Physical investigations in the field of unsaturated aryl ethers and their derivatives

Summary

Raman spectra and ultraviolet absorption spectra have been obtained for 15 vinyl ethers of p-and o-substitued phenols. Analysis of frequencies and integral intensities of the lines corresponding to the oscillations of the double bond (ca. 1640 cm⁻¹) and the benzene ring (ca. 1580 cm⁻¹) in the Raman spectra, and also of the value of the extinction at the maximum of the absorption band (ca. 280 mμ) leads to the following conclusions:

• 1. The halogen in the vinyl ether of p-halogen-substituted phenols has a weak effect on the value of the integral intensity of the line corresponding to the C=C double bond in the vinyl group, and does not alter the frequency of this line.

• 2. Introduction of ortho-substituents into the benzene ring of vinyl phenol ethers diminisbes the intensity of the line corresponding to the double bond, which may be explained as due to increase in steric hindrance against the existence of the compound in the form of a planar conjugated structure.

• 3. Substituents in the 2 and 6 positions in the benzene ring cause splitting of the characteristic frequencies at 1640 and 1310 cm⁻¹ for the oscillations of the vinyl group. This effect may be accounted for by the presence of two rotational isomers, formed by destruction of the coplanarity of the system by rotating the vinyl group around the C_aryl−O and O−C_vinyl bonds.