Katsuya Mukae

Effects of pressure and temperature on the solubility of monosodium L-glutamate monohydrate in water

Abstract The solubility of monosodium L-glutamate monohydrate (MSG.H2O) in water was measured at pressures in the range of 0.10-300MPa and 298.15K. The density of MSG solution at high concentrations and heat of solution at saturated concentration were also measured at atmospheric pressure. The solubility, ms, increased with increasing pressure and the pressure coefficient, Θp, [≊(∂ In ms,∂ p)T] at 0.10 MPa was (2.0 ± 0.1) × 10-10Pa-1. It agrees well with (2.1 ±0.2)× 10-10 Pa-1 thermodynamically estimated using the partial molar volume, the activity coefficient of the solute in solution, and the molar volume of the crystal. The excellent agreement at 0.10MPa gives us confidence in the solubility data at higher pressures. The heat of solution data and other pertinent values were used to calculate the temperature coefficient of solubility, ΘT [≊ (∂ In ms/∂(1/T))p], by a thermodynamic equality. The resulting ΘT compares well with the data directly measured by Ogawa.

Preparation and Optical Resolution of a New Helical Lactone Carrying the 2,8-Dioxabicyclo[3.3.0]octane Ring System

A new overcrowded lactone (3) carrying the 2,8-dioxabicyclo[3.3.0]octane ring system was prepared by a simple treatment of tetraol (1) (prepared from 2,7-dihydroxynaphthalene and glyoxal) with 3,5-xylenol, and readily resolved into its enantiomers having a specific rotation of >800° (absolute value). A preliminary experiment demonstrated that 3 would be a promising resolving agent.