in tetrahydrofuran; hexane byproducts: KCl; addn. of a soln. of t-butyldichlorophosphane in n-hexane to a soln. of K2((i-Pr)2NB(t-BuP)2) at -78°C, warming to 10°C within 12 h; filtn., washing with n-hexane, removal of the solvent in vacuo, cooling in a refrigerator, recrystn., elem. anal.;

in hexane