2.7- Naphthalenedicarboxylic acid

Crude 2,6-naphthalene dicarboxylic acid (2,6-NDA) can be prepared by oxidizing 2,6-dialkylnaphthalenes in the liquid phase with molecular oxygen in the presence of a transition metal catalyst and an oxidation promoter. Typically, such catalysts include mixtures of cobalt and manganese promoted with bromine as an oxidation promoter. The 2,6-NDA prepared by the process, contains impurities, such as trimellitic acid (TMLA), and aldehydes. Typical amounts of impurities are shown in Table 11.1. 

TMLA is produced by tbe oxidation of one of the rings of the 2,6-di-methylnaphthalene molecule. 2-Formyl-6-naphthoic acid results from the incomplete oxidation of one of the methyl groups of the 2,6-dimethylna-phthalene molecule.  

When bromine is used as an oxidation promoter, the bromination of tbe naphthalene ring occurs during the oxidation reaction and results in the formation of bromonaphthalenedicarboxylic acid. The loss of one methyl 

6-NDA can be purified by esterification with methanol and allow to fractionally crystallize the dimethyl-2,6-naphtbalene dicarboxylate (NDC) and monomethyl-2,6-naphthalene dicarboxylate. 

Another purification method consists in dissolving the crude material acid in water in a supercritical or subcritical state, and recrystallizing. A two-stage condensation process is simpler, in which an oligomer is produced that is purified before the second condensation to the high molecular product.  

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Naphthalenedicarboxylic acid has been prepared by the present method2 and by hydrolysis of 3-cyano-2-naphthoic acid, which is obtainable from 3-amino-2-naphthoic acid by the Sand-meyer reaction.3... 

Naphthalenedicarboxylic acid is useful in the synthesis of linear polyacenes,8 3-halo-2-naphthoic acids,4 and 3-amino-2-naphthoic acid.4... 

Zinc naphthalocyanine has been prepared in low yield (18%) by the template reaction of Zn(02CMe)2, urea and 2,3-naphthalenedicarboxylic acid.1138 The synthesis of zinc tetra-2,3-naphthoporphine by a template reaction has been described.1139... 

The same group has investigated the photo-addition of alkenes to 1,2- and 2,3-naphthalenedicarboxylic acid anhydride.No products of addition of the alkene to the naphthalene ring were observed instead the alkene inserts into the C(=0)-0 bond of the anhydride or adds to one of the carbonyl groups to produce an oxetane. By analogy with imides, the insertion reaction can be viewed as an addition to the partial C-o double bond Illustrated by the contributing structure (81) to give adduct (82) which collapses to the isolated insertion product (83). 

Naphtho[2,3-c]furan-1,3-dione 2,3-Naphthalenedicarboxylic acid anhydride Ci2Hg03 716-39-2 198.174 246 si EtOH, chi s eth, bz... 

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