Acrylonitrile (AN): Structure, Properties, and Safety

What is Acrylonitrile?

Acrylonitrile, with the chemical formula C₃H₃N, shows up in many manufacturing processes, and most folks come across it without even knowing. This material doesn’t just contribute to plastic production—it shapes a lot of what we bump into every day. Whether it’s molded into automotive parts, spun into fibers for clothing, or found in building insulation, this chemical quietly drives a wide swath of the modern world. Its molecular structure packs a double bond between carbon atoms and a nitrile group, making it reactive enough to build sturdy polymers and do a lot of heavy lifting.

Chemical Properties and Physical Forms

At room temperature, acrylonitrile presents as a clear, colorless liquid. Dip into its physical profile, and you’ll spot a sharp, slightly sweet odor—hard to ignore when you’re up close. It clocks in with a molecular weight of about 53.06 grams per mole and sits at a density near 0.806 grams per cubic centimeter at 20°C. The boiling point hovers around 77°C, which gives some flexibility for handling and shipping as a liquid, unlike more volatile stuff like benzene. Folks in chemistry labs or large-scale manufacturing usually see it bottled in liquid form, but under the right temperatures it can show up as a vapor or, less commonly, as a frozen solid. No matter its state, it mixes quite well with water, alcohol, and ether—flexibility matched only by its reactivity. You won’t find it in household powders, crystals, or flakes; industry prefers the liquid for its ease in polymer and copolymer production.

Manufacturing and Raw Materials

Acrylonitrile roots itself to petrochemical raw materials. Factories churn it out through the ammoxidation of propylene, a process hitching ammonia and oxygen to propylene over a catalyst. This approach produces efficient yields but always brings up concerns around sourcing and sustainability, since everything starts with fossil fuel feedstocks. The HS Code for acrylonitrile, important for logistics and customs, checks in at 29261000, mapping out tight international guidelines for safe passage and regulation. What always struck me while visiting chemical plants is how the same raw material—propylene—starts out as a simple gas and ends up in synthetic rubber, plastics, or even as fibers that hold up winter jackets.

Product Applications and Structure

The backbone structure of acrylonitrile gives it its straight-from-lab versatility. The carbon-carbon double bond opens up for addition reactions, while the nitrile group lends strength to everything it touches. Known for helping give strength and durability to plastics, acrylonitrile also makes appearances in the production of acrylic fibers, ABS (acrylonitrile butadiene styrene), and SAN (styrene acrylonitrile) plastics—each with its own role in automotive, home, and industrial settings. When working in a plastics research group, I saw firsthand how a tweak in feedstock purity transformed a brittle plastic into something with the toughness for car dashboards or helmet shells. The molecular structure brings a balance: rigid yet flexible, resistant to solvents, and tough enough to take daily knocks.

Specifications You’ll Find in Industry

Raw acrylonitrile intended for industrial use usually falls under strict purity requirements, often 99.5% or higher. Impurities like water, acetonitrile, or inhibitors such as hydroquinone tip the scales and can foul up reactions, so careful monitoring stays front and center during storage and transport. Producers store it in dedicated tanks, avoid moisture, and use nitrogen blankets to limit unwanted reactions. Flammability remains a constant worry—its flash point sits below room temperature, making open flames or even static sparks a real risk. Pipeline operators and loading dock workers all learn the rhythm of checks, double-checks, and safety drills, since a slipup can mean leaks or fires.

Hazards, Health Concerns, and Safety Measures

This material doesn’t just pack chemical power—it also brings some real hazards. Inhalation or skin contact can cause irritation, headaches, or worse in higher exposures, raising red flags for workers and communities near large plants. Acrylonitrile has earned classification as a probable human carcinogen, which pushes responsible handling and oversight to the top of every plant manager’s checklist. Regulations set strict exposure limits; safety training becomes part of daily routines for anyone within reach of the production or transport chain. Material safety data sheets flag it as harmful, especially if fumes build up in enclosed areas. I’ve seen a range of solutions: full-face respirators, emergency showers along every hallway, and high-tech containment alarms. Solid community outreach also helps everyone understand potential risks and the systems designed to keep drifting chemical clouds away from neighborhoods.

Responsible Use and Pathways to Safer Materials

Despite the challenges, acrylonitrile hasn’t lost relevance, thanks in large part to a relentless push for better containment, faster leak response, and upgraded production systems. Cleaner catalysts and closed-loop water systems chop down emissions and waste. Research teams develop next-generation materials that aim to match acrylonitrile’s flexibility and strength, all while looking to cut toxic byproducts. On the shipping and storage side, double-walled containers and automated vapor detection now catch small leaks before they become disasters. Every safety innovation pulls this chemical a little further from its riskier past.

Molecular Details and Industrial Benchmarks

C₃H₃N, also known as vinyl cyanide, draws chemists in with its compact yet reactive structure: a chain of three carbons capped with a nitrile group. Simple as it seems, every atom earns its place—open enough for polymerization, tough enough to last in tough environments. Industrial benchmarks usually define its density between 0.800 and 0.820 g/cm³ at 20°C. The liquid form’s handling requirements have been hammered out over decades, spelled out in international chemical codes and shipping manifests. Shelf life depends on inhibitor levels, which prevent runaway polymerization, especially during long sea journeys. Even as alternatives and greener chemistry press forward, acrylonitrile’s reliable performance keeps it vital for all sorts of downstream production.