Thermodynamic and Magnetic Studies on the Formation of gem-Diol in an Aldehyde–Water Mixture

• Published in: Bulletin of the Chemical Society of Japan Vol. 72; no. 5; pp. 975 - 980
• Main Authors: Nakazawa, Yoshinori, Takahashi, Fujio
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.05.1999; Chemical Society of Japan
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.72.975

A thermodynamic study on the formation of gem-diol in an aldehyde–water mixture was carried out by NMR measurements. The equilibrium constants for the formation of gem-diol were determined at 280.3—298.4 K. From the relationship between the equilibrium constant and the temperature, ΔH and ΔS were obtained to be −20.4 kJ mol−1 and −101 J K−1 mol−1 in the case of acetaldehyde, and −22.9 kJ mol−1 and −110 J K−1 mol−1 in the case of propionaldehyde, respectively. It is difficult to isolate the gem-diol from an aldehyde–water mixture. The diamagnetic susceptibility of gem-diol was estimated by measuring the susceptibilities of the aldehyde–water mixture at various molar ratios. The diamagnetic susceptibility was determined using Gouy’s method. The diamagnetic susceptibilities of 1,1-ethanediol and 1,1-propanediol were −39.1 × 10−6 cm3 mol−1 and −51.5 × 10−6 cm3 mol−1 at 287 K, respectively.