Background and overview[1]
Anhydrous oxalic acid Oxalic acid is also known as “ermic acid”, and its scientific name is “oxalic acid & polyurethane raw material”. It is a colorless and transparent monoclinic crystal, often found in rhubarb and other plants in the form of calcium salts. It is highly acidic and not easy to burn. . Relative density: 1.653 (19℃/4℃); melting point: 101.5℃; sublimation point: 150~160℃, toxic, soluble in hot water, ethanol and glycerin, slightly soluble in ether, harmful to eyes and skin It has a corrosive effect, and the effect is stronger after contact with water. People who take 2 grams orally can be poisoned and die. When storing, it should be protected from moisture, rain, and isolated from oxidants and alkali substances. The storage and transportation temperature should not be higher than 40°C. Avoid contact with food Contact with it should be kept away from the living area and should not be installed on the deck when loading the ship. Although this substance is not easy to burn, if it causes a fire, water and sand can be used as a fire-fighting method. If it enters the eyes or touches the skin, rinse with plenty of water. If swallowed by mistake, It should be sent to the hospital for treatment. In industry, it is generally synthesized from carbon monoxide and sodium hydroxide. It can be used as a solvent for refining rare metals, a dye reducing agent, a printing and dyeing bleaching agent, a metal rust remover, a marble polishing agent, a descaling agent, and a paper anti-wrinkle agent. Surface treatment agents are raw materials for manufacturing oxalates and organic synthesis. The main producing areas in my country are Shanghai, Tianjin, Mudanjiang, Zhuzhou, Lianyungang, Wuhan, Chengdu, Guangzhou, Nanjing, Ningbo and Xuzhou, with an annual export volume of more than 10,000 tons, mainly sold to the United States, Japan, Hong Kong, Singapore, Pakistan, the European Community and other countries and regions. United Nations Number (UNNo.): 2811/6154-2, Category 6.1.
Apply[2-3]
Anhydrous oxalic acid can be used in organic synthesis.
1) Preparation of lithium difluoroborate oxalate, including the following steps: (1) After all production reaction vessels are replaced with nitrogen, they are placed under the protection of high-purity nitrogen to add materials; (2) Dry and quantitatively anhydrous lithium tetrafluoroborate and catalyst are added to the quantitative organic solvent in the stirring reactor to dissolve and prepare a solution; (3) Slowly add a quantitative amount of anhydrous oxalic acid or anhydrous oxalic acid solution into the lithium tetrafluoroborate solution, and maintain the temperature under the specified temperature, specified pressure and exhaust gas absorption. Fully react under liquid control to obtain lithium difluoroxalate borate solution. The catalytic synthesis method of lithium difluoroxalate borate of the present invention has a simple process route and high product yield. The waste gas generated during the reaction process is absorbed by the alkali liquid, and there is no environmental pollution.
2) Synthesis of diisobornyl oxalate, using industrial camphene, camphene, tricyclic ene, isoborneol, etc. as raw materials, including the following steps: dissolve the raw materials in a certain amount of organic solvent, add boron anhydride, Pyboric acid, metaboric acid, titanium sulfate, metatitanic acid and other catalysts react with anhydrous oxalic acid at a certain temperature for a certain time. Filter to remove the anhydrous oxalic acid that has not reacted with the catalyst. Wash several times with water. The upper liquid is removed by rotary evaporation. Part of the solvent is then steam distilled to remove the unreacted raw materials camphene and tricyclic ene and a small amount of by-product isoborneol to obtain a crude product, which is then recrystallized to obtain diisoborneol oxalate. This reaction can use organic solvents such as aromatic hydrocarbons and branched alkanes as silicone as the reaction medium. The method adopts conventional heating with mild conditions, simple operation, easy separation of raw materials and products, few side reactions, and high product yield.
Preparation[4]
The method of preparing anhydrous oxalic acid from oxalic acid includes the following steps: heat the oxalic acid in a closed container, wait until the temperature rises to 50~60℃, control the temperature for 55 to 65 minutes, and then raise the temperature again, wait until the temperature rises to 101~ At 105°C, control the temperature for another 10 to 15 minutes to obtain anhydrous oxalic acid. The production device used to implement this method is as shown in the figure. It includes a bracket 1 and a hot air chamber 2 fixed above the bracket. One end of the hot air chamber 2 has a hot air inlet 3, and a drying chamber 5 is fixedly connected to the upper end of the hot air chamber 2. The hot air chamber and the drying chamber are connected through several pipes with air volume regulating valves 6. The drying chamber 5 has an inlet 7 and an outlet 8 on both sides respectively. A viewing window 13 and a manhole 14 are provided on the side wall of the drying chamber 5, and a thermometer 15 is installed. A pulse dust collector 16 is fixedly connected to the upper surface of the drying chamber. An inclined orifice plate 9 is provided in the drying chamber. A porous plate 10 is provided above the inclined orifice plate 9. A dust receiving bucket 12 is connected below the inclined orifice plate 9. The porous plate 10 has Multiple openings are connected with filter bags 11. The top of the drying chamber 5 has an air outlet 4 located above the perforated plate 10 .
Main reference materials
[1] Technical Dictionary of Container Transport Business·Volume 2
[2] Catalytic synthesis method of CN201610732281.9 lithium difluoroxalate borate
[3] CN201410243680.X A method for synthesizing diisoborneol oxalate
[4] CN201210173896.4 A method and production device for preparing anhydrous oxalic acid from oxalic acid
