The Molecule So Foul a Waitress Sprayed Deodorant at the Chemists Who Made It

What happened?

The compound is thioacetone. It is acetone — ordinary nail-polish-remover acetone — with its single oxygen atom swapped for a sulfur atom. That one substitution turns a familiar solvent into one of the foulest-smelling substances chemists have ever recorded.

It first appeared in 1889 at the University of Freiburg, in the laboratory of Eugen Baumann, a well-regarded German chemist better known for discovering that the thyroid gland concentrates iodine. Working with his colleague Emil Fromm, Baumann was treating acetone with hydrogen sulfide to make sulfur-containing versions of ketones. What they mainly got was trithioacetone — three thioacetone molecules linked into a ring, a waxy solid that melts at about room temperature. Thioacetone itself showed up only as a trace impurity. It was enough. Their results were published that year in Berichte der deutschen chemischen Gesellschaft under the flat, unpromising title “Ueber Thioderivate der Ketone” — “On Thio-Derivatives of the Ketones.”

What happened next in Freiburg is the part everyone repeats, and it deserves a careful hand. The story as it circulates today — the smell rolling across the city, residents fainting in the streets, a panicked mass evacuation within a half-mile of the lab — comes from retellings that have grown steadily more cinematic over 130 years. The contemporaneous record is real but more restrained: an offensive odor that spread rapidly over a large part of the town, with reports of nausea and vomiting. Whether anyone truly fainted, and whether “evacuation” is the right word for people leaving the area, is not something the original chemical literature settles. What is not in dispute is that a small quantity of a compound inside a university building made itself unmistakably known across a German city.

The English-speaking world got its own introduction the following year. In 1890, chemists at the Whitehall Soap Works in Leeds — people who worked around tallow and lye for a living, and were therefore not easily impressed by a bad smell — encountered the same class of compound and reported that the odor was “fearful.” They also noted something that sounds like nonsense and turns out to be the key detail: diluting it seemed to make it worse.

Then, in 1967, researchers at an Esso laboratory south of Oxford, in Abingdon, went back to thioacetone on purpose. Victor Burnop and Kenneth Latham were investigating whether thioketones could be made into useful polymers. Their published account, in the journal Polymer, contains what may be the most quietly devastating paragraph in industrial chemistry. A stopper popped out of a bottle of residues and was replaced immediately — and colleagues in a building two hundred yards away complained of nausea. Two chemists who had cracked only “minute amounts” of trithioacetone found themselves, as the paper puts it, “the object of hostile stares in a restaurant” and suffered “the humiliation of having a waitress spray the area around them with a deodorant.”

The lab staff insisted it wasn’t them. They were working in closed systems and could barely smell anything. So the team ran an experiment on themselves: observers were spread out around the site, some as far as a quarter of a mile away, and a single drop of the crude material was placed on a watch glass inside a fume cupboard. The odor was detected downwind in seconds.

Why was it strange?

Chemistry is built on the idea that swapping one atom for a chemically similar one produces a chemically similar result. Oxygen and sulfur sit in the same column of the periodic table. Acetone is so unremarkable that it’s sold in drugstores.

Thioacetone breaks that intuition in two directions at once. It is wildly unstable — above about −20 °C it clumps into a trimer or a polymer within moments, so the pure compound can only be held at low temperature. And its smell violates the everyday rule that dilution weakens a thing. The people standing inside the fume-hood room smelled less than the people a quarter mile downwind. That is why the Esso chemists “genuinely denied responsibility.” They weren’t being evasive. Their own noses were telling them the truth as they could measure it.

What did scientists learn?

The dilution paradox has a plausible explanation in how smell works. Olfactory receptors don’t report concentration the way a thermometer reports temperature; at very high concentrations, receptors saturate and the perceived character of an odor can change or flatten out — a familiar effect with strong solvents. Meanwhile, the detection threshold for small sulfur compounds is astonishingly low. Human noses are exquisitely tuned to volatile organosulfur molecules, a sensitivity that likely served our ancestors well, since rot and spoilage announce themselves in sulfur.

The 1967 work also mapped the practical chemistry: trithioacetone can be cracked back to the monomer at 500–600 °C, and the resulting polymer chains vary widely in length depending on how you make them. The polymer research was legitimate. It simply came with an occupational hazard no risk assessment had a column for.

How does it affect us today?

Our nose’s talent for sulfur is now a safety system. Natural gas is odorless; utilities deliberately add trace sulfur compounds — usually tert-butyl mercaptan or similar odorants — so that a leak is detectable long before it is dangerous. The whole warning system depends on the same biology that made thioacetone unbearable.

The Esso paper also endures as a small classic of scientific honesty. The team could have written “odor issues were encountered.” Instead they described the restaurant, the stares, and the deodorant, and in doing so left behind a permanent, citable reminder that lab hazards include ones nobody thought to list.

Fun fact

The 1967 researchers reported that a single drop of crude material on a watch glass, inside a fume cupboard, was detected by observers standing a quarter of a mile away — in seconds.

Sources

• Baumann, E.; Fromm, E. “Ueber Thioderivate der Ketone,” Berichte der deutschen chemischen Gesellschaft 22(2), 2592–2599 (1889) — the original synthesis paper. DOI: 10.1002/cber.188902202151 · full text
• Burnop, V. C. E.; Latham, K. G. “Polythioacetone Polymer,” Polymer 8, 589–607 (1967) — the primary source for the restaurant account. DOI: 10.1016/0032-3861(67)90069-9
• American Chemical Society, Molecule of the Week: Thioacetone
• Lowe, Derek. “Things I Won’t Work With: Thioacetone,” In the Pipeline, Science/AAAS (2009). Link
• Chemical News and Journal of Industrial Science, 1890, p. 219 — the Whitehall Soap Works (Leeds) report. Google Books