The i.r. spectrum and molecular conformation of bis-chloromethyl ether

Abstract

The i.r. spectra of bis-chloromethyl ether (ClCH 2) 2O have been recorded in the vapour, liquid and solid phases, in the region 4000-200 cm −1. The spectra indicate the presence of a conformational equilibrium between two rotameric forms, with the more stable rotamer having a gauche—gauche configuration with the two chlorine atoms opposed. A trans-gauche conformation is suggested for the less stable, but more polar, second rotamer. The dipole moment of bis-chloromethyl ether in benzene solution at 294 K was measured to be 1·29 ± 0·5D(4·30 ± 0·17 × 10 −30 Cm). From this value the energy difference between the two forms in dilute benzene solution is estimated to be 3·8 kJ mol −1. The energy difference in the vapour phase seems to be considerably larger.