The invention provides a preparation method of high-purity
rifapentine, which is characterized by comprising the following steps: 1. carrying out a cyclization reaction on
rifamycin S acid, acid and dimethyloltert-
butylamine in an N, N-
dimethylformamide solvent; 2, pouring the reaction solution into
acid water, standing, and filtering to obtain a rifaxizine
filter cake; 3, adding
urea, n-butyl
alcohol, Vc and
sodium carbonate into the rifaxizine
filter cake for a ring-opening reaction; 4, after the reaction is completed, increasing the purity to 1-amino-4-cyclopentylpiperazine for a
condensation reaction until the reaction is completed so as to obtain a
rifapentine reaction solution; and step 5, dropwise adding
acid water into the
rifapentine reaction solution, stirring, stopping heating after
crystallization, lowering the rotating speed after turning red, cooling after dropwise adding is finished, filtering to obtain the
filter cake, and carrying out secondary recrystallization on thefilter cake. According to the preparation method of the high-purity rifapentine, provided by the invention, the maximum single
impurity of the rifapentine can be controlled within 0.1%, and the residual n-butyl
alcohol and the residual
ethanol can be controlled within 0.5%.