’s photochemical action on methane gas, also present in these atmospheres: ultraviolet photons of shorter wavelengths than 160 nm can photo-dissociate the methane molecule into a methyl radical and a hydrogen atom. When two methyl radicals recombine, the result is ethane:

CH4 → CH3• + •H
CH3• + •CH3 → C2H6

On Earth’s atmosphere, hydroxyl radicals convert ethane to methanol vapor with a half-life of around three months.[27]

It was once widely hypothesized that ethane produced in this fashion on Titan rained back onto the moon's surface, and over time had accumulated into hydrocarbon seas or oceans covering much of the moon's surface. Infrared telescopic observations cast significant doubt on this hypothesis, and the Huygens probe, which landed on Titan in 2005, failed to observe any surface liquids, although it did photograph features that could be presently dry drainage channels. In December 2007 the Cassini probe found at least one lake at Titan’s south pole, now called Ontario Lacus because of the lake's similar area to Lake Ontario on Earth (approximately 20,000 km2). Further analysis of infrared spectroscopic data presented in July 2008[29] provided stronger evidence for the presence of liquid ethane in Ontario Lacus.

In 1996, ethane was detected in Comet Hyakutake,[30] and it has since been detected in some other comets. The existence of ethane in these distant solar system bodies may implicate ethane as a primordial component of the solar nebula from which the sun and planets are believed to have formed.

In 2006, Dale Cruikshank of NASA/Ames Research Center (a New Horizons co-investigator) and his colleagues announced the spectroscopic discovery of ethane on Pluto's surface.[31]

References

  1. ^ a b Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 4. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. Similarly, the retained names ‘ethane’, ‘propane’, and ‘butane’ were never replaced by systematic names ‘dicarbane’, ‘tricarbane’, and ‘tetracarbane’ as recommended for analogues of silane, ‘disilane’; phosphane, ‘triphosphane’; and sulfane, ‘tetrasulfane’.
  2. ^ "Ethane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Retrieved 7 December 2011.
  3. ^ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. p. 8.88. ISBN 0-8493-0486-5.
  4. ^ Faraday, Michael (1834). "Experimental researches in electricity: Seventh series". Philosophical Transactions. 124: 77–122. doi:10.1098/rstl.1834.0008.
  5. ^ Kolbe, Hermann; Frankland, Edward (1849). "On the products of the action of potassium on cyanide of ethyl". Journal of the Chemical Society. 1: 60–74. doi:10.1039/QJ8490100060.
  6. ^ Frankland, Edward (1850). "On the isolation of the organic radicals". Journal of the Chemical Society. 2 (3): 263–296. doi:10.1039/QJ8500200263.
  7. ^ Schorlemmer, Carl (1864). "Ueber die Identität des Aethylwasserstoffs und des Methyls". Annalen der Chemie und Pharmacie. 132 (2): 234. doi:10.1002/jlac.18641320217.
  8. ^ "the definition of ethyl". Dictionary.com. Retrieved 2016-03-12.
  9. ^ Van Nes, G.J.H.; Vos, A. (1978). "Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. I. Single-crystal X-ray structure determinations of two modifications of ethane" (PDF). Acta Crystallographica Section B. 34 (6): 1947. doi:10.1107/S0567740878007037.
  10. ^ "Ethane as a solid". Paarpraxis-rheinmain.de. Retrieved 2016-12-16.
  11. ^ J, McMurry (2012). Organic chemistry (8 ed.). Belmont, CA: Brooks. p. 95. ISBN 9780840054449.
  12. ^ Kemp, J. D.; Pitzer, Kenneth S. (1937). "The Entropy of Ethane and the Third Law of Thermodynamics. Hindered Rotation of Methyl Groups". Journal of the American Chemical Society. 59 (2): 276. doi:10.1021/ja01281a014.
  13. ^ Ercolani, G. (2005). "Determination of the Rotational Barrier in Ethane by Vibrational Spectroscopy and Statistical Thermodynamics". J. Chem. Educ. 82 (11): 1703–1708. Bibcode:2005JChEd..82.1703E. doi:10.1021/ed082p1703.
  14. ^ Pitzer, R.M. (1983). "The Barrier to Internal Rotation in Ethane". Acc. Chem. Res. 16 (6): 207–210. doi:10.1021/ar00090a004.
  15. ^ Mo, Y.; Wu, W.; Song, L.; Lin, M.; Zhang, Q.; Gao, J. (2004). "The Magnitude of Hyperconjugation in Ethane: A Perspective from Ab Initio Valence Bond Theory". Angew. Chem. Int. Ed. 43 (15): 1986–1990. doi:10.1002/anie.200352931.
  16. ^ Pophristic, V.; Goodman, L. (2001). "Hyperconjugation not steric repulsion leads to the staggered structure of ethane". Nature. 411 (6837): 565–8. doi:10.1038/35079036. PMID 11385566.CS1 maint: Multiple names: authors list (link)
  17. ^ Schreiner, P. R. (2002). "Teaching the right reasons: Lessons from the mistaken origin of the rotational barrier in ethane". Angewandte Chemie International Edition. 41 (19): 3579–81, 3513. doi:10.1002/1521-3773(20021004)41:19<3579::AID-ANIE3579>3.0.CO;2-S. PMID 12370897.
  18. ^ Bischoff, CA (1890). "Ueber die Aufhebung der freien Drehbarkeit von einfach verbundenen Kohlenstoffatomen". Chem. Ber. 23: 623. doi:10.1002/cber.18900230197.
  19. ^ Bischoff, CA (1891). "Theoretische Ergebnisse der Studien in der Bernsteinsäuregruppe". Chem. Ber. 24: 1074. doi:10.1002/cber.189102401195.
  20. ^ Bischoff, CA (1891). "Die dynamische Hypothese in ihrer Anwendung auf die Bernsteinsäuregruppe". Chem. Ber. 24: 1085. doi:10.1002/cber.189102401196.
  21. ^ Bischoff, C.A.; Walden, P. (1893). "Die Anwendung der dynamischen Hypothese auf Ketonsäurederivate". Berichte der deutschen chemischen Gesellschaft. 26 (2): 1452. doi:10.1002/cber.18930260254.
  22. ^ Vallero, Daniel (June 7, 2010). "Cancer Slope Factors". Environmental Biotechnology: A Biosystems Approach. Academic Press. p. 641. doi:10.1016/B978-0-12-375089-1.10014-5.
  23. ^ Trace gases (archived). Atmosphere.mpg.de. Retrieved on 2011-12-08.
  24. ^ a b Simpson, Isobel J.; Sulbaek Andersen, Mads P.; Meinardi, Simone; Bruhwiler, Lori; Blake, Nicola J.; Helmig, Detlev; Rowland, F. Sherwood; Blake, Donald R. (2012). "Long-term decline of global atmospheric ethane concentrations and implications for methane" (PDF). Nature. 488 (7412): 490–494. Bibcode:2012Natur.488..490S. doi:10.1038/nature11342. PMID 22914166.
  25. ^ Kort, E. A.; Smith, M. L.; Murray, L. T.; Gvakharia, A.; Brandt, A. R.; Peischl, J.; Ryerson, T. B.; Sweeney, C.; Travis, K. (2016). "Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift". Geophysical Research Letters. 43: 4617–4623. Bibcode:2016GeoRL..43.4617K. doi:10.1002/2016GL068703.
  26. ^ "One oil field a key culprit in global ethane gas increase". University of Michigan. April 26, 2016.
  27. ^ a b Aydin, Kamil Murat; Williams, M.B. and Saltzman, E.S.; ‘Feasibility of reconstructing paleoatmospheric records of selected alkanes, methyl halides, and sulfur gases from Greenland ice cores’; Journal of Geophysical Research; volume 112, D07312
  28. ^ Brown, Bob; et al. (2008). "NASA Confirms Liquid Lake on Saturn Moon". NASA Jet Propulsion Laboratory.
  29. ^ Brown, R. H.; Soderblom, L. A.; Soderblom, J. M.; Clark, R. N.; Jaumann, R.; Barnes, J. W.; Sotin, C.; Buratti, B.; et al. (2008). "The identification of liquid ethane in Titan's Ontario Lacus". Nature. 454 (7204): 607–10. Bibcode:2008Natur.454..607B. doi:10.1038/nature07100. PMID 18668101.
  30. ^ Mumma, Michael J.; et al. (1996). "Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin". Science. 272 (5266): 1310–1314. Bibcode:1996Sci...272.1310M. doi:10.1126/science.272.5266.1310. PMID 8650540.
  31. ^ Stern, A. (November 1, 2006). "Making Old Horizons New". The PI's Perspective. Johns Hopkins University Applied Physics Laboratory. Archived from the original on August 20, 2011. Retrieved 2007-02-12.

External links

1,2-Bis(diphenylphosphino)ethane

1,2-Bis(diphenylphosphino)ethane (dppe) is an organophosphorus compound with the formula (Ph2PCH2)2 (Ph = phenyl). It is a commonly used bidentate ligand in coordination chemistry. It is a white solid that is soluble in organic solvents.

1,2-Dichloroethane

The chemical compound 1,2-dichloroethane commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vinyl chloride, which is used to make polyvinyl chloride (PVC) pipes, furniture and automobile upholstery, wall coverings, housewares, and automobile parts.1,2-Dichloroethane is also used generally as an intermediate for other organic chemical compounds and as a solvent. It forms azeotropes with many other solvents, including water (b.p. 70.5 °C) and other chlorocarbons.

3,4-Methylenedioxyphentermine

3,4-Methylenedioxyphentermine (MDPH) is a lesser-known psychedelic drug. MDPH was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the dosage range is listed as 160–240 mg, and the duration as 3–5 hours. MDPH's effects are very similar to those of MDA: they both are smooth and "stoning," and do not cause any visuals. They also alter dreams and dream patterns. Shulgin describes MDPH as a promoter; it promotes the effects of other drugs, similarly to 2C-D. Very little data exists about the pharmacological properties, metabolism, and toxicity of MDPH.

Cyclopropylmescaline

CPM, or 4-cyclopropylmethoxy-3,5-dimethoxy-phenethylamine, is a lesser-known psychedelic drug. CPM was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the dosage range is listed as 60–80 mg, and the duration listed as 12–18 hours. CPM produces powerful closed-eye imagery, visuals, and fantasies. It also causes enhancement of music. Very little data exists about the pharmacological properties, metabolism, and toxicity of CPM.

DDT

Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochlorine, originally developed as an insecticide, and ultimately becoming infamous for its environmental impacts. It was first synthesized in 1874 by the Austrian chemist Othmar Zeidler. DDT's insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to control malaria and typhus among civilians and troops. Müller was awarded the Nobel Prize in Physiology or Medicine "for his discovery of the high efficiency of DDT as a contact poison against several arthropods" in 1948.By October 1945, DDT was available for public sale in the United States. Although it was promoted by government and industry for use as an agricultural and household pesticide, there were also concerns about its use from the beginning. Opposition to DDT was focused by the 1962 publication of Rachel Carson's book Silent Spring. It cataloged environmental impacts that coincided with widespread use of DDT in agriculture in the United States, and it questioned the logic of broadcasting potentially dangerous chemicals into the environment with little prior investigation of their environmental and health effects. The book claimed that DDT and other pesticides had been shown to cause cancer and that their agricultural use was a threat to wildlife, particularly birds. Its publication was a seminal event for the environmental movement and resulted in a large public outcry that eventually led, in 1972, to a ban on DDT's agricultural use in the United States. A worldwide ban on agricultural use was formalized under the Stockholm Convention on Persistent Organic Pollutants, but its limited and still-controversial use in disease vector control continues, because of its effectiveness in reducing malarial infections, balanced by environmental and other health concerns.

Along with the passage of the Endangered Species Act, the United States ban on DDT is a major factor in the comeback of the bald eagle (the national bird of the United States) and the peregrine falcon from near-extinction in the contiguous United States.

Dichlorodiphenyldichloroethane

Dichlorodiphenyldichloroethane (DDD) is an organochlorine insecticide that is slightly irritating to the skin. DDD is a metabolite of DDT. DDD is colorless and crystalline; it is closely related chemically and is similar in properties to DDT, but it is considered to be less toxic to animals than DDT. The molecular formula for DDD is (ClC6H4)2CHCHCl2 or C14H10Cl4, whereas the formula for DDT is (ClC6H4)2CHCCl3 or C14H9Cl5.

DDD is in the “Group B2” classification, meaning that it is a probable human carcinogen. This is based on an increased incidence of lung tumors in male and female mice, liver tumors in male mice, and thyroid tumors in male rats. Further basis is that DDD is so similar to and is a metabolite of DDT, another probable human carcinogen.DDD is no longer registered for agricultural use in the United States, but the general population continues to be exposed to it due to its long persistence time. The primary source of exposure is oral ingestion of food.1946 is the date of the earliest recorded use in English of the abbreviation “DDD” to stand for dichlorodiphenyldichloroethane, as far as could be determined.

Ethyl methanesulfonate

Ethyl methanesulfonate (EMS) is a mutagenic, teratogenic, and possibly carcinogenic organic compound with formula C3H8SO3. It produces random mutations in genetic material by nucleotide substitution; particularly by guanine alkylation. This typically produces only point mutations. It can induce mutations at a rate of 5x10−4 to 5x10−2 per gene without substantial killing. The ethyl group of EMS reacts with guanine in DNA, forming the abnormal base O6-ethylguanine. During DNA replication, DNA polymerases that catalyze the process frequently place thymine, instead of cytosine, opposite O6-ethylguanine. Following subsequent rounds of replication, the original G:C base pair can become an A:T pair (a transition mutation). This changes the genetic information, is often harmful to cells, and can result in disease.

EMS is often used in genetics as a mutagen. Mutations induced by EMS can then be studied in genetic screens or other assays.

Ethylene glycol

Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound with the formula (CH2OH)2. It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, sweet-tasting, viscous liquid. Ethylene glycol is toxic. Household pets are especially susceptible to ethylene glycol poisoning from vehicle antifreeze leaks.

Ethylenediamine

Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a strongly basic amine. It is a widely used building block in chemical synthesis, with approximately 500,000 tonnes produced in 1998. Ethylenediamine readily reacts with moisture in humid air to produce a corrosive, toxic and irritating mist, to which even short exposures can cause serious damage to health (see safety). Ethylenediamine is the first member of the so-called polyethylene amines.

Glyoxal

Glyoxal is an organic compound with the chemical formula OCHCHO. It is the smallest dialdehyde (a compound with two aldehyde groups). It is a crystalline solid, white at low temperatures and yellow near the melting point (15 °C). The liquid is yellow, and the vapor is green.Pure glyoxal is not commonly encountered because it forms hydrates, which oligomerize. For many purposes, these hydrated oligomers behave equivalently to glyoxal. It is produced industrially as a precursor to many products.

Hexachloroethane

Hexachloroethane, also known as perchloroethane (PCA), C2Cl6, is a white crystalline solid at room temperature with a camphor-like odor. It has been used by the military in smoke compositions, such as base-eject smoke munitions (smoke grenades).

Hyperconjugation

In organic chemistry, hyperconjugation is the interaction of the electrons in a sigma orbital (e.g. C–H or C–C) with an adjacent empty (or partially filled) non-bonding or antibonding σ or π orbital to give an extended molecular orbital. Increased electron delocalization associated with hyperconjugation increases the stability of the system. Only electrons in bonds that are in the β position can have this sort of direct stabilizing effect—donating from a sigma bond on an atom to an orbital in another atom directly attached to it. However, extended versions of hyperconjugation (such as double hyperconjugation) can be important as well. The Baker–Nathan effect, sometimes used synonymously for hyperconjugation, is a specific application of it to certain chemical reactions or types of structures.

Methoxychlor

Methoxychlor is a synthetic organochloride insecticide, now obsolete.

Methylenedioxydimethylamphetamine

3,4-Methylenedioxy-N,N-dimethylamphetamine (MDDM) is a lesser-known psychedelic drug. It is also the N,N-dimethyl analog of 3,4-methylenedioxyamphetamine (MDA). MDDM was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the dosage is unspecified and the duration unknown. MDDM produces only mild effects that are not well characterized in PiHKAL. Very little data exists about the pharmacological properties, metabolism, and toxicity of MDDM. This compound is however occasionally encountered as an impurity in 3,4-methylenedioxy-N-methylamphetamine (MDMA) which has been synthesized by methylation of MDA using methylating reagents such as methyl iodide. An excess of reagent or a reaction temperature that is too high results in some double methylation of the amine nitrogen, yielding MDDM as well as MDMA. The presence of MDDM as an impurity can thus reveal which synthetic route was used to manufacture seized samples of MDMA.

Methylenedioxyhydroxyethylamphetamine

MDHOET, or 3,4-methylenedioxy-N-hydroxyethylamphetamine, is a lesser-known psychedelic drug and a substituted amphetamine. It is also the N-hydroxyethyl analogue of MDA. MDHOET was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the minimum dosage is listed as 50 mg. MDHOET produces few to no effects. Very little data exists about the pharmacology, pharmacokinetics, effects, and toxicity of MDHOET.

Pennsylvania Shell ethylene cracker plant

The Pennsylvania Shell ethylene cracker plant is a chemical plant under construction in Potter Township, Pennsylvania near Pittsburgh that will be owned and operated by Shell Oil Company, the American subsidiary of supermajor oil company Royal Dutch Shell. The plant is being constructed near the interchange of Interstate 376 and Pennsylvania Route 18, expecting to open in the early 2020s.

Succinic acid

Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. The name derives from Latin succinum, meaning amber. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological roles as a metabolic intermediate being converted into fumarate by the enzyme succinate dehydrogenase in complex 2 of the electron transport chain which is involved in making ATP, and as a signaling molecule reflecting the cellular metabolic state. It is marketed as food additive E363. Succinate is generated in mitochondria via the tricarboxylic acid cycle (TCA), an energy-yielding process shared by all organisms. Succinate can exit the mitochondrial matrix and function in the cytoplasm as well as the extracellular space, changing gene expression patterns, modulating epigenetic landscape or demonstrating hormone-like signaling. As such, succinate links cellular metabolism, especially ATP formation, to the regulation of cellular function. Dysregulation of succinate synthesis, and therefore ATP synthesis, happens in some genetic mitochondrial diseases, such as Leigh syndrome, and Melas syndrome, and degradation can lead to pathological conditions, such as malignant transformation, inflammation and tissue injury.

Vinyl chloride

Vinyl chloride is an organochloride with the formula H2C=CHCl that is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). About 13 billion kilograms are produced annually. VCM is among the top twenty largest petrochemicals (petroleum-derived chemicals) in world production. The United States currently remains the largest VCM manufacturing region because of its low-production-cost position in chlorine and ethylene raw materials. China is also a large manufacturer and one of the largest consumers of VCM. Vinyl chloride is a gas with a sweet odor. It is highly toxic, flammable, and carcinogenic. It can be formed in the environment when soil organisms break down chlorinated solvents. Vinyl chloride that is released by industries or formed by the breakdown of other chlorinated chemicals can enter the air and drinking water supplies. Vinyl chloride is a common contaminant found near landfills. In the past VCM has been used as a refrigerant.

Β-Methylphenethylamine

β-Methylphenethylamine (β-Me-PEA, BMPEA), or 1-amino-2-phenylpropane, is an organic compound of the phenethylamine class, and a positional isomer of the drug amphetamine, with which it shares some properties. In particular, both amphetamine and β-methylphenethylamine are human TAAR1 agonists. In appearance, it is a colorless or yellowish liquid.

Relatively little information has been published about this substance. Hartung and Munch reported that it had good antihypotensive (pressor) activity in experimental animals, and that it was orally active. The MLD (minimum lethal dose) for the HCl salt was given as 500 mg/kg (rat, s.c.) and 50 mg/kg (rabbit, i.v.).A study by Graham and co-workers at the Upjohn Co., comparing a large number of β-methylphenethylamines substituted on the benzene ring showed that β-methylphenethylamine itself had 1/700 x the pressor activity of epinephrine, corresponding to ~ 1/3 the potency of amphetamine. The β-methyl compound also had ~ 2 x the broncho-dilating power of amphetamine (as measured using the isolated rabbit lung), and an LD50 of 50 mg/kg (rat, i.v.).

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.