A Measure of the Electron-donating Power and Electron-accepting Power of Liquid Organic Compounds

Abstract

Abstract A quantitative study has been made of the measurement of the electron-donating nature and the electron-accepting nature of various liquid organic compounds. The position of the O–D or C=O absorption band of a liquid compound which contained a small quantity of methanol-d or of acetophenone was measured by means of an infrared spectrophotometer. The relative magnitude of the electron-donating nature or of the electron-accepting nature of the compound was compared by a measurement of the perturbation which it produced on the O–D vibrational band of methanol-d or on the C=O vibrational band of acetophenone. The electron-donating power or the electron-accepting power of a compound is defined as the relative difference (counted as wave numbers) of the O–D or the C=O absorption band observed in the compound from that in benzene. From the results, it was found that, in a homologous series, the electron-donating power decreased with an increase in the ionization potential in the gaseous phase, or with an increase in the pKb value in the liquid phase, and that it increased linearly with the co-ordination power to diethyl zinc. It was also found that the electron-accepting power increased with an increase in the electron affinity in the gaseous phase and decreased with an increase in the pKa value in the liquid phase. Moreover, the various liquid organic compounds, classified into four typical groups, were considered on the basis of their electron-donating and electron-accepting power.