| 摘要 |
A condensed aromatic bis-(2,4-dihydroxypyridine) of the formula WHEREIN Ar represents a tetravalent aromatic radical such as phenylene, diphenylene, naphthylene, diphenyl ether, diphenyl methane and the like, and a process for producing these compounds by reacting an aryl diamidomalonic acid dialkyl ester with polyphosphoric acid at an elevated temperature and subsequently precipitating the reaction product.
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