Methylene Chloride, Methylene Dichloride, Dichloromethane, Methane Dichloride, DCM, 75-09-2

Methylene Chloride, Methylene Dichloride, Dichloromethane, Methane Dichloride, DCM, 75-09-2

METHYLENE CHLORIDE (DICHLOROMETHANE)

Methylene Chloride / Methylene Dichloride / Dichloromethane / DCM
CAS Number: 75-09-2
EC Number: 200-838-9

1. IDENTIFICATION INFORMATION

2. PHYSICAL PROPERTIES

3. CHEMICAL PROPERTIES

Thermal Decomposition Reaction (above 120°C):

2 CH₂Cl₂ + O₂  —[Heat]—> 2 COCl₂ (Phosgene) + 2 HCl (Hydrogen chloride)

Light-Induced Decomposition Reaction:

CH₂Cl₂ + hν → HCl + CHCl₃ → Phosgene (COCl₂)

Production Reaction (Methyl Chloride Chlorination):

CH₃OH + HCl → CH₃Cl (Methyl Chloride) + H₂O
CH₃Cl + Cl₂ → CH₂Cl₂ (Dichloromethane) + HCl

4. PRODUCTION METHODS

Reaction Steps:

Step 1 (Methyl Chloride Production):

CH₃OH + HCl → CH₃Cl + H₂O

Step 2 (Chlorination):

CH₃Cl + Cl₂ —[UV/Heat]—> CH₂Cl₂ + HCl
CH₂Cl₂ + Cl₂ —[UV/Heat]—> CHCl₃ (Chloroform) + HCl
CHCl₃ + Cl₂ —[UV/Heat]—> CCl₄ (Carbon Tetrachloride) + HCl

Process Note: The ratio of different chlorinated methane derivatives is controlled by reaction conditions (chlorine to methane ratio, temperature, UV intensity). The desired product is separated by distillation.

5. AVAILABLE FORMS AND SPECIFICATIONS

Typical Specifications (Technical Grade):

6. APPLICATIONS

6.1. Paint Strippers – Largest Use

6.2. Chemical Industry

6.3. Pharmaceutical Industry

6.4. Food Industry (Limited Use)

Note: Food applications are increasingly being replaced by alternatives such as supercritical CO₂.

6.5. Metal Industry

6.6. Rubber Industry

6.7. Aerosol and Adhesives

6.8. Electronics Industry

6.9. Polymer and Plastics Industry

6.10. Laboratory Applications

6.11. Other Applications

7. PHYSICAL PROPERTIES RELATION TO APPLICATIONS

8. SAFETY AND HEALTH INFORMATION (GHS CLASSIFICATION)

Note: Methylene chloride is classified as a Category 1B carcinogen in recent classifications (EC 1272/2008), associated with pharynx and liver cancer.

9. HAZARD STATEMENTS (H-CODES)

10. SAFETY STATEMENTS (P-CODES)

11. EXPOSURE LIMITS

Note: Exposure limits vary significantly between different agencies. The lowest (most protective) limits should be followed (especially NIOSH REL 25 ppm due to carcinogenicity concerns).

12. TOXICOLOGICAL INFORMATION

Health Effects:

Metabolism Note: Methylene chloride is metabolized in the body to carbon monoxide (CO), which elevates carboxyhemoglobin (COHb) levels. This reduces tissue oxygen delivery and creates cardiovascular stress. Smokers, individuals with heart disease, and those with anemia are at higher risk.

13. FIRST AID MEASURES

14. FIRE FIGHTING MEASURES

15. ENVIRONMENTAL INFORMATION

16. STORAGE AND HANDLING

Handling Notes:

• Use only in well-ventilated areas or under fume hood

• Avoid breathing vapors

• Avoid eye and skin contact

• Do not use aluminum, magnesium, zinc, or beryllium containers (reaction)

• Light exposure may cause decomposition (use stabilized grade)

• Collect spills immediately with absorbent material

• Keep away from heat and ignition sources

• Recycle used solvent or dispose at licensed waste facilities

17. TRANSPORT INFORMATION

18. REGULATORY INFORMATION

Ozone Layer: Montreal Protocol Class II ozone depleter (being phased out in developed countries)

VOC Status: Volatile Organic Compound (VOC) - subject to air quality regulations

EU Restrictions: Restricted in aerosols, paint strippers, and certain consumer products

FDA Status: Approved for specific food applications (caffeine decaffeination - restricted)

19. OTHER NAMES AND SYNONYMS

Database Identifiers:

20. SUMMARY AND IMPORTANT WARNINGS

SUMMARY:

Methylene chloride (dichloromethane, CH₂Cl₂, CAS 75-09-2) is a colorless, volatile liquid with a sweetish, ether-like odor. It has a molecular weight of 84.93 g/mol, boiling point of 40°C, and density of 1.33 g/cm³. It has water solubility of 17.5 g/L at 25°C and is completely miscible with ethanol, ether, and dimethylformamide. It is not flammable under normal conditions but produces toxic chloride fumes at high temperatures. It is produced industrially from methanol and hydrogen chloride via methyl chloride, followed by chlorination; by-products include chloroform and carbon tetrachloride. Major applications include paint strippers, chemical industry (solvent), pharmaceutical (extraction and crystallization solvent), food (caffeine decaffeination - restricted), metal cleaning, rubber industry, aerosol products, adhesives, electronics (PCB manufacturing), polymer processing, and laboratory applications. Methylene chloride is classified as IARC Group 2A (probably carcinogenic to humans) and is associated with pharynx and liver cancer.

Key Properties:

Main Application Areas:

Key Safety Points:

• CARCINOGEN: May cause cancer - pharynx and liver (H350, IARC Group 2A, NTP Category 2)

• TOXIC: May be fatal if swallowed and enters airways (H304)

• IRRITANT: Causes skin and eye irritation (H315, H319)

• CNS EFFECTS: May cause drowsiness and dizziness (H336)

• LIVER DAMAGE: Causes liver damage through prolonged exposure (H372)

• CO METABOLISM: Metabolizes to carbon monoxide in the body (forms carboxyhemoglobin)

• SPECIAL RISKS: Smokers, heart disease patients, anemia patients at higher risk

• USE PPE: Chemical goggles, face shield, chemically resistant gloves (nitrile, Viton, Teflon - neoprene or butyl not recommended), protective clothing, appropriate respiratory protection

• VENTILATION: Use in fume hood or well-ventilated area; air monitoring required in enclosed spaces

• STORAGE: Cool, well-ventilated area, protected from light, stabilized grade, avoid aluminum or magnesium containers

• INCOMPATIBLES: Strong oxidizing agents, alkali metals, aluminum, magnesium

IMPORTANT WARNINGS:

Cancer Risk (Carcinogenicity): Methylene chloride is classified as IARC Group 2A (probably carcinogenic to humans) and NTP Category 2. Epidemiological studies have shown increased incidence of pharynx and liver cancer. Avoid prolonged or repeated exposure. Use less toxic alternatives where possible. Use engineering controls (ventilation, closed systems) to keep exposure levels as low as reasonably achievable.

CO Metabolism (Carboxyhemoglobin Formation): When methylene chloride is metabolized in the body, it is converted to carbon monoxide (CO). CO binds to hemoglobin more strongly than oxygen, forming carboxyhemoglobin (COHb), which reduces tissue oxygen delivery. This creates stress on the cardiovascular system. Smokers, individuals with heart disease, anemia, or lung disease are at higher risk. COHb levels can remain elevated for 8-12 hours after exposure. Symptoms after exposure include headache, dizziness, nausea, fatigue, and confusion. At high concentrations, respiratory arrest and death can occur.

Aspiration Hazard (H304): Methylene chloride has low viscosity and high volatility. If swallowed, it can be aspirated into the lungs (enters airways) and cause chemical pneumonitis. Do NOT induce vomiting (vomiting increases aspiration risk). In case of ingestion, keep the airway open and seek immediate medical attention.

Carbon Monoxide Poisoning Symptoms:

• Headache, dizziness

• Nausea, vomiting

• Fatigue, weakness

• Confusion, drowsiness

• At high concentrations: Loss of consciousness, respiratory arrest, death

Post-Exposure COHb Levels:

• Normal: <1% (non-smoker), <5-10% (smoker)

• Mild poisoning: 10-20%

• Moderate poisoning: 20-30%

• Severe poisoning: 30-50%

• Fatal: >50-60%

Stabilization: Pure methylene chloride slowly decomposes when exposed to light, forming phosgene (COCl₂) and hydrogen chloride (HCl). Commercial grades are typically stabilized with 20-50 ppm amylene, ethanol, or cyclohexene. Do not use unstabilized methylene chloride. Old or opened containers without stabilizer may contain hazardous decomposition products.

Incompatible Materials: Methylene chloride reacts with certain metals including aluminum, magnesium, zinc, beryllium, and lithium. Contact with these metals can generate hydrogen gas and potential fire/explosion risk. Use stainless steel, glass, or compatible plastic containers. Avoid aluminum or magnesium piping, storage tanks, or equipment.

Flammability Considerations: Methylene chloride is not flammable under normal conditions. However, at high temperatures (above 120°C) it decomposes to produce toxic and corrosive gases (phosgene, HCl, Cl₂). The explosive limits (12-19% V) are relatively narrow and require high concentrations. However, in a fire situation (e.g., surrounding fire), methylene chloride containers may reach these temperatures and release toxic fumes. Firefighters should wear SCBA and full protective clothing.

VOC and Ozone Layer: Methylene chloride is classified as a Volatile Organic Compound (VOC) and is subject to air quality regulations. It is also listed as a Class II ozone depleter under the Montreal Protocol. In developed countries, methylene chloride use is being phased out, and alternatives exist for many applications.

Regulatory Status: Methylene chloride is increasingly regulated worldwide. In the EU, its use is restricted in many consumer and industrial applications including paint strippers (consumer use banned), aerosols, and certain cleaning applications. It is classified as Category 1B carcinogen (H350). In the US, it is regulated by EPA and OSHA; its use in consumer paint strippers is banned, and strict exposure limits and management requirements exist for industrial use.

Personal Protective Equipment (PPE) Selection:

• Gloves: Nitrile (butyl or neoprene not recommended - methylene chloride penetrates), Viton, Teflon. Gloves should be changed regularly.

• Respiratory Protection: Depending on concentration: Half-mask or full-face respirator with organic vapor cartridges. For high concentrations or confined spaces, SCBA (Self-Contained Breathing Apparatus) is required.

• Eye/Face Protection: Chemical safety goggles used with full-face shield.

• Body Protection: Chemically resistant apron (Viton, Teflon, Saranex).

Alternatives: Where possible, consider using the following alternatives instead of methylene chloride:

• For paint strippers: N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), benzyl alcohol-based strippers

• For extraction: Ethyl acetate, hexane, supercritical CO₂

• For decaffeination: Supercritical CO₂, ethyl acetate

• For cleaning: Water-based cleaners, less toxic organic solvents

Spill Response:

1. Evacuate area and provide adequate ventilation

2. Eliminate all ignition sources

3. Wear appropriate PPE (SCBA, chemically resistant suit, nitrile/Viton gloves)

4. Contain spill with inert absorbent material (sand, vermiculite, diatomaceous earth)

5. Collect absorbent and place in properly labeled hazardous waste container

6. Wash area with water (if local regulations permit)

7. Prevent entry into sewers or waterways

8. Contact licensed hazardous waste hauler for disposal

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS) provided by the manufacturer/supplier. Methylene chloride (dichloromethane) is a suspected carcinogen and is metabolized to carbon monoxide in the body. Use appropriate engineering controls, personal protective equipment, and work practices to minimize exposure. Use in well-ventilated areas. Avoid breathing vapors. Do not store in aluminum or magnesium containers. Protect from light (use stabilized grade). Do not eat, drink, or smoke when using this product. Seek immediate medical attention in case of exposure. This document summarizes information from various sources and is not a substitute for technical expertise or site-specific safety assessments.