Phthalonic acid

Homophthalic acid may be obtained by the oxidation of in-dene,3-4 the reduction of phthalonic acid,6-6 and the hydrolysis of o-carboxyphenylacetonitrile.7 Other methods are listed in an earlier volume.3... 

Homophthalic acid has been prepared from naphthalene via phthalonic acid 1 from hydrindone by nitrosation, hydrolysis, and hydrogen peroxide oxidation 2 from hydrindene by oxidation with chromic and sulfuric acids 3 and from o-toluic acid by bromination of the acid chloride followed by treatment with alcohol and sodium cyanide and hydrolysis with 50 per cent sulfuric acid.4 Since phthalide has become commercially available, the preparation outlined above, essentially that described by Wis-licenus 5 fifty-six years ago, is by far the simplest and most economical. 

Lutidine Pyridine, dimethyl- Phthalonic acid Benzeneacetic acid, 2-carboxy-a-oxo-... 

Preparation of acids by the reduction of keto acids is possible when the carbonyl group is in the alpha or gamma positions or further removed from the carboxyl group. The a-keto acid, phthalonic acid, is reduced to o-car-boxyphenylacetic acid (homophthalic acid) in excellent yield by phosphorus and potassium iodide in phosphoric acid " or by constant-boiling hydriodic acid." ... 

Another method of decarboxylating a-oxo acids makes use of the bisulfite compounds, the conversion of phthalonic acid into phthaldehyde described on page 1045 being an example of this. 

When naphthalene is degraded by permanganate under precisely defined conditions, phthalonic acid can be isolated instead of the usual phthalic acid, and this intermediate can be decarboxylated to phthalaldehydic acid (see page 1007) 150... 

Under photostimulation conditions, o-halogenated benzoic acid has been doubly car-bonylated to give phthalonic acid catalyzed by cobalt carbonyl complex. ... 

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