Oxals?ure Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSE KRISTALLE ODER WEISSES PULVER.
CHEMISCHE GEFAHREN
Bei Kontakt mit hei?en Gegenst?nden oder Flammen Zersetzung unter Bildung von Ameisens?ure und Kohlenmonoxid. Mittelstarke S?ure in w?ssriger L?sung. Reagiert sehr heftig mit starken Oxidationsmitteln unter Feuer- und Explosionsgefahr. Reagiert mit einigen Silberverbindungen unter Bildung explosionsf?higen Silberoxalats.
ARBEITSPLATZGRENZWERTE
TLV: 1 mg/m?(als TWA); 2 mg/m?(als STEL); (ACGIH 2005).
MAK nicht festgelegt (DFG 2006).
EG Arbeitsplatz-Richtgrenzwerte: 1 mg/m?(als TWA); (EG 2006)
AUFNAHMEWEGE
Aufnahme in den K?rper durch Inhalation des Aerosols und durch Verschlucken.
INHALATIONSGEFAHREN
Verdampfung bei 20°C vernachl?ssigbar; eine gesundheitssch?dliche Partikelkonzentration in der Luft kann jedoch als Pulver schnell erreicht werden.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: ?tzend. Die Substanz ver?tzt die Augen, die Haut und die Atemwege. ?tzend beim Verschlucken. Inhalation des Aerosols kann zu Lungen?dem führen (s.Anm.). M?glich sind Auswirkungen auf die Nieren. Exposition weit oberhalb der Arbeitsplatzgrenzwerte kann zum Tod führen. ?rztliche Beobachtung notwendig.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Wiederholter oder andauernder Hautkontakt kann Dermatitis hervorrufen. M?glich sind Auswirkungen auf die Nieren mit nachfolgenden Nierensteinen.
LECKAGE
Verschüttetes Material in Kunststoffbeh?ltern sammeln; falls erforderlich durch Anfeuchten Staubentwicklung verhindern. Reste sorgf?ltig sammeln. An sicheren Ort bringen. Pers?nliche Schutzausrüstung: Atemschutzger?t, P2-Filter für sch?dliche Partikel.
R-S?tze Betriebsanweisung:
R21/22:Gesundheitssch?dlich bei Berührung mit der Haut und beim Verschlucken.
R63:Kann das Kind im Mutterleib m?glicherweise sch?digen.
R34:Verursacht Ver?tzungen.
S-S?tze Betriebsanweisung:
S24/25:Berührung mit den Augen und der Haut vermeiden.
S23:Gas/Rauch/Dampf/Aerosol nicht einatmen(geeignete Bezeichnung(en) vom Hersteller anzugeben).
S36/37/39:Bei der Arbeit geeignete Schutzkleidung,Schutzhandschuhe und Schutzbrille/Gesichtsschutz tragen.
S27:Beschmutzte, getr?nkte Kleidung sofort ausziehen.
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
Chemische Eigenschaften
Oxalic acid is a colorless, odorless powder, or
granular solid. The anhydrous form (COOH)2 is an odorless,
white solid; the solution is a colorless liquid.
Physikalische Eigenschaften
Colorless and odorless rhombic crystals. Hygroscopic. soluble in ethanol, soluble in water, slightly soluble in ether, insoluble in benzene and chloroform.
Verwenden
Oxalic acid was used:
· in the synthesis of hemicellulose hydrolysates of yellow poplars;
· in the synthesis of three-dimensionally ordered macroporous metal oxides or carbonates via templating with polystyrene spheres;
· as supporting electrolyte in the electrochemical synthesis of polyaniline-polypyrrole composite coatings.
Vorbereitung Methode
Many industrial processes have been employed for the manufacture of oxalic acid since it was first synthesized. The following processes are in use worldwide: oxidation of carbohydrates, the ethylene glycol process, the propylene process, the dialkyl oxalate process, and the sodium formate process. Sodium formate process is no longer economical in the leading industrial countries, except for China.
Nitric acid oxidation is used where carbohydrates, ethylene glycol, and propylene are the starting materials. The dialkyl oxalate process is the newest, where dialkyl oxalate is synthesized from carbon monoxide and alcohol, then hydrolyzed to oxalic acid. This process has been developed by UBE Industries in Japan.Many attempts have been made to synthesize oxalic acid by electrochemical reduction of carbon dioxide in either aqueous or nonaqueous electrolytes.
Definition
ChEBI: Oxalic acid is an alpha,omega-dicarboxylic acid that is ethane substituted by carboxyl groups at positions 1 and 2. It has a role as a human metabolite, a plant metabolite and an algal metabolite. It is a conjugate acid of an oxalate(1-) and an oxalate.
Reaktionen
The reactions of oxalic acid, including the formation of normal and acid salts and esters, are typical of the dicarboxylic acids class. Oxalic acid, however, does not form an anhydride.
On rapid heating, oxalic acid decomposes to formic acid, carbon monoxide, carbon dioxide, and water. In aqueous solution, it is decomposed by uv, x-ray, or γ -radiation with the liberation of carbon dioxide. Photodecomposition also occurs in the presence of uranyl salts.
Oxalic acid is a mild reducing agent, and is oxidized by potassium permanganate in acid solution to give carbon dioxide and water. Oxalic acid is catalytically reduced by hydrogen in the presence of ruthenium catalyst to ethylene glycol, and electronically reduced to glyoxylic acid.
Oxalic acid reacts with various metals to form metal salts, which are quite important as the derivatives of oxalic acid. It also reacts easily with alcohols to give esters.
Allgemeine Beschreibung
Odorless white solid. Sinks and mixes with water.
Air & Water Reaktionen
Water soluble. Hygroscopic
Reaktivit?t anzeigen
Oxalic acid is hygroscopic and sensitive to heat. Oxalic acid may react violently with furfuryl alcohol, silver, sodium, perchlorate, sodium hypochlorite, strong oxidizers, sodium chlorite, acid chlorides, metals and alkali metals. . The heating of mixtures of Oxalic acid and urea has lead to explosions. This is due to the rapid generation of the gases, CO2, CO, and NH3, [Praxis Naturwiss. Chem., 1987, 36(8), 41-42]. Oxalic acid and urea react at high temperatures to form toxic and flammable ammonia and carbon monoxide gasses, and inert CO2 gas [Von Bentzinger, R. et al., Praxis Naturwiss. Chem., 1987, 36(8), 41-42].
Health Hazard
As dust or as a solution, can cause severe burns of eyes, skin, or mucous membranes. Ingestion of 5 grams has caused death with symptoms of nausea, shock, collapse, and convulsions coming on rapidly. Repeated or prolonged skin exposure can cause dermatitis and slow-healing ulcers.
Brandgefahr
Special Hazards of Combustion Products: Generates poisonous gases
Landwirtschaftliche Anwendung
Oxalic acid, (COOH)
2, also called ethanedioic acid, is a
white, crystalline solid, slightly soluble in water. It is a
naturally occurring highly oxidized organic compound with significant chelating activity. It is strongly acidic
and poisonous, produced by many plants like sorrel
(sourwood), the leaf blades of rhubarb, bark of
eucalyptus and many plant roots. In plant cells and
tissues, oxalic acid gets accumulated as either sodium,
potassium or calcium oxalate, of which the latter occurs
as crystals. In turn, salts of oxalic acids enter the bodies
of animals and human beings, causing pathological
disorders, depending upon the amount consumed. Many
species of fungi like Aspergillus, Penicillium, Mucor, as
well as some lichens and slime moulds produce calcium
oxalate crystals. Upon the death of these microorganisms,
plants and animals, the salts get released into
the soil, causing some amount of toxicity. However,
oxalate-degrading microbes, called Oxalobacter
formigenes, decrease oxalate absorption in animals and
humans.
Oxalic acid is the first of a series of dicarboxylic
acids. It is used (a) as a bleaching agent for stains like rust
or ink, (b) in textile and leather production, and (c) as
monoglyceryl oxalate in the production of ally1 alcohol
and formic acid.
m?gliche Exposition
Oxalic acid is used in textile finishing,
paint stripping; metal and equipment cleaning; as an intermediate;
as an analytic reagent and in the manufacture of
dyes, inks, bleaches, and paint removers; varnishes, wood,
and metal cleansers; dextrin, cream of tartar, celluloid, oxalates,
tartaric acid, purified methyl alcohol, glycerol, and
stable hydrogen cyanide. It is also used in the photographic,
ceramic, metallurgic, rubber, leather, engraving, pharmaceutical,
paper, and lithographic industries.
Environmental Fate
Biological. Heukelekian and Rand (1955) reported a 5-d BOD value of 0.12 g/g which is 66.7%
of the ThOD value of 0.18 g/g.
Chemical/Physical. At temperatures greater than 189.5 °C, decomposes to carbon dioxide,
carbon monoxide, formic acid, and water (Windholz et al., 1983). Ozonolysis of oxalic acid in
distilled water at 25 °C under acidic conditions (pH 6.3) yielded carbon dioxide (Kuo et al., 1977).
Absorbs moisture in air forming the dihydrate (Huntress and Mulliken, 1941).
Reacts with bases forming water soluble salts.
Versand/Shipping
UN3261 Corrosive solid, acidic, organic, n.o.s.,
Hazard class: 8; Labels: 8-Corrosive material, Technical
Name Required.
Inkompatibilit?ten
The aqueous solution is a medium-strong
acid. Compounds of the carboxyl group react with all bases,
both inorganic and organic (i.e., amines) releasing substantial
heat, water and a salt that may be harmful. Incompatible with
arsenic compounds (releases hydrogen cyanide gas), diazo
compounds, dithiocarbamates, isocyanates, mercaptans,
nitrides, and sulfides (releasing heat, toxic, and possibly flammable
gases), thiosulfates and dithionites (releasing hydrogen
sulfate and oxides of sulfur). Incompatible with oxidizers
(chlorates, nitrates, peroxides, permanganates, perchlorates,
chlorine, bromine, fluorine, etc.); contact may cause fires or
explosions. Keep away from silver compounds; strong alkalis;
chlorites. Contact with some silver compounds forms explosive
materials.
Waste disposal
Pretreatment involves chemical
reaction with limestone or calcium oxide forming calcium
oxalate. This may then be incinerated utilizing
particulate collection equipment to collect calcium oxide
for recycling.
Oxals?ure Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
7-(TRIFLUOROMETHYL)QUINOLINE
Oxalsure, Kaliumsalz
Kolophonium
Kaliumhydrogenoxalat
Triammoniumtrioxalatoferrat
Hydrogen(benzyl)[4-[[4-[benzylethylamino]phenyl](2,4-disulfonatophenyl)methylen]cyclohexa-2,5-dien-1-yliden](ethyl)ammonium, Natriumsalz
Dimethyloxalat
7-Chlor-2',4,6-trimethoxy-6'-methyl-spiro(benzo-furan-2(3H),1'-(2)cyclohexen)-3,4'-dion
Diethyloxalat
Bariumoxalat
Nickeloxalat
Lincomycin hydrochloride monohydrate
Dinatriumoxalat
Diammoniumoxalat
Diethyl[2-[2-(1-naphthylmethyl)-3-(tetrahydro-2-furyl)propionyloxy]ethyl]ammoniumhydrogenoxalat
Filth remover
Scandiumoxid
oxytetracyclin
3-METHYL-1H-PYRAZOLO[3,4-C]PYRIDAZINE-4,5-DIOL
1,4-Dihydroxybenzol
Oxalyldichlorid
Lubricant
Dikaliumtitanoxiddioxalat
Dibutyloxalat
Ammoniumvanadat
Cobaltoxid
Glyoxylsure
