Views: 2 Author: Site Editor Publish Time: 2023-01-06 Origin: Site
Formic acid is an organic compound with a chemical formula of HCOOH and a molecular weight of 46.03. It is commonly known as formic acid and is the simplest carboxylic acid. It is a colorless liquid with a pungent odor. Formic acid is a weak electrolyte, but its aqueous solution is weakly acidic and highly corrosive, which can stimulate the skin to blister. Usually found in the secretions of bees, some ants and caterpillars. It is an organic chemical raw material and also used as a disinfectant and antiseptic.
1. Anhydrous formic acid can be directly obtained by fractional distillation under reduced pressure, and condensed with ice water during fractional distillation. For aqueous formic acid, anhydrous copper sulfate can be used as a desiccant. For reagent grade 88% formic acid, the water can be removed by distillation after reflux of phthalic anhydride for 6 hours. Further purification may utilize fractional crystallization. When formic acid and acetic acid are mixed together, aliphatic hydrocarbons can be added for azeotropic distillation and separation.
2. Mix formic acid and phosphorus pentoxide, carry out vacuum distillation, and repeat 5-10 times to obtain anhydrous formic acid, but the yield is low and time-consuming, which will cause some decomposition. Distilling formic acid and boric acid is easy to operate and better in effect. Dehydrate the boric acid in a high-temperature dehydration medium until no bubbles are produced, pour the resulting melt on an iron sheet, cool it in a desiccator, and then grind it into powder. Add boric acid phenol fine powder to formic acid and let it stand for a few days to form hard lumps. Separate the clear liquid for vacuum distillation, and collect the 22-25 ℃/12-18 mm fraction as the product. Distillers shall be fully ground joints and protected by drying tubes.
Formic acid is one of the basic organic chemical raw materials, widely used in pesticide, leather, dye, medicine and rubber industries. Formic acid can be directly used in fabric processing, leather tanning, textile printing and dyeing and green fodder storage, and can also be used as metal surface treatment agent, rubber auxiliary agent and industrial solvent. In organic synthesis, it is used to synthesize various formic acid esters, acridine dyes and formamide series pharmaceutical intermediates. The specific classification is as follows:
1. Pharmaceutical industry: It can be used in the processing of caffeine, analgin, aminopyrine, aminophylline, theobromine borneol, vitamin B1, metronidazole, and mebendazole.
2. Pesticide industry: It can be used in the processing of tricloxazone, triadimefon, tricyclazole, triamazole, triazophos, paclobutrazol, uniconazole, dimechlor, and dicofol.
3. Chemical industry: raw materials for the manufacture of various formate, formamide, pentaerythritol, neopentyl glycol, epoxy soybean oil, epoxy soybean octyl, pivaloyl chloride, paint remover, and phenolic resin.
4. Leather industry: used as tanning agent, deliming agent and neutralizing agent for leather.
5. Rubber industry: used in the processing of natural rubber coagulant and the manufacture of rubber anti-aging agent.
7. Determination of cerium, rhenium and tungsten. Checks for aromatic primary and secondary amines and methoxyl groups. Determine the relative molecular mass and solvent methoxyl of the crystallization. Used as a fixative in microscopic analysis.
8. Formic acid and its aqueous solution can dissolve many metals, metal oxides, hydroxides and salts, and the formed formate can be dissolved in water, so it can be used as a chemical cleaning agent. Formic acid does not contain chloride ions and can be used for cleaning equipment containing stainless steel materials.
9. It is used for blending food flavors such as apple, papaya, jackfruit, bread, cheese, cheese, cream, etc., as well as flavors for whiskey and rum. The concentration in the final flavored food is about 1~18 mg/kg.
10. Others: It can also manufacture printing and dyeing mordants, fiber and paper dyes, treatment agents, plasticizers, food preservation, animal feed additives and reducing agents, etc.