A High-Resolution Microwave Study of the Conformations of Butan-2-ol in a Supersonic Expansion.
The microwave Fourier transform spectrum of the chiral, secondary alcohol butan-2-ol has been recorded in the range 6-18 GHz. The spectrum is relatively dense, due to the large number of species formed in the supersonic expansion used. Three conformational isomers of the butan-2-ol molecule have been identified and their spectra assigned using a semirigid, asymmetric-rotor model. They correspond to the three configurations that the central C-C bond can adopt. The basis of our assignment is a series of ab initio calculations, which have been performed using the GAUSSIAN 94 package, good agreement being observed between theoretical and experimental values of the rotational constants. First-order centrifugal distortion coefficients have also been extracted. It has proven possible, by examination of the relative strengths of a-, b-, and c-type transitions, to infer some further information about the position of the hydroxyl hydrogen atom within each conformer. Copyright 2001 Academic Press.
King
AK
Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, OX1 3QZ, United Kingdom
Howard
BJ