chemrox
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welding gas
I have been working through a published red. am that hasn't worked. STAB is the reducing reagent. Part of the procedure is an enamine formation in
DCE under N2. It seems welding gas could have 0.5% O2 and the Ar might have had 5-10% CO2 in it .. it was donated by a welder ..
I'm looking at everything to see where the problem lies and this occured to me tonight. I found the gas information in an old thread here. How can I
check the Ar I have? Bubble it through water and check pH? it seems there's something CO2 will cause a precipiate in but I can't remember .. also
the 0.5% O2 in the N2`shouldn't be total killer should it? I can take the tank in and get pure Ar. I can probably get pure n2 if I ask them to make
sure too .. but since Ar is nice and heavy and costs the same..
Anyway beware.. welding gasses may have other gasses in them. Check with the supplier.
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not_important
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Barium hydroxide is the best check for CO2, but strontium or calcium hydroxides will work too. Using boiled water make a saturated solution of the
hydroxide in a closed jar. Glass is best, plastics let some CO2 through. Let the undissolved hydroxide settle for some time, then pour the clear
solution into another jar and close tightly to preserve it. Bubbling a CO2 containing gas through some of the solution will cause it to get milky.
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chemrox
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That's what I was looking for. Thanks!
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YT2095
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it`s important to keep watching it also, if you Start the bubbling and walk away and come back to a still clear liquid you could still have had CO2
and missed it, excess CO2 will form a Hydrogen Carbonate of the calcium which is clear 
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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