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Author: Subject: Jones Reagent using dilute Sulfuric acid
peppovsky
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[*] posted on 2-8-2010 at 07:34
Jones Reagent using dilute Sulfuric acid


I'm interested at oxidizing a secondary alcohol (2-propanol, aka "isopropanol") to its ketone form (acetone), by use of Jones reagent. I've acquired Sodium Dichromate, and 1N sulfuric acid. I can theoretically get concentrated sulfuric acid, but it sounds too damn dangerous to handle.

So, my question is - can Jones reagent be made from this dilute acid solution, or is concentrated sulfuric acid absolutely necessary? (The mole equivalence will be the same - 1N H2SO4 is 0.5M H2SO4, so I'll have to use about 37 times the volume [conc. H2SO4 is about 18.5M])

[Edited on 3-8-2010 by peppovsky]
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DDTea
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[*] posted on 5-8-2010 at 22:32


I've only made Jones Reagent once. I don't know whether concentrated H2SO4 is absolutely required, but it is what I used. I suspect that the problem with using dilute H2SO4 is that the sodium dichromate might be more difficult to dissolve, but it's already pretty soluble so it probably wouldn't be so much of an issue. The only other issue I could think of is that it's just easier to use 25 mL of concentrated acid versus 925 mL of 1N acid. Really: how would you dilute that down? It seems very unwieldy.

Concentrated sulfuric is not too bad to handle. As far as reagents go, it will only burn you if you make a mistake--but you probably won't. Wear gloves and eye protection. You don't have to be afraid of chemicals, you just have to work carefully. Also, be sure to have the mixing vessel in an ice bath and add the sulfuric *slowly.* It will sputter, and Jones Reagent really stains! It's the one thing I was never able to wash out of my lab coat.




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cnidocyte
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[*] posted on 15-8-2010 at 05:50


I read that Jones reagent consists of chromium trioxide dissolved in sulfuric acid and acetone. Can other ketones be used instead of acetone?
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