PREPARATIONS 99 compounds taken. Thus in the preparation of ethyl acetate, the equation shows that 60 g. of acetic acid and 46 g. of ethanol react to give 88 g. of ethyl CH 3 COOH + C 2 H 5 OH = CH 3 COOC 2 H 5 + H 2 O 60 46 88 acetate. If equimolecular quantities of acid and alcohol had been taken in the preparation, the percentage yield of the ethyl acetate would clearly be the same if calculated on the basis of either reagent. Actually, however, an excess of ethanol was used and the yield can therefore be calculated on the basis either of the ethanol or of the acid. Thus 46 g. of ethanol should give 88 g. of ethyl acetate-'.4°g- »» M »» » 76 g. ,, M Actually 50 g. of ester were obtained. Hence yield of ethyl acetate = 5 ° X 10 ° = 66o/0 . 76 Similarly, since 60 g. of acetic acid should theoretically give 88 g. of ethyl acetate, 52 g. should give 77 g. of the ester, and hence the yield, calculated on the acetic acid, is = 65%. 77
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.