An Investigation of the Reduction of Carbon-Carbon Unsaturation by Alkali Metals in Liquid Ammonia

Introduction: The properties of liquid ammonia are similar in many ways to those of water. Liquid ammonia has the very high specific heat of 1.10 calories per gram. Hydrogen bonding occurs to a considerable degree although not as extensively as in water. Evidence of hydrogen bonding as reflected in boiling points is shown in Table I. The dielectric constant is 22 at -33° which is also very high for a solvent which is comparatively inert to reactive metals. (Hexane has a dielectric constant of 1.87.) Liquid ammonia is a much better solvent for organic compounds than water. Even such large molecules as steroids can be put into solution in ammonia by using co-solvent such as diethyl ether. Liquid ammonia's major disadvantage as a solvent is its low boiling point, -33.4°. However, for many purposes it can be used at room temperature without special equipment (other than a good hood) since it evaporates slowly due to its high heat of vaporization, 327 calories per gram.