Name | Ethylene |
Synonyms | Ethylene ETHYLENE Ethylene,Ethene Ethylene,high purity Ethylene, compressed. ethylene refrigerated liquid |
CAS | 74-85-1 |
EINECS | 200-815-3 |
InChI | InChI=1/C2H4/c1-2/h1-2H2 |
Molecular Formula | C2H4 |
Molar Mass | 28.05 |
Density | 0.00126 |
Melting Point | −169°C(lit.) |
Boling Point | −104°C(lit.) |
Flash Point | -100°C |
Water Solubility | 90.91g/L(25 ºC) |
Vapor Presure | 35.04 atm ( 20 °C) |
Vapor Density | 0.97 (vs air) |
Appearance | Colorless gas |
Merck | 13,3825 |
BRN | 1730731 |
Stability | Stable. Highly flammable - note wide explosion limits. Incompatible with strong oxidizing agents. Readily forms explosive mixtures with air. |
Explosive Limit | 36% |
Refractive Index | 1.363 |
Physical and Chemical Properties | Properties: it is a colorless flammable gas at normal temperature and pressure, with a slight characteristic odor of hydrocarbons. boiling point 103.71 ℃ freezing point -169.4 ℃ relative density 0.00126 refractive index 1.363 |
Use | Ethylene is an important organic chemical basic raw materials, mainly used in the production of polyethylene, Ethylene Propylene Rubber, polyvinyl chloride |
Risk Codes | R12 - Extremely Flammable R67 - Vapors may cause drowsiness and dizziness |
Safety Description | S9 - Keep container in a well-ventilated place. S16 - Keep away from sources of ignition. S33 - Take precautionary measures against static discharges. S46 - If swallowed, seek medical advice immediately and show this container or label. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) |
UN IDs | UN 1962 2.1 |
WGK Germany | - |
RTECS | KU5340000 |
FLUKA BRAND F CODES | 4.5-31 |
HS Code | 29012100 |
Hazard Class | 2.1 |
Toxicity | LC for mice in air: 950,000 ppm (Flury) |
at normal temperature and pressure, colorless, flammable gas, with a little sweet taste and mildew. Gas relative density at o C and latm (Air 1)0.978. Boiling point -103.8 °c, melting point -169.4 °c. The flammable limit in air is 2.9% to 79.9% (VOL). Gas density 1.261kg/m3(0 °c, 0.10 MPa). Liquid density 567/m3(-103.8 °c). The critical temperature is 9. 900 ℃, the critical pressure is 5117.0 kPa, and the critical density is 22 8kg/m3. Triple point -16 9.15 ℃(0. 1014kPa). Latent heat of evaporation 484kj/kg, latent heat of melting 119 kj/kg. Gas specific heat capacity at 1.5 °c and 1 atm [kj/( kg. °C)]:Cpl. 516,Cvl. 220. Solubility in water at 0 ° C. 0.26 (volume ratio). The flammable limit in air is 2.7% ~ 36%. The spontaneous combustion temperature in the air is 490 degrees Celsius. Active chemical properties, can form an explosive mixture with air, extremely flammable and explosive. Can be in the sun and chlorine intense combination of explosion. Can strongly react with the oxidant, meet Mars, high heat, combustion gas has the danger of combustion explosion. Slightly soluble in alcohol, ketone, benzene, soluble in ether. At 25 °c, about 9 parts of water can dissolve 1 part of ethylene.
with industrial ethylene products as raw materials, the co-adsorption of impurities such as water, acetylene and carbon dioxide in ethylene was realized by using molecular sieve adsorbent.
high purity ethylene is widely used as a standard gas, calibration gas and standard mixture of ethylene.
ethylene is flammable and asphyxiating. Irritation of the mucous membranes of the eyes, nose, throat and respiratory tract is light and often disappears after several hours of contact. There were no side effects and sequelae after awakening. Liquid ethylene can cause skin burns. When inhaled 25% to 45% ethylene can make the pain disappeared, but the consciousness is not affected. Human inhalation of 70% ~ 90% of the mixture of ethylene and oxygen immediately caused anesthesia, no obvious period of excitement, wake up faster. Long-term exposure to low concentrations of ethylene have dizziness, Head Pain, burnout Fatigue, sleep disorders, palpitations, memory loss, thinking is not concentrated and other symptoms of neurasthenia and gastrointestinal disorders and other symptoms. Ethylene cylinders should be stored in a cool and well-ventilated place, away from heat sources, fire, and chlorine, oxidant separation. Storage temperature should not exceed 30 ℃. Ethylene cannot be stored with oxygen, chlorine, or other oxidants or combustible cylinders. The filling coefficient of the cylinder shall not be greater than 0. 28kg/L.
freezing point | -169.4 ℃ |
NIST chemical information | information provided by: webbook.nist.gov (external link) |
(IARC) carcinogen classification | 3 (Vol. Sup 7, 60) 1994 |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
Overview | ethylene is a compound consisting of two carbon atoms and four hydrogen atoms, the two carbon atoms being linked by a double bond. Is the simplest olefin, molecular formula CH2 = Ch2. Is the basic chemical raw materials of synthetic fiber, synthetic rubber, synthetic plastics (polyethylene and polyvinyl chloride), synthetic ethanol (alcohol), also used in the manufacture of vinyl chloride, styrene, ethylene oxide, acetic acid, acetaldehyde, ethanol and explosives, etc., a small amount in plants, is a metabolic product of plants, can slow down the growth of plants, promote the ripening of leaves and fruits. It is a colorless flammable gas at room temperature. Melting Point -169 °c, boiling point -103.7 °c. Almost insoluble in water, insoluble in ethanol, soluble in ether and acetone. The bond length of the C = C double bond in the ethylene molecule is 1.33 × 10-10 m, and the two carbon atoms and the four hydrogen atoms in the ethylene molecule are all in the same plane. The bond angle between them is about 120 °. The bond energy of the ethylene double bond is 615 kJ/mol, the bond length of the ethane C- C single bond is 1.54 × 10-10 m, and the bond energy is 348 kJ/mol. This indicates that the bond energy of a C = C double bond is not twice that of a C- C single bond, but is slightly less than twice that. Thus, less energy is required to break a bond in a double bond. This is the reason why the nature of ethylene is active and the addition reaction is likely to occur. In the process of forming ethylene molecules, each carbon atom hybridizes with 1 2s orbital and 2 2p orbitals to form 3 equivalent sp2 hybrid orbitals. The 3 sp2 hybrid orbitals are in the same plane, and the angle of each other is 120 degrees. Thus, five sigma bonds are formed in the ethylene molecule, four of which are C- H bonds (sp2-s)1 is a C- C bond (sp2-sp2); The remaining two carbon atoms do not participate in the hybridization of the two parallel p orbitals in the side overlap, forming another Chemical Bond: pi bond, and is perpendicular to the plane in which the Sigma key is located. For example, the C = C double bond in the ethylene molecule is formed by a sigma bond and a pi bond. The degree of orbital overlap of the two bonds is different. The π bond is formed by the overlap of p orbitals from the side, and the degree of overlap is smaller than that of the Sigma bond from the front, so the π bond is not as strong as the Sigma bond, and it is relatively easy to break, less energy is also required for fracture. |
important chemical raw materials | ethylene is an important chemical raw material, a large amount of ethylene is used to make polyethylene, followed by ethylene oxide, styrene, acetaldehyde, ethanol, vinyl chloride, etc. The production of ethylene in industry mainly takes Petroleum as raw material and adopts tubular furnace cracking method to separate ethylene from cracking gas. In addition, ethylene can also be separated from the coke oven gas. Ethylene is prepared in the laboratory and can be obtained by dehydration of ethanol. after the Second World War, with the development of the oil industry, the production of ethylene in the world has been rising linearly. At present, ethylene products account for about half of the output value of all petrochemical products in the world. Therefore, the level of development of the petrochemical industry is often measured by the level of ethylene production. China's petrochemical industry is in the development of Daqing, Shengli, North China, Dagang, Karamay and other large oil fields, the realization of the basic self-supply oil developed after. In 1965, China's ethylene production achieved zero breakthrough, with an annual output of 3 000 tons of ethylene. In 1973, China introduced a large-scale plant with an annual output of 300,000 tons of ethylene, in this way, China's petrochemical industry has gradually developed. In 1983the annual production of ethylene was 650,000 tons. In 1989, it developed to an annual output of 1.65 million tons, ranking ninth in the world. At present, China has four projects with an annual output of 300,000 tons of ethylene. They are Daqing ethylene project, Nanjing Yangtze ethylene project, Qilu ethylene project and Shanghai ethylene project. |
raw materials for ethylene production | the selection of raw materials for ethylene production is a major technical and economic problem, the yields of ethylene and by-products are also different. This not only affects the investment and production cost of the ethylene plant, but also affects the production organization and management of the petrochemical industry, the selection of the production process route, and the stable production of the plant, and the production capacity and the effect of investment. The resource condition is the first factor to consider which raw material is used in a country. The United States is rich in wet natural gas resources, rich in light alkanes, and has developed natural gas processing industry. For a long time, light hydrocarbons recovered from wet natural gas have been used as raw materials for the production of ethylene. The North Sea coastal countries (such as the United Kingdom, Norway, etc.) in the development of the North Sea oilfield gas process, can obtain a part of light alkanes, so these countries use it as a raw material for ethylene. Some countries, such as Japan, do not have their own oil resources, but because of the stable supply of oil from the international community, it is possible to use imported oil. Western Europe, Japan imports oil mainly from the Middle East, the Middle East crude oil light component is more, naphtha fraction usually accounts for about 20% of crude oil. This naphtha has a low octane number and is not suitable for motor gasoline. Naphtha was once a residual fraction, which is one of the main reasons for the use of naphtha as a raw material for ethylene in Japan, Western Europe and other countries. |
A hormone synthesized in plants | at the end of the 19th century, it was found that the smoke caused by the burning of Canna detritus could promote the flowering of Baltic in the greenhouse, ignition of the coal furnace will also make the green lemon in the greenhouse gradually yellow mature. The substance that promotes fruit ripening was not discovered by scientists until the 60s of the 20th century. Ethylene is formed by the transformation and decomposition of methionine in plants. It is present in all parts of plants, and the content is very low. Temperature and oxygen concentration can affect the formation of ethylene. Under adversity, ethylene in the body is doubled or tens of times increased, which can cause accelerated senescence and shedding of organs, so that other parts of the plant are better preserved. This phenomenon is a defensive mechanism acquired by plants during long-term evolution. The most obvious biological effect of ethylene is to cause a "triple response", that is, to inhibit the elongation and growth of the stem, to promote the thickening of the stem and the negative disappearance of the stem, showing the horizontal direction of growth. Ethylene has accelerated ripening effect on fruit, can regulate the flowering period of plants, increase the number of female flowers, change the sex of the melon, and promote the germination of bulbs and bulbs. Ethylene can also improve cell membrane permeability, enhance respiratory intensity, promote RNA synthesis and transcription, improve the activity of peroxidase and cellulase enzymes. due to the inconvenience of using ethylene as a gas, China began to artificially synthesize ethephon (2-chloroethyl phosphate) and its esters with higher activity in 1970. This is a kind of liquid compound with the same function as ethylene, which can release ethylene gas at pH 4.1 and can be used for fruits (including tomato, citrus, pear, peach, banana, Persimmon, watermelon, etc.) the ripening, accelerating the shedding of old leaves of cotton. Pumpkin and other seedlings 1~4 leaves, spraying 100~200 ppm ethephon, can make the female flower node decreased, increase the number of female flowers. The dilution of ethephon is applied to the part under the cutting line of the rubber trunk, which can prolong the flow time and increase the yield of rubber. |
physiological effect | inhibits elongation growth, promotes coarsening and changes geotropism of etiolated pea seedlings (triple response) and the partial response of the leaves is a specific biological effect of ethylene, which is often used as a biological identification method. The most significant physiological role of ethylene is to initiate and promote the maturation, senescence, wilting and abscission of organs and tissues (fruit, Crown, leaf). Other effects include promoting flowering; Inducing the formation of female flowers; Breaking the dormancy of some seeds; Inhibiting the opening of seedling tip hook; Inhibiting root growth; Inducing the formation of adventitious roots and root hairs; Promoting the proliferation of skin holes; increased plant excretion. In general, the threshold value of the physiological effect of ethylene is 0.01ppm, the half-maximal reaction value is 0.1ppm, and 10ppm reaches saturation. |
biosynthetic pathway | in 1964, M. Liberman et al. proposed that ethylene is derived from methionine. In1979 Adams (D.A.Ada-ms) and Yang (S. F. Yang) discovered 1-aminocyclopropanecarboxylic acid (ACC) as a direct precursor of ethylene production and identified the pathway of ethylene biosynthesis in plants: methionine → adenosylmethionine (SAM)→ ACC → ethylene. ACC synthase, which catalyzes the formation of ACC from SAM, is the main rate-limiting factor of ethylene production. Aminoethoxyethylene glycine (AVG) and ammonoacetic acid (AOA) can effectively inhibit this reaction. ACC can also form the conjugate malonyl ACC(MACC). |
regulation of distribution and formation in vivo | almost all tissues of higher plants produce trace amounts of ethylene, ethylene production is high in germinating seeds and in rapidly growing meristems. Many fungi can also produce ethylene. Fruit and other organs mature, senescence and abscission of ethylene production in the tissue, the concentration of up to several orders of magnitude. Auxin promotes ethylene production as high as 3 400 NL/g · When The Orchid begins to wilt. Drought, waterlogging, extreme temperature, chemical damage and mechanical damage can stimulate the increase of ethylene in plants, known as "stress ethylene", will accelerate the aging and shedding of organs. |
Application | early production in the use of ethylene fumigation ripening bananas. Ethylene fumigation has been widely used for ripening of bananas, Degreening of citrus and lemon, and accelerating flue-cured tobacco. Liquid ethylene release agent ethephon is more convenient and extensive in application, in the field ripening tomato, cotton and tobacco can be early harvest, improve quality, and can make mature consistent, easy to mechanical harvest. For the melon can increase the number of female flowers, early seed and increase yield. In addition, it can also stimulate the rubber tree to secrete latex, induce pineapple flowering, increase sugar content in sugarcane and for thinning flowers and fruits. The technology of inhibiting the production and action of ethylene (such as controlled atmosphere storage) has also been widely used for the preservation of fruits, vegetables, flowers and seedlings during storage and transportation. |
uses | ethylene is an important organic chemical basic raw materials, mainly used in the production of polyethylene, ethylene-propylene rubber, PVC and other petrochemical one of the most basic raw materials. In terms of synthetic materials, a large number of used in the production of polyethylene, vinyl chloride and polyvinyl chloride, ethylbenzene, styrene and polystyrene and Ethylene Propylene Rubber; In organic synthesis, widely used in the synthesis of ethanol, ethylene oxide and ethylene glycol, acetaldehyde, acetic acid, propionaldehyde, propionic acid and its derivatives and other basic organic synthesis raw materials; Halogenated, chlorinated ethylene, chlorinated ethane, bromoethane; Oligomerization can produce α-olefin, and then the production of higher alcohols, alkylbenzene and so on. mainly used as standard gas for analytical instruments in petrochemical enterprises |
production methods | the industrial ethylene production methods include petroleum hydrocarbon cracking, ethanol catalytic dehydration, coke oven gas separation, etc. Due to the abundance of oil and gas resources, large-scale production of ethylene is low in cost and good in quality. Therefore, a large amount of ethylene is mainly produced by a petroleum cracking process. The ethanol catalytic dehydration method is limited to the situation where a small amount of ethylene is supplied to fine chemicals. |
category | hazardous gas |
toxicity grade | low toxicity |
Acute toxicity | inhalation-mammalian LCL0 950000 PPM/2 min |
explosive hazard characteristics | mixture explosive with Air |
flammability hazard characteristics | flammable; Spicy and irritating smoke emitted from fire scene; Prevention of scald |
storage and transportation characteristics | The warehouse is ventilated and dried at low temperature; It is stored separately from the oxidant |
fire extinguishing agent | foam, carbon dioxide |
Occupational Standard | TWA 11500 mg/m3 |
spontaneous combustion temperature | 842 ° F. |
DOT Classification | 2.1 (Flammable gas) |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |