isoprene

2-methyl-1,3-butadiene

(ī`səprēn, byo͞o'tədī`ēn), colorless liquid organic compound. It is a hydrocarbon, and is insoluble in water but soluble in many organic solvents; it boils at 34&degC;. The isoprene molecule contains two double bonds. It is readily polymerized by the use of special catalysts; large numbers of isoprene molecules join together to form a single large, threadlike polyisoprene molecule. Isoprene polymers also occur naturally. The natural rubber caoutchouc is cis-1,4-polyisoprene, and trans-1,4-polyisoprene is present in the natural rubbers balata and gutta-percha. (The cis and trans polyisoprenes are structural isomers.)

Isoprene

(2-methyl-l, 3-butadiene), an unsaturated aliphatic hydrocarbon, CH₂=C(CH₃)—CH=CH₂. It is a colorless, mobile, highly volatile inflammable liquid with a characteristic odor. Its melting point is — 145.95°C; boiling point, 34.067°C; flash point, -48°C; density, 0.681 g/cm³ (20°C); refractive index n_D²⁰, 1.42194; and heat of polymerization, —74.9 kJ/mole (—17.9 kcal/mole). Mixtures of isoprene and air are explosive at volume concentrations of 1.66–11.5 percent. Isoprene is insoluble in water but readily soluble in most hydrocarbon solvents. It forms binary azeotropes with such compounds as methanol, ethanol, acetone, diethyl ether, and carbon disulfide, as well as ternary azeotropes, for example, with acetone and water. Addition occurs readily between isoprene and hydrogen, halogens, hydrogen halides, and primary and secondary amines across the double bonds. An important property of isoprene is the capacity to easily polymerize and copolymerize, for example, with butadiene, styrene, acrylonitrile, and propylene.

The basic industrial methods of preparing isoprene are (1) the reaction of isobutylene with formaldehyde to give 4, 4-dimethyl-1, 3-dioxane, followed by catalytic decomposition of the latter to isoprene and formaldehyde (the so-called dioxane method); (2) the catalytic dehydrogenation of isopentane and isoamylenes; and (3) dimerization of propylene to 2-methyl-l-pentene, followed by isomerization to 2-methyl-2-pentene, followed by pyrolysis (650°-800°C) to isoprene. In addition, isoprene can be separated from the gases resulting during the thermal decomposition of petroleum products (from a C₅ fraction of the byproducts of ethylene production).

Isoprene is stored in the presence of inhibitors, such as hydroquinone, to prevent spontaneous polymerization. In high concentrations isoprene acts as a narcotic; in low concentrations it stimulates the mucous membrane. The maximum permissible concentration of isoprene in air is 40 mg/m³. Isoprene is used to make isoprene rubbers and butyl rubber.

isoprene

[′ī·sə‚prēn] (organic chemistry) C₅H₈ A conjugated diolefin; a mobile, colorless liquid having a boiling point of 34.1°C; insoluble in water, soluble in alcohol and ether; polymerizes readily to form dimers and high-molecular-weight elastomer resins.

isoprene

[i´so-prēn] an unsaturated, branched-chain, five-carbon hydrocarbon that is the molecular unit of isoprenoid compounds.

i·so·prene

(ī'sō-prēn), 2-Methyl-1,3-butadiene; an unsaturated five-carbon hydrocarbon with a branched chain, which in the plant and animal kingdom is used as the basis for the formation of isoprenoids, for example, terpenes, carotenoids and related pigments, rubber. Fat-soluble vitamins either are isoprenoid or have isoprenoid side chains; steroids are synthesized via isoprenoid intermediates, as are ubiquinone, dolichol, and prenylated proteins.

i·so·prene

(ī'sō-prēn) An unsaturated five-carbon hydrocarbon with a branched chain, the basis for the formation of isoprenoids (terpenes, carotenoids, and rubber). Fat-soluble vitamins either are isoprenoid or have isoprenoid side chains; steroids are synthesized through isoprenoid intermediates.

单词	isoprene
释义	isoprene i·so·prene I0255700 (ī′sə-prēn′)n. A colorless volatile liquid, C₅H₈, used chiefly to make synthetic rubber. [iso- + pr(opyl)ene.] i′so·pre′noid′ (-prē′noid′) adj. isoprene (ˈaɪsəʊˌpriːn) n (Elements & Compounds) a colourless volatile liquid with a penetrating odour: used in making synthetic rubbers. Formula: CH2:CHC(CH3):CH2. Systematic name: methylbuta-1,3-diene [C20: from iso- + pr(opyl) + -ene] i•so•prene (ˈaɪ səˌprin) n. a volatile liquid, C₅H₈, of the terpene class: used chiefly in the manufacture of synthetic rubber. [1860] Translations изопрен isoprene isoprene or 2-methyl-1,3-butadiene (ī`səprēn, byo͞o'tədī`ēn), colorless liquid organic compound. It is a hydrocarbon, and is insoluble in water but soluble in many organic solvents; it boils at 34&degC;. The isoprene molecule contains two double bonds. It is readily polymerized by the use of special catalysts; large numbers of isoprene molecules join together to form a single large, threadlike polyisoprene molecule. Isoprene polymers also occur naturally. The natural rubber caoutchouc is cis-1,4-polyisoprene, and trans-1,4-polyisoprene is present in the natural rubbers balata and gutta-percha. (The cis and trans polyisoprenes are structural isomers.) Isoprene (2-methyl-l, 3-butadiene), an unsaturated aliphatic hydrocarbon, CH₂=C(CH₃)—CH=CH₂. It is a colorless, mobile, highly volatile inflammable liquid with a characteristic odor. Its melting point is — 145.95°C; boiling point, 34.067°C; flash point, -48°C; density, 0.681 g/cm³ (20°C); refractive index n_D²⁰, 1.42194; and heat of polymerization, —74.9 kJ/mole (—17.9 kcal/mole). Mixtures of isoprene and air are explosive at volume concentrations of 1.66–11.5 percent. Isoprene is insoluble in water but readily soluble in most hydrocarbon solvents. It forms binary azeotropes with such compounds as methanol, ethanol, acetone, diethyl ether, and carbon disulfide, as well as ternary azeotropes, for example, with acetone and water. Addition occurs readily between isoprene and hydrogen, halogens, hydrogen halides, and primary and secondary amines across the double bonds. An important property of isoprene is the capacity to easily polymerize and copolymerize, for example, with butadiene, styrene, acrylonitrile, and propylene. The basic industrial methods of preparing isoprene are (1) the reaction of isobutylene with formaldehyde to give 4, 4-dimethyl-1, 3-dioxane, followed by catalytic decomposition of the latter to isoprene and formaldehyde (the so-called dioxane method); (2) the catalytic dehydrogenation of isopentane and isoamylenes; and (3) dimerization of propylene to 2-methyl-l-pentene, followed by isomerization to 2-methyl-2-pentene, followed by pyrolysis (650°-800°C) to isoprene. In addition, isoprene can be separated from the gases resulting during the thermal decomposition of petroleum products (from a C₅ fraction of the byproducts of ethylene production). Isoprene is stored in the presence of inhibitors, such as hydroquinone, to prevent spontaneous polymerization. In high concentrations isoprene acts as a narcotic; in low concentrations it stimulates the mucous membrane. The maximum permissible concentration of isoprene in air is 40 mg/m³. Isoprene is used to make isoprene rubbers and butyl rubber. isoprene [′ī·sə‚prēn] (organic chemistry) C₅H₈ A conjugated diolefin; a mobile, colorless liquid having a boiling point of 34.1°C; insoluble in water, soluble in alcohol and ether; polymerizes readily to form dimers and high-molecular-weight elastomer resins. isoprene isoprene [i´so-prēn] an unsaturated, branched-chain, five-carbon hydrocarbon that is the molecular unit of isoprenoid compounds. i·so·prene (ī'sō-prēn), 2-Methyl-1,3-butadiene; an unsaturated five-carbon hydrocarbon with a branched chain, which in the plant and animal kingdom is used as the basis for the formation of isoprenoids, for example, terpenes, carotenoids and related pigments, rubber. Fat-soluble vitamins either are isoprenoid or have isoprenoid side chains; steroids are synthesized via isoprenoid intermediates, as are ubiquinone, dolichol, and prenylated proteins. i·so·prene (ī'sō-prēn) An unsaturated five-carbon hydrocarbon with a branched chain, the basis for the formation of isoprenoids (terpenes, carotenoids, and rubber). Fat-soluble vitamins either are isoprenoid or have isoprenoid side chains; steroids are synthesized through isoprenoid intermediates.
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isoprene

i·so·prene

isoprene

i•so•prene

isoprene

isoprene

2-methyl-1,3-butadiene

Isoprene

isoprene

isoprene

isoprene

i·so·prene

i·so·prene