Studies on Molecular Structure by the Measurement of the Dielectric Constants of Gases. III. The Dipole Moment and the Structure of Alkyl Nitrites

The dipole moment measurement was made at various temperatures on ethyl, i-propyl and t-butyl nitrites. Observed moments are 2.41D for ethyl, 2.57D for i-propyl, 2.70D for t-butyl nitrite at room temperature. The moment of the latter two compounds decrease slightly with temperature while ethyl compound remains constant. These esters are considered to consist of two isomers: the trans and the cis separated by a barrier of several kcal. due to a resonance effect. The energy difference ΔE between the two isomers is found to be zero in ethyl, <140 cal. in i-propyl, and <340 cal. in t-butyl nitrite; in the latter two the trans from being more stable. This change in ΔE with replacing R is satisfactorily explained as due to the steric energy between R and the end oxygen atom.