Spectral and quantum-chemical investigation of ortho- and peri-hydroxy-substituted mono- and diformyl derivatives of 1,5-naphthalenediol

Spectral and quantum-chemical investigation of ortho - and peri -hydroxy-substituted aldehydes, 1,5-naphthalenediol derivatives, was carried out. An unusual spin-spin coupling through an intramolecular hydrogen bond was discovered in the molecule of 1,5-dihydroxynaphthalene-4,8-dicarbaldehyde. It was shown that this dialdehyde is involved into the ring-chain tautomerism. The position of this equilibrium was examined depending on the temperature and the solvent polarity. The effect of the solvent polarity on the benzoid-quinoid tautomerism in the dihydroxynaphthalene-2,6-dicarbaldehyde was established. By the method of quantum-chemical calculations the relative energy stability and conformational structure of dialdehydes were revealed.