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外観
白色/無色～ほとんど白色/ほとんど無色粉末～塊～透明液体
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性質
メタクリル酸は，無色の柱状結晶または液体で、刺激臭をもつ。水には常温で18％ほど溶け、エタノール（エチルアルコール）、エーテルなどの有機溶媒によく溶ける。酢酸よりも強い酸性を示す。重合をおこしやすく、長時間放置するだけで徐々に重合し、酸を数滴加えると速やかに重合する。激臭のある無色の結晶。融点16℃，沸点160.5℃。水，アルコールなどに易溶。不安定で光，熱，触媒によって容易に重合して，水溶性高分子化合物ポリメタクリル酸になる。メタクリル酸エステルなどはプラスチック原料として重要。
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定義
本品は、次の化学式で表される有機化合物である。
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解説
2-methyl-2-propenoic acid．C4H6O2(86.09)．CH2=C(CH3)COOH．α-メチルアクリル酸ともいう．アセトンシアノヒドリンを硫酸で加水分解するか，メタクロレインを酸化しても得られる．工業的製法として，イソブチレンまたはtert-ブチルアルコールの空気酸化による方法がある．無色の針状結晶．融点16 ℃，沸点160.5 ℃，81 ℃(4 kPa)．d204 1.0153．n20D 1.4314．pKa 4.66．引火点77 ℃．温水に可溶，エーテル，アルコールに易溶．加熱や痕跡の塩酸の存在下で容易に重合するので，重合防止剤として0.1％ のヒドロキノンを加えて保存する．還元するとイソ酪酸に，臭化水素を付加するとα-ブロモイソ酪酸になる．刺激臭があり，酢酸より酸性が強く，腐食性で，皮膚などに強い刺激性がある．水溶性高分子，イオン交換樹脂の原料として用いるほか，メチルエステルは有機ガラスの製造原料となる．[CAS 79-41-4]
森北出版「化学辞典（第2版）
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用途
主に塗料や接着剤、皮革処理剤、イオン交換樹脂などの原料となります。
- 塗料
- 接着剤
- 繊維処理剤
- ゴム改質剤
- 皮革処理剤
- 紙加工剤
- 潤滑油添加剤
- セメント混和剤
- その他
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用途
メタクリル酸2-エチルヘキシル合成原料、メタクリル酸N-ブチル合成原料、メタクリル酸グリシジル合成原料、メタクリル酸エステル合成原料、熱硬化性塗料、接着剤、ラテックス改質剤原料
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用途
コーティング剤、接着剤、樹脂改質剤
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製造法
メタクリル酸は，不飽和脂肪酸の一つ。α(アルファ)-メチルアクリル酸ともいう。1937年に開発されたアセトンシアノヒドリン法により、アセトンにシアン化水素を付加させてアセトンシアノヒドリンにしたのち、硫酸により脱水・加水分解して製造していた。しかし、シアン化水素は猛毒で入手や廃酸処理がむずかしいので、現在では、モリブデン系触媒を用いてイソブチレン（2-メチルプロペン）を空気酸化して合成している。工業的にはイソブチレンまたはt-ブチルアルコールの酸化によってつくる。
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化粧品の成分用途
可塑剤、人工爪剤
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説明
Methacrylic acid, abbreviated MAA, is an organic compound. This colourless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA) and poly(methyl methacrylate) (PMMA). The methacrylates have numerous uses, most notably in the manufacture of polymers with trade names such as Lucite and Plexiglas. MAA occurs naturally in small amounts in the oil of Roman chamomile.
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化学的特性
Methacrylic acid is is a colorless, moderately volatile, corrosive liquid with a strongly acrid odor. It was first prepared in 1865 from ethyl methacrylate, in turn obtained by dehydration of ethyl α-hydroxyisobutyrate.
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使用
Methacrylic acid is used in the manufacture of methacrylate resins and plastics. It is used as Monomer for large-volume resins and polymers, organic synthesis. Many of the polymers are based on esters of the acid, as the methyl, butyl, or isobutyl esters. Methacrylic acid and methacrylate esters are used to prepare a wide range of polymers [→ Polyacrylamides and Poly(Acrylic Acids), → Polymethacrylates]. Poly(methyl methacrylate) is the primary polymer in this category, and it provides water-clear, tough plastics that are used in sheet form in glazing, signs, displays, and lighting panels.
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製造方法
The most common route for the preparation of methacrylic acid is from
acetone as follows:
In a typical process, acetone is treated with hydrogen cyanide at 140??C in the
presence of ammonia as catalyst. The acetone cyanohydrin produced is
treated with concentrated sulphuric acid at 100??C to form methacrylamide
sulphate. This intermediate is not isolated but is directly converted to
methacrylic acid by treatment with water at about 90??C.
A competitive route now in commercial operation involves the two stage
oxidation of isobutene with air. The reaction proceeds via methacrolein:
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調製方法
The most common approach to methacrylic acid synthesis is the hydrolysis of methacrylamide sulfate, obtained from acetone cyanohydrin. Methyl methacrylate may be prepared directly in a similar way by adding methanol in the final reaction step.
In the manufacture of methacrylic acid, methacrylamide sulfate is reacted with water under conditions similar to those used for formation of the ester. The reactor effluent separates into two phases. The upper organic layer is distilled to provide pure methacrylic acid. The lower layer is steam stripped to recover dilute aqueous methacrylic acid, which is recycled to the hydrolysis reactor. The waste acid stream is treated as in the manufacture of the ester.
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定義
ChEBI: Methacrylic acid is an alpha,beta-unsaturated monocarboxylic acid that is acrylic acid in which the hydrogen at position 2 is substituted by a methyl group. It is functionally related to an acrylic acid. It is a conjugate acid of a methacrylate.
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一般的な説明
Methacrylic acid appears as a clear colorless liquid (or low-melting solid) with a pungent odor. Corrosive to metals and tissue. Flash point 170°F. Melting point 61°F. May polymerize exothermically if heated or contaminated. If the polymerization takes place inside a container, the container may rupture violently. Less dense than water. Vapors heavier than air. Used to make plastics.
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空気と水の反応
Soluble in water.
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反応プロフィール
Methacrylic acid reacts with strong oxidizing agents. Presents a storage hazard: violent exothermic polymerizations leading to explosion can occur spontaneously, particularly at low inhibitor or stabilizer concentrations [Anon., CISHC Chem. Safety Summ., 1979, 50, p. 34; Bond, J., Loss Prev. Bull., 1991, 101, p. 1].
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健康ハザード
Methacrylic acid is a highly corrosive liquid.Contact with eyes can result in blindness.Skin contact may produce burns. No inhalation toxicity was observed in rats. Exposureto its vapors may produce skin and eye irritation, which can be mild to moderate. Adermal LD50 value in rabbits is 500 mg/kg.
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火災危険
Combustible liquid; flash point (open cup)
76°C (170°F); vapor pressure <0.1 torr at
20°C (68°F). Fire-extinguishing agent: water
spray, “alcohol” foam, dry chemical, or CO2;
use a water spray to dilute and flush the spill
and to disperse the vapors.
Methacrylic acid polymerizes readily. The
reaction is exothermic. The rate of reaction
accelerates on heating, which may result
in violent rupture of closed containers. The
polymerization may be inhibited with a trace
quantity of hydroquinone and hydroquinone
monomethyl ether (Aldrich 2006). The acid
may be stored safely below its melting point.
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使用用途
メタクリル酸は、水溶性高分子の合成原料、他のビニル化合物との共重合体の製造、の製造などに用いられています。メタクリル酸のエステル化合物であるは、アクリル樹脂の原料として非常に重要です。
アクリル樹脂は透明度が高く丈夫であることから、有機ガラスとして利用されています。また、この他にも義歯材料や塗料、紙加工剤、繊維処理剤、、電気絶縁材などもメタクリル酸の用途として挙げられます。
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安全性プロファイル
Poison by
intraperitoneal route. Moderately toxic by
ingestion and skin contact. Corrosive to
skin, eyes, and mucous membranes.
Mutation data reported. Flammable when
exposed to heat, flame, or oxidizers. A
storage hazard; exothermic polymerization
may occur spontaneously. To fight fire, use
alcohol foam, spray, mist, dry chemical.
When heated to decomposition it emits
acrid smoke and irritating fumes.
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職業ばく露
Methacrylic acid is used in preparation of methacrylates and carboxylated polymers; in the
production of the material or its alkyl esters, as monomers
or comonomers for synthetic resins for the production of
plastic sheets, moldings, and fibers.
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発がん性
Methacrylic acid was considered
by the IARC Working Groups, but monographs were not
prepared because adequate data on its carcinogenicity were
not available. The IUCLID database reports a
dermal application study (dose unspecified) of mice treated
three times per week for 4 months and then observed for their
lifetimes. No excess dermal tumors were observed.
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製造方法
メタクリル酸は、工業的にはACH法とイソブチレン法の2つの方法で製造されています。ACH法は古くからある方法ですが、猛毒であるシアン化水素 (HCN) が原料であることや、大量の硫酸塩の廃棄物が出ることが課題です。
現在、欧米や中国では依然としてACH法が採用されていますが、国内ではモリブデン系触媒を使用して、イソブチレンを直接酸化して合成するイソブチレン法が多く取られています。さらに、近年はエチレンを原料にしてプロピオン酸を経由して合成するプロセスも開発されています。
1. ACH法
アセトンとシアン化水素を反応させて、アセトンシアンヒドリン (ACH) を合成します。アセトンシアンヒドリンを濃硫酸と混合し、反応させてアミド化し、メタクリルアミドを合成します。メタクリルアミドに水とメタノールを加えて反応させることで、メタクリル酸とメタクリル酸メチルが得られます。
CH3COCH3 + HCN → CH3COH(CH3)CN
CH3COH(CH3)CN + H2SO4 → CH2 = C(CH3)CONH2・H2SO4
CH2 = C(CH3)CONH2・H2SO4 + H2O + CH3OH → CH2 = C(CH3)COOH + CH2 = C(CH3)COOCH3 + NH4HSO4
2. イソブチレン法
イソブチレンをモリブデン系触媒 (Mo-Bi) の存在下で酸化し、2段階目の反応を触媒をMo-P系に変えて酸化反応を行うことでメタクリル酸を得られます。
CH2 = C(CH3)CH3 +O2 → CH2 = C(CH3)CH = O + H2O
2CH2 = C(CH3)CH = O +O2 → 2CH2 = C(CH3)COOH
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輸送方法
UN2531 Methacrylic acid, stabilized, Hazard
class: 8; Labels: 8-Corrosive material.
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純化方法
Aqueous methacrylic acid (90%) is saturated with NaCl (to remove the bulk of the water), then the organic phase is dried with CaCl2 and distilled under vacuum. Polymerisation inhibitors should be added to the distillate and include 0.25% p-methoxyphenol, 0.1% hydroquinone, or 0.05% N,N'-diphenyl-p-phenylenediamine. [Beilstein 2 IV 1518.]
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不和合性
Vapor may form explosive mixture
with air. A reducing agent; incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or
explosions. Aqueous solution is strongly acidic: incompatible
with strong acids; caustics, ammonia, amines, isocyanates,
alkylene oxides; epichlorohydrin. Will polymerize readily from
heating above 59F/15C, or due to the presence of light, oxidizers (e.g., peroxides); or in the presence of traces of hydrochloric acid, with fire or explosion hazard. Attacks metals. Note:
Typically contains 100 ppm of monomethyl ether hydroquinone (150-76-5) as an inhibitor to prevent polymerization
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廃棄物の処理
Dissolve or mix the material
with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal,
state, and local environmental regulations must be
observed.
