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				Preparation of Ethyl Acetoacetate
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The condensation of two molecules of an ester (e.g. ethyl acetate), or of two 
molecules of different esters, or of one molecule of an ester with one molecule 
of a ketone under the influence of sodium or sodium ethoxide, is termed Claisen 
condensation, and is one of the best methods for preparing beta-ketonic esters 
and beta-diketones. For the purpose of the preparation the ethyl acetate must 
be carefully purified and freed from traces of acetic acid and water, and most 
of the alcohol. The latter must not be completely removed, for then the 
reaction proceeds very slowly.

1) Purification of Ethyl Acetate

   A) Inglis and Knight recommend the following method of purification: 
	The ester is dried over anhydrous potassium carbonate and then treated 
	with phosphoric anhydride (10g for 100g of ester), and boiled in a reflux 
	apparatus for 20 minutes. It is distilled off, using a fractionating 
	column, the portion boiling between 76.7°C and 77.2°C (corr.) being 
	collected. This process gives an pure substance which gives good yields 
	of ethyl acetoacetate.

   B) The ester is allowed to stand for a day over freshly heated granular 
	calcium chloride in a well-stoppered bottle, filtered into a dry 
	distilling flask and redistilled, care being taken that all parts of 
	the apparatus are perfectly dry. The fraction boiling between 
	76.7-77.2°C is collected.

2) Preparation of Ethyl Acetoacetate

30g of clean sodium are cut into thin strips, or better, pressed into wire by 
means of a sodium press (or cut in small pieces under kerosene), and introduced 
into a clean, dry, round-bottomed flask. The latter is attached to a long reflux 
condenser inclined obliquely, and fixed on a water bath. 300g of the purified 
ethyl acetate is introduced through the condenser tube, which is then fitted 
with a drying tube, and after some 15 minutes the water bath is gradually 
warmed, the temperature being regulated so that gentle ebullition takes place 
within the flask. The heating is continued for 3 hours, or until all the sodium 
is dissolved, when a mixture of 100g of glacial acetic acid with an equal 
quantity of water is added gradually until the contents of the flask show an 
acid reaction. If any solid is deposited, it is redissolved by vigorously 
shaking the flask. The liquid is then poured into a separating funnel containing 
an equal volume of saturated common salt solution, the mixture shaken, and the 
lower aqueous layer removed. The upper layer, consisting of ethyl acetate and 
ethyl acetoacetate, is fractionally distilled. For this purpose the whole is 
placed in a large distilling flask, one or two pieces of porous pot are added, 
and the flask heated in a rapidly boiling water bath until the thermometer 
indicates a temperature of 90-95°C, when the residue in the flask is subjected 
to distillation under diminished pressure. Small amounts of impurities first 
pass over, and when the temperature rises to the bp of the procuct the receiver 
is changed, and the acetoacetic ester collected. Should a large amount of liquid 
distill over before the correct temperature for the given pressure is attained, 
the first fraction is redistilled and a further yield of the ester thereby 
obtained. The yield is 45-50g.

Note: The yield is considerably lowered if the whole experiment is not completed 
	in one day. The ester is a colourless mobile liquid with a pleasant fruity 
	odour. Its boiling-point at atmospherical pressure is 181°C, but it under-
	goes slight decomposition under these conditions; it is very sparingly 
	soluble in water, but dissolves in alcohol and ether.

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