The Properties of Solutions of Metals in Liquid Ammonia.

Abstract

Liquid ammonia is an excellent solvent for a large number of different types of substances (1). Although it does not surpass water as a solvent for most inorganic substances, it appears to excel as a medium for organic compounds; in this it resembles alcohol. It exhibits a distinct advantage over water in that it dissolves the alkali and alkaline earth metals without appreciable reaction with them. The fact that reaction does not proceed is undoubtedly due to the extremely low concentration of the amide ions present in liquid ammonia. This condition is substantiated by the low conductivity of pure ammonia and also by the small tendency for ammonolytic reactions to proceed as compared to hydrolytic reactions in water. Substances which are readily hydrolyzed in water are, as a rule, not ammonolyzed in liquid ammonia. Thus it is possible to study the chemical and physical properties of the strongly electropositive elements in a comparatively inert medium possessing a high dielectric constant. In the present discussion we shall confine ourselves to the physical properties of these solutions and shall attempt to give a critical account of the results of the numerous investigations. SOLUBILITY RELATIONSSolutions of the alkali metals in liquid ammonia were first investigated by Weyl in 1864 (2). He observed that sodium and potassium were soluble in this medium, producing highly colored solutions. At the time of his studies the radical theory domi-

Liquid Ammonia Chemical Lithiation: An Approach for High-Energy and High-Voltage Si–Graphite|Li1+xNi0.5Mn1.5O4 Li-Ion Batteries

“…38−43 Lithium, sodium, potassium, rubidium, cesium (alkali metals), calcium, strontium, and barium (alkali earth metals) have all been shown to form solutions with ammonia. 44 The solution of lithium metal and ammonia is a deep blue color, consisting of an ammonia complexed lithium cation and a solvated electron ([Li(NH 3 ) x ] + e − ) known as an electride salt. This solution is a powerful reducing agent that in contact with LNMO will reduce Mn 4+ to Mn 3+ .…”

“…Solutions of alkali metals in ammonia are widely used in synthetic organic chemistry to reduce aromatic compounds. Arthur Birch, an Australian chemist, first reported the “Birch reduction” reaction in 1944, in which sodium metal in ammonia was used to reduce benzene in the presence of ethanol. − Lithium, sodium, potassium, rubidium, cesium (alkali metals), calcium, strontium, and barium (alkali earth metals) have all been shown to form solutions with ammonia . The solution of lithium metal and ammonia is a deep blue color, consisting of an ammonia complexed lithium cation and a solvated electron ([Li­(NH 3 ) x ] + e – ) known as an electride salt.…”

On the Decay of theπ−Meson

“…2 Because of the very large probability for capture of the TT meson in nuclei, 3 its decay properties can only be studied in flight.…”

“…2 The results of this independent measurement of the fjT mass in terms of the w~ mass are given in Table I. The iT mass used 4 is 276w«.…”

“…This is to be compared with independent measurements of the meson masses. 2,4 The Berkeley work discussed in the last reference gives the most precise results for the w + t ir~, and M + mesons. Their method was not applied to the /x~ meson.…”