Quality Control and Testing Methods for Methyl 4-Bromobutyrate

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(C₅H₉BrO₂) is an important organic chemical intermediate widely used in pharmaceutical synthesis, the chemical industry, and other fields. To ensure the purity and quality of the product, a scientific quality control system and precise testing methods are essential. Below is a detailed introduction:

1. Key Points of Quality Control

Raw Material Control

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

Inspect solvents, catalysts, and other auxiliary materials to avoid introducing impurities.

Synthesis Process Monitoring

Reaction Temperature: Variations in temperature during synthesis directly impact product yield and byproduct formation. Reaction temperature must be strictly controlled as per process requirements.

Reaction Time: Insufficient reaction time may lead to low conversion rates, while prolonged reactions may cause decomposition or side reactions. Regular sampling to monitor conversion rates is necessary.

Bromine Excess Control: Add bromine in appropriate amounts to prevent byproduct formation and minimize raw material waste.

Storage and Packaging

Use clean, dry containers for storage to prevent moisture, oxidation, or degradation.

Packaging materials should have good sealing properties to protect the product from environmental influences.

2. Testing Methods

Appearance Inspection

Methyl 4-bromobutyrate is a colorless to pale yellow liquid at room temperature. Observe the product to ensure it meets appearance standards and is free of visible impurities or discoloration.

Gas Chromatography (GC)

Purpose: Analyze product purity and impurity content.

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

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

Fourier-Transform Infrared Spectroscopy (FTIR)

Purpose: Confirm the molecular structure of methyl 4-bromobutyrate.

Features: Compare the product spectrum with standard spectra to ensure characteristic absorption peaks (e.g., C=O and C-Br bonds) match.

Proton Nuclear Magnetic Resonance (¹H NMR)

Purpose: Verify the chemical environment of hydrogen atoms in the molecule to exclude structural anomalies or impurities.

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

Moisture Content Testing (Karl Fischer Method)

Purpose: Determine the water content in the product to prevent quality degradation or side reactions caused by excess moisture.

Key Points: Use titration to verify whether water content is within the standard range.

Acid Value Measurement

Purpose: Assess the content of free acids in the product to ensure compliance with acid value specifications.

Method: Conduct acid-base titration to determine the acid value.

3. Quality Standards (Example)

Here are reference values for common quality indicators:

Appearance: Colorless to pale yellow transparent liquid.

Purity (GC): ≥99.0%.

Moisture Content: ≤0.2%.

Acid Value: ≤0.1 mg KOH/g.

4. Conclusion

The quality control of Methyl 4-bromobutyrate spans the entire process from raw materials to finished products. Proper testing methods are key to ensuring product compliance. Techniques such as appearance inspection, GC, FTIR, and NMR effectively assess product purity, structure, and impurity levels. For manufacturers, strict adherence to quality standards not only enhances product competitiveness but also meets customer demands for high-quali