Thiophene-3,4-dicarboxylic acid

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty. The following is a description of the chemical properties of 3,4-dichlorobenzoic acid.
3,4-dichlorobenzoic acid, its shape is often white to light yellow crystalline powder. This material has a certain degree of acidity, because its carboxyl group can ionize hydrogen ions. It has a small solubility in water, and its molecular polarity is limited, so it interacts weakly with water molecules. However, in organic solvents such as ethanol and ether, the solubility is relatively high. This is due to the principle of similar compatibility, and its molecular structure is suitable for the interaction between organic solvent molecules.
In terms of stability, 3,4-dichlorobenzoic acid is quite stable under normal conditions. However, in case of strong oxidizing agent, oxidation reaction may occur. The chlorine atom on the benzene ring has a certain electronegativity, which can reduce the electron cloud density of the benzene ring, and cause the electrophilic substitution reaction activity of the benzene ring to be slightly lower than that of benzene. However, under suitable conditions, halogenation, nitrification, sulfonation and other electrophilic substitution reactions can still occur. And the presence of carboxyl groups will also affect the reaction check point and activity.
Its melting point is about 150-153 ° C. This physical property is crucial for the identification and purification of this substance. When heated, if the melting point is reached, it will gradually change from solid state to liquid state.
In addition, 3,4-dichlorobenzoic acid can neutralize with bases to form corresponding salts. Under acid catalysis, esterification reactions with alcohols can occur to form 3,4-dichlorobenzoic acid esters. Such reaction properties are widely used in the field of organic synthesis and can be used to prepare a variety of organic compounds.

"Tiangong Kaiwu" is a great scientific and technological masterpiece in ancient our country. It covers many fields of knowledge and describes in detail the manufacture and application of all things. Today, 5-3,4-dichlorobenzoic acid, an organic compound, has important applications in many fields.
In the field of medicine, it can be used as a key intermediate. Many drug synthesis requires this as the basic raw material and goes through a series of chemical reactions to obtain drugs with significant efficacy. For example, some antibacterial drugs, with 5-3,4-dichlorobenzoic acid participating in the reaction, can endow the drug with a specific chemical structure, enhance its antibacterial activity and stability, so as to better resist the invasion of bacteria and protect human health.
In the field of materials, 5-3,4-dichlorobenzoic acid is also indispensable. In the synthesis of polymer materials, it can be used as a modifier to improve material properties. Adding an appropriate amount of this substance to some plastic synthesis processes can significantly improve the flexibility and heat resistance of plastic products, expand the scope of plastic applications, such as manufacturing more durable automotive parts, electronic product shells, etc., to meet the needs of different scenarios for material properties.
Furthermore, in the agricultural field, it can be used to synthesize specific pesticides. Through precise chemical reactions, 5-3,4-dichlorobenzoic acid is converted into pesticide ingredients with high-efficiency insecticidal and weeding functions. Such pesticides can precisely act on pests, inhibit their growth and reproduction, and at the same time have a relatively small impact on the environment, which helps to achieve sustainable agricultural development and ensure crop yield and quality.
It can be seen from the above that although 5-3,4-dichlorobenzoic acid is a chemical substance, it plays an important role in many fields such as medicine, materials, and agriculture. Just like the technical materials recorded in "Tiangong Kaiwu", it is a key factor in all walks of life in the world, promoting the development and progress of human society.

There are various ways to prepare 5-nitro-3,4-dichlorobenzoic acid, and each has its own reasons. Let me give you a detailed list.
First, 3,4-dichlorotoluene can be used as the starting material. First, nitrification is performed with mixed acid (sulfuric acid mixed with nitric acid). Under appropriate temperature and conditions, the nitro group is introduced into the benzene ring of 3,4-dichlorotoluene to obtain 5-nitro-3,4-dichlorotoluene. Then, a strong oxidant, such as potassium permanganate, etc., is heated to oxidize this intermediate in an alkaline environment, and the methyl group can be converted to a carboxyl group, resulting in 5-nitro-3,4-dichlorobenzoic acid. This raw material is easy to obtain, but the nitrification step requires fine control of conditions to prevent the generation of polynitro by-products.
Second, 3,4-dichlorobenzoic acid is used as the starting material. First, the carboxyl group is protected by an appropriate protective group, and then the nitrification reaction is carried out with a nitrifying agent, and the nitro group is introduced at a specific position in the benzene ring. After the nitro group is introduced, the protective group is removed and the carboxyl group is restored. In this way, the target product can be obtained more accurately. This approach can effectively avoid the influence of carboxyl groups in the nitration process and improve the purity of the product. However, the introduction and removal steps of protective groups are slightly complicated, which increases the cost and difficulty of operation.
Third, starting from 3,4-dichloroaniline. First, through the diazotization reaction, the amino group is converted into diazonium salt, and then the nitro group is introduced through the substitution reaction with a nitro-containing reagent. After that, the diazonium group is converted into carboxyl group through a specific reaction. Although this path is more complicated, it can achieve precise control of the position of the substituent on the benzene ring. If there are strict requirements for the purity and structure of the product, this is a good method.
All kinds of production methods have their own advantages and disadvantages. In actual preparation, it is necessary to make careful choices based on factors such as the availability of raw materials, cost considerations, and product purity requirements, in order to achieve twice the result with half the effort.

The price of 55% -3,4-dichlorobenzoic acid sold in the market today varies according to the quality, quantity, and supply and demand of the market. The superior is pure without impurities, and the price must be high; the inferior is impure with impurities, and the price is low. If the quantity is wide, the price may decrease slightly due to small profits but quick turnover; if the quantity is thin, the price will be high. And the supply and demand situation of the market is also due to the necessity. The demand is prosperous and the supply is limited, and the price rises; if the supply exceeds the demand, the price decreases.
I heard that Jia people stocked up 55% -3,4-dichlorobenzoic acid when the production was prosperous. At the beginning, the market supply was sufficient but the demand was flat, and the price was stable. Not long after, the factories needed this material more and more, while the production was slightly reduced, and the goods in the market gradually became thinner. Seeing this, Jia people raised the price, which was quite profitable. From this point of view, the market price of 55% -3,4-dichlorobenzoic acid is not uniform, and often varies with various conditions.
Its price often fluctuates between tens of gold and hundreds of gold per catty. Such as cities in remote areas, where supply and demand are both small, the price may be slightly lower; in Dayi, the capital, where industry and commerce are prosperous, there are many people who need it, and the price may be slightly higher. There are also long-distance traffickers, who add freight, wear and tear, etc., and their price is also different from that of the place of origin. Therefore, if you want to know its exact price, you must carefully observe the market conditions and measure its quality, quantity, and supply and demand trends before you can obtain it.

In "Tiangong Kaiwu", it is recorded that saltpeter and sulfur are the main raw materials for gunpowder, and the preparation and preservation of saltpeter is extremely critical. Saltpeter, also known as flame nitrate, potassium saltpeter, etc., requires special attention to its preservation conditions.
In ancient times, saltpeter was mostly extracted from nitrate-containing soils. Because of its active nature, it was the first to dry when stored. Saltpeter is hygroscopic. If the environment is humid, it is very susceptible to moisture and dissolution, resulting in damage to its quality. Therefore, it must be placed in a dry place, such as a dry warehouse, and stored in an airtight container to prevent moisture from invading.
Second, it is necessary to avoid high temperature. Saltpeter is easy to decompose when heated, and high temperature can cause its chemical properties to change, affecting its effectiveness in gunpowder Therefore, the place where saltpeter is preserved should be kept away from fire and heat sources, and a cool place should be selected.
Furthermore, it should be prevented from mixing with other substances. Saltpeter is oxidizing and in contact with certain reducing substances, it is easy to cause chemical reactions or cause danger. Therefore, it must be stored separately and cannot be co-located with flammable and reducing substances such as sulfur and charcoal.
Proper preservation of saltpeter is related to the success or failure of gunpowder production and many other matters. Only by following the principles of dryness, shade and isolation can we ensure that saltpeter can maintain good quality for a long time for emergencies. This is a valuable experience accumulated by ancient craftsmen in practice and has far-reaching reference significance for the preservation of chemical substances in later generations.