Overview
Methylene Bromide (Dibromomethane) is a brominated derivative of methane, classified as a halogenated hydrocarbon. First synthesized in the 19th century, it gained industrial significance due to its unique solvent properties and role as a chemical intermediate. Its molecular structure—two bromine atoms attached to a single carbon—contributes to its high density and low flammability. While less common than its chlorine analogs, methylene bromide is valued in niche applications where heavier halogens are required. It is produced through bromination of methane or via haloform reactions. Industrial production typically yields ≥98% purity grades, with trace impurities carefully monitored for sensitive applications.
Physical and Chemical Properties
Methylene bromide is a dense (2.477 g/cm³), low-viscosity liquid with a sweet, chloroform-like odor. Its boiling point of 97°C makes it suitable for reactions requiring moderate heating. The compound's low vapor pressure (49 mmHg at 25°C) reduces evaporative losses during industrial use. Chemically, it exhibits typical halogenated alkane behavior—undergoing nucleophilic substitution reactions useful in synthetic chemistry. Unlike chlorinated analogs, its bromine atoms confer higher reactivity in SN2 reactions. It is thermally stable below 200°C but decomposes to release hydrogen bromide gas at higher temperatures, requiring corrosion-resistant equipment for high-temperature processes.
Main Applications
In industrial settings, methylene bromide serves three primary functions: as a specialty solvent for resins and waxes, as a flame retardant synergist in polymers, and as a building block in pharmaceutical synthesis. Its ability to dissolve polar and non-polar compounds makes it effective for extractions where other solvents fail. The agrochemical industry utilizes it as an intermediate in fungicide production, particularly for bromine-containing active ingredients. Emerging applications include its use as a heavy liquid for mineral separation and in NMR spectroscopy as a deuterated solvent (CD2Br2). However, environmental concerns have limited some historical uses in fumigation and refrigeration.
Safety and Storage
Classified as harmful (Xn) under EU regulations, methylene bromide requires strict handling protocols. Workplace exposure limits are typically set at 0.5-1 ppm (8-hour TWA). Engineering controls like fume hoods and closed systems are mandatory for industrial-scale operations. Storage demands amber glass or polyethylene-lined steel containers to prevent photodegradation. Incompatible with strong oxidizers and alkali metals, it must be segregated from these materials. Spill response requires non-sparking tools and adsorption with inert materials like vermiculite. Personal protective equipment (PPE) should include chemical goggles, bromine-resistant gloves, and respiratory protection for vapor concentrations above permissible limits.
B2B Procurement Guide
Industrial buyers should prioritize suppliers with ISO 9001 certification and batch-specific Certificates of Analysis (CoA). Key specifications to verify include bromine content (≥85% by weight), water content (<0.1%), and acid value (<0.01 meq/g). Bulk purchases (drum quantities or larger) typically offer 15-30% cost savings versus small-scale packaging. Just-in-time procurement is recommended due to shelf-life considerations—product should be used within 12 months of manufacture. Transportation requires UN/NA 3082 classification (PG III) for hazardous materials. Consider regional regulations like REACH or TSCA compliance when sourcing internationally.
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