2-Pyridinecarboxaldehyde, 3,6-dibromo-

Arsenic, or arsenic trioxide, has a wide range of uses.
First, it is used in the field of medicine. In the past, in the treatment of specific diseases, arsenic can be used as medicine after being processed. In ancient times, healers tried to treat certain sores and diseases with arsenic, using its poison-fighting properties to remove carrion and promote new muscle growth. However, arsenic is extremely toxic, and it is extremely difficult to control the dosage. If it is not careful, it will endanger life. Therefore, extreme caution is required when using it.
Second, arsenic also plays a role in agriculture. It can be made into an insecticide to kill field pests. Due to its strong toxicity, arsenic can cause pests to be poisoned to death after contact or swallowing, thus protecting crops from insect infestation. However, due to its great harm to the environment and humans and animals, it is rarely used today.
Third, arsenic also played a role in the ancient metallurgical industry. When smelting certain metals, adding arsenic in moderation can change the characteristics of the metal, improve the quality of the metal, and help it meet specific process requirements.
Fourth, arsenic also has traces in ancient alchemy. Scholars believe that arsenic and other mineral medicines contain special "spiritual energy", and hope that through refining, they will become elixirs for prolonging life and ascending to immortality. However, this practice has no scientific basis, and many people have died due to taking arsenic-containing elixirs.

"Tiangong Kaiwu" says: "Mercury, also known as mercury. Its substance is metal, with flowing properties, often in a liquid state, silver-white and shiny, under room temperature, it can be stable. However, when heated, it is volatile and toxic. Its specific gravity is quite large, heavier than ordinary metals."
Mercury is used in alchemy, medicine, and metallurgy. Ancient alchemists often used mercury to refine alchemy, seeking longevity, but the toxicity of mercury caused harm to the body. In medicine, mercury compounds are occasionally used as medicine, so it should be used with caution. In metallurgy, mercury can be used to extract gold, because it can form amalgam with gold, and then it can be distilled to separate the gold and mercury to obtain pure gold.
Mercury's metallic properties enable it to form alloys with many metals, and this property is also useful in industry. However, its toxicity cannot be underestimated. Accidental contact or inhalation of mercury volatiles can cause chronic poisoning and damage to the nervous, digestive, and urinary systems. Therefore, when using mercury, caution should be taken to prevent its leakage and avoid disasters.

To prepare 3% 2,6-di-tert-butyl-2-methoxyphenol, there are many synthesis methods, and the following are common methods:
First, 2,6-di-tert-butyl phenol is used as the starting material and prepared by methoxylation. In the reaction vessel, put 2,6-di-tert-butyl phenol and add an appropriate amount of base, such as potassium carbonate, to act as an acid binding agent. Then add a phase transfer catalyst, such as tetrabutyl ammonium bromide, to increase the reaction rate. After that, slowly add a methylating agent, such as dimethyl sulfate or iodomethane. Control the reaction temperature to a moderate temperature, such as 60-80 ° C, and continue to stir the reaction for several hours. After the reaction is completed, the target product can be obtained through post-processing procedures such as extraction, washing, drying, distillation, etc. The raw materials of this method are easy to obtain, and the reaction conditions are relatively mild. However, attention should be paid to the toxicity and safety of methylating reagents.
Second, 2,6-di-tert-butyl-3-methylphenol is prepared by tert-butyl-3-methylphenol with m-cresol as the starting material, and then methoxylated. The tert-butylation reaction of m-cresol with tert-butylation reagents, such as isobutylene or tert-butyl alcohol, is carried out under the action of acidic catalysts, such as concentrated sulfuric acid or p-toluenesulfonic acid. The reaction temperature is maintained in a suitable range, such as 80-100 ° C, to obtain 2,6-di-tert-butyl-3-methylphenol. Subsequently, according to the method of methoxylation described above, it is methoxylated. After post-treatment, 3% 2,6-di-tert-butyl-2-methoxyphenol can also be obtained. This path has a little more steps, but the source of raw materials is wide, and the cost may be reduced. < Br >
Third, 2,6-dibromophenol is used as the starting material, and tert-butyl is first reacted with potassium tert-butanol to introduce tert-butyl to obtain 2,6-di-tert-butyl phenol, and then methoxylated. React 2,6-dibromophenol with potassium tert-butyl phenol in a suitable solvent, such as DMF, control the temperature, so that tert-butyl can be introduced smoothly. After that, the target product is obtained through the methoxylation step. Although this method is complicated, it has good selectivity and can effectively reduce the occurrence of side reactions.
All synthesis methods have their own advantages and disadvantages. In actual production, it is necessary to comprehensively consider many factors such as the availability of raw materials, cost, and product quality requirements to select the most suitable method.

The art of smelting gold and silver is related to storage and transportation, and there are many things that should be paid attention to.
In terms of storage, the first choice for storage is heavy. Gold and silver are precious and easy to attract coveted, so they should choose a secret and solid place. The walls of the storage room should be thick and solid to prevent external forces from breaking it; the ground should also be dry, if it is wet, gold and silver are easy to rust and damage their color. Furthermore, the method of protection is indispensable. Set up a special person to guard, and patrol day and night to prevent thieves. And it should be prepared with a secret whistle, if there are uninvited guests, they can be immediately detected, so that it is difficult to succeed.
As for the transportation business, one of them must be properly packaged. Gold and silver are soft in texture and easy to wear when transported. Therefore, soft cushions should be used, such as satin, felt cloth, etc., to keep them apart from each other and avoid collision injuries. Second, the guards must be effective. The transportation of gold and silver is like walking in love, and thieves often want to rob it. Therefore, it is necessary to choose strong men, those with high martial arts and loyalty and reliability, to form a guard team. During transportation, you should also carefully plan the route to avoid dangerous routes that are rare and complicated to prevent ambushes. Third, the choice of timing is also the key. It is appropriate to choose the day, the sky is bright, so that you can observe the movement around you; and when there are many business travelers, thieves are also afraid and dare not act rashly.
In short, in the storage and transportation of gold and silver, whether it is hidden in a secret room or transported on the road, it is necessary to be careful and well-planned to ensure the safety of gold and silver and avoid losses.

In the scope of "Tiangong Kaiwu", it is related to 3% 2C6 (suspected that the expression is wrong, if it is "three or six", or there is a specific reference, it is difficult to deal with it according to the conventional understanding here), two mercury (mercury is mercury, which was often used in alchemy, metallurgy and other fields in ancient times) and two (the meaning of the single "two" here is unclear, more background information is required to assist understanding) and its safety information related to methylmercury are as follows:
Mercury, highly toxic. The ancients paid close attention to the art of mercury refining in Dan sand, and knew its danger well. In the place where Dan sand was collected, miners often had to face the harm of mercury. Because mercury is volatile, it turns into invisible gas and quietly enters the human body. If you inhale mercury gas, you may initially feel dizzy, and then you will be in a trance. Over time, your internal organs will be damaged, endangering your life.
In mercury processes such as metallurgy, there is also a great risk. If you want to extract metals such as gold and silver with mercury, when operating, if the protection is not good, the mercury gas will pervade, and the workers will bear the brunt. In the light, the limbs are weak, the joints are sore, and in the severe, the mind is confused, or even died suddenly.
The ancients dealt with mercury-related matters, and they have explored some ways to protect themselves. In alchemy sites, a well-ventilated place is often selected, or a passage is set up to disperse mercury gas. When workers work, or cover their mouths and noses with a damp cloth, hoping to slightly prevent the intrusion of mercury gas. Even so,
As for methylmercury, although it is not detailed in "Tiangong Kaiwu", it is deduced from the characteristics of mercury. Methylmercury may also be extremely toxic. If methylmercury is used in a specific process, its operation must be handled with caution. Store methylmercury in a special container to avoid heat and light to prevent its volatilization and leakage. Handling methylmercury must also be handled with care to avoid damage to the container, causing methylmercury to overflow and causing man-made disasters.