Dichloromethane (DCM), also called methylene chloride, is one of the most widely used chlorinated solvents in industrial extraction. Its combination of moderate polarity, low boiling point and water immiscibility makes it a practical choice for pulling organic compounds out of complex mixtures - from pharmaceutical intermediates to food ingredients.
Why DCM Is an Effective Extraction Solvent
Medium polarity: DCM dissolves a broad range of organic compounds while leaving highly polar materials such as salts behind.
Water immiscibility: It forms a clear separate layer with aqueous phases, enabling clean liquid-liquid separations.
Low boiling point (39.6 °C): The solvent evaporates quickly and gently after extraction, protecting heat-sensitive compounds.
High density (about 1.33 g/cm3): DCM settles as the lower layer, simplifying phase separation and recovery.
Non-flammability in standard testing: Unlike most volatile organic solvents, DCM does not exhibit a flash point in standard closed-cup tests, reducing fire risk in many operations.
Key Physical Properties
| Property | Value |
| CAS number | 75-09-2 |
| Molecular formula | CH2Cl2 |
| Molecular weight | 84.93 g/mol |
| Boiling point | 39.6 °C |
| Melting point | -95 °C |
| Density | 1.33 g/cm3 at 20 °C |
| Water solubility | About 20 g/L at 20 °C (slightly soluble) |
| Flash point | None in standard closed-cup testing |
Main Industrial Applications
DCM is used to remove caffeine from coffee and tea, to extract and purify active pharmaceutical ingredients (APIs) and natural products, and in analytical sample preparation. It also serves as a solvent in adhesive formulations, aerosol products, degreasing and solvent welding, and as a process solvent in chemical synthesis. In many regions, consumer paint-stripping uses are restricted because of exposure concerns, while controlled industrial use continues under strict occupational controls.
Safety, Classification and Transport
DCM requires careful handling. The International Agency for Research on Cancer (IARC) classifies it in Group 2A (probably carcinogenic to humans), and it carries EU hazard statements including H351 (suspected of causing cancer), along with H315, H319 and H335. Workplace exposure is controlled with ventilation and exposure limits such as a common 8-hour TWA of 25 ppm in the United States. For transport, DCM is shipped as UN 1593, Hazard Class 6.1, Packing Group III, and must be labeled accordingly. Always review the current Safety Data Sheet (SDS) for the jurisdiction of use.
Buying DCM for Industrial Use
When sourcing DCM, verify purity (industrial grades commonly exceed 99.9%), water content, acidity and non-volatile residue against a batch certificate of analysis. Choose packaging that minimizes vapor loss - drums, totes or ISO tanks - and confirm the supplier holds the relevant quality and regulatory certifications for your market. Storage areas should be cool, ventilated and equipped for spill containment.
Frequently Asked Questions
Is DCM flammable? DCM does not show a flash point in standard closed-cup tests and is widely described as non-flammable, but it can form flammable vapor mixtures under some high-temperature conditions. It is still handled as a hazardous chemical and stored away from ignition sources.
Why does DCM form the lower layer in a separation funnel? Because DCM is denser than water (about 1.33 g/cm3 versus 1.0 g/cm3), the organic phase settles below the aqueous phase, making it easy to drain off after extraction.
How is DCM removed after extraction? DCM's low boiling point means it is usually removed by distillation or rotary evaporation at mild temperatures, and the recovered solvent can often be recycled after purification.
Is DCM still used for decaffeination? DCM has historically been used to extract caffeine from coffee and tea. Food-grade applications are strictly regulated with residue limits, and some producers have moved to other processes, but DCM extraction remains an accepted industrial route in regulated markets.
What are the exposure limits for DCM? Common occupational limits include an 8-hour time-weighted average of 25 ppm in the United States, with comparable limits in many other jurisdictions. Local regulations should always be checked before designing ventilation and PPE programs.
Can DCM replace other extraction solvents? In many cases yes, thanks to its strong solvency, easy removal and non-flammability. The final choice depends on the solute, regulatory constraints and the safety infrastructure available at the site.