preparation of diethyl ether

7/30/2019 Preparation of Diethyl Ether

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Preparation of Diethyl ether

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Preparation 1

This is somewhat dangerous to perform with the right equipment, and

without the right gear, very dangerous!

Diethyl ether, or CH3CH2-O-CH2CH3, is a great solvent for many things, but

is extremely flammable. Professional chemists will be well appraised of the

hazards presented in using ether, but the layperson is less likely to be aware

of these dangers. Diethyl Ether vapors 'hug' the ground, and in dry air

explosive peroxides can form. In other words, even in a spark/flame free

environment, explosions can still happen when ether vapour is encountered.

For this reason its probably a good idea to have some way of removing

vapours from the vicinity (a fume hood would be a fine example) and

(Zaphraud suggests) one should not use ether on days with extremely low

humidity. Because diethyl ether is so flammable, and prone to ingition, this

procedure should be carried out using a hotplater/stirrer designed for use in

flammable environments. Such a heater/stirrer does not produce a contact

spark when the hotplate is turned on, and generally employs a brushless AC

motor for the stirrer, because DC motors with brushes generally producesmall sparks which could ignite any stray vapours.

Diethyl ether is prepared from ethanol (a.k.a grain alcohol, ethyl alcohol,

drinking alcohol) by heating it with concentrated. The reaction proceeds thru

an intermediary, "Ethyl sulfuric acid", as do most reactions of this type.

Preparation 1

by Zaphraud

The reaction is conducted as follows:


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Dry (anhydrous) or nearly dry ethyl alcohol is allowed to flow into a mixture of

alcohol and sulfuric acid heated to 130 c-140 c. The vapors are collected, and

ether and some alcohol and water condense out. The sulfuric acid is a

catalyst, but since it becomes more and more dilluted as a consequence of

the water produced by the reaction, the process becomes inefficient (which is

why anhydrous ethanol is the best!)

The temperature of the reaction should be controlled carefully. At

temperatures below 130 c, the reaction is too slow and mostly ethanol will

distill. Over 150 c, the ethyl sulfuric acid decomposes, forming ethylene

instead of combining with ethanol to form ether.

95% ethanol may be recovered from water + CH3CH2OH pulled from the

bottom of the fractioning column (marked 'out')... by connecting it to another

column and distilling it...

This may be converted to 100% ethanol by mixing the 95% with calcium

oxide and distilling - the water is used up to make Calcium hydroxide! This in

turn can be re-fed to the "FEED TANK" after cooling.

Preparation 2

by Eleusis

Though this is not the most pleasant process, Diethyl Ether may be produced

by the condensation of ethanol. To do this, assemble a typical fractional

distillation setup with a vigreux column and a three neck flask. Don't forget to

drop a stirrer magnet into the flask before clamping everthing up, and you

will be heating this on an oil bath (no flames allowed when Ether is around,

you know). The vigreux column goes in the central neck, an addition funnel in

one side beck, and a thermometer goes in the other side neck.

Add 2x moles (where the x is a multiplier, 1 = 2 moles, 1.5 = 3 moles, etc...)

of the azeotrope of Ethanol (ie. 95% ethanol, Everclear) to the flask. Add 2x

moles of concentrated (98%) Sulfuric Acid (ie - Instant Power Drain Opener)

to the Ethanol slowly (it will heat because of the water). Turn on the stirrer,

turn on the heat, and bring the flask up to 130C. Make sure your condenser is


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well supplied with cold water, and continue heating till the contents of the

reaction flask reach 135 C or so.

Once distillation commences, slowly add up to another 2x moles of Ethanol

through the addition funnel at a rate equal to the drops coming from the

condenser. 2 moles of alcohol (114g) should take 1 hour with a decent

vigreux column. A shorter column (or, gasp, no column at all) will require

slower distillation (and if you don't use a column, you will have to do some

extensive washing of the product with saltwater).

Dump the receiver flask contents into a large beaker or bowl and swirl with

10% Sodium Hydroxide solution until the pH is neutral. Pour this mixture into

a separatory funnel to separate the Ether from the aqueous hydroxide and

wash twice more with equal volumes of half-saturated Sodium Chloride

solution (~18g/100mL of water @ room temp). Let the last wash solution +

Ether rest in the flask until everything has settled, then carefully drain off the

wash, and pour the Ether out of the top into a round bottom flask. Add 15g of

Calcium Chloride (Damp-Rid) for every mole of Ether, drop in stirrer magnet

and stir for 2 hours.

Distill the Ether from the Calcium Chloride by heating on a bath (oil or water)

at no higher than 45C! Collect distillate that comes over in the range of 31-36

C.

Preparation 3

Diethyl Ether

This is also called ethyl ether or ether and must not be confused with

petroleum ether. If, for example, you see a formula calling for ether, then itrefers to diethyl ether, if it does not specify petroleum ether, then do not use

petroleum ether. 100g of ethanol (dry ethanol is best) is placed in a 1/2 liter

distilling flask, and with good cooling, 180g of concentrated sulfuric acid

(98% H2SO4 is added slowly. This flask needs a thermometer fitted, so that

the bulb dips down below the liquid surface. The addition funnel should

extend below the surface, so that the ethanol can be added below the

surface of the acid. Heat and maintain the mixture's temp at 140-145 c by


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heating on a sand bath. Ethanol is run in from the addition funnel at the same

rate as the liquid distills over (about 2 drops per second). Mark the flask

before distilling, so that you can be sure of the addition rate. After about

150g of alcohol (ethanol) has been added, stop heating. The distillate will

require the following purification steps: Shake twice with 50 cc of 10% sodium

hydroxide solution, to free from sulfuric acid. Shake twice with 50 cc ofsaturated sodium chloride solution, to free from ethanol. The ether is then

dried over anhydrous calcium chloride for 24 hours and distilled on a water

bath, collecting the fraction boiling at 35 C. Yield: 100g.

Anhydrous Ethyl Ether. This is for those formulas calling for dry, pure, or

anhydrous ether. The ether product from above is dried over thin slices of

metallic sodium (metallic sodium wire works well also) for 24 hours. Then the

ether is distilled on a water bath, over fresh (fresh means a different batch

than what you used to dry with) metallic sodium. Note: Ether developsexplosive peroxides upon sitting for any length of time, even if just purchased

from a supply house. Therefore, before handling ether, which has been

stored, shake with ferrous sulphate or with lead peroxide. To keep peroxides

from forming in fresh ether; add several sections of copper or iron wire to the

dark container and store in a cool place.

preparation of diethyl ether

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