alpha 1 2 3 5 tetra o acetyl l ribofuranoses and u02dc 27 of beta 1 2 3 5 tetra o acetyl l ribofuranoses 37 g of acetic anhydride at ambient temperature the mixture was distilled at atmospheric pressure bath temperature 90 u00b0 c when the pot temperature reached 85 u00b0 c and the distillation became very slow vacuum was applied up to 30 mbar and the distillation was continued for 40 minutes at 90 u00b0 c bath temperature and then for another 40 minutes at 120 u00b0 c bath temperature the pot temperature reached 117 u00b0 c the vacuum was released and 843 mg of triflic acid was slowly added after the addition the vacuum was restored and the mixture was stirred at 115 u00b1 5 u00b0 c pot temperature for 4 h upon the completion of the reaction the mixture was cooled to 70 u00b0 c and to it was added 750 ml of 2b alcohol ethyl alcohol when a homogeneous solution was formed the mixture was cooled to 50 u00b0 c and held until heavy precipitation formed seeding might be necessary the mixture was then slowly cooled to u2212 5 u00b0 c bath temperature in 2 h and held for at least 2 h the solid was filtered washed with 100 ml of cold 2b alcohol ethyl alcohol and dried under vacuum at 50 u00b0 c for 17 h to.