Nomenclature
CAS number: 144-62-7
Ethanedioic acid.
C
2H
2O
4; mol wt 90.03.
C 26.68%, H 2.24%, O 71.08%.
Description and references
Present in many plants and vegetables, notably
in those of the Oxalis and Rumex families, where
it occurs in the cell sap of the plant as the potassium or calcium
salt. It is a product of the metabolism of many molds. Several species
of Penicillium and Aspergillus convert sugar
into calcium oxalate with 90% yields under optimum conditions. Oxalic
acid was formerly manuf by fusion of cellulose matter, e.g. sawdust,
with NaOH or by oxidation with HNO3; it is now made by
passing carbon monoxide into concd NaOH or by heating sodium formate
in the presence of NaOH or Na2CO3: Wallace, US 1602802 (1926); Beckman, US 2687433 (1951 to Allied Chem.). Efficient laboratory prepn of anhydrous form: H. T. Clarke, A.
W. Davis, Org. Synth. coll.
vol. I, 421 (2nd ed., 1941). Toxicity study: E. H. Vernot et al., Toxicol. Appl. Pharmacol. 42, 417 (1977). Review: Wilson, “Miscellaneous Aspergillus Toxins” in Microbial Toxins vol. VI, A. Ciegler et al., Eds. (Academic
Press, New York, 1971) pp 268-273; C. A. Bernales in Kirk-Othmer Encyclopedia of Chemical Technology vol. 16 (Wiley-Interscience, New York, 3rd ed., 1981)
pp 618-636.
Derivative
Dihydrate.
Nomenclature
CAS number: 6153-56-6
C
2H
2O
4.2H
2O; mol wt 126.07.
C 19.05%, H 4.80%, O 76.15%.
Properties
Monoclinic tablets, prisms, granules. Poisonous. d418.5 1.653. mp 101-102° giving off water of crystn
and starting to sublime. pK1 1.27; pK2 4.28. pH of 0.1M soln 1.3. One gram dissolves in about
7 ml water, 2 ml boiling water; 2.5 ml alcohol, 1.8 ml boiling alcohol,
100 ml ether, 5.5 ml glycerol. Practically insol in benzene, chloroform,
petr ether. d417.5 of aq solns:
1% (w/w) 1.0035; 3% 1.0105; 5% 1.0175; 10% 1.0350; 13% 1.0455. Oxalic acid can be dehydrated by careful drying at 100°, but considerable
loss occurs through sublimation; this, moreover, is harmful to the
oven. LD50 orally in rats (5% solution): 9.5 ml/kg (Vernot).Derivative
Anhydr oxalic acid.
Properties
Crystallized from glacial acetic acid, is orthorhombic,
the crystals being pyramidal or elongated octahedra. Hygroscopic, mp 189.5° (dec). Sublimes
best at 157°. At higher temps dec into CO2, CO, formic
acid, and H2O. d417 1.90. 100 g of aq soln satd at 15°
contain 6.71 g, at 20° 8.34 g, at 25° 9.81 g.Caution
Potential symptoms of overexposure
by ingestion are corrosion of alimentary tract mucosa; localized pain;
vomiting, shock, hypotension, cardiovascular collapse; headache, muscle
cramps, tatany; convulsions, stupor, coma; kidney damage. Direct
contact may cause eye, skin and mucous membrane irritation; eye burns.
See NIOSH Pocket Guide to Chemical
Hazards (DHHS/NIOSH 97-140, 1997) p 238; Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Ed. (Williams & Wilkins,
Baltimore, 5th ed., 1984) Section III, pp 326-328.Use
As analytical reagent; in calico printing and dyeing;
for bleaching straw (hats) and leather; removing paint or varnish,
rust or ink stains; cleaning wood; manuf oxalates; blue ink; celluloid;
intermediates and dyes; in metal polishes; in indigo dyeing; in purifying
methanol; for decolorizing crude glycerol; for stabilizing hydrocyanic
acid. As a general reducing agent; in ceramics and pigments; in metallurgy
as cleanser; in the paper industry; in photography; in process engraving;
in the rubber mfg industry; in making glucose from starch; as condensing
agent in organic chemistry.
In vitro blood specimen anticoagulant.
Therapeutic Category (Veterinary)
In 5% solution with 5% malonic acid as
hemostatic agent.