The synthesis method of 4-bromobutyric acid methyl ester.

Basic Information:

Aliases: 4-Bromobutyric Acid Methyl Ester, 4-Bromo-n-butyrate Methyl Ester

CAS No: 4897-84-1

Molecular Formula: C5H9BrO2

Molecular Weight: 181.03

Physical State: Colorless to pale yellow transparent liquid

Melting Point: 175-190°C

Boiling Point: 186-187°C

Density: 1.434 g/cm³

Uses: It can be used to prepare cyclopropylmethylcyanide derivatives, which are important high-activity compounds.

Methyl 4-bromobutyrate  (CAS: 4897-84-1) is an important organic chemical intermediate, widely used in pharmaceutical synthesis, chemical industry, and other fields. To ensure the purity and quality of the product, a scientific quality control system and accurate testing methods must be employed. Below is a detailed introduction:

1. Key Points of Quality Control

Raw Material Control:

Ensure that the purity of production raw materials, such as brominating agents and other chemical reagents, meets the required standards.

Inspect solvents, catalysts, and other auxiliary materials to prevent the introduction of impurities.

Synthesis Process Monitoring:

Reaction Temperature: The temperature during the synthesis process directly affects the yield and the formation of by-products. The reaction temperature should be strictly controlled according to process requirements.

Reaction Time: Short reaction times may lead to insufficient conversion, while long reaction times may introduce decomposition or side reactions. Regular sampling should be conducted to monitor the conversion rate.

Excess Bromine Control: Ensure that the amount of bromine added is appropriate to avoid the generation of by-products and reduce raw material waste.

Storage and Packaging:

Store the product in pollution-free, dry containers to avoid moisture, oxidation, or degradation.

Packaging materials should have good sealing properties to prevent environmental factors from affecting the product.

2. Testing Methods

Appearance Inspection:

Methyl 4-bromobutyrate  is a colorless to pale yellow liquid at room temperature. The product should be examined to ensure it meets the appearance standards with no obvious impurities or discoloration.

Gas Chromatography (GC):

Purpose: To test the product’s purity and impurity content.

Key Points: Use a high-sensitivity GC instrument with high-purity nitrogen as the carrier gas. Optimize the separation conditions using an appropriate column temperature program.

Result Analysis: Calculate the percentage of the main peak area in relation to the total area to determine purity.

Fourier Transform Infrared Spectroscopy (FTIR):

Purpose: To confirm the molecular structure of  Methyl 4-bromobutyrate .

Features: Compare the product's spectrum with a standard spectrum to verify that the characteristic absorption peaks, such as those for C=O and C-Br bonds, match.

Nuclear Magnetic Resonance (¹H NMR):

Purpose: To verify the chemical environment of hydrogen atoms in the molecule and rule out structural anomalies or impurities.

Key Points: Use a high-resolution NMR instrument with an appropriate solvent (such as CDCl₃) and record chemical shifts.

Water Content Testing (Karl Fischer Titration):

Purpose: To measure the water content in the product and prevent quality degradation or side reactions caused by excessive moisture.

Key Points: Determine if the water content is within the standard range through titration.

Acid Value Measurement:

Purpose: To assess the content of free acids in the product and ensure the acid value is within the specifications.

Method: Use acid-base titration to measure the acid value.

3. Quality Standards (Example)

Below are reference values for common quality indicators:

Appearance: Colorless to pale yellow transparent liquid.

Purity (GC): ≥99.0%.

Water Content: ≤0.2%.

Acid Value: ≤0.1 mg KOH/g.

4. Conclusion

Quality control for Methyl 4-bromobutyrate spans the entire process from raw materials to finished products. Proper testing methods are the key to ensuring product quality. Through techniques like appearance inspection, GC, FTIR, NMR, and others, the purity, structure, and impurity content of the product can be effectively tested. For manufacturers, strictly adhering to quality standards not only enhances product competitiveness but also meets customer demands for high-quality chemicals.