2-Bromo-3-nitropyridine(link:https://www.bloomtechz.com/chemical-reagent/laboratory-reagent/2-bromo-3-nitropyridine-cas-19755-53-4.html) is a solid crystalline compound with the molecular formula C5H3BrN2O2, CAS 19755-53-4, and a molecular weight of 188.99 grams/mole. The common appearance is a light yellow to light brown crystalline powder. The specific surface area depends on its crystal morphology and particle size distribution. Usually, the specific values may vary depending on experimental conditions and measurement methods. Under conventional conditions, it is relatively stable, but it may be sensitive to light, heat, and oxygen. It should be stored in a cool and dry place to avoid prolonged exposure to sunlight. Pyridine derivatives have the universal properties of pyridine rings and can be used as denaturants, dyeing aids, and raw materials for synthesizing a series of products (including drugs, disinfectants, dyes, etc.) in industry. It can be used as an intermediate in pharmaceutical chemistry and organic synthesis. During synthesis and conversion, the nitro groups on the pyridine ring can be reduced to amino groups; Affected by the electron deficient properties of the pyridine ring and the strong electron withdrawing properties of the nitro group, the bromine atoms in the structure can easily be attacked by nucleophilic reagents such as alkylamines or oxygen negative ions to obtain further derivative products.
Synthesis of 2-bromo-3-nitropyridine
Pyridine bromide and nitric acid reaction method:
The reaction method of pyridine bromide with nitric acid is a commonly used method for synthesizing 2-bromo-3-nitropyridine. The specific steps are as follows:
Step 1: Prepare reactants and reagents
a. 2-Bromopyridine: The starting substance for the reaction, which can be obtained through existing synthesis methods or commercial purchases.
b. Concentrated nitric acid (HNO3): The nitration reagent in the reaction should be operated safely and use concentrated nitric acid with a concentration of no less than 65%.
c. Reaction solvent: Suitable organic solvents such as chloroform or dichloromethane can be selected.
Step 2: Reaction operation
a. Dissolve 2-bromopyridine in an appropriate amount of organic solvent to facilitate the reaction.
b. Slowly add concentrated nitric acid to the reaction solution, while controlling the reaction temperature under low temperature conditions. It can usually be carried out under ice bath conditions to ensure the selectivity and yield of the reaction.
c. During the process of adding nitric acid, attention should be paid to controlling the temperature and speed of the reaction to avoid uncontrolled side reactions.
d. After the reaction is complete, the reaction solution is subjected to appropriate treatment and purification, such as extraction, crystallization, or column chromatography.
Step 3: Crystallization purification
a. After treatment, the reaction solution can be purified by crystallization. The commonly used method is to crystallize the product using suitable solvents to obtain pure 2-bromo-3-nitropyridine crystals.
b. After crystallization, appropriate solvents can be used for washing and drying to obtain the desired 2-bromo-3-nitropyridine product.
Chemical reaction formula:
The chemical reaction formula for the reaction of pyridine bromide with nitric acid to produce 2-bromo-3-nitropyridine is as follows:
C5H4NBr+HNO3 → C5H3BrN2O2+HBr
In this reaction, the role of nitric acid is to introduce a nitro group (- NO2), replacing the hydrogen atom in 2-bromopyridine with a nitro group, thereby forming 2-bromo-3-nitropyridine.
Nitro compound and bromine compound reaction method:
Method 1: Bromine compound reaction method
Step 1: Prepare reactants and reagents
a. 2-Bromo-3-nitropyridine: As the starting substance of the reaction, it can be obtained through existing synthesis methods or commercial purchases.
b. Strong base bromide: such as hydrobromic acid (HBr) or sodium bromite (NaBr), used as a source of bromine.
Step 2: Reaction operation
a. Dissolve 2-bromo-3-nitropyridine in an appropriate solvent for the reaction to proceed. The commonly used solvents can be dichloromethane or ether.
b. Add an excess of strong alkali bromide. Bromine ions will attack the bromine atom in the 2-bromo-3-nitropyridine molecule, replacing its position.
c. The reaction is usually carried out at room temperature with sufficient reaction time to ensure its progress. Changes in color may be observed during the reaction process.
d. After the reaction is completed, the bromine compound is extracted from the reaction solution through acidic treatment. For example, hydrochloric acid (HCl) can be added to acidify the solution.
e. Extract, dry, and crystallize to obtain the required 2-bromo-3-nitropyridinium bromide compound.
Chemical reaction formula:
The chemical reaction formula for the reaction of 2-bromo-3-nitropyridine with bromide to produce bromine compounds is as follows:
C5H3BrN2O2+Br ^ - → C5H4Br2N2O2
Method 2: Nitro compound reaction method
Step 1: Prepare reactants and reagents
a. 2-Bromo-3-nitropyridine: As the starting substance of the reaction, it can be obtained through existing synthesis methods or commercial purchases.
b. Sodium hydroxide (NaOH): used as a reaction medium under alkaline conditions.
Step 2: Reaction operation
a. Dissolve 2-bromo-3-nitropyridine in an appropriate solvent for the reaction to proceed. The commonly used solvents can be water or organic solvents (such as ethanol).
b. Add an appropriate amount of sodium hydroxide to make the reaction system alkaline and promote the reaction. Usually carried out at room temperature.
c. The reaction takes a certain amount of time to ensure its full progress.
d. After the reaction is completed, the nitro compounds are extracted from the reaction solution through acidic treatment. For example, hydrochloric acid (HCl) can be added to acidify the solution.
e. Extract, dry, and crystallize to obtain the required 2-bromo-3-nitropyridine nitro compound.
Chemical reaction formula:
The chemical reaction formula for the reaction of 2-bromo-3-nitropyridine with sodium hydroxide to generate nitro compounds is as follows:
C5H3BrN2O2+OH ^ → C5H3BrN2O3
Electrophilic aromatic substitution reaction method:
2-Bromo-3-nitropyridine is a compound containing bromine and nitro functional groups that can be modified through electrophilic aromatic substitution reactions. Electrophilic aromatic substitution reaction refers to the reaction between electrophilic reagents and aromatic compounds, introducing functional groups from the reagents into the aromatic ring. Common steps of electrophilic aromatic substitution reaction method:
Step 1: Prepare reactants and reagents
a. 2-Bromo-3-nitropyridine: As the starting substance of the reaction, it can be obtained through existing synthesis methods or commercial purchases.
b. Electrophilic reagent: Select the corresponding electrophilic reagent according to the required functional group changes. Common electrophilic reagents include halogenated reagents (such as bromide, chloride) or electrophilic substitution reagents (such as nitro compounds, anhydride, etc.).
Step 2: Reaction operation
a. Dissolve 2-bromo-3-nitropyridine in an appropriate solvent for the reaction to proceed. Commonly used solvents can be organic solvents (such as dichloromethane, ether, etc.) or anhydrous polar solvents (such as dimethyl sulfoxide).
b. Add electrophilic reagents to react with 2-bromo-3-nitropyridine. The reaction conditions can be selected according to the specific reagents and reaction needs, with appropriate temperature and reaction time.
c. During the reaction process, it may be necessary to add catalysts or other auxiliary reagents to promote the reaction. For example, electrophilic substitution reagents often require the use of Lewis acid as a catalyst.
d. After the reaction is completed, remove impurities from the reaction solution through appropriate treatment methods (such as acidic hydrolysis, neutralization, etc.).
e. Extract, dry, and crystallize to obtain the desired product.
Chemical reaction formula:
The reaction formula of the product generated by the reaction of 2-bromo-3-nitropyridine with electrophilic reagents depends on the selected reagent. The following are several common examples of chemical reaction formulas for electrophilic aromatic substitution reactions:
1. Reaction of 2-bromo-3-nitropyridine with bromide:
C5H3BrN2O2+Br ^ - → C5H4Br2N2O2
2. Reaction of 2-bromo-3-nitropyridine with nitric acid:
C5H3BrN2O2+HNO3 → C5H3BrN2O4+HBr