Oxalic acid/oxalates toxicity

Self-Test F.5B The molar mass of oxalic acid, a toxic substance found in rhubarb leaves, is 90.0 g-mol, and its empirical formula is CH02. What is its molecular formula ... 

Ethylene glycol is a toxic diol. Its oxidation product is oxalic acid, the toxic compound found in the leaves of rhubarb and many other plants. 

Oxalyl chloride, (C0CI)2, is the double acid chloride of oxalic acid, or ethane-1,2-dioic acid, the toxic dicarboxylic acid found in rhubarb leaves. 

Oxalic acid Chenopodium album, Spinacia oleracea Sour (acid) taste [toxic ... 

Although oxalic acid is toxic, you would have to eat about nine pounds of spinach at one time to ingest a fatal dose. r/J... 

Evidence for renal oxalate toxicity was found from studies describing urinary enzyme excretion suggesting renal (tubular) damage in patients with stones [25]. Rat models of stone disease have been used to study such damage in greater detail and revealed brush border loss, release of cellular enzymes, and epithelial erosion [19, 26, 27]. However, all these arguments are indirect and cannot distinguish oxalate (or oxalic acid) mediated effects from calcium oxalate crystal induced effects. 

The remedy is to swab with a cold water solution of commercial quality oxalic acid solution (or alternatively use a proprietary solution for the removal of scale from pots and pans) followed by rinsing with water. Oxalic acid is toxic rubber gloves and goggles are recommended. 

Some dehydration reactions of sulfuric acid can be very vigorous. For example, the reaction with perchloric acid produces unstable CI2O7, and a violent explosion can result. Concentrated sulfuric acid produces dangerous or toxic products with a number of other substances such as toxic carbon monoxide (CO) from reaction with oxalic acid, H2C2O4 toxic bromine and sulfur dioxide (Bf2 and SO2) from reaction with sodium bromide, NaBr and toxic, unstable chlorine dioxide (CIO2) from reaction with sodium chlorate, NaClOj. 

Osmium tetroxide, reaction with alkenes, 235-236 toxicity of, 235 Oxalic add, structure of, 753 Oxaloacetic acid, structure of, 753 Oxetane, reaction with Grignard reagents, 680 Oxidation, 233, 348 alcohols, 623-626 aldehydes, 700-701 aldoses, 992-994 alkenes, 233-236 biological, 625-626 phenols, 631 sulfides, 670 thiols, 668... 

Potassium Oxalata. K2C2 04. HjO, mw 184.23 colorl, odorless crysts mp, loses H20 at about 160°, when iguited is converted into carbonate without appreciable charring d 2.13g/cc, sol in 3p of w. Can be prepd by heating a mixt of K formate or carbonate with oxalic acid and a small amt of K hydroxide, with subsequent extraction of w. Highly toxic by inhalation and ingestion... 

ADH also has clinical significance in the metabolism of methanol and ethylene glycol, two drugs with toxic metabolites. Methanol is oxidized by ADH to formaldehyde, which damages the retina and can cause blindness. Ethylene glycol is metabohzed by ADH to oxalic acid, which has renal tox-... 

Vegetables also contain carboxylic acids that contribute to their flavors. One example is oxalic acid, prevalent in spinach and rhubarb. Raw rhubarb leaves are mildly poisonous, and folklore holds that the toxic substance is oxalic acid. However, raw spinach can be eaten safely despite its equally high content of this acid. 

Aluminium toxicity is a major stress factor in many acidic soils. At soil pH levels below 5.0, intense solubilization of mononuclear A1 species strongly limits root growth by multiple cytotoxic effects mainly on root meristems (240,241). There is increasing evidence that A1 complexation with carboxylates released in apical root zones in response to elevated external Al concentration is a widespread mechanism for Al exclusion in many plant species (Fig. 10). Formation of stable Al complexes occurs with citrate, oxalate, tartarate, and—to a lesser extent— also with malate (86,242,243). The Al carboxylate complexes are less toxic than free ionic Al species (244) and are not taken up by plant roots (240). This explains the well-documented alleviatory effects on root growth in many plant species by carboxylate applications (citric, oxalic, and tartaric acids) to the culture media in presence of toxic Al concentrations (8,244,245) Citrate, malate and oxalate are the carboxylate anions reported so far to be released from Al-stressed plant roots (Fig. 10), and Al resistance of species and cultivars seems to be related to the amount of exuded carboxylates (246,247) but also to the ability to maintain the release of carboxylates over extended periods (248). In contrast to P deficiency-induced carboxylate exudation, which usually increases after several days or weeks of the stress treatment (72,113), exudation of carboxylates in response to Al toxicity is a fast reaction occurring within minutes to several hours... 

The kinetic parameters for the oxidation of a series of alcohols by ALD are shown in Table 4.1 (74). Methanol and ethylene glycol are toxic because of their oxidation products (formaldehyde and formic acid for methanol and a series of intermediates leading to oxalic acid for ethylene glycol), and the fact that their affinity for ALD is lower than that for ethanol can be used for the treatment of ingestion of these agents. Treatment of such patients with ethanol inhibits the oxidation of methanol and ethylene glycol (competitive inhibition) and shifts more of the clearance to renal clearance thus decreasing toxicity. ALD is also inhibited by 4-methylpyrazole. 

Reproductive toxicity has been noted in animal studies. Male mice administered 8400 mg/kg for 7 days before mating had decreased fertility. Female mice given the same dose 7 days before mating and throughout 21 days of gestation showed embryotoxicity and fetotoxi-city. Female rats had disrupted estrous cycles when maintained on diets containing 2.5% and 5% oxalic acid. ... 

Ethylene glycol is rapidly metabolised to glyco-laldehyde, then glycolic acid, glyoxylic acid and finally to oxalic acid. The metabolites are toxic to kidneys, brain and heart. 

All patients with methanol toxicity should be given folic acid 50 milligrams intravenously every 4 hours to increase the metabolism of formic acid. In ethylene glycol ingestion, folate, thiamine and pyri-doxine should all be administered, to enhance the metabolism of the poison to non-toxic products, and minimize oxalic acid production. Calcium supplements are required for symptomatic hypocalcaemia. 

Ethylene glycol, an industrial solvent and an antifreeze compound, is involved in accidental and intentional poisonings. This compound is initially oxidized by alcohol dehydrogenase and then further biotransformed to oxalic acid and other products. Oxalate crystals are found in various tissues of the body and are excreted by the kidney. Deposition of oxalate crystals in the kidney causes renal toxicity. Ethylene glycol is also a CNS depressant. In cases of ethylene glycol poisoning, ethanol is administered to reduce the first step in the biotransformation of ethylene glycol and, thereby, prevent the formation of oxalate and other products. 

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