Hinsberg’s Method For Characterizing Primary, Secondary, And Tertiary Amines
1.
Show by means of a schematic diagram how Hinsberg’s test distinguishes primary, secondary, and tertiary amines.
2.
Suggest another method of differentiating primary, secondary, and tertiary amines. The Hinsberg’s test has its limitations. It cannot be employed to distinguish amphiprotic amines because the carboxylic acid will be deprotonated thus resulting in soluble sulfonamide. Another method that can be used to differentiate primary, secondary, and tertiary am ines would be reacting amines with nitrous acid. Primary amines, when reacted with nitrous acid, g ive off an emission of nitrogen gas. Secondary amines, when reacted with nitrous acids, result in the production of nitrosamine-yellow oil which is a powerful carcinogen and is the reason why the nitrous ac id test is not quite commonly used. Tertiary amines, when reacted with nitrous acids, seem to have no observable react ion-it actually results in a colorless solution. The colorless solution is actually the result of the ter tiary amine reacting with the acid thus forming an ion. Another method applicable is the IR spectroscopy. The amines are differentiated by the IR absorption bands they give off from their N— N—H stretching vibrations. Tertiary amines lack N— N —H groups therefore they do not give off absorption bands in this area. Primary amines give off two w hile secondary amines give off one.
References: [1] Owen, T. (1969). Characterization Characterization of Organic Compounds By Chemical Methods. Methods. USA: Marcel Dekker, Inc. [2] Solomons TW, Fryhle C. (2011). Organic Chemistry . 10th ed. NJ: John Wiley & Sons Inc. s
