[FlaskBreaker]

Hello everyone. Today I was wondering: What is the nastiest chemical you've messed with? "Nastiest" is a pretty broad term, so I'll make it a bit more specific: Any chemical that has the most foul, eye-watering smell, or any chemical that you think is disgusting.

The nastiest chemical I've ever used is probably ammonia. Whenever I open up my jug of it, the foul fish-like smell hits you. Then, you pour it into a beaker. This is where the coughing comes in. You periodically have to leave the room. Even though it is just cleaning strength, and there is a low concentration of it in the air, you can still smell it. I don't have a fume hood, but my garage is still very well ventilated.

I refuse to use any chemical that puts out worse fumes than basic cleaning ammonia until I get a decent fume hood.

[marquis]

Try butyric acid.  A beaker of it has most of the wonderful nuances of baby barf.

[Enthalpy]

[...] The nastiest chemical I've ever used is probably ammonia [...]

Reasonable person. Recently on an other forum, a would-be rocket engineer imagined to use liquid ammonia (not the water solution) as a propellant, hence in kg and multi-ton amounts. As I answered "toxic" he meant "used in farms" (!) and "a matter of risk assessment". Obviously he had never had a milligram in his atmosphere.

It's true too that several launchers still use hundreds of tons of Mmh, Udmh and N₂O₄. I never dealt with them personally and it shall stay so.
Example, admire how varied nitrogen oxides are formed by the combustion too and in what amount:
http://www.spaceflightinsider.com/missions/commercial/proton-m-launcher-soars-skyward-communications-satellite/
And here it failed :-)
https://www.youtube.com/watch?v=OngbHZ2fsbA (more nice videos through links there)

When I worked on semiconductors, we had a few uneasy things at hand like hydrofluoric acid: no nasty smell but nasty burns. We also had phosphine and hydrazine but I didn't even think of using them. The chemists here certainly used much worse compounds.

Does tear gas count in this discussion? Even in small amount one doesn't go willingly in a cloud.

[OrganicDan96]

Try butyric acid.  A beaker of it has most of the wonderful nuances of baby barf.

I will second that, when i was doing undergraduate labs we had to make butyrate esters using butyryl chloride (hydrolyses to butyric acid) the whole lab stunk of vomit, you could tell who had been careless with it as they smelled like they had just thrown up. took some time for the smell to come out of our lab coats.

[wildfyr]

The combination of thionyl chloride and DMF to make various sulfonyl chlorides is pretty bad.

Mercaptoethanol is stinker too, its hydrophilic, volatile, and smells like rotting socks. I had to distill it, despite my best efforts to trap it my poor pump was pretty smelly for a few days.

Someone once rotovapped hexanethiol in the open lab and it was so bad we all got sore throats and headaches and had to clear out while he rinsed it out with bleach. That was fun.

[phth]

episulfides smell like garlic tastes

[Corribus]

I always dreaded working with pyridine. There's something about it that always went right to my sinuses.

[mjc123]

I agree with pyridine. I've worked with chemicals that would be "nastier" if you came into contact with them, like HF; or with more obviously "disgusting" smells (many sulfur compounds); but the slightest whiff of pyridine always makes me feel very nauseous.
There are also chemicals that are not obviously "nasty", but may have unfortunate consequences, e.g. moth pheromone: it doesn't smell to humans, but get any on you and you'll attract every moth for miles around. (Or so they said; I didn't put it to the test.)

[OrganicDan96]

I always dreaded working with pyridine. There's something about it that always went right to my sinuses.

When ever i work with stinky volatiles such as pyridine or triethylamine I normally leave the syringe and even my gloves at the back of the fume hood for a while before i take them out so that i don't stink the lab out with them.

[Flatbutterfly]

On my (subjective) list of smelly chemicals ammonia would get 6.5, pyridine 7.5, around 8 -9 would be low MW S and Se cmpds, phosphines; and in a separate class butyric acid.  However nothing, in my opinion, compares to the odor of t-butyl isocyanide (t-Bu -N≡C) that I put at 9.5.  The reason for this is that its revolting smell cannot be likened to any odor that a person is familiar with; only by smelling it can you understand just how horrible it is.  For me the odor also induces a feeling of dread.   Google odor of isocyanides where you will find that others agree with me.  I once answered a question on another forum asking about the smell of t-butyl isocyanide and I explained as above.  The person replied that he had read that it was the smell of a dead alien!

[wildfyr]

I almost want to order some t-butyl isocyanate to smell it and have this life experience. I wonder if all small alkyl isocyanates smell different.

BTW, I never found butyric acid to be so bad. It just smells like a really fresh dog turd to me.

[Flatbutterfly]

When I first read this post t-butyl isocyanide (not isocyanate) immediately came to mind.  I was unaware what other chemists thought of its unique odor and so I googled it.  Some descriptors that came up were “legendary”, “the smell from an abominable snowman’s armpit”, “the Godzilla of scent”!
I did think that chemists will now go out and obtain some to experience the odor first-hand.  Trust me - leave it alone!
It is a special ligand somewhat like CO.

[P]

My first though was the Sodium Sulphur Titanium complex amalgam - NaSTi.

...hmmm..  it seemed better in my head, now I have written it down it seems cheesy, lol. Maybe one for the Chemistry Christmas crackers.

[OrganicDan96]

according to the name, bromine stinks pretty bad as the nam bromine comes from the greek word bromos which means stench.

[dew3554]

Skatole, the essence of faeces