The first value in any group of runs is not included, as this result vas invariably lower than any of the following values. Average crrors run less than 2% for any compound and individual errors are also less than t,his value, except for two of the values for benzylamine. I n most cases an error of 1 second in determining the elapsed time of titration from reading the recordings would be equal t o 2 or 3 y of amine if the current were about 2 ma.Attempts were also made to determine several aromatic amines hy the same procedure. S o n e of the compounds tested (diphenylamine, p-toluidine and phenylenediamine) gave qnantitative results.When samples of diphenylamine m r e added to the pretitrated qolvent, t,he entire solution turned violet; this color eventually faded to yellox brown. S o break in the indicator current was noted when the sample was added. This behavior is believed to be due to oxidation of the amine by oxygen generated in solution at, the anode concurrently with hydrogen ion.Fieser and Fieser (6) state that diphenylamine is readily oxidized by chemical means to tetraphenylhydrazine. This may be the reaction undergone in this solution.If the amine and perchloric acid are mixed in acetonitrile, no rolor is exhibited. The color reaction occurs in pretitrated solution, however, even after the generating current has been turned o f f . The reaction cannot then be direct oxidation of the amine :it the anode.Phenylenediamine and p-toluidine both give breaks in the indicator current, hut rewlts are very low, indicating that partial oxidation has occurred. The phenylenediamine solution turns bright yellow during the course of the reaction.Caution must be exerted in making sure that chlorides are not present in solution when hydrogen ion i-generated. Chloride is evidently oxidized to chlorine in acetonitrile and high results will be obtained. The solution also turns yellow with prolonged generation if chlorides are present.
ACKNOW LEDG3lENT4 convenient and highly sensitive paper chronlatographic method for separating homologs of low molecnlar weight 2,4-dinitrophenylhydrazones is described. Ksing phenoxyethanol-impregnated paper as the stationary phase and heptane as the mobile phase it has been found possible to obtain good separation of as much as 230 -/ of 2,4-dinitrophenylhydrazones in a single spot..1RIOUS methods have been described for the separation of 2,4-dinitrophenylhydrazones of aldehydes and ketones by paper chromatogiaphy (1, 2, 4). However, many of these systems powess serious limitations in ability to separate homologs and have other inconvenient features. Some require eqpecially impregnated paper which has t o be prepared by difficultly repi oclucible technique.I n others, the quantity of 2,4-dinitrophenylh j drazone is limited to such small amounts that detection of the spots becomes uncertain. Attempts t o increase the quantity of 2,4-dinitrophenylhydrazone in such systems leads t o strenlmg and poor separation.Neher and Wettstein ( 3 ) have described a two-phase paper chromatographic syste...
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