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Experiment 12 Carboxylic Acids and Acid Derivatives 1. Write the chemical reactions involved in tests A-F. a.

Solubility of Carboxylic Acids in 5% NaHCO3. Glacial acetic acid

+ Benzoic Acid

+ H2O + CO2(g)

+ b. Test for Acetic acid

+ H2O + CO2(g)

+ NaOH Fe(OH)2(CH3COO-) c. Test for Benzoic Acid

+ NH4OH d. Formation of Esters From carboxylic acids

+ From acyl halides

+ H2O

+ e. Hydroxamic Test

+ H2O


+ Hydrolysis of Acid Derivatives Acetic anhydride


(CH3CO)2O + H2O Esters + NaOH Amines + NaOH + NH3 +

2. Why would acyl halides yield higher amides compared to carboxylic acids or esters on reactions with ammonia? Acy l halides have higher yield due to the fact that it is much more unstable and therefore much reactive than carboxylic acids and esters. The leaving group (X-) causes acyl halides to be more reactive than carboxylic acids and esters. 3. Why should excess alkali be avoided in the test for acetic and benzoic acid using FeCl3 solution? It should be avoided because the excess OH- would react with the Fe3+ forming a red orange complex [Fe(OH)3]. The Fe3+ would be less available for the production of the red complex Fe(OH)2(CH3COO) (with acetic acid) or the flesh colored precipitate Fe(C6H5COO) (with benzoic acid), and thus would yield to inaccurate results. Reference: