| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of producing 7,8-difluoro-2,3-dihydro-3-methyl-4H-1,4-benzoxazine. The method is realised via hydrogenation of 2-acetonyloxy-3,4-difluoronitrobenzene with hydrogen in the presence of palladium on a Sibunit carbon support as a catalyst. The process takes place in isopropyl alcohol at pressure 3.0-3.5 bars and temperature 30-50C. Extraction and drying of the desired product is carried out by successively turning it into 7,8-difluoro-2,3-dihydro-3-methyl-4H-1,4-benzoxazine hydrochloride by treating with 1.5-1.7-fold excess hydrochloric acid in a water-toluene solution and then into free 7,8-difluoro-2,3-dihydro-3-methyl-4H-1,4-benzoxazine by treating 7,8-difluoro-2,3-dihydro-3-methyl-4H-1,4-benzoxazine hydrochloride with an aqueous alkaline solution and vacuum distillation. ^ EFFECT: improved method of obtaining a composition with high content of basic substance. ^ 5 ex |
