General Description
Odorless white solid. Sinks and mixes with water.
Reactivity Profile
OXALIC ACID(144-62-7) is hygroscopic and sensitive to heat. This compound 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(144-62-7) 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(144-62-7) 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].
Air & Water Reactions
Water soluble. Hygroscopic
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.
Potential Exposure
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.
Fire Hazard
Special Hazards of Combustion Products: Generates poisonous gases
First aid
Move victim to fresh air. Call 911 or emergency
medical service. Give artificial respiration if victim is not
Oxalic Acid 2261
breathing. Do not use mouth-to-mouth methods if victim
ingested or inhaled the substance; give artificial respiration
with the aid of a pocket mask equipped with a one-way valve
or other proper respiratory medical device? Administer oxygen
if breathing is difficult. Remove and isolate contaminated
clothing and shoes. In the case of contact with
substance, immediately flush skin or eyes with running water
for at least 20 minutes. For minor skin contact, avoid spreading
material on unaffected skin. Keep victim warm and
quiet. Effects of exposure (inhalation, ingestion, or skin contact)
to substance may be delayed. Ensure that medical personnel
are aware of the material(s) involved and take
precautions to protect themselves. Medical observation is
recommended for 2448 hours after breathing overexposure,
as pulmonary edema may be delayed. As first aid for pulmonary
edema, a doctor or authorized paramedic may consider
administering a drug or other inhalation therapy.
Shipping
UN3261 Corrosive solid, acidic, organic, n.o.s.,
Hazard class: 8; Labels: 8-Corrosive material, Technical
Name Required.
Incompatibilities
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.
Physical properties
Colorless and odorless rhombic crystals. Hygroscopic.
Definition
A white crystalline
organic acid that occurs naturally in
rhubarb, sorrel, and other plants of the
genus Oxalis. It is slightly soluble in water,
highly toxic, and used in dyeing and as a
chemical reagent.
Definition
ChEBI: An alpha,omega-dicarboxylic acid that is ethane substituted by carboxyl groups at positions 1 and 2.
Production Methods
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.
Reactions
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.
Flammability and Explosibility
Nonflammable
Agricultural Uses
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.
Source
Oxalic acid occurs naturally in many plants including buckwheat leaves (111,000 ppm),
lambsquarter (140,000 to 300,000 ppm), black pepper (4,000 to 34,000 ppm), star fruit (50,000 to
95,800 ppm), purslane (1,679 to 16,790 ppm), nance bark (27,300 ppm), rhubarb 4,400 to 13,360
ppm), tea leaves (2,192 to 10,000 ppm), bitter lettuce (10,000 ppm), spinach (6,580 ppm), cacao
(1,520 to 5,000 ppm), bananas (22 to 5,240 ppm), ginger (5,000 ppm in rhizome), cashews (3,184
ppm), almonds (4,073 ppm), taro roots (1,334 ppm), tamarind (1,960 ppm), garden sorrel (3,000
ppm), mustard green leaves (1,287 ppm), peppers (257 to 1,171 ppm), sweet potato roots (1,000
ppm), pumpkins, oats (400 ppm), tomatillo (109 to 536 ppm), various cabbage leaves (59 to 350
ppm), and horseradish (Duke, 1992).
Oxalic acid was identified as a constituent in a variety of composted organic wastes. Detectable
concentrations were reported in all 21 composts extracted with water. Concentrations ranged from
0.60 mmol/kg in a straw + dairy cattle manure to 21.89 mmol/kg in straw + wood bark + dairy
cattle manure. The overall average concentration was 9.67 mmol/kg (Baziramakenga and Simard,
1998).
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.
