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解説
クロロプレン，脂肪族ハロゲン置換ジオレフィン類の一つ．工業的製法は，アセチレンを二量化してビニルアセチレンを合成し，これに塩化水素を付加する方法から，ブタジエンに塩素付加すると得られる3,4-ジクロロ-1-ブテンを，脱塩化水素して合成する方法へと転換している．重合すると得られる合成ゴムは，耐候性，耐老化性，耐油性，耐薬品性にすぐれている．揮発性の無色の液体．沸点59.4 ℃．0.9585．1.4583．各種有機溶剤に可溶，水に不溶．合成ゴム(クロロプレンゴム)の製造原料に用いられる．
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用途
乳化重合によるクロロプレンゴム(通称ネオプレン)は、耐油性、耐熱性、難燃性、強接着性を示し、ホース、ベルト、カバー、自動車内外装などに用いられる。
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主な用途／役割
クロロプレンゴムの原料。
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説明
Chloroprene, 2-chloro-1,3-butadiene, is a colorless, volatile
synthetic liquid that has a pungent ether-like odor. Synthesis
of chloroprene was first reported by chemists of the E. I. du
Pont de Nemours Company in 1931 following studies of
acetylene polymerization with the objective of producing
synthetic rubber. The chloroprene monomer differs from
isoprene, the fundamental monomer of natural rubber, only
by substitution of chlorine for the methyl group of isoprene.
Chloroprene was observed to polymerize much more
quickly than did isoprene. In industrial processes prior to
1960, chloroprene was produced in relatively high yields by
reacting vinyl acetylene with hydrogen chloride. Today,
chloroprene is produced more efficiently by chlorination of
1,3-butadiene.
When compared with natural rubber the chloroprene
synthetic polymer, polychloroprene, was noted to be much
denser, more resistant to water and hydrocarbon solvents,
less permeable to many gases, and was more resistant
to degradation by oxygen, ozone, hydrogen chloride,
hydrogen fluoride, and other chemicals. Due to desirable
physical and chemical properties, polychloroprene and its
latex polymers are produced in quantities exceeding
200 000 metric tons at a limited number of facilities
around the world. Chloroprene production is closely tied to
demand for polychloroprene.
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化学的特性
Chloroprene (2-chloro-1,3-butadiene) is a flammable, colorless liquid at room temperature with a characteristic ether-like odor. The Odor Threshold is 0.4 milligram per cubic meter. It is slightly soluble in water and more soluble in organic solvents. It has not been found to occur naturally. Chloroprene is very unstable and reacts in air with oxygen and other compounds to form epoxides, peroxides, and other hazardous compounds.
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使用
Manufacture of neoprene.
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調製方法
Chloroprene can be synthesized by addition of HCl to vinyl acetylene H2C=CH?C≡CH +HCl → H2C=CH?CCl=CH2, and by dehydrochlorination of dichlorobutenes or 2,2,3-trichlorobutane.
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定義
A colorless liquid derivative of
butadiene used in the manufacture of neoprene
rubber.
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製造方法
Preparation of chloroprene from butadiene
In this method, the following route is used:
In the first step, butadiene is chlorinated in the vapour phase at 330-420??
and atmospheric pressure. The main products are 3,4-dichloro-l-butene and
1,4-dichloro-2-butene in approximately equal amounts. The latter material is
then isomerized to the former by heating with a copper catalyst such as
cuprous chloride. The 3,4-dichloro-l-butene is dehydrochlorinated by treatment with 10% aqueous sodium hydroxide at 85??. Chloroprene is isolated
by distillation under reduced pressure in the presence of polymerization
inhibitors.
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一般的な説明
A clear colorless liquid. Flash point -4°F. May polymerize exothermically if heated or contaminated. If polymerization takes place inside a container, the container may rupture violently. Less dense than water. Vapors heavier than air. Used to make neoprene rubber.
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空気と水の反応
Highly flammable. Slightly soluble in water.
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反応プロフィール
CHLOROPRENE emits highly toxic fumes of chlorine gas when heated to decomposition. Autooxidizes very rapidly with air and, even at 0°C, produces unstable peroxides that catalyze exothermic polymerization [Bretherick, 5th ed., 1995, p. 507]. This reactivity is greatly slowed by presence of an inhibitor.
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危険性
Toxic by ingestion, inhalation, and skin
absorption. Flammable, dangerous fire risk, explosive limits in air 4.0–20%. Eye and upper respiratory
tract irritant. Possible carcinogen.
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健康ハザード
INHALATION: Fatigue, psychic changes, irritability, oppression in chest, occasionally substernal pain, tachycardia upon exertion. EYES: Can cause conjunctivitis, corneal necrosis and edema of eyelids. SKIN: May cause dermatitis and temporary loss of hair. Rapidly absorbed by skin.
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職業ばく露
The major use of chloroprene is in the production of artificial rubber (Neoprene, duprene); polychloroprene elastomers. Chloroprene is extremely reactive, e.g., it can polymerize spontaneously at room temperatures; the process being catalyzed by light, peroxides, and other free radical initiators. It can also react with oxygen to form polymeric peroxides and because of its instability, flammability, and toxicity, chloroprene has no end-product uses as such.
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発がん性
Chloroprene is reasonably anticipated to be a human carcinogen based on evidence of carcinogenicity from studies in experimental
animals.
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輸送方法
UN1991 Chloroprene, stabilized, Hazard Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous material.
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不和合性
Can form unstable peroxides; chloroprene may polymerize on standing with fire or explosion hazard. May form explosive mixture with air. Reacts with liquid or gaseous fluorine, alkali metals; metal powders, oxidizers, creating a fire or explosion hazard. Attacks some plastics, rubber, and coatings. May accumulate static electrical charges, and may cause ignition of its vapors.
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廃棄物の処理
Incineration, preferably after mixing with another combustible fuel. Care must be exercised to assure complete combustion to prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids produced.
