Paul M. Laughton Carleton University Ottawa, Canada
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A Separation and ldentifica+ion Experiment for ~lementaryOrganic Chemistry 'laboratory
Although a separation problem is a desirable means of drawing together many of the techniques learned in the first organic 'course, a full-scale separation and identification is too time-mnsuming and precarious, while a simple separation is not enough of a challenge. For two years we have tried a formalized and limited separation and identification experiment as a year-end project and can now recommend such an amroach to others facing the same dilemma. .. The student chooses test tube containing roughly 10 g each of two unknowns, which may or may not form a single phase. He is told that the two are selected from two of three groups: 1 (a) a primary amine or (b) a tertiary amine; 2 ( a ) an aldehyde or (b) a ketone; and 3 (a) an acid or (b) a phenol. The components are to be separated, their physical properties determined, their categories assigned, and one specified derivative prepared for each. The routine laboratory work has included most of the characterization tests, but otherwise the students are left on their own with the collection of texts and references used by the organic qualitative analysis course. The derivatives specified are: 1 ( a ) benzenesulfonamide, (b)methiodide; 2 ( a ) and (b) 2,4dinit,rophenyl-
a
hydrazone; 3 ( a ) anilide, (b) aryloxyacetic acid. The table gives a list of pairs of unknowns not found to be too difficult. The requirement is not that the unknowns necessarily be identified, but that the remaining possibilities be evaluated. Students are told that the unknowns are all to be found in the tables in a t least one of the standard texts. They may ask for any reagents they wish, but knowns for the tests are supdied a t the choice of the instructor.
Examples of Possible Combinations of Unknowns
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Ben~aMeh~~de and hen&
acid
~ ' ~ ~ a p h t h o l *,iline and pnitrohenEoie N,N-dimethylaniline and crotonaldehyde N,N-diethylaniline and acetophenone a-Naphthylamine and p-ani8ic acid Aniline and cinnamic acid and phenol ~ r i . ~ . b ~ and t ~ isobutyraldehyde l ~ ~ i ~ ~ Isoquinoline and 2-pentanone a-picoline and o-cresol Butyraldehyde and butyric acid %Pentanone and beneoic acid ~ ~ p.cresal ~ l o-Toluidine and o-cresol
Volume 37, Number 3, March 1960
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