The Analysis oi an Amine Mixture: An Introductory Analysis Experiment
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In recent ye.xr-. rheanalytic:tlchem:it has hem c ,lltct upon I. Ise v e n .Ihrt., all prohlrrns.Therr hns been iL*n-iderablr discussion of the need to hring problem sdving m u the student*' underyr.dtute expcrience, and several ACS meetings have mnde this their i d point. A t t h e ~ n w time, then! have been wry few lhhomwry exprriments which a d d m 11wmselvn t o the training of students. For over five years, the students in our beginning analytical chemistry course have performed the analysis of a binary mixture of smines. They are asked t o identify each component and determine the weight percentage of each compound. It is necessarv for the students to draw unon their nrevious knowledge of omanic chemisttv t o solve this problem. While there are no specific directions given to tde student; several general techniques are employeh. In order t o get the students started, they are asked to perform an aqueous potentiometric titration. This quick experiment gives them some information concerning the nature of the amines such as the water solubility, mole percent of each component and a rough estimate of the pK. values of the bases. In the past several years, an automatic titration system has been set up and the data fed into a PDP-11 computer. A print-out gives the volumes required for each amine and an estimate of the pK .values. After this experiment has been completed the student has to decide whether the endpoints are sufficiently well-defined in aqueous solution. If not, nonaqueous solvents such as acetonitrile or glacial acetic acid are used for the titrations. After these titrations are oerformed. the students have established the relative mole nercent of each com~onent. In order w idwlify each n~rnpounrl,;I wide range dteehniques have bwn utilized. Most studenlv employ ~nlriaredand Some wc ultra-violet analysis I v lmd oul NMR s p ~ c t r a analysis l as rlwir methods ot'choire t u irlrntcfy thv if the ~c,mponent< are aromxn. \Ian! atmlents chn
