Condensation of o-Phthalaldehydic Acid with Dihydroxy Benzenes, Part VII: Synthesis of 3-(Dihydroxyphenyl) Phthalides and their Nitration Reactions

Abstract

The condensation of o-phthalaldehydic acid (1) with hydroquinone,

resorcinol and catechol in 30-55% H₂SO₄ afforded the corresponding

3-arylphthalide (2a, b, 3a) respectively, while with more concentrated acid

> 70% they afforded the unisolated 1,3-diaryl isobenzofuran of type (4).

Nitration of compound 2a–b, 3a–c with aqueous nitric acid/acetic acid

mixture gave the corresponding mono-nitro derivative (5, 6a–d), but in one

case the dinitro derivative(6e) was isolated. Some of these mono-nitro

derivatives show acid-base indicator behaviour. The structures of isolated

products were confirmed from their spectral and analytical data.