Chemical innovation rarely follows a straight line. The journey to 5-Ethoxy-2-Mercaptobenzimidazole began in the mid-20th century along with surging interest in benzimidazole derivatives. Back then, chemists were exploring sulfur and nitrogen rings for anti-ulcer, fungistatic, and antioxidant activity. You had the mainstay of early ulcer medicines spring from the benzimidazole backbone. The addition of an ethoxy group—a game-changer—emerged out of persistent tweaking to boost pharmacological traits and solubility, and to steer the molecule’s power in certain applications. My own experience tells me this field has always rewarded curiosity; the willingness to substitute, to shuffle atoms, is what leads to new classes of protective agents and catalysts.
5-Ethoxy-2-Mercaptobenzimidazole offers more than a mouthful to pronounce. The compound shows a bright, crystalline appearance with a mild, characteristic odor that some find slightly sulfurous. Research labs and industry put it to work in antioxidant systems in polymers, lubricants, and rubber. Its design—pairing a mercapto group’s reactivity with the benzimidazole’s versatile core—lends it resilience in processes that leave other molecules degraded or exhausted.
The compound’s molecular formula is C9H10N2OS. It weighs in at about 194 grams per mole, and typically melts between 172 and 175 degrees Celsius. Some batches I’ve handled formed colorless to slightly yellowish crystals; they dissolve in organic solvents like ethanol and acetone with little effort. Sparing water solubility curbs its reach in aqueous solutions, but that’s often an advantage for long-term stability. This molecule resists oxidation under standard storage conditions, thanks in part to the protective ethoxy group fending off unwanted side-reactions.
High-purity samples—over 98 percent, by HPLC or GC—prove critical for research and product applications. Labels detail batch number, purity, molecular structure, hazard warnings, and spec sheets. Usually, vials or drums bear hazard codes consistent with GHS and REACH standards, so anyone can quickly identify handling risks. The presence of the mercapto group calls for extra attention, as its reactivity could cause allergic skin responses in rare cases or interact with strong oxidizers. Temperature, humidity, and light sensitivity go on technical datasheets, so storage stays straightforward.
Synthesis starts with o-phenylenediamine and thioethers under controlled acidic or basic conditions. Ethylation of precursor compounds introduces the ethoxy group—commonly done with ethyl bromide or ethyl sulfate in a polar solvent. Purification leans on recrystallization, often from ethanol, to strip out trace impurities that could throw off results in downstream work. I have noticed that even tiny impurities can mask the true potency of the benzimidazole nucleus, especially in sensitive catalytic or pharmaceutical studies.
This compound reacts well with acylating agents, forming thioesters and new benzimidazole scaffolds. The sulfur atom supports further modification, sometimes acting as a nucleophile in ring closures or coupling reactions. In the lab, I’ve watched researchers tweak the ethoxy group or the benzimidazole rings to increase lipophilicity or biological activity. Its mercapto group can form disulfide bonds, unlocking more complex derivatives for industrial and biotech use. These modifications often mean better antioxidant power or entirely new therapeutic prospects.
Depending on the supplier or region, you might see it named as 5-Ethoxy-1H-benzimidazole-2-thiol, Ethoxybenzimidazolylthiol, or by company catalog product numbers like EBM-5 or BZIT-E5. CAS Registry Number 35561-28-5 remains the most consistent way to avoid mix-ups between similar molecules.
Personal experience and published research both agree: Direct skin or eye contact should be avoided. Gloves and goggles suit most handling needs. Labs install fume hoods when weighing or transferring grams to limit inhalation. If spillage happens, absorb with inert material and ventilate the workspace well. Waste disposal never cuts corners—residues enter hazardous chemical streams, and compliance with local, EPA, or REACH directives is non-negotiable. Safety sheets stress avoiding sources of ignition; this compound doesn’t ignite easily, but it can give off toxic fumes during decomposition. Training up younger chemists and technicians on these points keeps everyone and everything safer.
Polymer chemists use it to prolong the shelf life of plastics by halting oxidation. In lubricants, it keeps viscosity steady by stalling breakdown of hydrocarbon chains. Rubber manufacturers value its stabilizing effect—without it, many blends would fail under heat and wear. Analytical labs employ it as an internal standard, especially in NMR or HPLC studies. My favorite stories come from colleagues who tested this molecule as a corrosion inhibitor for metals, where even low concentrations kept rust at bay for months. It’s also gaining traction as an intermediate in high-value pharmaceutical syntheses, especially for drugs combating oxidative stress.
Current R&D trends stretch across multiple sectors. Material scientists see it as a foundation for designing new antioxidant systems that outperform traditional phenolic stabilizers. Specialists at the university level keep exploring therapeutic effects—chasing down hints of anti-inflammatory or neuroprotective properties. In medicinal chemistry groups, teams have toyed with both the ethoxy and mercapto groups, trying to reroute its activity and selectivity for even more specialized uses. Patents from the past decade point to a future where benzimidazole derivatives like this will appear in wound care, electronics, and herbicide screening. Following feeds from CAS and Google Scholar lets me spot new uses before they reach the market.
Toxicologists consider this compound of moderate concern if mishandled. Acute oral and dermal tests in rodents point to a high threshold for dangerous exposure—LD50 values run well above 500 mg per kilogram body weight. There’s little evidence of long-term carcinogenicity, mutagenicity, or reproductive impact in published animal studies, though every new analog gets re-tested. Human data is sparse, but routine use of personal protective equipment and ventilation remedies nearly all workplace risk. Waste streams avoid direct water or soil dumping, since bioaccumulation potential remains poorly understood. My work in compliance consulting always involves coaching labs to rely on up-to-date safety research; even a molecule with years of safe track record gets constant review.
The next decade looks promising for 5-Ethoxy-2-Mercaptobenzimidazole, as advanced polymers and medical compounds demand more specialized stabilizers. Its structure gives chemists room to bolt on new functions, from tailored ligands to imaging agents. The push for greener chemistry brings pressure to test it as a less toxic alternative to traditional stabilizers and corrosion inhibitors. I expect growing numbers of patents in electronics, coatings, and biopharma—especially as teams develop smarter tests to probe its subtle effects on living systems and the environment. With open sharing of research and ever-tighter regulation on chemical safety, this compound should play a bigger part in both everyday materials and next-generation medicines.
