4-bromo-2-pyridinemethanol

The methyne of 4-bromo-2-pentyne has unique chemical properties. In this alkyne, due to the existence of a triple bond, it is endowed with active chemical activity.
As far as the addition reaction is concerned, it can undergo electrophilic addition with halogens. In case of bromine elemental substance, bromine atoms can be added to the triple bond in steps. Initially, 1,2-dibromo-4-bromo-2-pentene is formed. If the bromine elemental substance is sufficient, it can be further reacted to obtain 1,1,2,2-tetrabromo-4-bromopentane. This is due to the high density of the π electron cloud of the triple bond, which is vulnerable to electrophilic attack.
Addition to hydrogen halide follows the Markov rule. In the case of hydrogen chloride, the hydrogen atom is added to the carbon atom containing more hydrogen, and the chlorine atom is added to the carbon atom containing less hydrogen to form the corresponding halogenated olefin. This is due to the different stability of the carbon positive ions formed during the reaction.
In addition, the substance can undergo oxidation reactions. Under mild oxidation conditions, the triple bond can be oxidized to a carbonyl group. If treated with a strong oxidizing agent, such as an acidic potassium permanganate solution, the triple bond will break and form a carboxyl-containing compound. The specific product depends on the molecular structure.
Under metal catalysis, coupling reactions can also occur. For example, with some metal-organic reagents under the action of appropriate catalysts, new carbon-carbon bonds can be formed, which is used to construct more complex organic molecular structures, which is of great significance in the field of organic synthesis.
Due to the presence of bromine atoms in the molecule, the substance can also undergo nucleophilic substitution reactions. Nucleophiles can attack carbon atoms connected to bromine, and bromine atoms leave as leaving groups, thereby generating new compounds and enriching their chemical transformation pathways.

4-1-2-pentanone, and acetylacetone, which is often synthesized as follows:
1. ** Acetone-ethyl acetate method **: acetone and ethyl acetate are used as feedstocks, and under the action of gold (or ethanol catalysis), the Claisen reaction is generated. Here, the carbonyl group of the methyl acetone-ethyl acetate is synthesized, and one molecule of ethanol is removed to produce an enol of acetylacetone, which is then acidified to obtain acetylacetone. Its reverse process is first to take the methylacetone on the acetone methyl group to form a carbonyl carbon, and the carbonyl carbon of the ethyl acetate is attacked. The nuclear addition of the acetone is generated, and the ethoxyl is removed to obtain an enol. This method is easy to obtain raw materials, but the reverse parts are harsh, and it is necessary to control the dosage and the degree of reflection. It is easy to produce side effects and the influence rate.
2. ** Ethyl acetoacetate-acetic anhydride method **: Ethyl acetoacetate-acetic anhydride is reacted under the catalysis of acetic acid. The acetyl group of the acetic anhydride is acylated to the methyl group of ethyl acetoacetate to form a medium compound, which is then hydrolyzed and carboxylate to obtain acetylacetone. In the reaction, the acetic acid prompts the methyl group of the acetoacetate to form carbon particles, and the acetic anhydride is reacted. The hydrolysis step makes the ester group crack, the carboxylic group is removed, and the acetylacetone is reduced. The method of inversion is high, but the cost of raw materials is high.
3. ** Acetone-acetic anhydride method **: Acetone-acetic anhydride is reversed in the presence of a specific catalytic compound such as boron trifluoride ether complex. The catalyst promotes the nucleation of acetone's carbonyl-acetic anhydride to replace and gradually generate acetylacetone. This catalyst can effectively activate the reactor and improve the reaction rate. This method has the advantages of low reactivity and short reactivity, etc., but the catalytic cost is high, and the reaction process is low.

In "Tiangong Kaiwu", it goes: "Where gunpowder is pure yang, and nitrate is pure yin, this universe is a fantasy of gods." Sulfur and saltpeter are used in many fields.
In the military field, gunpowder is very important. In ancient wars, it was loaded into firearms to achieve long-range attacks. For example, in the Song Dynasty, the flamethrower used a bamboo tube as the body of the gun, and it was filled with gunpowder and a child nest. After igniting the gunpowder, it could shoot out the child nest and kill the enemy a hundred steps away. In the Ming Dynasty, firearms developed more rapidly. Guns, artillery, etc. were all powered by gunpowder, which greatly enhanced the combat effectiveness of the army and changed the pattern of war.
In the civilian field, one of them was the production of fireworks. Gunpowder is mixed with various metal salts, and through ingenious formulations and production processes, it can be made into colorful fireworks. During festivals and celebrations, fireworks bloom in the night sky, creating a joyous and peaceful atmosphere. The second is for mining. In mining, the use of gunpowder blasting can break ore, improve mining efficiency and reduce labor costs.
In addition, in the field of traditional medicine, gunpowder also has a place. Sulfur, saltpeter and other ingredients were used in the refining of some ancient medicinal pills. Although it is different from the concept of modern medicine, it has a certain curative effect on certain diseases under medical conditions at that time. In short, sulfur and saltpeter are widely used in military, civilian, medical and other fields, and have a profound impact on the development of human society.

In today's market, it is difficult to determine the price of Ma Jiesan. In the past, Hua Tuo created Ma Jiesan, which was a prescription for medicine and Taoism. However, with the passage of time, its prescription was not passed down, and it was difficult for future generations to repeat it. Therefore, it is difficult to determine the price of its market.
Thinking back to when Hua Tuo was alive, he used Ma Jiesan to perform abdominal dissection and saved countless people. At that time, the price of Ma Jiesan was precious, needless to say, and it was probably an unusual price. It may vary according to the wealth of the patient, the severity of the disease, and the difficulty of obtaining medicinal materials. If you are in a wealthy family and your illness is critical, if you need to use Ma Jiesan to prolong your life, the price is high; while for the poor, Hua Tuo has a kind heart, or reduces its price, or even does not take a penny to save the suffering.
As for today, although the original prescription of Ma Jiesan has been lost, the medical way is prosperous, there are many methods of anesthesia, and there are also various anesthetic drugs. If the ancient Ma Jiesan is compared with today's anesthetic, its system is different, and its effect is also different. And today's medicines are all developed according to the scientific method, which is not comparable to the ancient ones. However, if the price of hemp boiling powder is emphasized, with its magic and rarity in the past, if it still exists, according to today's market conditions, it also costs medicinal materials, manpower, and craftsmanship, or it is a high-priced thing. However, if it is a medicine to help the world, it should not make the price so high that it is beyond the reach of ordinary people, and it should be important to benefit the sick. In a nutshell, if hemp boiling powder exists in today's market, its price may vary according to various reasons, which is difficult to be sure. It must be aimed at benefiting people and curing diseases, and it must not be mercenary and cause the price to be lost.

In "Tiangong Kaiwu", the conditions for storing silkworm seeds are quite particular.
Silkworm seeds need to be properly preserved and the temperature should be adjusted first. The winter is severe cold, so the silkworm seeds should not be frozen, and they should be placed in a warm place, but they should not be too warm to prevent premature germination. Warm conditions should be kept in a warm environment, just like a person in a room of spring and scenery. Only when it is not cold or dry can silkworm seeds be safely dormant.
As for humidity, it is also the key. Silkworm seeds should be stored in a dry place. If the environment is humid, it is easy to cause mildew and rot of silkworm seeds, just like when you leave something in a place of rain, it will break for a long time. Therefore, when choosing a place for seed storage, it is necessary to avoid moisture and choose a high and dry place to ensure the integrity of silkworm seeds.
Furthermore, air circulation is also indispensable. Although silkworm seeds have not hatched, they still need to breathe. If they are hidden in an occluded place, the air is not smooth, such as a secret room in a person, the breath is difficult to pass, and silkworm seeds are easy to suffocate and damage. Therefore, the place where seeds are stored should be properly ventilated so that fresh air can enter and exit.
And the device for seed storage is also elegant. Use a clean basket or a special box. The material should be natural and harmless, and no odor-containing device should be used to avoid odor affecting silkworm seeds. Soft and clean grass or cloth should be used for the bedding in the vessel, so that the silkworm seeds are stable and not damaged.
In short, the silkworm seeds need to be stored in a suitable temperature, dry humidity, and good ventilation environment, and stored in a clean and harmless vessel, so as to ensure that the silkworm seeds hatch smoothly in the coming year and the silkworm breeding is successful.