[Zyklonb]

[Sorry if this topic already exists, I did search, couldn't find anything]

What are the most dangerous, complex, or otherwise interesting chemicals you guys have synthesized (or elements you've isolated).

Some of the scariest I've made (or isolated) include:
ClO₂, Cl₂I₆, N₂O_4/5, Br, BrO_x (it's been a while, forgot the oxidation state), TNT, nitrocellulose, nitroglycerin, NI₃ • NH₃. I have isolated sodium, and tiny amounts of potassium from reduction of their salts with Aluminum or magnesium, but never enough (and certainly not pure enough) to be worth an ampule for my element collection.

Anyway, that most of my list, interested to see what you guys have done.
[EDIT] I guess this might belong in "Citizen Chemist" as the question is directed manly at citizen chemists.

[kriggy]

Probably nitroftalic acid in a organic lab last year. Because the separatory funnel of my classmate didnt work as expected and about 10 ml of fuming nitric acid was added not slowly for about an hour but fast in like 5 minutes. The temperature rose to +- 230 °C (should be kept at no more than 110 or so) and lot of orange fumes went out.
So the TA closed the fume hood and we waited till it ends. I made this vid after about 20 minutes when it was almost over so its not that exciting probably. (notice the black condenser)
https://www.youtube.com/watch?v=SR19gmpoB2A&feature=youtu.be
(sorry for rotated video but I dont know how to rotate it to be normal)

btw we were bit scared at that time but now its just funny story

[nightguy]

Not a lot of them, but here are some:

Cl2, NO2, H2S, HNO3, H2SO4 and PbCl2.

These are probably not so special for you, but I'm only chemistry hobbyist.

Best regards, nightguy

PS: not so dangerous, but intrusting for me were LiCl and CuCl2, as they give nice red and green coloured flame. I also tried to make KCl, but couldn't find out how to do that with only KNO3 and few other chemicals available.

Intrusting was also CHCl3 (one of my first organic chemistry reactions), I was scared that it wouldn't put me in to sleep, while making it, but it wasn't so hard to make it, just dont breathe it, because it's carcinogenic.

[mjc123]

Not me, but a colleague at a former job made polyaniline by a method involving the use of a perchlorate salt. Having filtered off the polymer, he noticed that the filtrate was coloured, and assuming some of the polymer was still in solution, and being unwilling to lose any, he evaporated off the water in a dish and added the residue to the filtration residue, and put this in a vacuum oven to dry overnight. It blew up the oven (fortunately at night when nobody was in the lab).

At university, someone (debate still rages over who) managed to put a large steel adjustable spanner into a bowl of aqua regia. When we returned after coffee, it was belching out NO₂ like a steam train, fortunately it all went up the fume hood. We were more concerned about the loss of the expensive spanner than the chemical hazard!

On the subject of NO₂, I once had to make LiCoO₂ (by a way that was supposed to give better properties than the commercial material). Started with reagents in solution in a 25L reactor; as the water evaporated and reaction proceeded, the mixture got thicker, and as it reached the gel point it bubbled up (NO₂ was evolved) and pink foam (full of carcinogenic Co) overflowed uncontrollably from the reactor like something out of the Sorcerer's Apprentice. Though wearing a lab coat, the right cuff of my blue shirt was bleached white by acidic gases (from going into the reactor with a long spoon to check the state of the mixture). I wanted to abandon the proedure but boss insisted on proceeding.

An interesting little curiosity: I once made an azobenzene-terminated polymer (polysulfone of some kind I think) via diazotisation of the amine-terminated polymer. I used it to test some GPC systems we were thinking of buying. The idea was that at 254 nm the signal would be proportional to the mass concentration (being due to the benzene rings in the backbone), while at the azo wavelength (I forget, perhaps about 400 nm) it would be proportional to the molar concentration (as each molecule has just 2 azo groups). So the chromatograms ought to give the weight fraction and number fraction distributions respectively. Worked quite well, if I remember, though not perfectly.

[discodermolide]

Usually making boranes is exciting, accompanied by a lot of smoke and occasional flames. Phosphines are just as interesting and very smelly and toxic.