2 Iodo 4 Methylaniline

4-Ethylpyridine, also known as 2-methyl-5-ethylpyridine, has a wide range of main uses.
In the field of medicine, it is an important pharmaceutical intermediate. The synthesis of many drugs requires this as the starting material or key intermediate. With its unique chemical structure, complex drug molecular structures are constructed through a series of reactions. It is used in the preparation of some cardiovascular disease treatment drugs and antibacterial drugs, which is of great significance to promote the development of medicinal chemistry and enrich the variety of drugs.
In terms of pesticides, it can be used to synthesize a variety of highly efficient and low-toxic pesticides. Transformed into compounds with specific insecticidal, bactericidal or herbicidal activities by chemical reaction, it contributes significantly to ensuring the healthy growth of crops and improving agricultural yield and quality.
In the field of organic synthesis, as an important basic raw material, many organic compounds with special properties can be derived. These compounds are widely used in many fields such as materials science and fine chemistry, such as the preparation of high-performance engineering plastics and special optical materials, providing a material basis for technological innovation and product upgrading in these fields.
In the dye industry, 4-ethylpyridine can be used as a key raw material for the synthesis of new dyes. With its structural characteristics, dyes give unique color, stability and dyeing properties, and are widely used in textile, printing and dyeing and other industries to meet diverse dyeing needs.
In the fragrance industry, its synthetic fragrances have unique aromas, which can add unique flavors to perfumes, food additives and other products, and enhance product added value and market competitiveness.
It can be seen that 4-ethylpyridine plays a key role in many industries, promoting the development and progress of related industries.

4-Aminopyridine is an organic compound. Its physical properties are quite unique.
Looking at its appearance, it is often in the state of white to light yellow crystalline powder, delicate and uniform in texture, occasionally flickering with a subtle luster under light, just like concealing light.
When it comes to solubility, it shows a certain solubility in water, and can interact with water molecules and gradually melt in water. This property allows it to play a role in some chemical reactions or solution systems involving the aqueous phase. At the same time, it also has a certain solubility in organic solvents such as ethanol and ether. By virtue of specific forces with different organic solvent molecules, it can be dispersed and dissolved, thus providing many possibilities for related organic synthesis experiments or industrial processes.
As for the melting point, the melting point of 4-aminopyridine is about 158-162 ° C. When the temperature gradually rises to this range, the lattice structure of this substance will disintegrate under the impact of thermal energy, and the solid substance will gradually transform into a liquid state. This melting point characteristic is of great significance for its purification, identification and participation in the reaction process under specific temperature conditions.
In terms of boiling point, under normal pressure environment, its boiling point is about 273 ° C. At this temperature, the liquid 4-aminopyridine molecule obtains enough energy to get rid of the liquid phase and escape into a gaseous state. This boiling point data is of great reference value for its separation, distillation and other operations.
In addition, 4-aminopyridine has certain sublimation properties. Under certain temperature and pressure conditions, it can directly change from solid to gaseous without going through the liquid stage. This property can be exploited in specific purification or analysis processes. Its density is slightly larger than that of water, about 1.17g/cm ³. When placed in water, it will sink to the bottom. This density characteristic will also have a corresponding impact in some experiments and application scenarios involving phase separation or density.

4-Aminopyridine is active and has unique properties in various chemical reactions. It is alkaline, and its nitrogen atom has lone pairs of electrons, which can be combined with protons. This is a significant characteristic of it in acid-base reactions.
Looking at its nucleophilicity, the amino group of 4-aminopyridine can be used as a nucleophilic reagent. In nucleophilic substitution reactions, it can attack substrates with electrophilic centers, and then generate novel compounds. Its electron cloud distribution characteristics, the nitrogen atom of the amino group is rich in electrons, so the nucleophilic activity is quite high.
Talking about stability, in the structure of 4-aminopyridine, the conjugated system of the pyridine ring gives it a certain stability. However, the introduction of amino groups also has a slight impact on its stability. Under specific conditions, in case of strong oxidizing agents or high temperatures, the structure may change, and reactions such as oxidation and decomposition can occur.
In terms of solubility, 4-aminopyridine has a certain solubility in polar solvents such as water because of its polar functional groups. However, the hydrophobicity of the pyridine ring makes its solubility not very high. In comparison, in organic solvents such as alcohols, the solubility is better, because alcohols and 4-aminopyridine can form hydrogen bonds and other interactions.
In the field of organic synthesis, 4-aminopyridine is an important intermediate. Due to its special chemical properties, it can participate in the construction of many complex organic molecules. Through nucleophilic substitution, condensation and other reactions, it can be connected to a larger molecular structure, providing the possibility for the creation of compounds with specific biological activities or material properties.
In summary, 4-aminopyridine is an important research object in the field of organic chemistry due to its diverse chemical properties.

The synthesis method of 2-bromo-4-methylfuranobenzoic acid, although "Tiangong Kaiwu" did not directly record the synthesis method of this specific compound, it has many inspirations in chemical, pharmaceutical and other technologies. Our generation can participate in the ancient method and use modern chemical knowledge to deduce its synthesis path.
First, it can be started by substitution reaction of raw materials containing corresponding groups. Looking at the processes of salt and metallurgy recorded in "Tiangong Kaiwu", the selection of raw materials and the control of reaction conditions are all important. If you want to make 2-bromo-4-methylfuranobenzoic acid, you can first use 4-methylfuran as the starting material. Because of its furan ring and methyl, bromination can be carried out with a brominating agent under appropriate conditions. The ancient method of making salt from brine requires precise control of temperature, time and other conditions. This bromination reaction also requires temperature control, selection of brominating agents and solvents. For example, under the catalysis of suitable catalysts (such as iron powder, etc.), at low temperature and in the dark, slowly add liquid bromide to 4-methylfuran solution dropwise, stir and react for a certain period of time to obtain 2-bromo-4-methylfuran.
After obtaining 2-bromo-4-methylfuran, carboxyl groups are to be introduced. The idea of conversion of many substances in Tiangong Kaiwu can be used for reference, and the Grignard reagent method can be used. React magnesium with 2-bromo-4-methylfuran in anhydrous ether to make Grignard reagent. Then it is introduced into carbon dioxide gas and hydrolyzed to obtain 2-bromo-4-methylfuranobenzoic acid. This process is the ancient method of winemaking, and each step is interconnected, which requires strict requirements on the environment and material ratio. The preparation of Grignard's reagent requires absolute anhydrous and oxygen-free, and the rate and amount of carbon dioxide introduced need to be precisely controlled. The pH and temperature of the hydrolysis step all affect the purity and yield of the product.
In addition, there are other paths. 4-methylfuran can be oxidized first to convert methyl to carboxyl groups to obtain 4-methylfuranbenzoic acid, and then the bromination reaction can be carried out. However, this order is adjusted. The position selectivity of bromide may be different from the former. It is necessary to consider the reaction conditions and the catalyst used in detail to make the bromine atom exactly at the 2-position. This kind of synthesis method needs to learn from the ancient rather than the ancient, and combine the technological wisdom contained in "Tiangong Kaiwu" with modern chemical knowledge to form the synthesis of the target compound.

Two Flavors and Four Gentlemen Soup is a traditional Chinese medicine prescription. It is widely used. Many matters need to be paid attention to during storage and transportation.
First storage environment. The medicinal materials of this soup contain many plant ingredients and are prone to moisture and mildew. Be sure to store in a dry place. The humidity should be controlled between 40% and 60% to prevent the drug from deteriorating and causing the drug effect to be damaged. If it is in a humid place, a desiccant can be prepared to absorb excess water vapor. And it needs to be placed in a cool place, away from direct sunlight. Due to light or the decomposition of drug components, its chemical structure will be damaged and the curative effect will be affected.
The second time is the storage period. Different medicinal materials have different shelf life. The Codonopsis, Atractylodes, Poria, Licorice, etc. used in the Four Gentlemen Soup are relatively stable in nature, but they also have a shelf life. After purchase, they should be used as soon as possible. Generally speaking, dried medicinal materials can be stored for one to two years under suitable conditions. However, after making the decoction, the shelf life is greatly reduced, mostly one to two days. When it is hot in summer, it should be shortened to prevent deterioration.
Furthermore, pay attention to packaging when transporting. The packaging of medicinal materials must be tight to prevent collision and extrusion, which will cause the medicinal materials to break and affect the quality. If using strong cartons or plastic containers, add cushioning materials. If transporting the decoction, make sure that the container is well sealed to prevent leakage. In hot weather, or cold chain transportation is required to maintain low temperature and ensure its quality.
In addition, during storage and transportation, rodents and insects must be prevented. The aroma of medicinal materials is easy to attract rodents and insects, and deworming drugs can be spread at the storage place, or protective facilities can be set up. The means of transportation should also be clean, and there are no hidden dangers of rodents and insects. In this way, the quality and efficacy of Erwei Sizi Gentleman Soup can be guaranteed during storage and transportation.