結晶水あるいは結晶溶媒を有する有機化合物の研究 (第7報)

Abstract

Menadione sodium bisulfite is given as containing 2 moles of crystal water in J.N.F. II, and as 3 moles in U.S.P. XV. Therefore, a sample containing 2.03 moles of water was submitted to isotherm reaction with water vapor. Absorption of water vapor on this sample was carried out at 29.5° and the amount absorbed and equilibrium pressure were measured with a quartz spring balance and mercury manometer. Absorption curve showed a very slow rate in reaching equilibrium and the curve did not overlap the desorption curve, from which the absorption was found to be a reaction. Since the desorption curve and resorption-desorption curve were identical, reversible, and the time required to reach the equilibrium was so short that the curve is assumed to be a physical desorption curve, and the level portion of 19.0-19.5% of water content, was taken as that of crystal water. Relationship between the amount and time of reaction was determined by varying the temperature and humidity, and the value became constant 19.6% of water at a low temperature and humidity, at 0° and 90%, which agreed well with a theoretical value of 19.54% for 3 moles of crystal water. When the temperature became higher and humidity lower, dehydration reaction occurs and, therefore, the sample used containing 2.03 moles of water must be a product, in which a part of 3 moles of crystal water had been dehydrated.