3-Thiophenecarboxylic acid, 2-chloro-

The arsenic of 3 + - is a highly toxic thing. Its chemical essence is arsenic trioxide, and the chemical formula is $As_2O_3 $. Arsenic is white in color and looks like frost and snow, so it gets its name. Its sex is fierce, and a small amount can kill people. It is often used by the ancients to poison and murder drugs, and it is also used for punishment. In medicine, although the dosage is very small, it can be used as medicine to treat diseases, but it needs to be cautious. A little carelessness will lead to disaster.
2 + - cyanide, cyanide-containing compounds are highly toxic. Cyanide ions ($CN ^ - $) can combine with iron ions in cytochrome oxidase to block the respiratory chain of cells, making cells unable to uptake and utilize oxygen, causing organisms to quickly suffocate and die. Common cyanides, such as potassium cyanide ($KCN $) and sodium cyanide ($NaCN $), are white crystals or powders with a bitter almond taste. Their toxicity is rapid and extremely harmful. If not handled properly in industrial production, leakage can cause serious environmental pollution and personal casualties. In criminal investigation cases, there are also many cases of cyanide crimes. Both are extremely dangerous chemicals. The world should be well aware of their harm and treat them with caution. Do not be negligent to prevent unexpected disasters.

Saltpeter is strong and fickle, and has a wide range of uses. First, it is effective in the way of fire attack. In the past, there were still frequent wars, and saltpeter was an essential agent for firearms. It was combined with sulfur and charcoal to make gunpowder. If it burned, it would explode, and its power was amazing. When attacking cities and resisting the enemy, it could cause severe damage to the enemy and reverse the trend of the war.
Second, it is also wonderfully useful in the art of doctors. Its cold nature has the effect of diarrhea and clearing away heat. It can treat the disease of heat accumulation and constipation in the body. With its characteristics, it can channel the viscera, make the evil heat vent, and restore the yin and yang of the human body to peace. However, its nature is strong, it needs to be used carefully, and the dosage is accurate to keep it safe.
As for alum stone, it has a variety of uses. In the industry of dyeing and weaving, it has an indispensable contribution. Treating fabrics with alum stone can fix and enhance color, so that the dyed cloth will have a bright color and will not fade for a long time. It adds bricks and tiles to the beauty of splendid embroidery and makes the world gorgeous.
In the method of purifying water, alum stone also bears a heavy responsibility. Throwing alum stone into turbid water can make the sediment and filth in the water condense and settle, turn the water from turbid to clear, and obtain clean water for people's livelihood needs, and ensure the well-being of everyone. In all these ways, the use of saltpeter and alum stone is of great significance to the national economy and people's livelihood. It is actually a gift of creation, making extraordinary contributions to the prosperity of the world.

There are currently methods for preparing 3-pentanoic acid and 2-bromo-valeraldehyde, which are described in detail as follows.
To prepare 3-pentanoic acid, ethyl acetate can be taken first, and sodium alcohol can be used as the catalyst to cause the clayson ester condensation reaction. In this reaction, the α-hydrogen of a molecule of ethyl acetate leaves under the action of sodium alcohol to form a carboanion, which undergoes nucleophilic addition to the carbonyl of another molecule of ethyl acetate, and then loses the ethoxy group to form ethyl acetoacetate.
Then, ethyl acetoacetate is alkylated with a halogenated alkane. Select a suitable halogenated alkane, such as bromoethane. Under basic conditions, the bromine of bromoethane is replaced by the active methylene in ethyl acetoacetate to form the corresponding alkylation product.
Finally, the alkylation product is hydrolyzed in a basic manner, then acidified and heated to decarboxylate. During basic hydrolysis, the ester group is converted to a carboxylate, and the corresponding carboxylic acid is obtained after acidification. Under heating conditions, the carbon-carbon bond between the carboxyl group and the adjacent carbonyl group is broken, and carbon dioxide is removed to obtain 3-pentanoic acid.
As for the preparation of 2-bromo-valeraldehyde, n-butyl aldehyde is first taken, and in a suitable solvent, under the action of light or initiator, the bromination reaction of α-hydrogen with bromine occurs. The α-hydrogen of n-butyraldehyde has certain activity due to the influence of carbonyl group. Light or initiator prompts the bromine molecule to split into bromine radical, and the bromine radical captures n-butyraldehyde α-hydrogen to form α-carbon radical, which reacts with bromine molecule to obtain 2-bromo-pentanaldehyde. During the reaction process, attention should be paid to the control of reaction conditions, such as temperature, light intensity, and the proportion of reactants, to improve the yield and purity of the product. In this way, 3-pentanoic acid and 2-bromo-pentanal can be obtained.

The question I heard from you is about the market price range of alum sand and salt. Alum sand is strong in nature and rarely used, and is also a rare thing in the market. Its price varies depending on the quality, the distance of the source, and the abundance of time. Generally speaking, the price per catty may be between tens and hundreds of dollars. If its quality is pure and fine, and the source is rare, the price may be more expensive; if the quality is varied and abundant, and it is time for the abundance of goods, the price is slightly lower.
As for salt, it is necessary for people's livelihood, and it is often sold in the market. The types of salt are different, and the prices are also different. Ordinary salt, the price per catty, is probably between a few to more than ten dollars. If it is official salt, it is supervised by the official office, and the quality is guaranteed, and the price may be slightly higher; if it is private salt, although the quality may not be inferior, the price may be slightly lower because it does not go through the official route. However, the sale of private salt is prohibited by law, so the circulation of official salt is more common in the city.
There is no constant price in the city, and it all changes with changes in supply and demand and changes in the times. If in a disaster year, the grain is not available, and everything is expensive, the price of alum sand and salt will also rise; if it is a good year, the product is abundant, and everything is cheap, the price may also drop. And the terroir is different in different places, and the price is also different. If you want to know the exact price, you need to look carefully at the local market conditions.

Mercury is a highly toxic substance, and its storage conditions are extremely strict. Although the "Tiangong Kaiwu" does not specifically describe the storage conditions of mercury in detail, it may be inferred from ancient principles and other storage methods.
The characteristics of mercury, which is a liquid metal at room temperature, is easy to evaporate into mercury vapor, and mercury vapor is highly toxic, which determines that its storage needs to be prevented from volatilization. In ancient times, mercury may be stored in containers with good sealing. If a thick ceramic container is used, its texture is tight, which can prevent mercury volatilization to a certain extent. On the container, it must be sealed with a special lid or sealed with mud to enhance the sealing effect.
Furthermore, mercury is chemically active and will react with a variety of substances, so the storage environment needs to be dry and free of substances that are easy to react with. If the environment is humid, or there are substances such as acid and alkali, the mercury may change and affect its quality.
Because mercury has a high density and is liquid, the container should be sturdy during storage to prevent it from being damaged and leaked due to gravity or accidental collision. In the place where mercury is placed, it should also be well ventilated, so that even if a small amount of mercury evaporates, it can be discharged as soon as possible to reduce toxic hazards.
For borax, this is an important mineral and boron compound. Borax is usually a colorless translucent crystal or white crystalline powder. Its storage requires a dry environment because it has a certain water absorption. If the environment is humid, it is easy to deliquescent, which affects its shape and purity.
In ancient times, borax was stored in dry cloth bags, pottery jars, etc. The cloth bag is easy to use, and the pottery jar has good sealing performance. It can be selected according to actual needs and conditions. Where borax is stored, it should also be avoided to mix with acidic substances, because it will react with acids and change its own chemical properties. In short, the storage point of borax is to keep it dry and isolate it from incompatible substances.