C-Acid (Clt Acid), known in chemical circles as 2-Amino 5-Chloro Toluene Sulfonic Acid or 2-Amino 4 Methyl 5-Chloro Benzene Sulfonic Acid, is a key raw material in the manufacture of dyes and pharmaceuticals. In the laboratory, it turns up in solid, powdered, flaked, or crystal form, with a distinctive aromatic structure recognizable by an attached chlorine, a methyl group, and a sulfonic acid function. The raw material composition points directly to the aromatic ring's backbone, shaped by its methyl, amino, and sulfonic acid side groups. The molecular formula C7H8ClNO3S underlines the complexity and utility of this compound. Chemists and dye manufacturers handle this material for its reactivity and solubility, which depend heavily on its form—powder, crystalline solid, or solution. For logistics, the HS Code marks this substance most often under 290410, facilitating its identification and regulation across borders.
C-Acid appears as an off-white to light tan substance, which varies in density and granularity depending on how it is processed—flakes handle differently compared to free-flowing powder or chunky crystals. The density lands around 1.5–1.7 g/cm3, making it heavier in the hand than many organic powders. The melting point sits typically above 200°C, a feature that supports its use in high-temperature chemical processes without risk of decomposition during early steps. Solubility shows itself most prominently in water, giving a clear solution that stands up to quick filtration and accurate measurement in industrial tanks. With a chemical structure centered on a benzene ring decorated by an amino group at the 2-position, chlorine at the 5-position, methyl at the 4-position, and sulfonic acid at the 1-position, each functional group sets the stage for targeted reactions. This architecture is not only fascinating to organic chemists but essential to the unique reactivity profile required in sulfonation and azo dye formation.
C-Acid comes up repeatedly in synthetic dye work, contributing as a raw material in azo dye and direct dye manufacture. The compound’s sulfonic acid group grants water solubility and helps dyes anchor to fibers in textile manufacture. Its amino group, on the other hand, enters into diazotization and coupling steps, broadening the range of colors that result in finished textiles. In pharmaceuticals, C-Acid appears less frequently but its presence as an intermediate opens routes to specialized sulfa drugs and antiseptics. I’ve stood on the production floor, watching skilled hands blend flakes of C-Acid for a dye batch, understanding firsthand how the grain size and purity change handling and even final product color intensity. Whether the material rolls in as powder, pearl, or solid, end users want consistency, which ties back to defined specifications covering purity, grain shape, and moisture level.
Industry customers ask for assays of at least 95% purity, with low limits on moisture—often below 1%—so that the material does not clump or dissolve before use. The specific gravity and appearance do more than fill out paperwork; they guide best storage practices and inform the design of mixing and conveying systems in large plants. Handling equipment set for flakes can’t always run fine powder without clogging, and some applications even demand the raw material shipped in sealed bags or drums to keep it bone dry. In terms of safety, the sulfonic acid group brings some concern when dust is generated: inhalation can irritate the respiratory system, and direct skin contact sometimes causes rash or sensitivity. From my experience, staff always don gloves, long sleeves, and, if powder is flying, proper face masks—good habits built up from seeing what happens when short-cuts get taken. While the chemical does not carry the hazards of more aggressive industrial acids, regulatory labels call for careful respect in storage, handling, and disposal, particularly in operations using hot, caustic, or acidic conditions.
Working with C-Acid on a daily basis sharpens awareness of risk. Though not classified as highly hazardous, the chemical ought to be treated with more caution than everyday materials due to the presence of its sulfonic acid and chloroarene structure. Chronic exposure to dust during large-scale transfers can provoke allergic reactions or even bronchial irritation across a workforce, which can drive up absenteeism and affect morale. Spills in powder or crystal form track easily around a plant, which calls for prompt cleaning and regular air sampling. On the environmental front, effluents from dye and pharmaceutical manufacture sometimes leave traces of C-Acid or its byproducts in wastewater, making strong water treatment systems a must. Installing modern filtration and neutralization units counters the worst effects, keeping these strong sulfonic compounds out of local rivers. I have seen customers get shut down temporarily due to lapses, proving that keeping ahead of regulations and reinforcing a culture of responsibility not only prevents fines but shows real care for worker and community health.
Supply chains for specialty chemicals such as C-Acid now face more scrutiny than ever. Producers ask not only about price and delivery but about the sustainability of raw inputs and the working conditions in the manufacturing plants. As European and North American regulations tighten, Indian and Chinese suppliers supplying most global C-Acid need to adjust, moving from open-air, small-batch production to closed reactor systems with better environmental controls. Solutions rest on partnerships—buyers and sellers who lay out expectations up front, back them with testing and audits, and commit to transparent reporting. My experience says making the entire chain safer and cleaner attracts more stable business and fewer compliance headaches over time. On the technical front, research continues on improved C-Acid blends and derivatives that retain dyeing performance while being less hazardous, pointing to a shift where chemistry innovation and safety will both guide growth.
