Electric dipole moments of N-alkyl-nipecotamides from measurements in benzene solution

Abstract

Dipole moments of piperidine, nipecotamide, N-methylnipecotamide, N-ethylnipecotamide, NN-dimethylnipecotamide, NN-diethylnipecotamide, 1-methyl-NN-diethylnipecotamide, and NN-di-n-propylnipecotamide were measured at 25° in dilute benzene solution. The moment of N-ethylnipecotamide was also measured in dilute dioxan and mixed benzene–dioxan solutions, and was found to be larger in benzene than in dioxan. Unexpectedly low moments were found for the disubstituted derivatives. Free rotation moments were calculated for all four conformers of the nipecotamides. The moment for 1-methyl-NN-diethylnipecotamide is interpreted in terms of restricted rotation of the amide group about its bond to the ring.