8-Crown-6

Introduction 18-crown-6, also known as crown ether, belongs to the macrocyclic ether class of organic compounds. Its main applications include efficient phase transfer catalysts for fine organic synthesis, complexing agents, and extractants for the separation and extraction of precious metals and rare earth elements. In chemical analysis, it can be used for ion enrichment, separation, and masking. It can also be used in the fields of medicine, biochemistry, and electronics as an ion conductive material and a material for making liquid crystal display elements. Chemical properties: 18-crown-6 appears as a colorless viscous liquid with boiling points of 115-116 ℃ (240Pa), 93-96 ℃ (18.3Pa), 78 ℃ (6.67Pa), relative density of 1.113 (20/4 ℃), and refractive index of 1.4615. 18-Grown-6,4,7,10,13,16-Hexaoxacy clooctadacane, white crystals. Melting point 38-39.5 ℃, boiling point 116 ℃ (26.6Pa). Crown ethers, also known as macrocyclic ethers, are macrocyclic compounds containing multiple oxygen atoms. When naming, mark the total number of atoms contained on the ring before the word "crown", and the number of oxygen atoms contained after the name. This was accidentally discovered by Pedersen of DuPont in 1967, and it was found that this type of compound has many abnormal properties. One of the main characteristics of crown ethers is that they can form stable complexes with various metal salts, ammonium salts, organic cationic compounds, etc. By utilizing this property, various salts can be dissolved in organic solvents. Crown ethers can chelate cations into the ring, and due to the outward facing organic genes, they can form complexes and dissolve in non-polar organic solvents. At this point, the undissolved anions exist in the solvent in the form of bare anions, making them highly active. Crown ethers can dissolve alkali metal and organic alkali metal compounds in organic solvents. Therefore, it has found wide applications in organic synthesis, optical resolution, heavy metal chelation, separation, analysis, and physiological activities in pharmaceuticals, biochemistry, and other fields. For example, as a phase transfer catalyst, many reactions that are difficult to react or even do not occur under traditional conditions can proceed smoothly. These reactions have fast rates, simple conditions, convenient operation, and high yields. For example, the condensation reaction yield of benzoin in aqueous solution is extremely low. If 7% crown ether is added to the aqueous solution, benzoin with a yield of 78% can be obtained. This reaction can also be carried out in benzene (or acetonitrile), although potassium cyanide is insoluble in benzene, if 18-crown-6 is added, not only can the reaction occur, but the yield can reach up to 95%. Toxicity of 18-crown-6: The oral lethal dose for rats is 300mg/kg. Irritating to eyes and skin.