Initial Melting Method of Suberic Acid

1. Introduction to Suberic Acid

Suberic acid (chemical name: Octanedioic acid, molecular formula HOOC-(CH₂)₆-COOH, CAS No.: 505-48-6) is a straight-chain saturated dicarboxylic acid belonging to the aliphatic dicarboxylic acid family. It is widely used in pharmaceutical intermediates, fragrance synthesis, polymer materials, and chemical research. Due to its stable molecular structure, suberic acid plays an important role in organic synthesis and polymer chemistry. In evaluating its physical properties, the initial melting method is an essential technique for assessing its purity and quality.

2. Melting Point Range of Suberic Acid

Suberic acid appears as a white crystalline powder or granule. Its melting point is typically in the range of 141–143℃. In practical testing, if the melting range is too wide or significantly lower than the theoretical value, impurities are usually present. By measuring the melting point using the initial melting method, one can quickly determine the purity of the sample.

3. Procedure of the Initial Melting Method

Sample Preparation: Take a small amount of Suberic acid  , grind it into fine powder to ensure uniform particle size, and dry the sample thoroughly to avoid moisture interference.

Loading into Capillary Tube: Fill the powdered sample into a capillary tube to a height of about 2–3 mm; gently tap the tube to make the sample compact and evenly distributed.

Heating Apparatus: Use a melting point apparatus or an oil bath system; maintain a heating rate of 1–2 ℃/min to ensure accurate temperature readings.

Observation of Initial Melting Point: When the edges of the crystalline sample begin to appear moist, glossy, or partially transparent, this temperature is recorded as the “initial melting point.” Continue heating until the sample is completely melted; the corresponding temperature is the “final melting point.”

Recording and Calculation: Record both the initial and final melting points, then calculate the melting range. A wide melting range often indicates impurities or insufficient sample purity.

4. Factors Affecting the Measurement

Sample Purity: Impurities lower the melting point and broaden the melting range.

Heating Rate: Excessive heating rate may cause the melting point to appear higher than the actual value.

Sample Condition: Uneven grinding or moisture content may lead to inaccurate measurements.

Instrument Accuracy: Proper calibration of the melting point apparatus directly affects the reliability of the results.

5. Significance of the Initial Melting Method

Purity Testing: The method provides a simple and fast way to determine whether a Suberic acid sample meets laboratory or industrial requirements.

Quality Control: In chemical production and pharmaceutical synthesis, melting point measurement is a crucial quality inspection indicator.

Research Reference: In material science and polymer development, melting point data serve as fundamental physical parameters.

6. Conclusion

The initial melting method of Suberic acid  (CAS No.: 505-48-6) is a simple yet practical approach for determining purity and quality. Standardized operation ensures reliable laboratory results and strict quality control in industrial applications. With the growing demand for fine chemicals and advanced polymer materials, the initial melting test of suberic acid will continue to play an increasingly important role in both research and production.