990-91-0

1623-08-1

990-91-0

An overhead stirrer, thermocouple, N2 inlet and charging funnel were assembled in a 12L round bottom flask. Dibenzyl phosphate (762 g) and isopropyl acetate (3 L) were added to the reaction flask. The mixture was cooled to 3 ± 3 °C, followed by the slow addition of 1.08 M solution of dicyclohexylcarbodiimide (DCC) (1.30 L) through the addition funnel while the reaction temperature was controlled to maintain at 3 ± 3 °C. The addition time was usually 25-35 min and the reaction was usually completed within 30 min. Upon completion of the reaction, the cold slurry was filtered and the dicyclohexylurea filter cake was washed with isopropyl acetate (3 x 600 mL). The filtrate and washings were combined and concentrated under vacuum to a final volume of 1.5 L. The concentrate was transferred to another 12 L round-bottomed flask, which was also equipped with an overhead stirrer, a thermocouple, an N2 inlet, and a charging funnel. The concentrate was diluted with heptane (500 mL) and 1 mol% of tetrabenzyl pyrophosphate (8 g) was added as a crystal seed to promote crystallization. Subsequently, heptane (4.0 L) was slowly added to the stirring slurry over 30 min at room temperature. The mixture was cooled to 3 ± 3 °C and aged for 1 hour. The slurry was filtered and the filter cake was washed with 20% isopropyl acetate/heptane solution (3 x 500 mL). The product filter cake was dried under vacuum and under nitrogen protection at room temperature overnight. The final product was obtained as tetrabenzyl pyrophosphate (671 g, 1.25 mol, corrected for crystalline species) as a white crystalline solid in 91% regulated yield and the product was stored in a refrigerator.