Dichloromethane (CAS 75-09-2): Applications, Solvency Mechanism and Solvent Selection Guide
September 30, 2026 · Sourcing Guide
Summary. Dichloromethane (DCM, methylene chloride, CAS 75-09-2, CH2Cl2, MW 84.93) is a clear, dense, non-flammable chlorinated solvent with a boiling point of 39.6 °C and high solvency for resins, oils, waxes, adhesives and polymers. Its main uses are pharmaceutical extraction and reaction media, paint strippers and industrial degreasing, auxiliary blowing agent for flexible polyurethane foam, electronics and precision cleaning, film, adhesive and aerosol formulations, and decaffeination or natural extract production. DCM is classified as an ICH Q3C Class 2 residual solvent with a 600 ppm concentration limit, so control of residual solvent and worker exposure is a standard part of qualification. This guide summarises specifications, manufacturing, the mechanism behind its performance, downstream products and how it compares with chloroform, perchloroethylene and non-chlorinated solvents.
Basic information
| Item | Value |
|---|---|
| Product name | Dichloromethane (methylene chloride) |
| CAS number | 75-09-2 |
| Molecular formula / MW | CH2Cl2 / 84.93 g/mol |
| Synonyms | DCM, methylene chloride, methylene dichloride |
| Appearance | Clear colourless liquid with a characteristic sweet odour |
| Assay | ≥99.9% (industrial grade); electronic and pharmaceutical grades available |
| Water content | ≤0.02% (typical) |
| Boiling point | 39.6 °C |
| Density (20 °C) | 1.32 g/cm³ (heavier than water) |
| Flash point | None — not flammable under normal handling conditions |
| Water solubility | ~13 g/L at 20 °C; miscible with most organic solvents |
| Azeotrope | Low-boiling azeotrope with water (≈38 °C), useful for drying |
| ICH Q3C | Class 2 residual solvent, concentration limit 600 ppm |
| Packaging | 250 kg drum, 1000 kg IBC, ISO tank |
| HS code | 2903.12 (confirm with local customs) |
| Storage | Cool, dry, shaded, well ventilated; away from strong oxidisers and hot surfaces |
| Main uses | Extraction and reaction solvent, paint stripping, degreasing, PU foam blowing, electronics cleaning |
1. Product overview
DCM combines four properties that are difficult to obtain in one solvent: high solvency for a broad range of resins and oils, non-flammability, a low boiling point that makes recovery by distillation easy, and low water solubility with a density above 1, which gives clean and fast phase separation in liquid–liquid extraction. It is a volatile solvent with a high vapour pressure, so closed systems and local exhaust ventilation are standard practice.
2. Manufacturing (brief)
Industrial DCM is produced by the chlorination of methanol or methane, in which methyl chloride is further chlorinated to dichloromethane and then to chloroform and carbon tetrachloride. The reaction mixture is separated by a train of distillation columns, and DCM is obtained as the main intermediate fraction; process conditions and the chlorination ratio determine the product distribution. Crude DCM is washed to remove dissolved acid, neutralised, dried and fractionated. Electronic and pharmaceutical grades are produced by additional distillation and filtration steps with tight control of water, acidity, non-volatile residue and trace metals.
3. Application principles
- Solvency. DCM is a medium-polarity solvent (Hansen parameters roughly 18.2 / 6.3 / 6.1 MPa^0.5) with a high dispersion component. It swells and dissolves hydrocarbon resins, waxes, fats, oils, bitumen and many polymers that are insoluble in alcohols or water, which is the basis of its use in paint removers, degreasers and extraction.
- Non-flammability and volatility. With no flash point and a boiling point below 40 °C, it can replace flammable solvents in stripping and cleaning operations and is easily recovered by distillation or condensation.
- Extraction behaviour. Its low water solubility and high density produce a lower organic phase, so extraction and washing steps separate quickly and cleanly. The low-boiling water azeotrope also allows azeotropic drying of water-sensitive streams.
- Reaction medium. DCM is inert to a wide range of reagents and is used as a medium for chloromethylation, acylation, oxidation and polymer-solubilisation reactions, and for peptide and API processing.
4. Application areas in detail
4.1 Pharmaceutical extraction and API processing
DCM is a workhorse in API manufacturing and generic drug production: extraction of antibiotics, vitamins, steroids, hormones, alkaloids and natural active ingredients, crystallisation and purification of intermediates, and reaction media for API steps. Downstream users include finished-dose pharmaceutical plants, nutraceutical and veterinary drug manufacturers. Residual solvent limits follow ICH Q3C Class 2 (600 ppm), with validated drying and stripping steps.
4.2 Paint removers, coatings and inks
Because it penetrates and swells cured coatings, DCM is a core component of industrial paint strippers, graffiti removers and furniture refinishing products, and is used for ink removal and cleaning of coating equipment. Downstream formulations include brush-on and immersion strippers for alkyd, epoxy, polyurethane and nitrocellulose systems. Regulatory restrictions on consumer paint-stripper products apply in some regions, so industrial and professional formulations dominate.
4.3 Metal degreasing and precision cleaning
DCM dissolves cutting oils, stamping lubricants, greases and flux residues, and evaporates without leaving residue, making it suitable for vapour degreasing, cold cleaning and pre-weld preparation of metal parts. Typical downstream applications are automotive components, aerospace hardware, bearing and fastener cleaning, and electronics defluxing of printed circuit boards and connectors.
4.4 Auxiliary blowing agent for flexible polyurethane foam
In flexible slabstock and moulded foam, DCM acts as a physical auxiliary blowing agent together with water and the isocyanate/polyol system. It lowers foam density and softens the foam, and is used in mattresses, furniture cushions, automotive seating and packaging foam. Foam producers value its non-flammability and low boiling point, and control emissions by carbon adsorption or condensation recovery.
4.5 Film, adhesive and polymer processing
DCM is a solvent for cellulose acetate film and photographic film production, for membrane casting by phase inversion, and for adhesives and sealants that require fast drying. It is also used in polymer and resin processing where a non-flammable, fast-evaporating medium is required.
4.6 Natural extracts and decaffeination
In food-related processing, DCM has been used for decaffeination of coffee and tea and for hop, spice and oleoresin extraction. Because product residue is regulated, food-contact use requires validated residue control and compliance with local food law; many producers now use alternative solvents for these applications.
4.7 Other uses
Additional applications include aerosol formulations and propellant blends, adhesive and rubber cements, laboratory extraction and chromatography, and fumigation-type pest control products in some markets, all subject to local chemical control regulations.
5. Comparison with alternative solvents
| Solvent | Key difference vs DCM | Practical implication |
|---|---|---|
| Chloroform (CAS 67-66-3) | Higher toxicity, ICH Q3C limit 60 ppm | Restricted where DCM's 600 ppm limit is already tight; DCM is preferred for extraction |
| Perchloroethylene (CAS 127-18-4) | Higher boiling point, higher toxicity, dry-cleaning solvent | DCM evaporates faster and leaves less residue; PERC better for high-temperature degreasing |
| 1,1,1-Trichloroethane | Ozone-depleting | Phased out; DCM is a common replacement where non-flammability is required |
| n-Propyl bromide | Ozone-depleting, odour | Regulated; DCM remains the standard non-flammable cleaner |
| Acetone / ethyl acetate | Flammable, lower solvency for some resins | Cheaper and lower toxicity but require explosion-proof handling and often perform worse on cured coatings |
| NMP / DMF | High boiling point, reproductive toxicity | Difficult to recover and more tightly regulated; DCM is easier to strip and recover |
| Benzyl alcohol / ester-based strippers | Slower, water-rinsable, low volatility | Preferred for consumer and low-VOC products; slower action than DCM |
DCM advantages: strong and broad solvency, non-flammable, low boiling point for easy recovery, clean phase separation, low residue. Limitations: volatility and inhalation exposure, ICH Q3C Class 2 status, GHS carcinogenicity category 2 classification, and regional restrictions in consumer paint strippers.
6. Safety, storage and regulatory notes
DCM is a central nervous system depressant on inhalation; occupational exposure limits are typically set around 50 ppm (8-hour TWA), and closed handling with local exhaust ventilation is standard. Above roughly 120 °C in the presence of moisture, DCM can decompose to hydrogen chloride and trace phosgene, so contact with hot surfaces, flames and strong oxidisers must be avoided. Store in shaded, cool, well-ventilated areas with sealed drums; DCM slowly hydrolyses in the presence of water and light, so acidity and moisture should be monitored on long storage.
FAQ
Q1. Is dichloromethane flammable? No. DCM has no flash point under normal conditions and is used where flammable solvents cannot be tolerated, although its vapour is a narcotic and must be controlled by ventilation.
Q2. What is the ICH Q3C limit for dichloromethane? DCM is an ICH Q3C Class 2 residual solvent with a concentration limit of 600 ppm, which is normally met by drying, stripping or vacuum treatment of the final API.
Q3. What are the main uses of dichloromethane? Pharmaceutical extraction and reaction solvent, paint stripping, industrial degreasing, auxiliary blowing agent for flexible polyurethane foam, electronics and precision cleaning, film and adhesive formulations, and natural extract processing.
Q4. Why is DCM preferred over chloroform for extraction? It has a higher permitted residual limit (600 ppm vs 60 ppm), lower toxicity and a lower boiling point, so it is easier to remove from the product.
Q5. Can DCM be used for decaffeination? It has been used for coffee and tea decaffeination and for oleoresin extraction, but food-contact use must comply with local food regulations and validated residue limits.
Q6. How is DCM stored and handled? Store sealed in a cool, dry, shaded, well-ventilated area, away from strong oxidisers, flames and hot surfaces above about 120 °C. Use closed transfer, local exhaust ventilation, gloves and eye protection.
Q7. What is the HS code for dichloromethane? HS 2903.12; classification should be confirmed with the importing customs authority.
Q8. Is electronic grade DCM available? Yes. Electronic grade material with controlled water, acidity, non-volatile residue and trace metal content is available for precision cleaning applications.
Keywords: dichloromethane, DCM, methylene chloride, CAS 75-09-2, chlorinated solvent supplier, paint remover solvent, API extraction solvent, polyurethane foam blowing agent, metal degreasing solvent, ICH Q3C Class 2 residual solvent.