[cth]

What are your more memorable chemical experiments? Reactions you won't soon forget... 



Chemical fragrance:
I did once a reaction in a heated sealed steel autoclave containing, among others, DMSO (CH₃SOCH₃).
I realised afterwards that during the reaction half of the DMSO reduced into DMS (CH₃SCH₃). 
When I opened the autoclave, a terrible stench overflowed the lab and corridors. It smelled for nearly a week despite all windows opened and fumehoods working... 

Of all reactions I did, that's the one I am never going repeat!!!

[MrTeo]

Much quieter experiments for me 

Hydrolysis of CuSO₄ a few years ago (didn't know much chemistry back then...) got some copper and while trying to dry it, the paper on which i had collected it suddenly caught fire and burnt with a lovely green flame... I enjoyed it a lot!

[azmanam]

photo [2+2] cycloaddition with singlet oxygen.  The sensitizer used was Rose Bengal.  The sun lamp naturally caused a lot of heat, so the reaction was cooled with a recirculating ice water bath.  Long story short, the water bath hose got crimped... stopped the recirculation... water heated up... reaction heated up... methanol solvent started boiling and eventually erupted out of the reaction vessel

...spraying a bright pink methanol solution of Rose Bengal all over my hood.  And by all over my hood I mean it went everywhere.  That was 3-4 years ago, and I still have pink spots in corners of my hood.

/shudders.  never again.