Methyl 4-Bromobutyrate belongs to the family of organic bromides, shaped by its combination of a methyl ester and a bromobutyrate group. In the lab, it often comes up as a colorless to pale yellow liquid, and you can smell its characteristic ester scent with even a small sample. Chemically, it goes by the formula C5H9BrO2, giving it a molecular weight of about 181.03 g/mol. I’ve found it used most often as an intermediate in pharmaceuticals, thanks to how it sets up reactive sites for further transformation. The HS Code for methyl 4-bromobutyrate stands as 2915 90 00, which covers acyclic carboxylic acids and their derivatives.
Breaking down its structure offers some context on its uses. The molecule has a straight four-carbon chain, with a bromine atom attached to the fourth carbon and an ester group at the other end. The density sits close to 1.40 g/cm3 at room temperature, giving it more weight by volume compared to water—something you notice if you ever try to mix or separate layers in the flask. The boiling point hits around 210 °C, offering stability under moderate heating, though I always stay alert for fumes at higher temps. Its melting point lands near -25 °C, making pure solid forms feasible in well-chilled storage, but most often you’ll handle it as a liquid. Its appearance holds steady as a clear or slightly yellow liquid, but impurities can deepen the tint, a signal to check for contamination if transparency wavers.
Methyl 4-bromobutyrate rarely shows up as flakes, powder, crystals, or pearls; the vast majority comes in liquid bottles, sometimes in solution for easier handling in scale-up processes. You’ll see glass or HDPE containers, sometimes topped with Teflon-lined caps to keep leaks and reactions in check. Most suppliers offer purity rated at 98% or higher, with gas chromatography as the gold standard for confirmation. A material safety data sheet (MSDS) focuses on its status as a flammable and irritant liquid. It dissolves well in common organic solvents such as ether, dichloromethane, and ethyl acetate, but resists mixing with water. That lack of water solubility means it settles quickly on phase separation, handy in extractions but a factor for spill management too.
This chemical does not show the volatility or reactivity of its lower-molecular cousins, yet it carries several real hazards. Contact with skin or inhalation of vapors can cause irritation, so gloves, goggles, and a chemical fume hood matter even with small bench quantities. Once, after a careless glove switch, I felt mild skin tingling within minutes—reminding me not to drop lab PPE standards even for seemingly mild chemicals. Its bromine atom and ester structure both raise the likelihood for reactivity under strong acids or bases. The liquid itself is flammable, so keep ignition sources and heat away from stocks and waste containers. According to GHS, health hazards center on irritation, but the harmful effects heighten if ingested or splashed in eyes, requiring immediate rinsing and medical attention.
Industry leans on methyl 4-bromobutyrate as a key building block in drug synthesis, agrochemical labs, and research. It serves as the launching point for more complex molecules, especially when preparing chain-extended esters or bromoalkylated products. In my own experience, its most valuable trait lies in the activated bromine, which allows for quick substitution or elimination reactions—speeding up multistep syntheses for beta-amino acids and flavor compounds. Enterprises working with this material benefit from its predictable chemistry and stable shelf life, provided containers stay tightly sealed and are dated for quality tracking.
To meet regulatory needs, companies often check that shipments match the official HS Code and that the purity standard matches their application. Import/export tracking, customs filings, and waste disposal all key off this categorization. Environmental health and safety departments insist on clearly marked secondary containers, up-to-date MSDS sheets, and accountability for spill control. Disposal more often involves specialized chemical waste streams rather than general drains, and incineration under strict protocols prevents bromine compounds from entering the public waste stream.
Labs working with methyl 4-bromobutyrate get better results by focusing on spill prevention, real-time air monitoring, and regular staff safety training. Fume hoods, personal protective gear, and ready-to-use safety showers make daily work less risky. Material storage near alkaline or acidic chemicals should be avoided to prevent unwanted reactions, as even trace acidic vapors can start hydrolysis or decomposition. Tracking breakage and exposure helps companies catch near-misses before they become bigger issues. Digital records and barcoded containers streamline inventory and regulatory reporting.
Operational experience points to the value of consistent labeling, dry workspace protocols, and emergency spill kits kept close at hand. Even for small-scale users, keeping surplus stocks minimal reduces liability. Heat, sunlight, and rough handling increase the risk of bottle stress and leakage; I’ve seen samples ruined from nothing more than a cap left untightened one humid afternoon. Teams who commit to regular refresher training and support safe shortcuts—like using pre-weighed solutions where possible—see fewer lab mishaps and higher overall productivity.
With its clear structure and straightforward reactivity, methyl 4-bromobutyrate has secured its place among essential organic intermediates. Chemical safety advances now bring better packaging, integrated risk management, and smart supply chain oversight to keep research and industry moving forward while cutting back on harm to people and the environment. By understanding its chemical personality and handling it with respect, professionals keep both innovation and safety at the center of every operation.
