Chemistry, like any craft, moves forward by building on earlier discoveries, and thiophenol’s story goes back to the 19th century, a time when curiosity pushed chemists to explore the boundaries of aromatic and sulfur chemistry. Charles Gerhardt and Auguste Cahours independently dug into benzenoid compounds, striking on the realization that swapping out oxygen for sulfur in phenol led to distinct chemical territory. Thiophenol, or benzenethiol, had a strong, garlic-like smell that demanded respect in the lab—a sensory warning that science had tripped into new ground. The properties of this compound stoked interest both in theory and in hands-on applications. Researchers realized pretty soon that the aromatic ring and the mercaptan group opened up a playground for new syntheses, and thiophenol started popping up in patent books and technical monographs as chemical manufacturing expanded through the 20th century.
Thiophenol, formula C6H5SH, takes shape as a clear-to-pale yellow oily liquid at room temperature. It draws a crowd in organosulfur chemistry, tied closely to its siblings in the thiol group. It has kept a steady place in organic labs because it reacts readily, delivers a handy starting point for sulfur-containing pharmaceuticals, agrochemicals, and dyes, and pushes research into new sulfur-organic frameworks. Commercial labels include benzenethiol, phenyl mercaptan, and phenylthiol. Packaging varies by volume, but the advice is simple: always tightly capped, no sunlight, no air. Bench chemists learn quickly that spill management is vital, since even a few drops let off a powerful stench that can clear a room faster than a safety drill.
Cracking open a bottle of thiophenol fills the air with a heavy, skunky smell; the mercaptan group—the SH on the benzene—is a major reason. The liquid boils at about 169°C (336°F), melts at -16°C (3°F), and doesn’t mix with water but freely blends with organic solvents like ether, alcohol, or chloroform. That lone hydrogen on the sulfur is easily lost, which makes thiophenol so reactive in nucleophilic substitution reactions. The SH group matches the acidity of phenol, so handling the liquid with gloves and goggles is routine. Over time, exposure to light and air can give rise to sulfonic acid derivatives, giving chemists another reason to keep bottles shut tight. In the lab, thiophenol shows up under UV light due to pi-electron activity in the benzene ring. Chemical suppliers ship it with purity info—often 99%+ for research, but some technical grades go lower if purity doesn’t matter for downstream steps.
Labels on bottles of thiophenol aren’t just for show. Regulatory standards force suppliers to list the CAS Number (108-98-5), the chemical formula, purity grade, weight/volume, and hazard information. UN codes point out the fire risk and acute toxicity, flags that rattle any seasoned chemist’s memory bank. Datasheets spell out flash point, recommended storage temperature (cool, away from oxidizers), and emergency spill plans. Certificates of analysis back up the purity claim, sometimes with impurity profiles. Countries like the US and EU set strict controls under environmental and workplace hazard regulations, so paperwork stacks up from the loading dock to the fume hood. Most labs keep detailed logs of use and disposal for compliance and to limit accidental exposure.
Old-school chemistry texts describe the original synthesis from benzene sulfonic acid reduction. Sodium benzene sulfonate gets reduced under strong acidic conditions with zinc and hydrochloric acid, freeing the SH group. Modern labs streamline the process using catalytic hydrogenation of diphenyl disulfide, a route that avoids some of the nastier side products. Other approaches swap out reagents—like thiourea acting on aryl halides in the presence of base, followed by hydrolysis. Disulfide reduction tends to dominate in industry because it scales up well, minimizing batch-to-batch variation and supporting sector demands from pharmaceuticals and advanced materials to specialty polymers. Each step carries occupational hazards, especially risks tied to hydrogen sulfide evolution and corrosive intermediates. Manufacturing plants run strict air monitoring and ventilation, because even trace leaks affect worker health and site compliance.
Anyone tinkering with thiophenol in the lab learns fast that it’s a practical nucleophile. The SH group slams into alkyl and acyl halides, forging thioethers and thioesters under simple conditions—heat, solvent, maybe a little base. Oxidation brings drastic changes, with mild oxidants generating disulfides and serious oxidants pushing to sulfonic acids or sulfoxides. Electrophilic aromatic substitution stays possible on the benzene ring, so nitration, halogenation, or sulfonation modify product lines without wiping out the useful SH function. Scientists pioneering new catalytic cycles experiment with metal-thiophenolate complexes, using thiophenol as a ligand or reducing agent. Its adaptability keeps it in researchers’ toolkits for assembling sulfur-rich heterocycles, mining for new ligands, and as an intermediate for custom synthesis targeting tailored pharmaceuticals or biological tools.
Across borders and supply chains, chemists look for consistency in product names. Thiophenol shows up under several banners: benzenethiol, phenyl mercaptan, phenylthiol, or just PhSH on a reaction scheme. In catalogues, it can turn up with language variations or proprietary names, and physical samples in global commerce might follow older naming conventions. Checking for synonyms matters to clear up confusion—especially when swapping between catalogs or reading international research literature. Most suppliers follow IUPAC and CAS standards, but older texts or legacy regulatory paperwork may ask for a moment’s translation, linking “mercaptan” with “thiol” for the uninitiated.
Handling thiophenol means respecting both its chemical power and its health risks. The toxic vapor, flammability, and ability to absorb through the skin land it in the moderate hazard range—not as bad as phosgene, but not something to wave around. Inhalation can spark headaches, nausea, and in worse cases, nervous system effects. Safety data sheets spell out required protective gear: respirators in confined spaces, thick nitrile gloves, and double containment for transfers. Labs set up active ventilation—strong fume hoods, local extraction, sometimes full-face shields for larger batches. Accidents with spills don’t just risk chemical burns or exposure; the stench can force a building out of action. Emergency showers, eyewash stations, and containment kits keep the fallout from turning physical hazards into legal ones. Emergency response training in industrial settings drills for thiophenol leaks with cleanup agents and full PPE, avoiding water since the liquid can spread across floors and release vapor.
Chemists rely on thiophenol in both academic and industrial spaces. In organic synthesis, it acts as a building block for thioethers—molecules needed for drug leads, dyes, and agricultural chemicals. Its reactivity helps craft base-sensitive pharmaceuticals, highlighting its importance when milder conditions fail. Dye and pigment industries work with thiophenol derivatives to create sulfur-rich colors, and some advanced materials draw on its flexible coordination chemistry to build electronic or optoelectronic devices. Researchers testing sulfonic acid catalysts or high-value organometallics choose thiophenol for its handy SH group and tuneable aromatic ring. Fast-moving fields like medicinal chemistry grab for thiophenol to access new scaffolds targeting resistant bacteria or tricky biological pathways. Peptide chemists use the SH group as a frontline tool, introducing sulfur into custom biologics meant for imaging or anti-cancer trials.
Science doesn’t stand still, and neither does research with thiophenol. Automated flow chemistry and microreactor technologies open the door to safer, more consistent synthesis with smaller chemical footprints. Medicinal chemists push for new derivatives to break old patents or raise pharmaceutical efficacy. Computational chemistry and machine learning now help identify new product spaces for thiophenol scaffolds, especially in targeted drug delivery, photodynamic therapy, and enzyme targeting. Teams studying catalysis loop in thiophenol for gold or platinum complexes, exploring routes toward cost savings and higher performance in key industrial transformations. Environmental chemists explore its role in capturing or converting hazardous metals, feeding into green chemistry targets for the next decade of materials and remediation science.
There’s no point hiding from the facts—thiophenol carries risks beyond the immediate irritation. Studies show acute toxicity in mammals, with ingestion or inhalation leading to systemic toxicity at relatively low doses. Animal models reveal rapid onset of central nervous depression, and researchers tracing metabolic fate see oxidative stress on the liver and kidney tissues after exposure. Regulatory bodies classify it as a hazardous substance, which prompts strict workplace monitoring and environmental release limits. Ongoing toxicological research weighs the impact of trace exposures and investigates new cleanup and containment strategies. Scientists look at potential biodegradation strategies, hunting for bacteria that can neutralize or process thiophenol as a step toward safer industrial ecology.
As the chemical industry shifts toward sustainability, the future for thiophenol will depend on safer production, responsible handling, and creative reuse. Researchers keep probing greener synthetic routes, including biocatalytic steps and recyclable reagents, to minimize byproducts and energy costs. Regulations will likely tighten, but the push for sulfur-based functional materials in electronics and medical fields keeps thiophenol on the horizon. Startups and big pharma test new analogs in pipelines for crop protection, imaging agents, and catalytic residues. The rise of circular chemistry and “benign by design” innovation continues to shape how scientists approach thiophenol—a challenging, powerful, and still vital ingredient at the intersection of science and society.
Thiophenol stands out in the lab with a strong, pungent smell, even before anyone pulls out the safety data sheet. The compound, an organosulfur molecule, belongs to the family of thiols, which pop up everywhere from natural products to chemical manufacturing. Shelves of reagent bottles in university labs and pharma plants each hold a few drops of this liquid, despite the headache that comes from its fumes. So, why bother with something so unpleasant?
Synthesis chemists keep thiophenol in their toolkit because it’s reliable for adding a sulfur atom to molecules quickly. When building up complex drug molecules or specialty chemicals, chemists use thiophenol to form aromatic thioethers. These thioethers show up in medicines, dyes, and electronics. For example, certain HIV treatments and antiviral drugs start out as simple building blocks, then pick up a sulfur atom using thiophenol. Without this compound, many reactions would slow down or require harsher conditions.
Agriculture relies on some of the sulfur-rich pesticides and fungicides, and thiophenol plays a role in making these chemical protections affordable. The molecule acts as a key player in the synthesis of several important crop protection agents. Not every field or orchard needs direct application, but the production lines at agrochemical plants would grind to a halt without the efficiency thiophenol brings. In the textile industry, thiophenol helps make certain dyes more stable and colorfast, which keeps shirts and pants looking brighter after months of heavy wear.
In university labs, researchers run into bottlenecks when trying to attach a sulfur group to an aromatic ring. Here, thiophenol saves the day. Graduate students and postdocs know that with the right conditions, thiophenol reacts cleanly and predictably. This reliability cuts down on wasted time and minimizes troubleshooting — a blessing when working on deadlines for grant proposals or patent filings. Each successful reaction using thiophenol speeds up the process of discovering new molecules with the potential to treat disease or improve industrial processes.
Familiarity with thiophenol’s hazardous properties reminds everyone of the importance of strict lab safety. Breathing it in burns the nose, and splashes can sting the skin. Strict handling protocols, fume hoods, gloves, and safe waste disposal keep accidents rare. Overexposure leads to health problems, and there’s little forgiveness for mistakes in training. Still, industries and labs with strong safety cultures continue to show accident rates lower than many other manufacturing sectors.
Some companies are finding ways to use smaller amounts or substitute safer chemicals, but for many applications, nothing beats thiophenol’s unique role. Working with this reagent urges scientists and process engineers to design reactions that limit exposure and waste. More research into greener alternatives gets funded by both governments and the private sector, but the toolkits in most chem labs will hold thiophenol for a while longer. Understanding its uses, risks, and the value returned keeps chemists honest about the trade-offs that come with every scientific advance.
I’ve worked with a handful of nasty chemicals over the years, but the memory of Thiophenol's suffocating smell sticks with me. Recognizing the risks means facing them head-on. The chemical carries a potent odor that says “danger” with every whiff. If you’ve been near an open bottle, you know how fast your instincts kick in. Handling this material without respect invites trouble—a strong skin irritant, toxic to breathe, and able to burn its way through gloves, clothing, and even a bit of your confidence if you let your guard down.
Nothing beats solid personal protective equipment (PPE). Ordinary disposable gloves won’t cut it—thiophenol can seep straight through, so sticking with thicker nitrile or even butyl gloves works best. Lab goggles aren’t optional either. One splash and you could regret life choices, so covering every inch matters. Lab coats, buttoned up tight, also keep accidental spills off your skin—no rolling up sleeves and no shortcuts.
If you ever think about opening a bottle outside a fume hood, remember your last headache from chemical fumes. That’s a lightweight compared to thiophenol. Its vapors irritate eyes and lungs within seconds. Robust fume hoods with steady airflow turn a miserable job into a safe one. Never take a chance on local exhaust fans or open windows—they just don’t pull their weight. Fume hood sashes stay low, and freshly checked airflow means you’re breathing easier, not risking harm.
Here’s what’s kept me safe more than anything: keeping a predictable workflow, free of distractions. Everything—reagents, pipettes, spill kits—sits within arm’s reach before the bottle comes out. Spill management supplies like absorbent pads save a panic later. Mixing containers and tools should stand up to strong chemicals—no cracked glass or low-grade plastics. Keeping the bottle capped except for each measured transfer keeps loose vapors from escaping, making the air less harsh for you and everyone around.
Disposal demands real attention. Keep used pipette tips, contaminated gloves, and any waste solution in a sealed, labeled hazardous waste container. Any leaks here travel fast and affect more than just the immediate workbench. Talking with your hazardous waste staff before handling and disposal ensures the right steps, every time. Water alone won’t wash thiophenol away, and flushing it risks more than a temporary smell—it can contaminate pipes or threaten others downstream.
No one starts with all the answers—including safety. Asking colleagues, reviewing Safety Data Sheets, and keeping up with procedure updates brings confidence. Every lab accident I’ve seen involved skipped steps in training or rushed work—rarely a random mishap. Taking five minutes to check your process and understand the nature of this sharp-smelling chemical makes sure danger never gets the upper hand.
I’ve watched labs swap glass bottles for shatter-resistant plastic versions, add extra ventilation, and switch over to smaller aliquots to minimize exposure. These practical shifts, grounded in experience and attention to detail, serve as the foundation for keeping everyone healthy and the lab productive. Thiophenol’s dangers fade to the background when you work with clear rules, tested equipment, and a healthy dose of caution every single day.
Stroll into a well-stocked industrial lab, and you might not spot thiophenol right away, but you’ll know it by its punchy, unmistakable odor. The chemical formula for thiophenol is C6H5SH. It sounds like something out of a dry textbook, yet this tiny string of letters and numbers means a lot across various fields — not just for chemists, but for anyone invested in materials science, pharmaceuticals, or even photography.
C6H5SH shows a benzene ring – six carbon atoms looped in a hexagon – and a single hydrogen-sulfur combo tagging along. In simpler terms: swap the -OH group from phenol with an -SH, and voilà, you’ve got thiophenol. That “SH,” or thiol group, brings a signature smell some would call overpowering. The smell isn’t just a quirky fact; it’s a direct sign of how sulfur changes the game in organic chemistry.
Years ago, handling thiophenol for a synthesis, the lingering smell meant I needed to double-bag my gloves and make friends with the fume hood. This sulfur-linked molecule finds its place in making dyes, polymers, and many specialty chemicals. It reacts in ways that regular phenol can’t, all because of that sulfidic swap.
Voice of experience says that getting the structure right matters. Thiophenol (C6H5SH) can escape the flask and signal a spill before anything dangerous happens. Those telltale fumes draw attention—a kind of built-in safety mechanism—and nudge chemists to stay alert.
Few people outside the lab realize thiophenol’s acute toxicity and the need for careful handling. Swallowing it, breathing in the vapors, or letting it directly touch skin can result in unpleasant—and sometimes serious—reactions. According to safety data, it’s harmful even at low levels. For those of us working with compounds carrying the -SH group, the risk isn’t abstract, but a daily reality. Safety equipment, exhaust fans, and respect for the stuff keep incidents in check.
Synthesis of thiophenol typically starts with benzene derivatives, giving industries the raw material for molecules that appear in everything from drug intermediates to pesticides. Researchers also use it to build sulfur-containing compounds, which often turn up in medications for cancer, heart disease, and more. Many organic molecules lack the versatility found in the thiol group, making thiophenol especially valuable in research and production.
Current challenges echo through the world of chemical safety and green chemistry. The sharp aroma of thiophenol reminds everyone of its presence, but spills and waste call for improved controls. Investing in tight storage, detection sensors, and worker training brings real value in preventing accidents. Some labs experiment with lower-toxicity substitutes or work to recycle thiophenol byproducts. Building a safer culture doesn’t slow progress—it accelerates new discoveries by keeping research sustainable.
Thiophenol isn’t just a funny-smelling lab liquid. Its formula, C6H5SH, packs history, risk, and innovation into seven characters. For those pushing the frontiers of science, keeping a sharp eye on both the chemistry and the context of use turns a risky compound into something transformative—and safe.
I remember the first time I read through a thiophenol safety data sheet. My eyes caught on the words “toxic,” “flammable,” and “unpleasant odor”—not the sort of product anyone wants leaking through storage shelves. Thiophenol isn’t some casual lab material. With its strong, garlic-like smell and serious health hazards, storing it poorly puts both workers and the environment at risk. Exposure can trigger headaches, dizziness, and irritation. Long-term or concentrated contact raises the stakes to organ damage. Handling this stuff casually doesn’t cut it.
Thiophenol likes to react with oxygen. Air can kick off slow oxidation reactions that spoil its purity and build up pressure in sealed containers. If humidity gets in, those problems multiply—moisture causes it to degrade faster and risks generating sulfur-based byproducts. Light speeds up these reactions. So an open shelf in a bright, busy storeroom is a nonstarter.
Any chemist who’s stored thiophenol knows: it goes into tightly sealed, amber glass bottles. Glass won’t react like metal, and the deep color blocks out light. These bottles stand in well-ventilated chemical storage cabinets, far from heat and any sources of ignition. Flammable liquids and acids don’t share space with thiophenol—mixing them can turn a quiet lab into an accident scene.
Temperature control also makes a real difference. Keeping things cool slows down those unwanted chemical reactions. No need for deep freezer conditions—a stable, cool cabinet keeps thiophenol manageable. Years in a teaching lab taught me the value of labeling: clear, bold hazard labels save a lot of confusion during emergencies. If you cut corners on this, sooner or later somebody’s left guessing under pressure.
Labs running at scale need more than just basic good habits. Fume hoods and dedicated solvent cabinets kick in extra layers of protection. Ventilation matters not just for those storing the chemical, but for cleanup if any spills sneak by. Even after following storage recommendations, it pays to monitor shelves for leaks or crystal formation inside the container. Pressure buildup shows things are going wrong. Inspections stop escalation before small issues turn nasty.
Everything leads to one big lesson: don’t treat thiophenol—or any reactive chemical—as an afterthought. I’ve seen well-organized labs rotate stock, track expiration, and teach everyone on-site exactly how to respond if something leaks or cracks. Getting everyone involved cuts down on the “it’s not my job” attitude. Training also builds respect for personal protective equipment. Splash goggles, gloves, and lab coats aren’t optional with thiophenol. Direct skin exposure is a real threat, and inhalation can send someone to the ER.
Good habits prevent emergencies. Regular checks, separating incompatibles, and storing only what you actually use each year reduce risk. Emergency plans that work on paper, but get practiced in drills, set a lab up to react fast under stress. Call in waste management specialists for disposal—pouring thiophenol down the drain or tossing it in regular trash invites environmental trouble.
Responsible storage might seem like more work. But it protects people, reputation, and equipment. Drawing from years around fume hoods and chemical cabinets, I know that skipping a few steps isn’t worth the accident that could happen next.
Thiophenol, sometimes called benzenethiol, pops up in chemical labs more often than many might expect. Its strong, almost gag-inducing aroma gets your attention before anything else—like a cocktail of garlic and rubber. Any chemist who spent time in an organic lab knows that smell means trouble, and not just for your nose. This chemical packs a punch, both in the lab and to human health.
Most worrying is its acute toxicity. Even small amounts can set off an intense reaction. Inhaling the vapors can burn your throat, irritate your lungs, and bring on nausea. Skin contact leaves you with red, sore patches and sometimes even blisters. If you swallow it—hopefully by accident—vomiting and dizziness are likely, with damage to vital organs if things go far enough. Animal tests highlight these dangers, showing liver and kidney damage with repeated exposure.
People sometimes underestimate how fast thiophenol can get through gloves or even clothes. Its low molecular weight and oily consistency make it slippery and hard to keep contained. There's also the fire risk: the low flash point lets it catch fire at temperatures not much warmer than a summer day. Explosive fumes build up without much warning, especially in small or stuffy spaces. That makes lab accidents more likely.
Working with thiophenol always changed the mood in the room. Seasoned chemists would stop chatting and pull on thicker gloves, double-check their goggles, and turn the fume hoods all the way up. After just a hint of it wafting through the lab, you'd notice everyone checking their sleeves and washing their hands—nobody wanted to risk it lingering on their skin or clothes. Folks with asthma or sensitivities often excused themselves until the cleanup was done, which spoke louder than any safety poster.
Few people think about what constant small exposures to thiophenol can do. Over time, it can damage the central nervous system, leading to headaches, fatigue, and sometimes confusion. The chemical breaks down slowly in the environment, sticking around in soil or water near where it gets used. Accidental spills don’t just harm lab workers—there’s a real risk for local wildlife if proper disposal isn't enforced. Regulatory agencies like OSHA and NIOSH label it as a hazardous substance, requiring strict controls for transport, storage, and disposal.
Solving the thiophenol hazard isn't about buying fancier equipment—it's about disciplined habits. Labs that go accident-free store small amounts in tightly-sealed containers, far from heat sources. Fume hoods do the heavy lifting, but personal vigilance makes a bigger difference. Gloves must be chosen for chemical resistance, not convenience. If a spill happens, trained crews react quickly, using absorbent pads, not letting panic slow them down. Regular safety drills sharpen these responses and keep complacency out of the routine.
There are moves towards finding alternatives for thiophenol in industry, but nothing matches its unique chemistry in some reactions. Until substitutes catch up, the real solution lies in education and respect. It never hurts to pause and recall how unforgiving thiophenol can be, even for the experienced hand.
| Names | |
| Preferred IUPAC name | Benzenethiol |
| Other names |
Mercaptobenzene Benzenethiol Phenyl mercaptan |
| Pronunciation | /θaɪ.oʊˈfiː.nɒl/ |
| Identifiers | |
| CAS Number | 108-98-5 |
| Beilstein Reference | 1209227 |
| ChEBI | CHEBI:17590 |
| ChEMBL | CHEMBL1406 |
| ChemSpider | 505 |
| DrugBank | DB03260 |
| ECHA InfoCard | 100.002.228 |
| EC Number | 207-439-9 |
| Gmelin Reference | C1617 |
| KEGG | C01742 |
| MeSH | D013851 |
| PubChem CID | 7967 |
| RTECS number | XN8575000 |
| UNII | 78A2FDS08W |
| UN number | UN1708 |
| Properties | |
| Chemical formula | C6H6S |
| Molar mass | 110.18 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | garlic-like |
| Density | 1.07 g/mL at 25 °C(lit.) |
| Solubility in water | slightly soluble |
| log P | 2.58 |
| Vapor pressure | 1 mmHg (20°C) |
| Acidity (pKa) | 6.6 |
| Basicity (pKb) | 9.38 |
| Magnetic susceptibility (χ) | -37.7×10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.591 |
| Viscosity | 3.267 cP (20°C) |
| Dipole moment | 1.64 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 163.0 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | 8.0 kJ mol⁻¹ |
| Std enthalpy of combustion (ΔcH⦵298) | -553.3 kJ mol‑1 |
| Hazards | |
| GHS labelling | GHS02, GHS06, GHS05, GHS08 |
| Pictograms | GHS06,GHS05 |
| Signal word | Danger |
| Hazard statements | H301 + H310 + H330, H311, H314, H370, H400 |
| Precautionary statements | P210, P260, P261, P271, P273, P280, P301+P310, P302+P352, P304+P340, P305+P351+P338, P310, P330, P501 |
| NFPA 704 (fire diamond) | 2-4-2-W |
| Flash point | 54 °F |
| Autoignition temperature | 572°F (300°C) |
| Explosive limits | 1.8% - 11.0% |
| Lethal dose or concentration | LD50 oral rat 260 mg/kg |
| LD50 (median dose) | LD50 (median dose): Oral-rat 46 mg/kg |
| NIOSH | SN 6125000 |
| PEL (Permissible) | PEL (Permissible Exposure Limit) for Thiophenol: 0.1 ppm (skin) as established by OSHA. |
| REL (Recommended) | 0.1 ppm |
| IDLH (Immediate danger) | 15 ppm |
| Related compounds | |
| Related compounds |
4-Chlorothiophenol 4-Nitrothiophenol 4-Methylthiophenol Phenol Aniline Benzyl mercaptan |
