hi everyone
i have some diethyl ether which seems to have some yellow colored impurities, i want to distill it, knowing that the boiling point is ~ 34 °C, it doesn't seem to need much heating but the problem is the peroxides, wont 30-40 degrees be dangerous in case there are peroxides present? i know i can apply a slight vacuum to lower the boiling point, but can i distill it without using vacuum?
Old stock of diethyl ether can acquire a pale yellow colour and this solvent has a great tendency towards forming peroxide during storage.
You may carry out a simple test to establish the formation of peroxide. Take a bit of potassium iodide (KI) and add a bit of acetic acid to it and to this mixture add a few drops of your sample of diethyl ether. Presence of peroxide will be indicated by brown colouration of the KI-Acetic acid mixture due to liberated iodine.
Now let us go over to distillation of diethyl ether.
Direct distillation of any ether, such as diethyl ether, tetrahydrofuran etc., can be dangerous and should be avoided as far as possible.
Please add anhydrous potassium hydroxide (KOH) pellets in your ether and keep at room temperature over night and then decant the ether, press sodium wire into it and then distill. The distillate would be pure anhydrous ether.
The treatment with anhydrous KOH will (a) destroy peroxide and (b) remove most of the water present in the ether.
Please observe the colour of the KOH pellets at the end of over night stay with impure ether.
Please ensure that you never distill any ether to dryness.
I would also like to request you to go through a textbook such as Practical Organic Chemistry by Vogel / Organikum.
Old stock of diethyl ether can acquire a pale yellow colour and this solvent has a great tendency towards forming peroxide during storage.
You may carry out a simple test to establish the formation of peroxide. Take a bit of potassium iodide (KI) and add a bit of acetic acid to it and to this mixture add a few drops of your sample of diethyl ether. Presence of peroxide will be indicated by brown colouration of the KI-Acetic acid mixture due to liberated iodine.
Now let us go over to distillation of diethyl ether.
Direct distillation of any ether, such as diethyl ether, tetrahydrofuran etc., can be dangerous and should be avoided as far as possible.
Please add anhydrous potassium hydroxide (KOH) pellets in your ether and keep at room temperature over night and then decant the ether, press sodium wire into it and then distill. The distillate would be pure anhydrous ether.
The treatment with anhydrous KOH will (a) destroy peroxide and (b) remove most of the water present in the ether.
Please observe the colour of the KOH pellets at the end of over night stay with impure ether.
Please ensure that you never distill any ether to dryness.
I would also like to request you to go through a textbook such as Practical Organic Chemistry by Vogel / Organikum.
We can purify diethyl ether from its most usual impurities by shaking with a solution of 3 g FeSO4 + 3 cm3 conc. H2SO4 + 55 cm3 H2O, and/or with 10 wt% Na2SO3 aq. ― approx. 1 vol% washing solution : ether, repeatedly. That should be followed by washing with distilled water, drying with anhydrous CaCl2 (1 day), and filtering. Alternatively, it can be dried with activated anhydrous alumina or with 4Å molecular sieves. Further purification (if required) can be achieved by distillation, possibly over sodium wire or P2O5.
First pass the solvent through alumina filter column then add anhydrous potassium hydroxide (KOH) pellets in your ether and keep at room temperature over night and then decant the ether, press sodium wire into it and then distill in the presence of 60W bulb. That temperature is enough for diethyl ether. In the case of THF you can use other systems. Then put activated seives and purge with argon.
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