Only imidazole derivatives exist in nature, but no free imidazole. Precipitated from benzene is a monoclinic prismatic colorless crystal. Ammonia smell. The relative molecular mass is 68.08. The relative density is 1.0303 (101/4°C). Melting point 89～91℃, boiling point 257℃, 165℃～168℃ (2.67×103Pa), 138.2℃ (1.60×103Pa). Flash point 145 ℃. Refractive index 1.4801 (101°C). Viscosity 2.696mPa·s (100°C). Slightly soluble in benzene, petroleum ether, soluble in ether, acetone, chloroform, pyridine, easily soluble in water (room temperature 70), ethanol. Weakly alkaline. Because a hydrogen bond is formed between the -NH- bond at the 1-position and the -N= bond at the 3-position, the boiling point is higher. When the hydrogen at the 1-position is replaced, the hydrogen bond cannot be formed, and the boiling point decreases. It is thermally stable and hardly decomposes below 250°C (decomposition temperature is 590°C).
It is also stable to reducing and oxidizing agents, but can form stable salts with inorganic acids. With some aromatic properties, it can be halogenated, nitrated, sulfonated and methylolated under the action of a catalyst. And can be coupled with the diazonium salt in the 2 position. In addition, since the =NH group (1 position) connects two double bonds, it is somewhat "acidic" and can be replaced by a metal to form a salt. The 3-position nitrogen has a coordination effect on metal ions and can form chelates. Although it is difficult to be reduced, it can be added with protons to form a cationic and resonant structure to form a stable form. The tautomers of the imidazole ring are very easy to change, so the isomers at the 4th and 5th positions are not easy to distinguish.
1. Chemical Properties
Toxic, oral LD50 to mice: 18.80mg/kg. Injection of LD50610mg/kg, its toxicity and protection methods are similar to ethylenediamine.
Other harmful effects: The substance may be harmful to the environment, special attention should be paid to water bodies.
2. Properties and stability
Weakly alkaline. Toxic, the production equipment should be sealed to prevent running, running, dripping and leaking. Operators should wear protective equipment to avoid direct contact with this product.
