2-bromo-5-nitropyridine

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2-Cyanogen-5-fluorobenzoic acid is an important pharmaceutical and pesticide intermediate, and its synthesis methods are diverse. The following are the common methods for you:
###Take 2-methyl-5-fluorobenzoic acid as the starting material
1. ** Oxidation first and then cyanidation **: Take 2-methyl-5-fluorobenzoic acid as the starting material, and under the action of strong oxidants such as potassium permanganate or potassium dichromate, methyl is oxidized to a carboxyl group to obtain 2-carboxyl-5-fluorobenzoic acid. Subsequently, the carboxyl group is converted into a suitable leaving group. For example, it is first reacted with thionyl chloride to form an acid chloride, and then reacted with cyanide reagents such as sodium cyanide in an appropriate solvent (such as DMF) to obtain the target product by cyanide substitution. This process requires strict control of the reaction conditions to avoid side reactions in the cyanidation reaction.
2. ** Direct cyanidation **: In the presence of suitable catalysts and ligands, 2-methyl-5-fluorobenzoic acid undergoes a direct cyanidation reaction with cyanide reagents (such as trimethylsilyl cyanide). For example, transition metal catalysts, such as palladium, copper and other complexes, are used to guide the cyanide group to selectively replace the methyl group to generate 2-cyano- 5-fluorob The steps of this method are simple, but the choice of catalyst and the optimization of reaction conditions are crucial to improve the yield and selectivity of the reaction.
###With 2-halo-5-fluorobenzoic acid as raw material
1. ** Halogen-cyano substitution **: If 2-halo (e.g. chlorine, bromine) -5-fluorobenzoic acid is used as the starting material, it can be reacted with cyanide reagents under the conditions of nucleophilic substitution reaction. If 2-halo-5-fluorobenzoic acid reacts with sodium cyanide or potassium cyanide in a polar solvent (such as DMSO) under basic conditions (such as potassium carbonate and other bases) and in the presence of a phase transfer catalyst, the halogen atom is replaced by a cyanyl group to obtain 2-cyano-5-fluorobenzoic acid. Care should be taken to control the reaction temperature and time to prevent side reactions such as hydrolysis of halogen atoms.
2. ** Transition metal catalyzed cyanide **: Transition metal catalyzed system, such as palladium catalyzed cyanide reaction of halogenated aromatic hydrocarbons. Using 2-halo-5-fluorobenzoic acid as a substrate, under the action of palladium catalyst (such as Pd (PPh) < unk >, ligand and base, and reacting with cyanide reagents (such as Zn (CN) < unk >, etc.), the conversion of halogen atoms to cyano groups can be efficiently realized. This method requires harsh reaction conditions, and parameters such as catalyst, ligand-substrate ratio and reaction temperature need to be precisely regulated to achieve the best reaction effect.

The physical properties of 2-%-5-carboxypyridine are not the same. This is a chemical substance with specific physical properties.
Its external properties are often solid, but depending on the size and degree of crystallization, it may appear crystalline, crystal shape or complete, with a certain shape, or under light. Its color is mostly white to black, if it contains yellow, or the color is slightly yellow.
Melting is also important for physical properties. 2-%-5-carboxypyridine has a specific melting property, and it is subject to this degree, and the solid material is easy to melt. This melting can help its stability. If it contains yellow, the melting will often drop and the melting range will be low.
The solubility cannot be ignored. In different solubility levels, its solubility is high. In water, it may have a certain solubility, but it is not easily soluble. Because the molecule contains a carboxyl group, it has a certain water content. However, pyridine has hydrophobicity, resulting in limited solubility in water. For solubility levels, such as alcohols and ketones, the solubility may be higher than that of water. Due to the principle of similar miscibility, the part of the pyridine is soluble and compatible.
In addition, the density is also a characteristic. Its density has a certain ratio to water, which can help in operations such as fractionation and extraction. For example, in liquid-liquid extraction, 2-% -5-carboxypyridine is separated from other substances according to the density difference.
2-% -5-carboxypyridine has specific physical properties such as externality, melting, solubility and density, which are of great significance in chemical research, engineering and application.

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In today's market, the quality of the product can be determined by two or five millimeters. The quality of the product is always determined by the quality, age, workmanship and supply and demand.
If it is based on the ancient quality of the product and the quality of the workmanship, its price or height. In the collection market, if it comes from the hands of famous craftsmen, or has special historical implications, the price is not bad. If it is in good condition and has a clear origin, it may be worth thousands of gold, or even more than gold. It is unknown.
However, if it is an ordinary product, the quality is average, and it is a special product, the price is relatively low. The ordinary two to five millimeters of the product in the city is usually worth only one hundred gold. If there is any shortage or shortage, the price will be greatly discounted, or it will be worth a hundred gold.
Because the market situation is instantaneous, the supply and demand will be low. If it is high, collectors are all satisfied with this. If the buyer is low and the supplier is low, the price will rise; on the contrary, if the supply is low and the demand is low, the price will fall. In order to know its cutting quality, it is necessary to check its quality, and consider the supply and demand of the market. Only then can we obtain an estimate of the price.