Methylacetat Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSE FLüSSIGKEIT MIT CHARAKTERISTISCHEM GERUCH.
PHYSIKALISCHE GEFAHREN
Die Dämpfe sind schwerer als Luft und können sich am Boden ausbreiten. Fernzündung möglich.
CHEMISCHE GEFAHREN
Zersetzung beim Erhitzen unter Einfluss von Luft, Basen, starken Oxidationsmitteln, UV-Licht. Feuer- und Explosionsgefahr. Starkes Reduktionsmittel. Reagiert mit Oxidationsmitteln. Greift viele Metalle in Gegenwart von Wasser an. Greift Kunststoffe an.
ARBEITSPLATZGRENZWERTE
TLV: 200 ppm (als TWA); 250 ppm (als STEL); (ACGIH 2005).
MAK: 100 ppm, 310 mg/m? Spitzenbegrenzung: überschreitungsfaktor I(4); Schwangerschaft: Gruppe C; (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation der Dämpfe.
INHALATIONSGEFAHREN
Beim Verdampfen bei 20°C kann schnell eine gesundheitsschädliche Kontamination der Luft eintreten.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz reizt die Augen und die Atemwege. Möglich sind Auswirkungen auf das Zentralnervensystem mit nachfolgender Bewusstseinstrübung. Exposition weit oberhalb der Arbeitsplatzgrenzwerte kann zum Tod führen.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Die Flüssigkeit entfettet die Haut. Möglich sind Auswirkungen auf den Sehnerv mit nachfolgenden Sehstörungen.
LECKAGE
Ausgelaufene Flüssigkeit möglichst in abdichtbaren Behältern sammeln. Reste mit Sand oder inertem Absorptionsmittel aufnehmen und an einen sicheren Ort bringen. NICHT in die Kanalisation spülen. Persönliche Schutzausrüstung: Umgebungsluftunabhängiges Atemschutzgerät.
R-Sätze Betriebsanweisung:
R11:Leichtentzündlich.
R36:Reizt die Augen.
R66:Wiederholter Kontakt kann zu spröder oder rissiger Haut führen.
R67:Dämpfe können Schläfrigkeit und Benommenheit verursachen.
S-Sätze Betriebsanweisung:
S16:Von Zündquellen fernhalten - Nicht rauchen.
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S29:Nicht in die Kanalisation gelangen lassen.
S33:Maßnahmen gegen elektrostatische Aufladungen treffen.
Beschreibung
Methyl acetate, also known as MeOAc , acetic acid methyl ester or methyl ethanoate, is a carboxylate ester with the formula CH3COOCH3. It is a flammable liquid with a characteristically pleasant smell reminiscent of some glues and nail polish removers. Methyl acetate is occasionally used as a solvent, being weakly polar and lipophilic, but its close relative ethyl acetate is a more common solvent being less toxic and less soluble in water. Methyl acetate has a solubility of 25% in water at room temperature. At elevated temperature its solubility in water is much higher. Methyl acetate is not stable in the presence of strong aqueous bases or aqueous acids. Methyl acetate is VOC exempt.
Chemische Eigenschaften
Methyl acetate has a pleasant, fruity odor and slightly bitter flavor. May be prepared by boiling acetic acid and methanol in the presence of acid catalysts; or by heating methanol with an excess carbon monoxide under pressure in the presence of a catalyst (phosphoric acid, cobalt salts).
Methyl acetate occurs naturally in low concentrations in mint, fungus,grapes, banana, coffee (Furia and Bellanca, 1975) and is a volatile constituent of nectarines (Takeoka et al., 1988). It is also present in some distilled alcoholic beverages (Shimoda et al., 1993). It is produced industrially via the carbonylation of methanol as a byproduct of acetic acid production or by esterification of acetic acid with methanol in the presence of strong acid such as sulfuric acid.
Physikalische Eigenschaften
Colorless liquid with a pleasant odor. An odor threshold concentration of 48 ppb
v was reported by
Nagata and Takeuchi (1990). Cometto-Mu?iz and Cain (1991) reported an average nasal pungency
threshold concentration of 112,500 ppm
v.
Occurrence
Reported found in apple, banana, sweet and sour cherry, tangerine juice, black currants, guava, grapes, melon,
peach, pear, pineapple, strawberry, cabbage, tomato, clove bud, peppermint oil, vinegar, bread, cheeses, butter, yogurt, beef, beer,
cognac, rum, whiskies, cider, sherry, grape wines, cocoa, coffee, filbert, peanut, honey, soybean, olive, passion fruit, fruit brandies,
fig, gin, kiwifruit, clary sage, arrack and nectarine.
Verwenden
Methyl acetate is used as a solvent forlacquers, resins, oils, and nitrocellulose; inpaint removers; as a flavoring agent; and inthe manufacture of artificial leather.
synthetische
Methyl acetate is produced industrially via the carbonylation of methanol as a byproduct of the production of acetic acid.Methyl acetate also arises by esterification of acetic acid with methanol in the presence of strong acids such as sulfuric acid, this production process is famous because of Eastman Kodak's intensified process using a reactive distillation.
2–1-Reactions In the presence of strong bases such as sodium hydroxide or strong acids such as hydrochloric acid or sulfuric acid it is hydrolyzed back into methanol and acetic acid, especially at elevated temperature. The conversion of methyl acetate back into its components, by an acid , is a first-order reaction with respect to the ester. The reaction of methyl acetate and a base, for example sodium hydroxide, is a second-order reaction with respect to both reactants.
3-Applications A major use of methyl acetate is as a volatile low toxicity solvent in glues, paints, and nail polish removers. Acetic anhydride is produced by carbonylation of methyl acetate in a process that was inspired by the Monsanto acetic acid synthesis.
Application
Methyl acetate may be used for the preparation of fatty acid methyl esters and triacetin from rapeseed oil via non-catalytic trans-esterification reaction under super-critical conditions.
Methyl acetate may be used in the following:
As acyl acceptor in the preparation of biodiesel.
Synthesis of ethanol.
Preparation of n-butyl acetate, via transesterification reaction with n-butanol in the presence of acidic catalysts.
It may also be used as a precursor in the synthesis of the following:
acetic anhydride
methyl acrylate
vinyl acetate
ethyl amide
Definition
ChEBI: Methyl acetate is an acetate ester resulting from the formal condensation of acetic acid with methanol. A low-boiling (57°C) colourless, flammable liquid, it is used as a solvent for many resins and oils. It has a role as a polar aprotic solvent, a fragrance and an EC 3.4.19.3 (pyroglutamyl-peptidase I) inhibitor. It is an acetate ester, a methyl ester and a volatile organic compound.
Allgemeine Beschreibung
Methyl acetate appears as a clear colorless liquid with a fragrant odor. Moderately toxic. Flash point 14 °F. Vapors heavier than air.
Air & Water Reaktionen
Highly flammable. Water soluble.
Reaktivität anzeigen
Methyl acetate presents a fire or explosion hazard when exposed to strong oxidizing agents. Emits irritating fumes and acrid smoke when heated to decomposition, [Lewis, 3rd ed., 1993, p. 826]. Methyl acetate reactivity is consistent with other compounds of the ester group.
Hazard
Flammable, dangerous fire and explosion
risk, explosive limits in air 3–16%. Irritant to respiratory tract. Headache, dizziness, nausea, eye damage (degeneration of ganglion cells in the retina).
Health Hazard
(Very similar to those of methyl alcohol, which constitutes 20% of commercial grade.) Inhalation causes headache, fatigue, and drowsiness; high concentrations can produce central nervous system depression and optic nerve damage. Liquid irritates eyes and may cause defatting and cracking of skin. Ingestion causes headache, dizziness, drowsiness, fatigue; may cause severe eye damage.
Brandgefahr
Behavior in Fire: Vapor is heavier than air and may travel a considerable distance to a source of ignition and flash back.
Sicherheitsprofil
Moderately toxic by
several routes. A human systemic irritant by
inhalation. A moderate skin and eye irritant.
Mutation data reported. Dangerous fire
hazard when exposed to heat, flame, or
oxidizers. Moderate explosion hazard when
exposed to heat or flame. When heated to
decomposition it emits acrid smoke and
fumes. See also ESTERS.
mögliche Exposition
Methyl acetate is used as a solvent
in lacquers and paint removers; and as an intermediate
in pharmaceutical manufacture.
Environmental Fate
Photolytic. A rate constant of 2.00 x 10
-13 cm
3/molecule?sec was reported for the reaction of
methyl acetate and OH radicals in aqueous solution (Wallington et al., 1988b).
Chemical/Physical. Slowly hydrolyzes in water yielding methyl alcohol and acetic acid
(NIOSH, 1997). The estimated hydrolysis half-life in water at 25 °C and pH 7 is 2.5 yr (Mabey and
Mill, 1978).
At an influent concentration of 1,030 mg/L, treatment with GAC resulted in an effluent
concentration of 760 mg/L. The adsorbability of the carbon used was 54 mg/g carbon (Guisti et
al., 1974).
Versand/Shipping
UN1231 Methyl acetate, Hazard Class: 3;
Labels: 3-Flammable liquid.
läuterung methode
Methanol in methyl acetate can be detected by measuring its solubility in water. At 20o, the solubility of methyl acetate in water is ca 35g per 100mL, but 1% MeOH confers complete miscibility. Methanol can be removed by conversion to methyl acetate, by refluxing for 6hours with acetic anhydride (85mL/L), followed by fractional distillation. Acidic impurities can be removed by shaking with anhydrous K2CO3 and distilling. An alternative treatment is with acetyl chloride, followed by washing with concentrated NaCl and drying with CaO or MgSO4. (Solid CaCl2 cannot be used because it forms a crystalline addition compound.) Distillation from copper stearate destroys peroxides. Free alcohol or acid can be eliminated from methyl acetate by shaking with strong aqueous Na2CO3 or K2CO3 (three times), then with aqueous 50% CaCl2 (three times), saturated aqueous NaCl (twice), drying with K2CO3 and distilling it from P2O5. [Beilstein 2 IV 122.]
Inkompatibilitäten
Vapor may form explosive mixture with
air. A Strong reducing agent. Incompatible water, acids,
nitrates, strong oxidizers; alkalis. Attacks some plastics.
Attacks many metals in presence of water. Reacts slowly
with water, forming acetic acid and methanol. Decomposes
in heat; on contact with air, bases, strong oxidizers;
UV-light; possible fire and explosion hazard
Waste disposal
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.
Methylacetat Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
