3-Bromo-5-methylpyridine

3-Bromo-5-methyl pyridine is a key intermediate in organic synthesis and has a wide range of uses in many fields, as follows:
First, in the field of medicinal chemistry, this compound can be used as a key intermediate for the synthesis of many drugs. Pyridine ring structure is widely present in many drug molecules, and its unique electronic properties and spatial structure can endow drugs with specific biological activities. The introduction of methyl and bromine atoms can affect the lipophilicity, electron cloud distribution, and interaction with targets of drug molecules, thereby optimizing the activity, selectivity, and pharmacokinetic properties of drugs. For example, in the process of drug development for the treatment of cardiovascular diseases and neurological diseases, 3-bromo-5-methylpyridine can be spliced with other functionalized molecules through a series of chemical reactions to construct complex drug molecular structures with specific pharmacological activities.
Second, in the field of materials science, 3-bromo-5-methylpyridine can be used to synthesize functional materials. Pyridine groups can be combined with metal ions by coordination to produce metal-organic framework materials (MOFs). These materials exhibit excellent performance in the fields of gas adsorption and separation, catalysis, and fluorescence sensing. The bromine atom can act as a reaction check point, introducing other functional groups through reactions such as nucleophilic substitution to regulate the properties of the material. For example, by reacting with reagents containing specific functional groups, materials with high selective adsorption capacity for specific gases can be prepared.
Third, in the field of organic synthetic chemistry, as an important synthetic block, the bromine atom of 3-bromo-5-methyl pyridine and methyl can participate in diverse chemical reactions respectively. Bromine atoms can undergo metal-catalyzed coupling reactions such as Suzuki coupling and Heck reaction, thereby forming carbon-carbon bonds and realizing structural modification and expansion of pyridine derivatives. Methyl groups can be further derived through oxidation, substitution and other reactions, providing the possibility for the synthesis of complex and diverse organic compounds. For example, when constructing polycyclic pyridine compounds, its bromine atom can be used for Suzuki coupling reaction with suitable aryl boronic acid, and then the methyl group can be functionalized to achieve the synthesis of the target compound.

3-Bromo-5-methylpyridine is an organic compound with the following physical properties:
In appearance, it is mostly colorless to light yellow liquid under normal conditions. This property is convenient for visual identification and confirmation in actual operation.
In terms of boiling point, it is about 190-195 ° C. As a key physical constant, boiling point is of great significance for the separation and purification of compounds. In this temperature range, 3-bromo-5-methylpyridine changes from liquid to gaseous state and can be separated from the mixture by means of distillation.
Melting point is about -20 ° C. Melting point characterizes the temperature at which a substance changes from solid to liquid. The compound has a low melting point and is liquid at room temperature. It may solidify in a low temperature environment. Pay attention to temperature control during storage and transportation.
Density is about 1.45 g/cm ³. Density reflects the mass per unit volume of a substance. In chemical production and experimental operations, it is of great significance for accurate measurement and calculation of dosage.
In terms of solubility, it is slightly soluble in water and soluble in organic solvents such as ethanol and ether. This solubility characteristic determines its dispersion and reaction in different solvents, providing a basis for selecting suitable reaction solvents and separation methods. For example, in organic synthesis reactions, matching solvents are selected according to their solubility to promote the smooth progress of the reaction.
In addition, 3-bromo-5-methylpyridine is volatile and should be operated in a well-ventilated environment to avoid inhalation. Its odor is special, although it is difficult to describe accurately, it can be clearly perceived during operation, and it can be preliminarily judged whether it leaks or evaporates.

3-Bromo-5-methylpyridine is a key intermediate in organic synthesis and is widely used in many fields such as medicinal chemistry and materials science. The synthesis method is as follows:
1. ** Pyridine as the starting material **:
- ** Halogenation reaction **: Pyridine is first halogenated with bromine. Generally speaking, with liquid bromine as the bromine source, under the catalysis of Lewis acid (like FeBr), pyridine will undergo bromination reaction at the 3-position to generate 3-bromopyridine. The reaction mechanism is electrophilic substitution. The nitrogen atom on the pyridine ring makes the electron cloud density at the 3-position relatively high, which is more susceptible to the attack of positive bromide ions.
- ** Methylation Reaction **: The obtained 3-bromopyridine reacts with methylating reagents (such as K 2O CO) and suitable solvents (such as DMF) to achieve 5-position methylation. This step is a nucleophilic substitution reaction. The alkaline environment increases the electron cloud density on the 5-position carbon of 3-bromopyridine, which is easily attacked by methyl negative ions, resulting in the formation of 3-bromopyridine.
2. ** Construction of Pyridine Ring via Pyridine Derivatives **:
- ** Construction of Pyridine Ring **: Select suitable raw materials and build a pyridine ring through a multi-step reaction. For example, using β-carbonyl esters, ammonia and halogenated hydrocarbons as starting materials, pyridine derivatives are formed by condensation, cyclization and other reactions. If the halogenated hydrocarbons are properly selected, bromine atoms and methyl groups can be directly introduced at suitable positions in the pyridine ring.
- ** Subsequent Modifications **: The resulting pyridine derivatives may require further modification, such as conversion, protection and deprotection of certain functional groups, and finally obtain 3-bromo-5-methylpyridine.
3. ** Transition metal catalytic coupling reaction **:
- ** Coupling of halopyridine with methylating reagents **: Using 3-halopyridine (such as 3-chloropyridine or 3-bromopyridine) as a substrate, the coupling reaction occurs with methylating reagents (such as methyl borate, methyl zinc reagents, etc.) under the action of transition metal (such as palladium, nickel, etc.) catalysts and ligands (such as phosphine ligands). Transition metal catalysis can effectively promote the formation of carbon-carbon bonds, accurately achieve 5-position methylation, and then synthesize 3-bromo-5-methylpyridine. Such methods have relatively mild conditions and good selectivity, and are widely used in the field of organic synthesis.

When storing and transporting 3-hydroxy- 5-methylpyridine, there are many key things to pay attention to.
During storage, the first environmental conditions. It should be placed in a cool, dry and well-ventilated place. Due to its chemical properties, if the environment is humid, water vapor is easy to react with 3-hydroxy- 5-methylpyridine, or cause it to deteriorate, affecting the quality and utility. Temperature must also be controlled. If the temperature is too high, it may cause its decomposition and volatilization, and then its active ingredients will be lost.
Furthermore, the packaging must be tight. Suitable packaging materials, such as sealed containers, should be used to prevent contact with air. Due to the oxygen, carbon dioxide and other components in the air, or chemical reactions with 3-hydroxy- 5-methylpyridine, its chemical structure and properties are changed.
When transporting, it is important to be stable. Avoid violent vibration and collision to prevent package damage. Once the package is damaged, 3-hydroxy- 5-methylpyridine leaks, which may not only cause its own loss, but also cause harm to the surrounding environment and personnel.
At the same time, the temperature and humidity of the transportation environment also need to be paid attention to. To ensure that the temperature and humidity meet its storage requirements during transportation and maintain stable conditions.
In addition, it needs to be reasonably isolated from other chemicals. 3-Hydroxy-5-methylpyridine may have incompatible reactions with certain chemicals, so it should not be transported with chemicals that are contrary to their properties to avoid dangerous accidents.
Only by paying full attention to the above points during storage and transportation can the quality and safety of 3-hydroxy- 5-methylpyridine be guaranteed, so that it can be effectively used in subsequent production and scientific research activities.

3-Chloro-5-methylpyridine, which does have an impact on the environment and human health.
In the environment, it will exhibit many characteristics. If 3-chloro-5-methylpyridine enters the water body, it may be toxic to aquatic organisms due to its chemical properties. Aquatic organisms are more sensitive to it. Once exposed, it may cause physiological disorders, such as fish respiration, reproduction and other behaviors or disturbance, which in turn affects the balance of aquatic ecosystems. In soil, it may affect the activity and species of soil microorganisms. Soil microorganisms are of great significance to soil fertility and material circulation. The existence of 3-chloro-5-methylpyridine may change the soil microbial community structure, affect the normal function of soil, and in the long run, or have an indirect impact on vegetation growth. Moreover, this substance has a certain persistence in the environment, is not easy to degrade rapidly, and will remain in the environment for a long time, continuously releasing potential hazards.
As for human health, 3-chloro-5-methylpyridine has many potential threats to the human body. If it enters the human body through the respiratory route, it will irritate the respiratory mucosa, cause symptoms such as cough and asthma, and long-term exposure may increase the risk of respiratory diseases. If it comes into contact with the skin, it may cause skin allergies, itching, redness and swelling, and in severe cases, it may even penetrate the skin into the blood circulation, causing adverse effects on the internal organs of the body. If accidentally ingested, it will harm the digestive system, cause nausea, vomiting, abdominal pain and other symptoms, and seriously damage human health.
Therefore, substances such as 3-chloro-5-methylpyridine need to be treated with caution, and controls should be strengthened in production and use to reduce their adverse effects on the environment and human health.