QUINOLINE-3-BORONIC ACID PINACOL ESTER

Borax is a common mineral, and its chemical properties are unique. Borax, chemically known as sodium tetraborate decahydrate, has a chemical formula of $Na_2B_4O_7 · 10H_2O $.
It has many properties. At room temperature, borax is a colorless translucent crystal, or a white powder, which is soft and creamy. Borax is soluble in water, and its aqueous solution is weakly alkaline. This alkalinity is derived from the hydrolysis of borax in water. Borate ions combine with hydrogen ions ionized by water to increase the concentration of hydroxide ions, so it appears alkaline.
Borax also changes when heated. When heated, borax will gradually lose its crystalline water and melt into a glassy substance. This glassy substance can react with a variety of metal oxides to form borates with specific colors. With this property, in ancient metallurgy, borax was often used as a flux to reduce the melting point of metals, help them melt, and remove oxide impurities on the metal surface, making metal smelting smoother.
Borax also has buffering properties. In a specific chemical reaction system, borax can adjust the pH of the solution to maintain a relatively stable range. Because borax and boric acid can form a buffer pair, when a small amount of acid and alkali are added to the outside world, it can move through its own equilibrium and inhibit the large change in the pH value of the solution.
In addition, borax can be used as a coordination agent in some chemical reactions. Due to the outer electronic structure of boron atoms, it can form coordination compounds with some metal ions, altering the chemical activity and properties of metal ions. This plays a significant role in the preparation of certain fine chemicals and specific catalytic reactions.

The synthesis of borax has been used in ancient times, and the common ones are listed below:
First, boron-magnesium ore can be used to co-heat with soda ash. Boron-magnesium ore is a mineral containing boron. Mix it with soda ash in an appropriate proportion, place it in a furnace, and calcinate it at high temperature. In this process, boron-magnesium ore chemically reacts with soda ash. Boron in boron-magnesium ore combines with sodium in soda ash to form sodium borate and other substances. The key to this reaction lies in the control of temperature. If the temperature is too high or too low, it is not conducive to the reaction. If the temperature is too high, the raw material may cause excessive decomposition; if the temperature is too low, the reaction will be slow and the yield will not be high. When the temperature is suitable, sodium borate can be formed smoothly, and borax crystals can be obtained by subsequent steps such as water leaching, filtration, and crystallization.
Second, the method of neutralizing boric acid and sodium hydroxide is also commonly used. Boric acid is weakly acidic. Place an appropriate amount of boric acid in a container and slowly add sodium hydroxide solution, and the two undergo a neutralization reaction. During the reaction, the hydrogen ion of boric acid and the hydroxide ion of sodium hydroxide combine to form water, and the boron element and sodium ion combine to form sodium borate. This process requires precise control of the amount of boric acid and sodium hydroxide, so that the two just react completely. If there is too much sodium hydroxide, the product is impure; if there is too much boric acid, the borax yield will decrease. After the reaction is completed, borax can be obtained by evaporation, concentration, cooling and crystallization. < Br >
Third, the method of direct refining with borax ore. In borax ore, although borax contains it, it is also accompanied by impurities. First, the borax ore is broken and leached with water, so that the borax is dissolved in the water, and the impurities are mostly insoluble. Then filtered to remove insoluble impurities. The obtained filtrate is evaporated and concentrated, and the characteristics of borax solubility with temperature can be utilized. When cooled, borax crystals precipitate and filtered again to obtain a purer borax product.
This method is a common method of borax synthesis, each with its own advantages and disadvantages, depending on the specific situation.

Borax is widely used in organic synthesis.
Borax can be used as a buffer to stabilize the acid and base of the system. In many reactions, the acid-base balance of the reaction environment is crucial, and borax can adjust the pH value to make the reaction smooth. For some organic reactions that need to be carried out efficiently in a specific acid-base range, borax can create suitable acid-base conditions to maintain the activity and selectivity of the reaction.
can also be a complexing agent, complexing with metal ions. This property is particularly critical in catalytic reactions. Metal catalysts often require a suitable coordination environment to develop their effectiveness. Borax complexes with metal ions, which can change the electron cloud density and spatial configuration of metal ions, and improve the activity and stability of the catalyst. For example, in the organic synthesis reaction catalyzed by partial transition metals, the participation of borax can optimize the catalytic efficiency, increase the reaction rate and yield.
Borax is also useful in the cyclization reaction of organic synthesis. It can form a specific interaction with the reactants, promote the formation of intracellular rings, and help to construct complex cyclic compounds. This is of great significance in the fields of drug synthesis and total synthesis of natural products. Many biologically active compounds contain cyclic structures, and borax can be used as a boost for the construction of such structures.
Furthermore, borax can be used for the separation and purification of organic compounds. Take advantage of its interaction with specific organic compounds to achieve the separation of target compounds in the mixture. For example, in some organic acid-base mixtures, borax can interact with acidic or basic components, and it can be separated by extraction, crystallization, etc., to obtain a pure target product.
Borax is used in the field of organic synthesis. With its unique chemical properties, it has important uses in the regulation of reaction conditions, optimization of catalytic process, structure construction and product purification. It is an important auxiliary for organic synthesis.

In the Guanfu market, the price of sugar cubes, sucralose, and aspartame each has its own situation.
Sugar cubes are common daily sugars, derived from sugar cane or beets, refined through many processes. Its nature is pure, sweet and genuine, with natural sweetness. In the market, its price varies depending on the grade, packaging, and origin. Ordinary bulk sugar cubes cost between a few yuan and more than ten yuan per catty; if they are refined and branded boxed sugar cubes, their price may be slightly higher, up to twenty or thirty yuan per catty. The coarse production process, the quality of raw materials, and the simplicity of packaging are all factors that affect their price.
Sucralose is a synthetic sweetener with extremely high sweetness, hundreds of times that of cane sugar. However, its calories are extremely low, and it is very popular among those who pursue a low-calorie diet. Its production process is more complicated and requires high technical requirements. Sucralose in the market has different prices due to its purity and manufacturers. Generally speaking, those with high purity are more expensive. The price per kilogram may be around a few hundred yuan. In the food industry, due to its low dosage and high sweetness, in the long run, it may have a cost advantage. Therefore, its market pricing also takes into account many factors, such as research and development costs, production scale, and market demand.
Aspartame is also a synthetic sweetener with a sweetness of about 180-220 times that of cane sugar. It has been widely used in various types of food and beverages. However, due to the controversy over safety, its market position has changed. Its price is also affected by the production process and market supply and demand. The price per kilogram varies depending on the quality, or between more than 100 yuan and several hundred yuan. When the market doubts its safety, the demand may decrease, and the price may be affected; if its safety is further recognized, the demand will rise, and the price may have a different direction.
In summary, the market prices of sugar cubes, sucralose, and aspartame are the result of a variety of factors, such as raw materials, processes, market supply and demand, and safety awareness, which all affect their pricing.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty. Although it does not directly mention the content of modern scientific expressions such as "what are the storage conditions for the frequency of light-3-boric acid?", the book involves the storage and processing of various substances, which can be speculated from the perspective of similar principles.
In ancient times, the preservation of many substances often paid attention to moisture protection, sun protection, fire protection, etc. If boric acid is placed in ancient conditions, moisture protection is the key. Because of its solubility, if the storage environment is humid, boric acid is easily dissolved by moisture, causing its shape and properties to change. Therefore, a dry place should be selected and sealed containers such as ceramic pots and porcelain bottles should be used to prevent water vapor from invading.
Protection from sun exposure is also indispensable. Direct sunlight can easily cause the temperature to rise, or cause changes in the chemical properties of boric acid. In ancient times, there was no modern shading equipment, so it was often placed in shady places, such as cellars, shady warehouses, etc.
Fire prevention is also extremely important. Although boric acid is not flammable, the temperature of the fire environment rises sharply, which may affect its chemical stability. In ancient buildings, most of them are wooden structures, which pose a great fire hazard. Therefore, the storage of boric acid should be kept away from the fire source, and there should be certain fire-extinguishing objects around, such as sand piles.
Although "Tiangong Kaiwu" did not accurately explain the storage conditions of boric acid, it can be inferred from the wisdom of the ancients on material preservation that boric acid storage should pay attention to dryness, shade, and fire protection to maintain its stable state.