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I am trying to get anhydrous diethyl ether. So, I am considering using a condensor to heat up diethyl ether and extract water. Would this method work?

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    $\begingroup$ No. However you can get your ether very water-poor by drying it over sodium sulphate or magnesium sulphate. Truely dry ether can only be obtained by rigorous drying (e.g. sodium) and subsequent destillation; to be stored under inert gas. Luckily, most suppliers sell dry solvents over molecular sieve with water contents less than 50 ppm. Also, welcome to chemistry.stackexchange.com. Feel free to take a tour and visit the help center for questions about the site. $\endgroup$ – Jan Oct 7 '15 at 12:56
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    $\begingroup$ I generally prefer to pay a little more for small containers of anhydrous ether and then use them up quickly. Once the container is open, your ether is not dry anymore. $\endgroup$ – Ben Norris Oct 7 '15 at 12:58
  • $\begingroup$ I am trying to synthesis phenylmagnesium bromide and I have to use anhydrous ether. Would it matter if I use normal ether for this synthesis? $\endgroup$ – Edmond Lee Oct 7 '15 at 13:02
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    $\begingroup$ @EdmondLee The definition of "have to use X" is that it does matter if you don't use X. So I don't understand how you can simultaneously believe that you "have to use anhydrous ether" and that it might be OK to use water-containing ether. $\endgroup$ – David Richerby Oct 7 '15 at 13:53
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    $\begingroup$ What @DavidRicherby said. Of course, there's a difference between "have to use X or the yield will suffer" and "have to use X or it'll catch fire and explode." If the OP doesn't have convenient access to anhydrous ether, they'll need to figure out what level of "have to" applies here. $\endgroup$ – Ilmari Karonen Oct 7 '15 at 17:28
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No it would not work. Ether boils at a lower temperature than water. Plus, it forms an azeotrope with water: a composition of 98.7 % (by weight) ether boils at 34.2 °C and the vapor phase has identical composition as the liquid, meaning that distillation cannot remove the final 1.3% of the water (at atmospheric pressure).

The standard way to remove water is (i) first to use drying agents such as magnesium sulfate to remove most of the water, and then (ii) if needed, eliminating the final traces of water with small amounts of sodium (or potassium) metal.

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Ether is notoriously difficult to remove all traces of water from. Don't even bother unless you have a means to store dry ether without its contacting air, from which it will extract humidity very rapidly. I would recommend using a desiccant such as calcium sulfate (drierite) or a molecular sieve, and let it stand for a few hours. You could then either decant or distil the dry ether, but distilling it with a desiccant filled drying tube on the receiver vent, or under an inert gas blanket, is a must.

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