4-Chlorobutyric acid is an organic compound defined by its straightforward molecular structure, a four-carbon chain terminated by a carboxylic acid group with a chlorine atom fixed at the fourth position. This compound holds practical significance across a range of chemical industries. Built on a formula of C4H7ClO2, it weighs about 122.55 g/mol. On the shelf or in the laboratory, this acid often shows up as a clear, colorless to faintly yellow liquid, although certain storage methods or temperature changes can make it appear as a crystalline solid or in flakes. Its versatility as a building block in chemical synthesis springs from both this accessible structure and its manageable set of physical properties.
A closer look at the molecular layout of 4-chlorobutyric acid shows a backbone derived from butyric acid, but with a chlorine replacing a hydrogen atom at the terminal end. This chlorinated tail adds a reactive site, opening doors to esterification, amidation, and other transformations. The added polarity and altered electronic distribution from chlorine affect solubility and boiling point, two factors that chemists rely on for separation or downstream reactions. The structure also explains why this acid resists rapid degradation and stands up to standard storage conditions, as both a solid and as a solution.
Physical examination yields key markers for identification and handling: the density of 4-chlorobutyric acid hovers around 1.17 g/mL at 25°C. Expect a boiling point in the 220–225°C range, making it stable through a range of heating cycles, whether distilled, converted, or blended into other compounds. In practice, its melting point rests between 35°C and 38°C, which explains why storage at lower ambient temperatures brings out flakes, powder, or crystals instead of fluid. The strong, pungent odor stands out, a reminder to keep workspaces well ventilated.
Those using 4-chlorobutyric acid as a raw material soon learn the need for sturdy gloves and goggles. Skin contact causes irritation, and inhaling the vapors brings discomfort. Strict chemical plant protocols treat it as a hazardous substance due to both its corrosive nature and potential to harm internal organs after repeated exposure. Even a brief spill on stainless steel workstations prompts prompt cleaning. The acid dissolves readily in ethanol and is miscible with water to a limited extent, but the reactive chlorine atom means storerooms must avoid strong bases, oxidizers, or incompatible organic materials. A Material Safety Data Sheet (MSDS) highlights these points, making explicit the need for good hygiene and careful storage in tightly sealed drums away from sunlight and moisture.
Practical experience with 4-chlorobutyric acid teaches that its function as a raw material stretches far. It enters into chains of synthesis leading to pharmaceuticals and agrochemicals. The acid serves as a reliable intermediate for the creation of crop protection agents, plant growth regulators, and specialty organic compounds. In research labs, it provides a solid path to ketones, esters, and amides by simple, reproducible routes. It even finds a spot in production lines where strong acids must stay pure and consistent, as purity levels and batch-to-batch reproducibility remain essential.
In the global market, shipments of 4-chlorobutyric acid move under the HS Code 2915.90, designed for carboxylic acids with additional substituted groups and derivatives. Its classification as a hazardous good brings extra labeling requirements, making logistics more complicated but also ensuring proper tracking and response protocols. Drums and containers seal the contents against leaks and vapor escape. Anyone involved in the supply chain must follow regulations not just for worker safety, but for community health, as accidental releases would put local populations and groundwater at risk.
Being a chlorinated compound, 4-chlorobutyric acid brings up discussions about persistence in the environment. Once spilled or improperly disposed of, it resists quick breakdown, causing headaches for site managers and environmental health teams alike. Spills at manufacturing sites over years have prompted regulatory updates aimed at both waste minimization and emergency remediation. Chemical exposure can stress wildlife and aquatic systems. Researchers argue for stronger closed-loop manufacturing and improved neutralization processes.
4-Chlorobutyric acid stands as a foundation for a range of products found in daily life, from agricultural agents to specialty chemicals. Yet its hazards, persistence, and regulatory strictness demand more than routine attention. Companies leaning on this acid in their operations benefit from investing in up-to-date safety training, well-maintained protective equipment, and robust chemical containment systems. On the broader front, ongoing research seeks substitute routes—possibly using greener haloacids or biocatalytic processes—that deliver needed reactivity with lower health risks. As industry standards rise and oversight grows stronger, every stakeholder—from lab technician to logistics handler—has a shared role in building a safer, more sustainable chemical future.
