soma - 11-11-2012 at 07:13
Are there any simple methods to determine if ethyl ether is anhydrous - or how much water is in it? Like a test strip?
Thanks.
Vargouille - 11-11-2012 at 07:38
Of course. Adding a small amount to potassium or sodium will result in a reaction if there is water, but no reaction if there is not. Anyhdrous copper
sulfate also works, as it will absorb water and become blue. If there's no water, it'll stay white. You can make the anhydrous copper sulfate by
heating the pentahydrate until it is no longer blue. Alkali metals can either be made or purchased.
kristofvagyok - 11-11-2012 at 08:05
Diethyl ether can contain a LOT water, even up to 10%.
Adding alkali metals is NOT recommended, because potassium will ignite it, and sodium can ignite it. Also the low boiling point of
ether and the highly exothermic reaction between alkalies and water is not a good idea.
Add anhydrous potassium carbonate, magnesium sulfate, sodium sulfate or the previously mentioned copper sulfate to dry it, or determine the water
cont. of your ether.
soma - 11-11-2012 at 09:35
Thanks. I'll try the copper sulfate. I had been 1st drying it with molecular sieve and then adding P205 and distilling. I tested it with LAH after the
sieve and then again after the P205. It fizzed alot less after the P205.
soma - 12-11-2012 at 06:33
Would you know how sensitive the anhydrous copper sulfate is?
chemrox - 12-11-2012 at 15:50
You could weigh the K2CO3 making sure you weigh any additional you add. Then because the ether is easy to remove you can re-weigh the (hydrated)
K2CO3 and calculate the amount of water.