1. Oxalic acid can be used for rust removal. However, exercise caution as it strongly corrodes stainless steel. High-concentration oxalic acid may also irritate hands. The resulting oxalate salts are highly soluble but possess some toxicity. Avoid ingestion during use. If skin contact occurs, rinse immediately with water.Oxalic acid begins subliming at 100°C, rapidly subliming at 125°C, and extensively subliming at 157°C, where it also begins decomposition. It reacts with alkalis and can undergo esterification, acyl halogenation, and amidation reactions. It also undergoes reduction reactions and decarboxylation when heated. Anhydrous oxalic acid is hygroscopic. Oxalic acid forms water-soluble complexes with many metals.
3. In production and daily life, oxalic acid is used to produce antibiotics and pharmaceuticals like borneol, as a solvent for refining rare metals, a dye reducing agent, and a tanning agent.
4. In the chemical industry, oxalic acid is used to manufacture pentaerythritol, cobalt oxalate, nickel oxalate, basic green pigment, steel and soil analysis reagent kits, and chemical reagents.It serves as a color development aid in fast dyes and as a bleaching agent for straw and wheat straw products (due to its reducing properties).
5. Oxalic acid has extensive applications in other industries. In organic synthesis, it is primarily used to produce chemicals like hydroquinone, pentaerythritol, cobalt oxalate, nickel oxalate, and gallic acid.In the plastics industry, it is used to produce polyvinyl chloride (PVC), amino plastics, urea-formaldehyde plastics, and lacquer flakes. In the dye industry, it is used to manufacture basic green dyes. In the printing and dyeing industry, it can replace acetic acid as a color development auxiliary and bleaching agent for pigment dyes. In the pharmaceutical industry, it is used to manufacture chlortetracycline, oxytetracycline, tetracycline, streptomycin, and ephedrine.
Oxalic acid's lethality lies in its ability to reduce calcium ion levels in human blood to critical thresholds. Calcium is known to play a vital role in maintaining stable blood acidity and viscosity, as well as facilitating phosphate transport and coagulation within the body. If oxalic acid poisoning occurs, how to counteract its effects may be of concern!From a chemical equilibrium perspective, we should promptly replenish calcium ions in the blood. Calcium gluconate, once a hot topic in TV commercials, serves as the ideal antidote. Even if oxalate levels are not yet life-threatening, its effect on calcium ions cannot be ignored. It forms insoluble calcium oxalate crystals that can develop into stones in organs like the bladder and kidneys, causing severe pain.While we can generally avoid excessive consumption of these foods, it's impossible to completely eliminate oxalic acid from our bodies, as it can be obtained through other channels. For instance, renowned chemist Linus Pauling advocated taking large doses of vitamin C to prevent colds, and during the SARS epidemic, health experts recommended vitamin C to boost immunity. However, excess leads to the opposite effect: our bodies cannot store surplus vitamin C, which then converts into oxalic acid.Therefore, excessive vitamin C intake can easily cause diarrhea and may even lead to kidney stones. If we consume insufficient water daily, these issues are more likely to occur.