Effect of Ring Size on the Infrared Spectra of Cyclic Ethers. Characteristic Frequencies of Trimethylene Oxides and Tetrahydrofurans

Abstract

The infrared spectra of several trimethylene oxides and tetrahydrofurans have been obtained. These rings are characterized by very strong bands at 10.2 to 10.3 and 9.1 to 9.3 n respectively. The trimethylene oxides also show consistently strong bands at 8 microns. It is also shown that these strong infrared bands fit in regularly with similar bands of the 3- and 6-membered rings. It is shown that this series of infrared bands arises from an antisymmetric type vibration of the ether links and that corresponding vibrations of the cyclic hydrocarbons give rise to frequencies which form a similar series. The strong polarized Raman bands of these series are also added for comparison. © 1953, American Chemical Society. All rights reserved.