Dichloromethane (DCM) is a versatile polar aprotic solvent widely used in biochemical and analytical research. Owing to its low boiling point and strong solvation properties, it is particularly effective for extracting non-polar biomolecules such as lipids and steroid compounds from aqueous systems.

Chemical Properties

Dichloromethane (CH₂Cl₂) is characterized by a tetrahedral carbon atom bonded to two chlorine atoms and two hydrogen atoms. It is a colorless liquid with a density of approximately 1.33 g/mL and a boiling point of 39.6°C. The molecule exhibits a dipole moment of about 1.6 D due to the electronegativity difference between carbon and chlorine atoms.

DCM shows slight water solubility (around 13 g/L) but is readily miscible with organic solvents such as chloroform, ether, and ethanol. Its high vapor pressure (approximately 353 mmHg) contributes to rapid evaporation during laboratory procedures. Stabilized grades, typically containing 50–150 ppm amylene, are used to inhibit degradation and prevent hydrogen chloride formation.

Biochemical Applications

In lipid biochemistry, dichloromethane is sometimes used as a complementary solvent in Folch-type extraction systems to improve recovery of complex lipid species such as gangliosides and cholesterol. It is also applied in biphasic extraction protocols for isolating plant secondary metabolites prior to GC-MS analysis.

In proteomics workflows, DCM can assist in precipitating membrane proteins following detergent-based cell lysis. In molecular biology, it is used during phenol-chloroform extraction steps to remove residual protein contaminants while minimizing nucleic acid loss.