FURO[3,4-B]PYRIDINE-5,7-DIONE

Although the description of the chemical structure in "Tiangong Kaiwu" is not as accurate as that of modern times, we can try to solve this problem by using ancient principles.
Saltpeter [3,4-B] pyridine, which is relatively complex, is difficult to find a direct correspondence in ancient books. However, according to ancient chemical thinking, it is known that substances are polymerized from different "gas" and "qualities". The pyridine ring in its structure has a unique shape, which is like an ancient ring-shaped utensil, connected by carbon and nitrogen atoms in a specific order, like some endless cycle between heaven and earth. And the modification of [3,4-B], like the delicate decoration on the utensil, has its own special rules.
As for the structure of the 5,7-dihydroxyl group, the hydroxyl group can be regarded as the nature of "moisturizing" and "wetness". The ancient cloud water moisturizes all things, and this dihydroxyl group is on the molecule, giving it the nature of matching with water. The combination of oxygen and hydrogen atoms of the hydroxyl group is just like the shape of a water drop. In the overall structure of the molecule, it affects its affinity and reaction with other things.
From the perspective of "Tiangong Kaiwu", the structure of the substance determines its properties. The structure of saltpeter [3,4-B] pyridine-5,7-dihydroxyl group makes the substance have special chemical activity. Such as ancient alchemy and pharmaceuticals, different substances may have different structures due to structural differences, or they may coexist and resist each other, or undergo wonderful changes. This structure may cause it to exhibit a unique reaction in a specific environment, such as when exposed to heat, water, or other chemicals. It may be discolored, combined, or decomposed, just like the wonders witnessed by the ancient alchemists in the pill furnace. All of them originated from the mystery of the internal structure of matter. Although the ancients could not describe it in a modern and accurate way, the insight into the structure and change of matter was also the embryo of chemistry, laying the foundation for future generations to explore the structure of the microscopic world.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty, and the book describes many crafts and technologies in detail. If you ask what are the main uses of the crossbow [3,4-B] to its -5,7-two strings, I will say it in ancient Chinese.
The - 5,7-two strings of the crossbow have a crucial purpose. First, it concerns the opening string of the crossbow. These two strings cooperate with each other, which can make the crossbow arm accumulate strong elastic force. When the crossbow hand pulls the trigger, the force stored in the string is instantly released, and the arrow can be shot like a meteor, achieving the effect of defeating the enemy. Without this two-string coordination, the crossbow would be difficult to exert its long-range killing power.
Second, this second string is also very useful in adjusting the range and accuracy of the crossbow. By fine-tuning the tightness of the second string, the angle and initial speed of the arrow can be changed, so that the crossbow can accurately adjust the shooting parameters according to different target distances and battlefield situations, so as to improve the probability of hitting. On the battlefield, accurate strike is crucial, and the power of this second string cannot be underestimated.
Third, the material and condition of the second string have a profound impact on the overall performance and life of the crossbow. High-quality string materials are tough and elastic, which can ensure the long-term use and stability of the crossbow. Crossbowmen need to carefully maintain this second string on weekdays, check its wear and slack conditions, and replace or adjust it in a timely manner to ensure that the crossbow is always available and will not delay the fighter at critical moments.
The - 5, 7 - two strings of the crossbow play a pivotal role in stretching the string, adjusting the range accuracy and ensuring the performance life of the crossbow. It is an indispensable key component of the crossbow.

"Tianwen" has a saying: "Yuan is the ninth level, who can achieve it? But what kind of power is there, and who first made it?" This is all a search for the mysteries of all things in the world. What are the physical properties of Jun Gong [3,4-B] to its -5,7-second string? And ask questions in ancient Chinese.
Fu Jun Gong [3,4-B] has an exquisite shape, and the material may be of copper and iron, and its nature is strong and tough. When hit with a hammer, the sound is clear and clear, and the sound is far away. This is because its material is dense, and when it vibrates, it can make an orderly sound. The frequency and loudness of the sound are determined by its shape and material.
As for the -5,7 -second string, the string is mostly made of silk bamboo and metal. The silk string is soft and tough, with a melodious voice and a soft voice. The cover is flexible because of its material, and the vibration is slow and orderly, so the sound has a curling state. The metal string is strong, and the sound is clear and exciting. With its hard texture, it vibrates quickly when hit, so the sound is strong.
Compared with the two, the sound of the gong is loud and bright, and it spreads across the universe; the sound of the second string is soft or hard, delicate and changeable. The physical properties of the gong are related to the hardness of the material, the size and thickness of the shape; the physical properties of the string are related to the softness, hardness, length and thickness of the material, and the degree of relaxation. All are condensed by the wisdom of the ancients, in the way of sound, each presenting its wonders, entertaining people's ears and eyes, and connecting the rhythm of heaven and earth.

The method for the synthesis of [3,4-B] to its-5,7-diethyl is covered by the following numbers:
First, the corresponding halogenated aromatic hydrocarbons can be started. First, the aromatic hydrocarbons are halogenated with appropriate halogenated reagents to obtain halogenated intermediates. Then, in the presence of suitable bases and catalysts, a nucleophilic substitution reaction occurs with ethyl-containing nucleophiles. In this process, the reaction solvent needs to be carefully selected to facilitate the progress of the reaction. For example, the use of aprotic polar solvents, such as N, N-dimethylformamide, may promote the activity of nucleophiles and improve the reaction efficiency. < Br >
Second, it can also be achieved by direct alkylation of aromatic hydrocarbons. Alkylation of aromatic hydrocarbons is carried out with a suitable alkylation reagent, such as ethyl halide, under the action of Lewis acid catalyst. The key to this reaction lies in the choice and dosage of the catalyst. Too much or too little may affect the selectivity and yield of the reaction. For example, anhydrous aluminum trichloride is often used as a catalyst for such reactions, but its activity is quite high. When used, the dosage needs to be precisely controlled to prevent side reactions of excessive alkylation.
Third, it can also be obtained through the route of organometallic reagents. First prepare ethyl-containing organometallic reagents, such as Grignard reagents or organolithium reagents. Then, react with the corresponding aromatic derivatives. This method requires strict reaction conditions and needs to be operated in an anhydrous and anaerobic environment to ensure the activity of organometallic reagents. And during the reaction process, temperature control is also crucial. Different reaction stages may require different temperatures to optimize the reaction process.
These several synthesis methods have their own advantages and disadvantages. In actual operation, when depending on the specific situation, such as the availability of raw materials, the cost of the reaction, and the purity requirements of the product, the choice is made.

Alas, if you want to use the crossbow [3,4-B] to its-5,7-second string, there are indeed all kinds of things to pay attention to when you use it.
The leader, observe the shape and condition of the crossbow. This crossbow [3,4-B] needs to be carefully examined for cracks in its crossbow arm and whether the crossbow machine is flexible. If the crossbow arm has hidden wounds, it may collapse when it is exerted, and the crossbow machine does not work, it will be sent inaccurately, delaying major events. As the "Tiangong Kaiwu" says: "Whoever makes a crossbow, its body is made of bamboo or wood, must choose the one that is strong, and its texture is straight, and there are no knots and dark wounds, before it can be used."
Second, the adjustment of the string is very important. 5,7 - Second string, its tension should be observed. If the string is loose, the arrow will be weak, difficult and far; if the string is tight, it will be easy to break, and it will affect the accuracy of the launch. It is necessary to relax the string line moderately according to the strength of the crossbow. Just like the ancient cloud: "Strings are like the tendons of a bow and crossbow, and they should be firm and soft, so that the arrow can be shot like a meteor."
Furthermore, the choice of the arrow should not be ignored. The length and weight of the suitable arrow should be in line with the performance of the crossbow. If the arrow is too long or too heavy, the crossbow force will be difficult to support, and the arrow will not be far away; if the arrow is too short or too light, the flight It is written in "Tiangong Kaiwu": "The system of arrows depends on the force of the crossbow, and the length and weight must match."
In addition, when launching, the person's position and strength are also exquisite. The body should stand calmly, like a loose stand, and the force should be smooth and smooth, not abrupt. The force should be sent and received freely, so that the direction of the arrow can be controlled.
Again, you should also pay attention to the realm of using the crossbow. The direction of the wind and the ups and downs of the ground all disturb the flight of the arrow. The speed of the arrow will decrease when the wind is headwind, and the arrow will be easily deviated when the wind is downwind; the terrain is uneven, which affects the launch angle. Therefore, when the crossbow is about to be used, it is necessary to judge the situation and make the best use
In short, use the crossbow [3,4-B] to its -5,7-second string, and in the realm of crossbow tools, string arrows, human power, and crossbow use, all need to be careful to make the crossbow effective and hit the target.