Solubility of glycine, leucine, and tyrosine in liquid ammonia.

Tank liquid ammonia (Ohio Chemical and Manufacturing Company) was distilled from sodium shavings into a tube of about 120 cc. volume. This was equipped with a thermocouple well, inlet and outlet side arms protected with calcium chloride and phosphorus pentoxide drying towers, and a standard taper cap containing a mercury seal stirrer. A current of dry nitrogen could be passed through the tube, over the liquid ammonia. The amino acids were C.P. products (Interchemical Corporation). After drying 3 days in a vacuum desiccator, a sample of 10 to 15 gm. was added to the liquid ammonia. The solubility tube was surrounded by partially melted crystals of ethylene dichloride (m.p. 35.39, chlorobenzene (-45.79, chloroform (63.59, or solid carbon dioxide and acetone (779, depending on the constant temperature desired. After stirring for 8 to 16 hours, the suspended particles were allowed to settle until the supernatant solution appeared perfectly clear. Then, while dry nitrogen was flowing, a glass dipper of calibrated volume was filled with the solution and placed in a test-tube immersed in frozen ethylene dichloride. Evaporation of ammonia proceeded slowly and without spattering of the solution. Finally, the solid residue was dried in the vacuum desiccator and weighed. Determinations were continued at intervals of several hours until there was no further increase in the amount dissolved. Glycine, nn-leucine, and L-tyrosine dissolved to yield clear solutions. L-Glutamic acid and L-cystine formed oily liquids which on stirring went into suspension in the liquid ammonia phase. Most of this settled out on