Organic Synthesis

Ethyl acetate and acetamide preparation

Theory: 

Ethyl acetate CH3COOC2H5 is an ester of acetic acid and ethyl alcohol. The compound is a colourless liquid  at a room temperature with a boiling point of 77.1 °C and density 0.902 g/cm3. The liquid is immiscible with water but miscible with most of the organic solvents. On laboratory scale the compound is prepared by the Fisher esterification with yield up to 65 %. In industry it can be prepared using from acetic acid and ethylene with silicotungstic acid used as a  catalyst [1]. The compound is widely used as a solvent mainly for column chromatography in organic chemistry and also as a nail polish remover in a daily life. It can be used for decaffeinating of tea or coffee besides carbon dioxide supercritical fluid extraction proccess.

acetamid

ethyl acetate and acetamide structures

Acetamide is a colourless hygroscopic solid at a room temperature. It is a primary amide that is produced by dehydratation of ammonium acetate. Acetamide is naturally found as a rare mineral acetamide that crystallizes in trigonal crystal system. The other route to acetamide envolves ethyl acetate and concentrated ammonia water solution and is described below.

Procedure:

To a 250 mL round bottom flask 96 % ethanol (40 mL, 32.05 g, 668 mmol) was placed along with the same volume of pure acetic acid (40 mL, 42.15 g, 688 mmol). Few drops of concentrated sulfuric acid and boiling chips were added to a mixture. A simple apparatus for reflux was set up. The mixture was refluxed for an hour. After cooling down it was transfered into a separatory funnel. Lower aqueous phase was discarded. Organic phase was washed twice with 15 mL of distilled water and then twice with 30 mL of approximately 15 % water solution of sodium carbonate. Organic phase was dried over anhydrous calcium chloride and the product was redistilled collecting a fraction boiling between 76-78 °C. Yield: 50-60 %.

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Ethyl acetate (10 mL, 9.02 g, 102 mmol) was placed into a 250 mL beaker along with 7 mL of 27 % ammonia water solution. Additional 13 mL of water were added to the mixture. Two separate layers are observed at this stage. The mixture was vigorously stirred for 24 hours until homogenous water solution resulted. The solution was poured to a large container and let freely to crystallize (the solution should not be heated due to a hydrolysis of the product!). Crystalline product should appear after several days.

Literature:

[1] Gurav, H.; Bokade, V. V. Journal of Natural Gas Chemistry, Vol. 19, p. 161–164 (2010).

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