Pyridinedicarboxylic acids, aromatic

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

Emission-titration experiments for the Eu-(1) diacetate chloride in methanol solution were carried out with the following compounds in neutral or anionic form 1,10-phenanthroline 2,2 -bipyridine tribenzylphosphine oxide benzoic, 2-pyridine-carboxylic, 3-pyridinecarboxylic, 2-furancarboxylic, 2-thiophenecarboxylic, and 2-pyr-rolecarboxylic acids various pyridinedicarboxylic adds (2,3- 2,4- 2,5- 2,6- and 3,5-). These experiments showed that neutral ligands of the phenanthroline and bipyridine type do not enhance the Eu emission even though they produce intensely luminescent complexes with the free Eu(III) ion. Aromatic monocarboxylato ligands without heteroatoms readily replace the acetate(s) in the original substrate, as shown by the... 

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