| 摘要 |
PURPOSE: Provided is a process for preparing 4,6-dichloro-5-fluoropyrimidine which allows the preparation on an industrial scale without addition of bases and where phosphate-containing wastes are avoided or produced in only small amounts. CONSTITUTION: The process for preparing 4,6-dichloro-5-fluoropyrimidine (I), comprises: a) reacting a compound of the formula(II), in which R represents methyl or ethyl with formamide in the presence of alkali metal alkoxides, optionally in a diluent at elevated temperature, optionally, under pressure, and the reaction mixture is, optionally acidified with an acid after the reaction, and, optionally without intermediate isolation of the compounds of the formula(III); and b) reacting the resulting 4,6-dihydroxy-5-fluoropyrimidine (III) or its alkali metal salt with phosphorus oxychloride, to form reaction mixture 1, subsequently reacting reaction mixture 1 with chlorine in the presence of phosphorus trichloride such that up to 99.9% by weight of any chlorophosphonic acid is converted to phosphorous oxychloride, thereby forming reaction mixture 2, and distilling reaction mixture 2 to separate the 4,6-dichloro-5-fluoropyrimidine formed and to recover the phosphorus oxychloride.
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