|Name ||Methylene chloride |
|Chemical formula ||CH2Cl2 |
|Appearance ||Colorless liquid |
|Molecular weight ||80.9 amu |
|Melting point ||176 K (-97 °C) |
|Boiling point ||313 K (40 °C) |
|Density ||1.32 ×103 kg/m3 (liquid) |
|Solubility ||slightly soluble in water |
|ΔfH0gas ||? kJ/mol |
|ΔfH0liquid ||? kJ/mol |
|ΔfH0solid ||? kJ/mol |
|S0gas, 1 bar ||? J/mol·K |
|S0liquid, 1 bar ||? J/mol·K |
|S0solid ||? J/mol·K |
|Ingestion ||Causes nausea and vomiting, with possible headache, dizziness, or unconsciousness. |
|Inhalation ||In high concentration, may cause dizziness, unconsciousness, coma, and possible respiratory failure. May cause delayed inflammation of the lungs. |
|Skin ||Prolonged or chronic exposure may cause irritation or burns. |
|Eyes ||Strongly irritating, producing tearing and burning sensations. |
|More info ||Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/7/6399.html) |
SI units were used where possible. Unless otherwise stated, standard conditions were used.
Disclaimer and references
Dichloromethane or Methylene chloride is a chemical compound widely used as a solvent for organic materials. It is a colorless, volatile liquid with a strong, sweet, vaguely pleasant aroma.
Methylene chloride was first prepared in 1840 by the French chemist Henri Victor Regnault, who isolated it from a mixture of chloromethane and chlorine that had been exposed to sunlight.
Industrially, methylene chloride is produced by reacting either methyl chloride or methane with chlorine gas at 400-500°C. At these temperatures, both methane and methyl chloride undergo a series of reactions producing progressively more chlorinated products.
- CH4 + Cl2 → CH3Cl + HCl
- CH3Cl + Cl2 → CH2Cl2 + HCl
- CH2Cl2 +Cl2 → CHCl3 + HCl
- CHCl3 + Cl2 → CCl4 + HCl
The output of these processes is a mixture of methyl chloride, methylene choride, chloroform, and carbon tetrachloride. These compounds are then separated by distillation.
Methylene chloride's volatility and ability to dissolve a wide range of organic compounds makes it an ideal solvent for many chemical processes. It is mainly used as a paint stripper and a degreaser. In the food industry, it is used to decaffeinate coffee and to prepare extracts of hops and other flavorings. Its volatility has led to its use as an aerosol propellant and as a blowing agent for polyurethane foams. It is also used as a fumigant pesticide for stored strawberries and grains. However, concerns about its health effects have led to a search for alternatives to it in many of these applications.
It is also used in Christmas lights called bubble lights, in a sealed vial which bubbles when the incandescent light bulb below it is lit.
Methylene chloride is the least toxic of the simple chlorohydrocarbons, but it is not without its health risks. Chronic exposure to methylene chloride has been linked to cancer of the lungs, liver, and pancreas in laboratory animals. It is a mutagen and may cause birth defects if women are exposed to it during pregnancy. Prolonged skin contact can result in the methylene chloride dissolving some of the fatty tissues in skin, resulting in skin irritation or chemical burns.
In many countries, products containing methylene chloride must carry labels warning of its health risks. However, it is often mistaken for paint thinner which can be applied freely to the skin.