Microwave Spectrum of trans-2,3-Epoxybutane

The microwave spectrum of[Complex chemical formula]was studied from 8 to 40 Gc/sec. The rotational constants and the dipole moment of the main isotopic species in the ground torsional state were found to be A = 12 237.38 Mc/sec, B = 3 423.02 Mc/sec, C = 3 072.52 Mc/sec (κ=−0.9235122) and μ=2.03±0.04 D, respectively. An approximate structure was obtained by varying the two least-well-known structural parameters to fit the observed moments of inertia, and a barrier to internal rotation of 2444±150 cal/mole was obtained from the splittings of the lines in the ground torsional state. These results are discussed in terms of steric effects in this molecule and in the cis isomer studied by Sage.