Thiophene-2,5-Dicarboxyl Acid

Although "pentazole-2,5-dicarboxylic acid" is not explicitly mentioned in "Tiangong Kaiwu", its possible uses can be deduced according to the thinking of the ancients' exploration of material properties and uses.
Pentazole-2,5-dicarboxylic acid contains carboxyl groups and is acidic. In ancient times, it may be used in some dyeing processes. The ancients often needed additives to adjust the pH of the dye solution to promote the binding of the dye to the fabric. Pentazole-2,5-dicarboxylic acid may play a similar role, helping the dye to adhere better to the fabric, making the dyeing more uniform, firm, and more vivid and lasting.
In the pharmaceutical field, the ancients attached great importance to drug processing and ingredient extraction. The unique chemical structure of pentazole-2,5-dicarboxylic acid may participate in the reaction of specific drug components, change the solubility and stability of the drug, and improve the efficacy of the drug. For example, in some prescriptions that need to adjust the acidity and alkalinity of the drug to achieve the best curative effect, it may be used as an auxiliary agent.
In metal processing, the production of ancient metal utensils and anti-rust treatment are important. Pentazole-2,5-dicarboxylic acid may be used for metal surface treatment. Its acidity can slightly corrode the metal surface, form a fine oxide film, enhance the corrosion resistance of metals, and prolong the service life of metal utensils. And in metal smelting, it may help separate impurities and improve metal purity.
In leather tanning, the ancients used vegetable tanning agents mostly Pentazole-2,5-dicarboxylic acid may be used as a new tanning agent or auxiliary material. It can combine with protein in leather to make leather softer and tougher, improve leather quality, and after treatment, leather may have better resistance to microbial erosion, which is conducive to preservation.

The "Hardware" article of "Tiangong Kaiwu" says: "All gold, silver, copper, iron, lead, and tin are ordinary." Today, 2,5-dichlorobenzoic acid has quite specific physical properties.
2,5-dichlorobenzoic acid, white in color and in the shape of a powder, looks fine. It is quite stable at room temperature and does not easily combine with surrounding objects. The melting point is between 150-154 ° C. If it is heated to this temperature, it will gradually transform from solid to liquid, just like ice and snow melting when warm.
Its density is 1.54 g/cm ³, which is heavier than ordinary water. If it is placed in water, it sinks to the bottom of the water. And this substance is slightly soluble in water, but it has good solubility in organic solvents, such as ethanol and ether. It is like a fish getting water and can be evenly dispersed in it.
Its smell is light but not strong. Although it is not a rich fragrance, it has no pungent smell and does not disturb people's sense of smell. Under the light, it is slightly shiny, like a subtle crystal glow.
Furthermore, the granularity of 2,5-dichlorobenzoic acid is very uniform, and the particle size is mostly concentrated within a certain range. This property makes it easy to disperse and mix in many industrial processes and experimental operations, providing many conveniences for the implementation of related processes.
Looking at its various physical properties, they are all unique characteristics of it, and play an indispensable role in many fields such as chemical industry and medicine. They can contribute to various products and achieve extraordinary success.

In "Tiangong Kaiwu", there is a genus of burnt stone, and there is alum stone. In today's words, 2,5-dichlorobenzoic acid, which is made by modern chemistry, although "Tiangong Kaiwu" has not been detailed, its properties can also be known by chemical common sense.
2,5-dichlorobenzoic acid, in the shape of white to light yellow crystalline powder. It is acidic, because of the carboxyl group. The carboxyl group can dissociate hydrogen ions, which can be weakly ionized in water, so it can react with alkali substances. In case of sodium hydroxide, the two combine to form 2,5-dichlorobenzoate sodium and water.
This substance has a certain solubility. In organic solvents, such as ethanol and ether, the solubility is acceptable, because there are parts in the molecular structure that can interact with organic solvents. However, in water, the solubility is relatively small, and the interaction with water molecules is weak because of the large non-polar part.
And the halogen atom of 2,5-dichlorobenzoic acid, that is, the chlorine atom, also gives it unique properties. The chlorine atom has a certain electronegativity, which can change the density distribution of the electron cloud of the benzene ring, which in turn affects its chemical activity. Under appropriate conditions, the chlorine atom can undergo a substitution reaction or be replaced by other groups to form new compounds.
Furthermore, its melting point and boiling point are fixed. The existence of the melting point is due to the fact that the intermolecular force at a certain temperature is not enough to maintain its solid structure. The molecule begins to gain enough energy and the motion intensifies, and the lattice structure disintegrates. The boiling point is when the molecule obtains enough energy to overcome the attractive force between molecules and transform from liquid to gaseous state. The melting boiling point of 2,5-dichlorobenzoic acid has a corresponding value due to the van der Waals force and hydrogen bonds between molecules. This value is crucial for its separation, purification and other operations.

The method of 5-nitro-2,5-dicarboxylbenzoic acid
For 5-nitro-2,5-dicarboxylbenzoic acid, the following method can be followed.
The first amount of raw material is taken, and the starting material is 2,5-dimethylbenzoic acid. This is because it is similar to the original material of the original material, and it can be used to provide a base.
In the reverse container of the combination, 2,5-dimethylbenzoic acid is placed in a mixed acid system formed by sulfuric acid and nitric acid. Sulfuric acid here plays the role of catalysis and water absorption. Its catalytic reaction line absorbs the water generated by the reaction, and prompts the reaction to move in the direction of generating nitro compounds. Nitric acid provides the source of nitro groups, allowing the nitro group to replace the atom on the benzene. The reaction rate needs to be controlled, and it is generally maintained at an appropriate temperature, such as about 50-60 ° C, in order to maintain the reaction energy and avoid a large amount of reaction. In this case, a nitro group is introduced into the benzene of 2,5-dimethylbenzoic acid to generate 5-nitro-2,5-dimethylbenzoic acid.
Next, 5-nitro-2,5-dimethylbenzoic acid is oxidized. In this process, the methyl group is oxidized with carboxylic acid, etc., and it is dissolved in a suitable solution. The reaction needs to be carried out under the addition of oil and rubber parts. The reaction environment can make the oxidation reaction more easy to produce, and the addition of oil can improve the reaction rate. In this process, the methyl group is oxidized carboxyl group, which is formed from a series of oxidation processes, 5-nitro-2,5-dimethylbenzoic acid. After the reaction is completed, it needs to be extracted in a row. First, the reaction is mixed with liquid cooling, so that the liquid is precipitated, and then the solid is collected by the method of water. The water is washed with the appropriate solution to remove the water. If washed multiple times in cold water, the water-soluble water can be removed. The most important factor is that 5-nitro-2,5-dicarboxybenzoic acid can be obtained.

Looking at the current market, the price of 5- (2-methoxyethoxy) -2-methyl-2,4-pentanedione is complicated and intertwined due to many factors.
These compounds may be used in various industrial processes and pharmaceutical research and development. The price range varies depending on the quality, origin, supply and demand.
If the quality is excellent, it comes from a famous factory, and it is suitable for high-end pharmaceutical research and development, the price may remain high. In the prosperous places of Kyoto and Shanghai, when the supply is scarce and the demand is strong, the price per gram can reach tens of gold, or even hundreds of gold.
However, if it is a grade for ordinary industrial use, with a wide range of origins and abundant supply, in the market, the price per gram may only be a few gold.
Furthermore, the times change, and supply and demand are fickle. During the peak demand season, all parties bid, and the price will rise; if the supply exceeds the demand, merchants will sell urgently, and the price will tend to fall. It is at the market price of 5- (2-methoxyethoxy) -2-methyl-2,4-pentanedione, which often fluctuates between a few gold per gram and a hundred gold per gram. It is difficult to give a conclusive price range. It is necessary to gain real-time insight into the market state to know the general idea.