Maleins?ure Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
WEISSE KRISTALLE.
CHEMISCHE GEFAHREN
Zersetzung beim Erhitzen und Verbrennen unter Bildung stark reizender Rauche mit Maleinanhydrid. Mittelstarke S?ure in w?ssriger L?sung.
ARBEITSPLATZGRENZWERTE
TLV nicht festgelegt (ACGIH 2005).
MAK nicht festgelegt (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den K?rper durch Inhalation und durch Verschlucken.
INHALATIONSGEFAHREN
Verdampfung bei 20°C vernachl?ssigbar; eine gesundheitssch?dliche Partikelkonzentration in der Luft kann jedoch beim Dispergieren schnell erreicht werden, vor allem als Pulver.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz reizt stark die Augen, die Haut und die Atemwege.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Wiederholter oder andauernder Hautkontakt kann Dermatitis hervorrufen. M?glich sind Auswirkungen auf die Nieren.
LECKAGE
NICHT in die Kanalisation spülen. Verschüttetes Material in Beh?ltern sammeln; falls erforderlich durch Anfeuchten Staubentwicklung verhindern. Reste mit viel Wasser wegspülen. Pers?nliche Schutzausrüstung: Atemschutzger?t, P2-Filter für sch?dliche Partikel.
R-S?tze Betriebsanweisung:
R22:Gesundheitssch?dlich beim Verschlucken.
R36/37/38:Reizt die Augen, die Atmungsorgane und die Haut.
S-S?tze Betriebsanweisung:
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S28:Bei Berührung mit der Haut sofort abwaschen mit viel . . . (vom Hersteller anzugeben).
S37:Geeignete Schutzhandschuhe tragen.
Aussehen Eigenschaften
C4H4O4; cis-Butendisäure. Farbloser, feinkristalliner Feststoff mit säuerlichem Geruch.
Gefahren für Mensch und Umwelt
Gesundheitsschädlich beim Verschlucken. Reizt die Atmungswege, Augen und die Haut.
LD
50 (oral, Ratte): 708 mg/kg
Schutzma?nahmen und Verhaltensregeln
Geeignete Schutzhandschuhe als kurzzeitiger Staubschutz.
Verhalten im Gefahrfall
Trocken aufnehmen. Der Entsorgung zuführen.
Kohlendioxid, Wasser, Pulver.
Brennbar.
Erste Hilfe
Nach Hautkontakt: Mit reichlich Wasser abwaschen.
Nach Augenkontakt: Mit reichlich Wasser bei geöffnetem Lidspalt mindestens 10 Minuten ausspülen. Sofort Augenarzt hinzuziehen.
Nach Einatmen: Frischluft. Arzt hinzuziehen.
Nach Verschlucken: Reichlich Wasser trinken lassen. Erbrechen auslösen. Arzt hinzuziehen.
Nach Kleidungskontakt: Kontaminerte Kleidung sofort entfernen.
Ersthelfer: siehe gesonderten Anschlag
Sachgerechte Entsorgung
Gelöst in z.B. Ethanol als halogenfreie, organische Lösemittelabfälle.
Beschreibung
Maleic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO
2CCHCHCO
2H. Maleic acid is the cis-isomer of butenedioic acid, where as fumaric acid is the trans-isomer. It is mainly used as a precursor to fumaric acid, and relative to its parent maleic anhydride, maleic acid has few applications.
Chemische Eigenschaften
Maleic acid, also known as maleinic acid and toxilic acid, is a white crystalline (monoclinic) powder and possesses a faint acidulous odor and an astringent taste. It is soluble in water and alcohol. Maleic acid and fumaric acid are the simplest unsaturated carboxylic diacids. These acids experience two-step dissociation in aqueous solutions.They have the same structural formula but different spatial configurations. Fumaric acid is the trans and maleic acid the cis isomer. The physical properties of maleic acid and fumaric acid are very different. The cis isomer is less stable. Maleic acid is used in the preparation of fumaric acid by catalytic isomerization.
Physikalische Eigenschaften
Maleic acid is a less stable molecule than fumaric acid. The difference in heat of combustion is 22.7 kJ·mol?1. The heat of combustion is -1355 kJ / mole. Maleic acid is more soluble in water than fumaric acid. The melting point of maleic acid (135 °C) is also much lower than that of fumaric acid (287 °C). Both properties of maleic acid can be explained on account of the intramolecular hydrogen bonding that takes place in maleic acid at the expense of intermolecular interactions, and that are not possible in fumaric acid for geometric reasons.
Vorbereitung Methode
Maleic anhydride is the main source of maleic acid produced by
hydration. Maleic anhydride is prepared commercially by the
oxidation of benzene or by the reaction of butane with oxygen in the
presence of a vanadium catalyst.
Definition
ChEBI: Maleic acid is a butenedioic acid in which the double bond has cis- (Z)-configuration. It has a role as a plant metabolite, an algal metabolite and a mouse metabolite. It is a conjugate acid of a maleate(1-) and a maleate.
Application
Maleic acid is an industrial raw material for the production of glyoxylic acid by ozonolysis. It may be used to form acid addition salts with drugs to make them more stable, such as indacaterol maleate. Maleic acid is also used in manufacturing synthetic resins; in textile processing; in preserving oils and fats; to retard rancidity of fats and oils in 1:10,000 (these are said to keep 3 times longer than those without the acid); dyeing and finishing wool, cotton, and silk; preparing the maleate salts of antihistamines and similar drugs.
Reaktionen
Although not practised commercially, maleic acid can be converted into maleic anhydride by dehydration, to malic acid by hydration, and to succinic acid by hydrogenation (ethanol / palladium on carbon). It reacts with thionyl chloride or phosphorus pentachloride to give the maleic acid chloride (it is not possible to isolate the mono acid chloride). Maleic acid, being electrophilic, participates as a dienophile in many Diels - Alder reactions.
Allgemeine Beschreibung
Maleic acid is a colorless crystalline solid having a faint odor. Maleic acid is combustible though Maleic acid may take some effort to ignite. Maleic acid is soluble in water. Maleic acid is used to make other chemicals and for dyeing and finishing naturally occurring fibers.
Air & Water Reaktionen
Soluble in water.
Reaktivit?t anzeigen
Maleic acid is a colorless to white crystalline solid. Moderately toxic. When heated to decomposition Maleic acid emits irritating fumes and acrid smoke [Lewis, 3rd ed., 1993, p. 790].
Hazard
Toxic by ingestion.
Health Hazard
Inhalation causes irritation of nose and throat. Contact with eyes or skin causes irritation.
Brandgefahr
Special Hazards of Combustion Products: Irritating smoke containing maleic anhydride may form in fire.
Pharmazeutische Anwendungen
Maleic acid is used in the pharmaceutical industry as a pH modifier
and a buffering agent.It is also used to prevent rancidity of oils
and fats; a ratio of 1 : 10 000 is usually sufficient to retard rancidity.
Maleic acid is commonly used as a pharmaceutical intermediate to
form the maleate salts of several categories of therapeutic agents,
such as salts of antihistamines and other drug substances.
Sicherheitsprofil
Moderately toxic by
ingestion and skin contact. Passes through
intact skin. A skin and severe eye irritant and
a corrosive. Believed to be more toxic than
its isomer, fumeric acid. Combustible when
exposed to heat or flame. When heated to
decomposition it emits acrid smoke and
irritating fumes.
Sicherheit(Safety)
Maleic acid is generally regarded as a nontoxic and nonirritant
material when used at low levels as an excipient. Maleic acid is used
in oral, topical, and parenteral pharmaceutical formulations in
addition to food products.
LD
50 (mouse, oral): 2.40g/kg(7)
LD
50 (rabbit, skin): 1.56g/kg
LD
50 (rat, oral): 0.708g/kg
m?gliche Exposition
Maleic acid is used to make artificial
resins, antihistamines, and to preserve (retard rancidity) of
fats and oils
Carcinogenicity
In chronic feeding studies, 12
Osborne–Mendel rats per group were fed 0.5, 1.0, or 1.5%
maleic acid in their diets for 2 years. Concentrations of 1.0
and 1.5% maleic acid retarded the growth rate of rats, and
all concentrations of maleic acid increased mortality rate;
no tumorigenesis was reported. Toxicological differences
from controls were not marked, and the pathology was
nonspecific.
Lager
Maleic acid converts into the much higher-melting fumaric acid
(mp: 287°C) when heated to a temperature slightly above its melting
point.
Maleic acid is combustible when exposed to heat or flame. The
bulk material should be stored in airtight glass containers and
protected from light. It is recommended not to store it above 25°C.
Versand/Shipping
UN2215 Maleic acid, Hazard class: 8; Labels:
8-Corrosive material.
l?uterung methode
Crystallise the acid from acetone/pet ether (b 60-80o) or hot water. Dry it at 100o. [Beilstein 2 H 748, 2 I 303, 2 II 641, 2 III 1911, 2 IV 2199.]
Inkompatibilit?ten
Maleic acid can react with oxidizing materials. Aqueous solutions
are corrosive to carbon steels.
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. Liquid: incinerate after mixing with a flammable
solvent. Use afterburner for complete combustion. Solid:
dissolve in a flammable solvent or package in paper and
burn. See above
Regulatory Status
Included in the FDA Inactive Ingredients Database (IM and IV
injections; oral tablets and capsules; topical applications). Included
in nonparenteral and parenteral medicines licensed in the UK.
Maleins?ure Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
