JUNE. 1953
PREPARATION OF SOLUTIONS OF PHOSPHORUS IN CARBON DISULFIDE SIDNEY HEILVEIL E. I. du Pont de Nernours & Company, Inc., Camden, South Carolina
IN GENERAL, the procedure for preparation of solutions of white phosphorus in carbon disulfide is hazardous and unsatisfactory. A method is presented here which obviates most of the dangers and leads to solutions of higher purity. Usually instructions call for the cuttmg of sticks of white phosphorus under water. These pieces are then dried with absorbent toweling t o remove the water and then placed in a beaker containing the desired amount of the solvent, carbon disulfide. If the pieces are too small, there is a serious danger of ignition upon drying. If the pieces are too large, solution is slow, and in either case the solution is contaminated with the oxides of phosphorus from the surface of the sticks, and water that was not removed during drying.
I t is suggested that solutions be prepared in this fashion: Place the carbon disulfide in a separatory funnel, choosing such a size that the funnel will be less than half-full. Then cut the sticks of phosphorus under water into small pieces. These pieces are transferred without drying to the separatory funnel and 5 ml. to 10 ml. of water for every 200 ml. of carbon disulfide are added. This additional water may be necessary to break the emulsion formed when the CS2/H20 ratio is too large. The separatory funnel is shaken to dissolve the phosphorus (care being taken t o relieve the pressure built up). A relatively pure solution of phosphorus in carbon disulfide can then be drawn off, since the water and carbon disulfide are immiscible and the surface oxides of phosphorus remain a t the interface.
