Carboxylic Acids and Acid Derivatives

Experiment 12 Carboxylic Acids and Acid Derivatives

1.  Write the chemical chemical reactions involved in tests A-F. a. Solubility of Carboxylic Acids in 5% NaHCO 3. Glacial acetic acid



+ Benzoic Acid

+ H2O + CO2(g)

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+ b.  Test for Acetic Acetic acid

+ H2O + CO2(g)

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

+ NH4OH  d. Formation of Esters From carboxylic acids

+ From acyl halides

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+ H2O

+ e. Hydroxamic Test

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+ H2O

+ f. Hydrolysis of Acid Derivatives  Acetic anhydride anhydride

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CH3CONHOH +

(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 FeCl 3 solution? It should be avoided because the excess OH - would react with the Fe 3+ 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(C 6H5COO –  ) (with benzoic acid), and thus would yield to inaccurate results. 

Reference: http://chemistry2.csudh.edu/rpendarvis/carboxder.html http://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/crbacid2.htm