| 词条 | Isobutylene |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 451537760 | ImageFile1 = Isobutylene-2D-skeletal.png | ImageName1 = Skeletal formula of isobutylene | ImageSize1 = 200px | ImageFileL2 = Isobutylene-3D-balls.png | ImageNameL2 = Ball-and-stick model of isobutylene | ImageFileR2 = Isobutylene-3D-vdW.png | ImageNameR2 = Space-filling model of isobutylene | PIN = 2-Methylprop-1-ene | OtherNames = 2-Methylpropene Isobutene γ-Butylene 2-Methylpropylene Methylpropene |Section1={{Chembox Identifiers | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C4H8/c1-4(2)3/h1H2,2-3H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = VQTUBCCKSQIDNK-UHFFFAOYSA-N | CASNo = 115-11-7 | CASNo_Ref = {{cascite|correct|CAS}} | UNNumber = 1055 In Liquefied petroleum gas: 1075 | EINECS = 204-066-3 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 7957 | PubChem = 8255 | ChEBI_Ref = {{ebicite|changed|EBI}} | ChEBI = 43907 | SMILES = CC(=C)C | UNII_Ref = {{fdacite|correct|FDA}} | UNII = QA2LMR467H | InChI = 1/C4H8/c1-4(2)3/h1H2,2-3H3 | RTECS = UD0890000 |Section2={{Chembox Properties | Properties_ref = [1] | C=4 | H=8 | MolarMass = 56.106 g/mol | Appearance = Colorless gas | Density = 0.5879 g/cm3, liquid | MeltingPtC = −140.3 | BoilingPtC = -6.9 | BoilingPt_notes = | Solubility = Insoluble | SolubleOther = | Solvent = | MagSus = -44.4·10−6 cm3/mol }} |Section7={{Chembox Hazards | Hazards_ref = [2] | GHSPictograms = {{GHS02|Flam. Gas 1}}{{GHS exclamation mark|Press. Gas}} | GHSSignalWord = DANGER | HPhrases = {{H-phrases|220}} | PPhrases = {{P-phrases|210|377|381|403}} | NFPA-H = 1 | NFPA-F = 4 | NFPA-R = 0 | NFPA-S = | FlashPt = flammable gas | AutoignitionPtC = 465 | AutoignitionPt_notes = | ExploLimits = 1.8–9.6% |Section8={{Chembox Related | OtherFunction = 1-Butene cis-2-Butene trans-2-Butene | OtherFunction_label = butenes | OtherCompounds = Isobutane }} Isobutylene (or 2-methylpropene) is a hydrocarbon of industrial significance. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. At standard temperature and pressure it is a colourless flammable gas. UsesIsobutylene is used as an intermediate in the production of a variety of products. It is reacted with methanol and ethanol in the manufacture of the gasoline oxygenates methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE), respectively. Alkylation with butane produces isooctane, another fuel additive (similarly, isobutylene can be dimerized to diisobutylene (DIB), then hydrogenated to make isooctane). Isobutylene is also used in the production of methacrolein. Polymerization of isobutylene produces butyl rubber (polyisobutylene or PIB). Antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are produced by Friedel-Crafts alkylation of phenols using isobutylene. ManufacturePolymer and chemical grade isobutylene is typically obtained by dehydrating tertiary butyl alcohol (TBA) or catalytic dehydrogenation of isobutane (Catofin or similar processes).[3] Gasoline oxygenates MTBE and ETBE are produced by reacting methanol or ethanol with isobutylene contained in butene streams from olefin steam crackers or refineries, or with isobutylene from dehydrated TBA. Isobutylene is not isolated from the olefin or refinery butene stream before the reaction as separating the ethers from the remaining butenes is simpler. Isobutylene can also be produced in high purities by "back-cracking" MTBE or ETBE at high temperatures and then separating the isobutylene by distillation from the much higher boiling resulting alcohols. By-productIsobutylene is the by-product of the ethenolysis of diisobutene to prepare neohexene.[4] (CH3)3C-CH=C(CH3)2 + CH2=CH2 → (CH3)3C-CH=CH2 + (CH3)2C=CH2 SafetyIsobutylene is a highly flammable gas and presents an explosion danger. Usually stored as a compressed, liquefied gas, if released it may produce an oxygen-deficient atmosphere that presents an asphyxiation hazard.[2] See also
References1. ^{{Merck11th|5024}}. 2. ^1 {{ICSC-ref|1027|name=Isobutene|date=April 2000}} 3. ^{{citation | title = Hydrocarbon Chemistry | first1 = George A. | last1 = Olah | authorlink1 = George Andrew Olah | first2 = Árpád | last2 = Molnár | publisher = Wiley-Interscience | isbn = 978-0-471-41782-8}}. 4. ^{{cite encyclopedia|title=Metathesis|encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology|authors=Lionel Delaude, Alfred F. Noels|publisher=Wiley}} External links
1 : Alkenes |
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