Dichloromethane
[CAS# 75-09-2]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Hydrocarbon halide
• Name: Dichloromethane
• Synonyms: Methylene dichloride
• Molecular Formula: CH₂Cl₂
• Molecular Weight: 84.93
• CAS Registry Number: 75-09-2
• EC Number: 200-838-9
• SMILES: C(Cl)Cl

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*, 1.325 g/mL (Expl.)
• Melting point: -97 °C (Expl.)
• Boiling point: 39.6 °C 760 mmHg (Calc.)^*, 39.8 - 40 °C (Expl.)
• Flash point: -14.1±22.4 °C (Calc.)^*, 230 °C (Expl.)
• Solubility: 2.0 g/100g (20 °C) (Expl.)
• Index of refraction: 1.398 (Calc.)^*, 1.424 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS08 Warning
• Risk Statements: H351
• Safety Statements: P203-P280-P318-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Carcinogenicity	Carc.	2	H351
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute toxicity	Acute Tox.	4	H302
Germ cell mutagenicity	Muta.	2	H341
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Specific target organ toxicity - single exposure	STOT SE	3	H335
Carcinogenicity	Carc.	2	H350
Specific target organ toxicity - single exposure	STOT SE	1	H370
Oxidising liquids	Ox. Liq.	1	H271
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Acute hazardous to the aquatic environment	Aquatic Acute	2	H401
Organic peroxides	Org. Perox.	A	H240
Explosives	Expl.	1.1	H200
Pyrophoric solids	Pyr. Sol.	1	H250
Acute toxicity	Acute Tox.	1	H330
Oxidising solids	Ox. Sol.	1	H271
Flammable solids	Flam. Sol.	1	H228
Flammable liquids	Flam. Liq.	1	H224
Reproductive toxicity	Lact.	-	H362Aerosols
Substances or mixtures which in contact with water emit flammable gases	Water-react.	1	H260
Self-reactive substances or mixtures	Self-react.	A	H241
Aspiration hazard	Asp. Tox.	1	H304
Pyrophoric liquids	Pyr. Liq.	1	H250
Acute toxicity	Acute Tox.	1	H310
Oxidising gases	Ox. Gas	1	H270
Respiratory sensitization	Resp. Sens.	1	H334
Eye irritation	Eye Irrit.	2B	H320
Flammable gases	Flam. Gas	1	H220
Skin sensitization	Skin Sens.	1	H317
Skin corrosion	Skin Corr.	1A	H314
Reproductive toxicity	Repr.	1A	H360
Self-heating substances or mixtures	Self-heat.	1	H251
Acute toxicity	Acute Tox.	1	H300
Gases under pressure (compressed)	Press. Gas (Comp.)		H280
Serious eye damage	Eye Dam.	1	H318
Germ cell mutagenicity	Muta.	1A	H340

• Transport Information: UN 1593; UN 1912

Discovery and Applications

Dichloromethane, also known as methylene chloride, is a colorless, volatile liquid with the chemical formula CH₂Cl₂. It has a sweet, chloroform-like odor and is moderately soluble in water but miscible with many organic solvents. Dichloromethane is a chlorinated hydrocarbon widely used as an industrial solvent due to its excellent ability to dissolve a broad range of organic compounds.

The compound was first synthesized in the early 19th century by the reaction of chlorinated methane derivatives with hydrochloric acid. Industrially, dichloromethane is produced mainly by the chlorination of methane or chloromethane under controlled conditions. Its production involves free radical substitution reactions, resulting in a mixture of chlorinated methanes, which are separated by distillation.

Dichloromethane is extensively employed as a solvent in numerous applications including paint stripping, degreasing metals, pharmaceutical manufacturing, and in the production of films and adhesives. Its relatively low boiling point (around 40 °C) allows easy removal by evaporation after the dissolution process. In the laboratory, dichloromethane is valued as an extraction solvent due to its density, which is higher than water, allowing efficient phase separation.

In the pharmaceutical industry, dichloromethane is used as a reaction medium and solvent for extraction and purification of compounds. It plays a crucial role in the synthesis of various active pharmaceutical ingredients. In addition, dichloromethane is applied in the food industry for decaffeination of coffee and tea, although its use in food processing is strictly regulated due to toxicity concerns.

Dichloromethane’s volatility and potential health effects require careful handling. It is classified as a probable human carcinogen and can cause irritation to the skin, eyes, and respiratory tract. Prolonged exposure or high concentrations can affect the central nervous system, leading to symptoms such as dizziness, headache, and nausea. Therefore, industrial and laboratory use must include adequate ventilation, protective equipment, and exposure monitoring.

Environmental considerations are also significant for dichloromethane. Although it does not deplete the ozone layer like some other chlorinated solvents, it contributes to air pollution and may persist in aquatic environments. Its disposal and emissions are regulated in many countries to minimize environmental impact.

Overall, dichloromethane remains an important solvent in industrial chemistry and scientific research. Its combination of solvent power, volatility, and chemical stability supports a wide range of processes, while safety and environmental controls continue to be critical in its application.

References

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DOI: 10.1002/tcm.1770100206

1979. Residues of mancozeb and ethylenethiourea in grain samples. Bulletin of Environmental Contamination and Toxicology, 23(6).
DOI: 10.1007/bf02026973

1979. Use of XAD-2 macroreticular resin for the recovery of ambient trace levels of pesticides and industrial organic pollutants from water. Bulletin of Environmental Contamination and Toxicology, 23(6).
DOI: 10.1007/bf02026987