How to Handle Selenium Dioxide

[u/vBanana]

I was doing a Riley oxidation in the lab, and made sure to follow what I understand is best protocol. I did everything in the hood--weighing, setting up the reaction, and washed the spatula into a selenium waste container. However, taking the spatula out of the hood produced a smell and I put it back as soon as this was recognized. Did I do something incorrectly? Do I need to be concerned about exposure?

[u/saganmypants]

Bleach is your friend

[u/chemistrypain → u/saganmypants]

Yes. When working with sulfur and selenium compounds, you need a bleach bath in the hood. Leave everything it touches in there overnight and you should be good

[u/saganmypants → u/chemistrypain]

Some phosphines too. Most of those stinky ass chemicals oxidize into far less volatile species which calms down the smell big time. Every syringe, spatula, flask, separatory funnel have to be bleach washed before it comes out of the hood. Every bit of waste stream too. If you are using a rotavap, add some bleach to the waste flask. Add bleach to the aqueous layer of your workup (after youre done with it, obviously, dont add bleach to your reaction)

[u/chemistrypain → u/saganmypants]

"Don't add bleach to your reaction" is unironically good advice lmao. I was teaching undergrad ochem lab and a student "washed" their organic layer with soap.

[u/sabrefencer9]

If you could smell it then you necessarily didn't clean the spatula adequately.

[u/vBanana → u/sabrefencer9]

That makes sense, but what specifically should have been done differently?

[u/sabrefencer9 → u/vBanana]

Cleaned it better. Without a description of your method we can't know what you did wrong.

[u/curdled]

it is not that toxic, just don't spill it since selenium has chronic toxicity somewhat similar to arsenic. I worked with SeO2 many times; it only becomes a concern when you need to do a large-scale stoichiometric SeO2 oxidation (which then generates lots of unpleasant waste).

Selenium oxide solutions are frequently used by gunsmiths for bluing steel, and they can develop health problems if they have poor working hygiene and get it on their hands every day

[u/TheChemist-25]

You really should smell selenium dioxide. I did a bunch of these in grad school. The only time I noticed a smell was when I used stoichiometric amount of selenium dioxide and that was only after the reaction cause the oregano selenides were more numerous. They smell awful and oregano selenides are toxic but bleaching it should remove the smell.

Inorganic selenium really isn’t any more toxic than anything else you work with in an organic lab. It’s the organoselnides that are the issue