2-pyridinecarboxylic acid, 6-chloro-3-fluoro-

Mercury, arsenic, lead and other heavy metal salts have a wide range of main uses.
Mercury has a very important position in ancient alchemy. The alchemists believed that through complex refining, mercury could undergo wonderful changes and refine the so-called elixir that can make people live forever. Many emperors and generals flocked to it, hoping to realize the dream of immortality. At the same time, mercury was also used in ancient metallurgy, which can be used to extract precious metals such as gold and silver. Its principle is that mercury can form amalgam with gold and silver, thereby separating pure precious metals.
Arsenic has been used in the field of medicine. In ancient times, some doctors believed that it had certain medicinal value and would use it cautiously in the treatment of certain diseases. However, due to the toxicity of arsenic, extreme caution is required when using it. In addition, in agriculture, arsenic-containing compounds can be used as pesticides, which can effectively kill field pests and protect crop growth.
Lead was widely used in the field of ancient architecture. For example, in ancient Rome, lead pipes were widely used in water supply systems. Due to its good ductility and corrosion resistance, lead can be made into pipes for water transportation. In ancient China, lead was also used to make lead powder, and women often used it as cosmetics to apply to their faces to make their faces whiter. In the foundry industry, lead is often mixed with other metals to improve the properties of alloys and make the cast utensils stronger and more durable.
Of course, it needs to be understood that although these heavy metal salts have many uses, their toxicity cannot be ignored. Improper use can easily cause serious harm to the human body and the environment.

Mercury, arsenic, selenium and other elements and their compounds have unique physical properties. The following is described according to the classical style of "Tiangong Kaiwu":
Mercury, at room temperature, is a liquid state, and silver optical flow turns, such as mercury cascading to the ground, all-pervasive, heavy in texture, and cool to the touch. It is volatile and quietly escapes in the air, but steam is highly toxic, which must be prevented. Mercury can be fused with many metals to form amalgam, which is very useful in metallurgy and other techniques.
Arsenic, common forms are realgar and orpiment. Realgar is like a chicken crown, bright and eye-catching; orpiment is golden in color, soft in texture, and can be ground into powder. Arsenic compounds are mostly toxic, but when they are in small amounts, they are also useful in medical techniques. Its brittle nature makes it fragile into powder.
Selenium, although not a common thing, still has characteristics. Its color is changeable, either red-brown or gray-black. It has the properties of semiconductors, and it gradually shows its ability in the science of optoelectronics. Its elemental texture is brittle, and it is easy to melt when heated, and it emits a specific smell when melted. Although it is slightly toxic, it is beneficial to ingest it in moderation in the body of living beings, and it is related to health and should not be ignored.

To prepare 6 + - cyanogen, 3 + - alkene, and 2 + - carboxylate, the following method can be used.
First, the method of preparing cyanogen. Usually, halogenated hydrocarbons are heated with sodium cyanide or potassium cyanide in a suitable solvent to carry out nucleophilic substitution reaction. For example, when halogenated alkanes (R-X, X is a halogen) and sodium cyanide (NaCN) are heated in alcohol solvents, the halogenated atoms are replaced by cyanide groups to obtain nitrile compounds (R-CN). After proper hydrolysis of this nitrile compound, the corresponding cyanide-containing acid with the required carbon number and functional group position can be obtained, that is, 6 + - cyanide-related compounds. The principle of this reaction is that the cyanide anion has strong nucleophilicity, which can attack the α-carbon of halogenated hydrocarbons, and the halogen ions leave to form carbon-cyanide bonds.
The second method of making alkenes. The method of dehydration of alcohols or dehalogenation of halogenated hydrocarbons is commonly used. To make alkenes from alcohols, a dehydrating agent such as concentrated sulfuric acid is required to heat alcohols. If you want to obtain 3 + - alkenes, if there is a suitable 3-position hydroxyl alcohol, under the catalysis of concentrated sulfuric acid and at an appropriate temperature, the alcohol molecules are dehydrated, and the hydroxyl group and the hydrogen on the adjacent carbon are removed in the form of water to form a carbon-carbon double bond, and the corresponding 3 + - alk Hydrogen dehalogenation of halogenated hydrocarbons requires a strong alkali alcohol solution. Under the action of strong bases, halogenated hydrocarbons dehalide hydrogen from the hydrogen on the adjacent carbon to form a double bond, and 3 + - alkenes can also be obtained. In this principle, alcohol dehydration is due to the protonation of the hydroxyl group under acidic conditions, making it easy to leave in the form of water, and the hydrogen on the adjacent carbon is transferred in the form of positive ions to form a double bond; hydrogen dehalogenation of halogenated hydrocarbons is when a strong base captures the hydrogen on the adjacent carbon of the halogen atom, the halogen ions leave, and the electrons rearrange to form a double bond.
As for the production of 2 + - to its carboxylic acid, the corresponding olefin can be hydroformylated with carbon monoxide and water under the action of a catalyst to obtain an aldehyde compound, and the aldehyde can be oxidized to obtain a carboxylic acid, and the carboxylic acid reacts with a base to obtain a carboxylic acid. If the 2 + - alkene is used as the raw material, the hydroformylation reaction can be under the action of a transition metal catalyst (such as cobalt, rhodium and other complexes), carbon monoxide and hydrogen are added to the double bond to obtain a 2-position aldehyde compound, and common oxidants such as potassium permanganate and oxygen are oxidized as carboxylic acids. The carboxylic acid is neutralized with bases such as sodium hydroxide to obtain a 2 + - to its car This series of reactions is based on the principles of electrophilic addition of olefins double bonds, oxidation of alaldehyde, and acid-base neutralization.
The above methods carefully adjust the reaction conditions according to the reaction characteristics and the desired product structure, such as temperature, pressure, catalyst type and dosage, etc., to efficiently obtain 6 + - cyanide, 3 + - alkene, and 2 + - dicarboxylates.

Looking at the sea, river, and riverbank of Fufu, there is a thing called boric acid. What is the value in the city? The cover varies from time to place, and it is difficult to determine.
The market of Fufu City is often changing like the wind and clouds, and it is difficult to fathom the depth. If you want to find out the approximation, or you can follow the traces of the past and the appearance of the present. Boric acid is a product with a wide range of uses, and it is involved in the genus of medicine and chemical industry.
If you buy ordinary boric acid between markets, the price may vary depending on the grade and origin. Coarse, the price may be slightly cheaper; fine, the price must be high. And in the four-sided city, the price is not the same. In prosperous places, material resources are abundant, and transactions are frequent, and the price may fluctuate due to changes in supply and demand. In remote places, transportation is difficult, and the price may rise or fall due to tariffs.
In the past, the price of boric acid, low or dozens of dollars per catty, high or not more than a hundred dollars. However, today is different from the past, the world changes, the cost of materials and labor has changed, and the price has also fluctuated. Or in the busy city, the price of high-quality boric acid per catty is as high as one hundred and twenty or thirty dollars; and ordinary products are also around eighty or ninety dollars. However, this is only a rough number. If you want to know the exact price, you must go to the city in person and ask the merchants before you can get it. After all, the city situation is complicated, and it is not enough to describe it in one word.

Those who are good at making tools in ancient times have many good crafts that can produce boric acid in the land of brine, rivers and rivers.
On the coast of the East China Sea, there are craftsmen, whose skills are exquisite, and they extract boric acid from brine. They are skilled in their skills, and the products they produce are of high quality and abundant. Every time and place is right, the essence of brine is fully collected. The craftsman handles the equipment with exquisite methods to make boric acid stand out, white and pure, and is valued by the four sides.
On the banks of the river, there is also a home for boric acid production. They are familiar with the nature of river water, observe its rheology, and wait for the opportunity to extract boric acid in a unique way at the intersection of water and water. His family has been passed down from generation to generation, and his skills are becoming more and more refined. The boric acid produced is praised by those who use it. In all kinds of craftsmanship, more depends on its strength.
As for the side of the river, there is no shortage of such craftsmen. With the ingenuity of the river, supplemented by exquisite techniques, the production of boric acid is unique. Its production of boric acid also pays attention to the control of heat and the balance of quantity, so the boric acid obtained is of high quality and has a long reputation. There is an endless stream of buyers from all over the world.
These families, in the domains of halogen, rivers and rivers, use their own ingenious methods to produce boric acid, adding color to the world's utensils. Among all kinds of skills, they are unique, and they are really good at utensils.