AN IMPROVED SYNTHESIS OF L-ASCORBATE 2-POLYPHOSPHATE

L-Ascorbate (0) reacted rapidly with sodium trimetaphosphate (STMP) at 20-25 degrees C and constant pH 9.5-10.0 in the presence of calcium i on. Barium and strontium ions also catalyzed the phosphorylation react ion, but not magnesium ion. The optimum reaction mixture was initially 1.4 M L-ascorbate, 1.8 M STMP, 1.7 M calcium hydroxide, and 0.4 M cal cium chloride. Over a 20-min reaction period, pH was maintained by add ing approximately 0.1 g calciumhydroxide in a 20% aqueous slurry. The initial and final Ca/P ratios were similar to 0.36 and 0.42, respectiv ely. The reaction products were 98.8% 2-phosphorylated L-ascorbate, 1. 2% unreacted 0, and a trace of 4,5-ene, probably formed through 5,6-ph osphorylated L-ascorbate 2-polyphosphate. High-performance liquid chro matography with W detection and preparative anion-exchange chromatogra phy showed the presence of eight 2-phosphorylated derivatives of 0 and two of the 4,5-ene skeleton. Rapid 2-phosphorylation prevented accumu lation of the 4,5-elimination reaction, and three 5,6-cyclophosphoeste rs of 0 were found in the reaction products. A Ca/Na (3fl) salt of L-a scorbate 2-polyphosphate was isolated in 88% yield as a white, odorles s powder containing 33% of L-ascorbate equivalents. Crystalline cycloh exylammonium salts of L-ascorbate 2-mono, di, and triphosphates were p repared.