Method for obtaining rifapentine with a new crystalline form

A process for the preparation of the pure crystalline form of rifapentine comprising:

• mixing Dimethylformamide, tert-Butylamine and paraformaldehyde;
• adding Rifamycin S and glacial Acetic acid at 40° C.±5;
• adding paraformaldehyde and heating at 62-68° C. for 2 hours;
• adding a solution of 1-Amino-4-cyclopentyl piperazine in Dimethylformamide at a temperature of 68° C. for 16 hours;
• cooling the reaction mixture at 50° C.;
• adding a solution of ascorbic acid in water (400 mL) and mixing at 55-60° C.;
• adding ethyl acetate and water, cooling at 5-20° C.;
• filtering and washing the product with a mixture of Ethanol/water (1:1);
• squeezing and dry under vacuum at 60-65° C.;
• purify crude rifapentine and carry out re-pulping of the product.