Undergraduate Analytical Chemistry Experiment: The Determination of Formation Constants for Acetate and Mono- and Dichloroacetate Salts of Primary, Secondary, and Tertiary Methyl- and Ethylamines

• Autores: Ronald P. D' Amelia, Stephanie Chiang, Stephanie Pollut, William F. Nirode
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 91, Nº 7, 2014, págs. 1070-1072
• Idioma: inglés
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• Resumen

  • The formation and the hydrolysis of organic salts produced by the titration of a 0.1 M solution of the following amines: methyl-, dimethyl-, trimethyl-, ethyl-, diethyl-, and triethylamine with a 0.1 M solution of acetic, chloroacetic, and dichloracetic acids are studied. The pKb of the amine and the pH at the end point were determined for each reaction from the corresponding titration curve. The experimentally determined values were in very good agreement with the literature and calculated values. The salt formation constants (Ksf) for acetate and mono- and dichloroacetate salts of primary, secondary, and tertiary methyl- and ethylamines were also determined. The conclusions were as follows: (1) the pH at the end point decreased as the strength of the titrating acid increased, (2) the stronger the amine base, the higher the pH at the end point, and (3) the Ksf increased with increasing acid and base strength.