| 摘要 |
A novel, simple, high-yield process for the production of 2,3,5,6-tetrachloropyridine comprises reacting an ester of 2,2,4-trichloro-4-cyanobutyric acid with excess phosphorus oxychloride in the presence of a catalytic amount of hydrogen chloride and optionally in the presence of an aprotic inert solvent, at a temperature of 100-160 .degree.C, preferably at 120-140 .degree.C for about 5-10 hours, under elevated pressure, if necessary.
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