The oxidation of chloroform is dangerous because it results in phosgene formation under exposure to UV light. Along with the minimization of UV exposure, this reaction is usually prevented with 1% ethanol by mass (or less commonly, amylene). I find this information everywhere online, but never find a clear explanation of why this is the case.
Since isopropanol is so similar to ethanol, how come people don't use it to stabilize chloroform? Does it not work? Is it because its less volatile than ethanol? Does the prevention of phosgene primarily work in the gas phase?
Also, what would happen if the concentration of ethanol was increased from 1% by mass? What would be the problem with this aside from purity concerns? Would the same concerns apply to isopropanol if it does stabilize chloroform?
Why does compound A react while B does not? Because the end product(s) are more stable and/or the kinetics is more favorable. The mechanism of alcohol/phosgene reaction is elecrophilic addition. Isopropanol has a more bulky side chain than ethanol so it seems that both reasons favor ethanol.
https://ask.learncbse.in/t/give-the-reaction-for-the-formation-of-phosgene-gas/10567
Why 1%? It may just be a "magical number" found out by experimentation or just taken from the top of somebodys head.
Thank you Jukka Salminen that was helpful.
So theoretically, adding more isopropanol than we would ethanol to a fixed volume of chloroform should prevent phosgene from forming. Correct?
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