Hexadecanethiol: Description, Properties, and Applications

What is Hexadecanethiol?

Hexadecanethiol stands out as an organic compound with a long carbon chain, featuring the chemical formula C₁₆H₃₄S. This material goes by other names like 1-Hexadecanethiol and cetyl mercaptan. The structure combines a sixteen-carbon saturated alkane tail ending in a thiol (-SH) group. That thiol side provides reactive qualities, making the compound a favorite in surface science. I’ve seen it pop up often in labs focused on self-assembled monolayers (SAMs), especially when building thin coatings for gold surfaces. Those coatings unlock a surprising amount of control over nanoscale interfaces, helpful in research and manufacturing.

Molecular and Physical Properties

Hexadecanethiol appears as white to pale yellow flakes, although I have also come across it in crystalline solid, powder, and even pearl-like granular forms. Under a microscope, fine crystals shine, but at room temperature, flakes and powders prove much easier to handle for most bench work. Melting occurs around 41–45°C; above this range, it transitions to a clear, oily liquid that gives off a subtle odor. With a density of about 0.846 g/cm³ and a molar mass of 258.51 g/mol, Hexadecanethiol dissolves stoutly in organic solvents like ethanol, chloroform, and ether. Water, on the other hand, barely nudges it; solubility remains close to zero. The molecular structure—a long hydrocarbon chain paired with a sulfur-based end—means it resists mixing with polar fluids. That stubborn hydrophobicity shapes many of its uses, especially smoothing out surface chemistry and controlling interactions at the molecular level.

Chemical Structure and Reactivity

Looking closer at the molecule, the thiol group (-SH) draws the most attention from a reactivity standpoint. This sulfur-hydrogen bond easily attaches to metal surfaces. Labs often use it to create strong sulfur-gold bonds—this quality underpins entire areas of nanotechnology, biosensing, and anti-fouling coatings. The carbon backbone, with its straight sixteen-carbon chain, feeds the molecule’s stability and changes the way surfaces behave: hydrophobic, low friction, and chemically inert to most mild reagents. I’ve noticed it holds up against acids and bases, yet oxidizing agents can slowly attack the sulfur, turning the thiol into a sulfonic acid—so airtight storage and minimizing shelf time really matter. Reactivity does introduce risk, especially inhalation and skin exposure: the compound can irritate mucous membranes and may pose acute hazards if not handled with gloves, goggles, and a chemical fume hood.

Uses and Industrial Role

In industry and research, Hexadecanethiol’s unique pairing of a long hydrocarbon chain and thiol group sets it apart as a crucial raw material for modifying surfaces. In clean rooms building next-generation electronics, this material lays the groundwork for self-assembled monolayers, altering gold or other metal surfaces to make them repel water or bind to specific molecules. Research labs rely on it for AFM (atomic force microscopy) tips, helping them adjust how a probe interacts with biological or inorganic samples. Outside physics and biology, organic synthesis uses Hexadecanethiol as an intermediate for more complex compounds. I’ve watched teams in specialty chemical firms scale up this raw material into solutions in ethanol or hexane, optimizing concentration by the liter for tailored surface treatments or specialty coatings. Because of its easy reactivity and oil-like chain, it sometimes appears in lubricants and anti-corrosive mixtures—though only in tightly regulated quantities, for safety’s sake.

Specifications, Handling, and Safety

Specifying Hexadecanethiol for purchase means tracking purity (at least 98%), physical form (flakes, powders, or crystalline), and packaging (sealed containers, often under nitrogen or argon). Storage in a cool, dry, well-ventilated place limits oxidation and sulfurous smell buildup. Safety concerns hinge largely on skin irritation, eye irritation, and risks from inhaling vapors. I always urge wearing gloves, long sleeves, and goggles, and never handling Hexadecanethiol outside a proper fume hood. Spills should be contained with activated carbon or sand, never washed down the drain. The material falls under HS Code 2930.90, marking it as an organosulfur chemical for customs tracking. In the EU, it's labeled as harmful, and transport requires attention to UN/ADR regulations for minor hazardous goods. MSDS documents give detailed instructions, but the main lesson is to respect both the chemical and physical aspects of this compound. I recommend clear labeling of any lab stock, strict log tracking, and routine disposal of old or contaminated material.

Improving Safety, Reducing Hazards

The risks from Hexadecanethiol are real, but with discipline and the right protective gear, harm can be minimized. Engineers in facilities using this material can upgrade fume hoods, automate fluid transfers, and train all users on the odor as an early warning sign of vapor leaks. Since the thiol group oxidizes over time, integrating oxygen-absorbing packets alongside inert gas fills inside storage containers further stretches shelf life and cuts down on hazardous waste. It’s worth investing in localized extraction systems and clear waste labeling to avoid mix-ups—especially when handling large quantities destined for research or coatings. Any business relying on Hexadecanethiol as a raw material should document its sourcing, purity, and chain of custody to avoid introducing impurities that might trigger unwanted reactions. Better procurement, storage, and end-of-life disposal ultimately keep users and the environment safer, no matter the project.