This part of the preparation was carried out, as far as possible, under a nitrogen atmosphere. Equivalent quantities of ascorbic acid (0.463 g) and tributylamine (0.487 g) were heated in 20 ml of 200 proof ethanol at 60° C. to give a clear solution. This was cooled to room temperature and a half-equivalent of trimetrexate trifluoroacetate (0.635 g; assumed unsolvated) added and the mixture heated to near reflux to give a clear yellow solution. To the hot solution was added 50 ml of 2-propanol. A light-colored flocculent solid was immediately precipitated. The mixture was heated at 50° C. for 3 minutes, and then allowed to stand in air for about 1.5 hours. The solid was collected, washed with 2:1 2-propanol/ethanol at room temperature, and immediately transferred to a desiccator and dried (diaphragm pump vacuum) over P2O5 to give 0.425 g of the salt as a very pale yellow-green powder.
