V O L U M E 2 1 , NO. 10, O C T O B E R 1 9 4 9
1209
The effect of solvents was studied by adding 0.10 ml. of ,tcrylonitrile to the solvent, then adding 0.10 ml. of piperidine, ind after 5 minutes treating the mixture with 5.0 ml. of picric icid solution. The results are summarized in Table 111. The nielting point&are those of the once recrystallized picrates. DISCUSSION
If the sample of unknown is neutral or nearly so and contains significant amount of acrylonitrile, the most likely cause of i’nilure of the method is the use of too high a proportion of piperidine. This is illustrated by the data of Table 11. The aminonitrile is formed but its picrate is not precipitated in the presence of excess piperidine. Other bases of the same order of basic ,sti,ength interfere for the same reason, but aniline is too weak a I m e to cause interference. .kids such as acetia acid apparently interfere by conversion of t lir piperidine to the corresponding nonreactive salt. \T’ith inert solvents interference probably arises through retardiiig of thta reaction between acrylonitrile and piperidine by simple ililution Pffect. For example, if the mixture of 0.10 ml. of acrylonitril(,, 1 .O ml. of tienzene, and 0.10 ml. of benzene (Table 111)is :illo\\-otI to stand for 10 minutes instead of 5 before being added t o picric ticid solution, a considerably larger amount. of picrate is obt:iinecl. .icrylonitrile a t 1% by volume in benzene is readily derwted b~ adding the appropriate amount of piperidine, refluxing :I fe\v minute.
