Abiotic conversion of dihydrophloroglucinol to resorcinol

Chemical conversion of a dihydrophloroglucinol preparation (a mixture of the tautomers 1,3,5-trihydroxy-1,3-cyclohexadiene, 1,3-dioxo-5-hydroxycyclohexane, and 3,5-dihydroxy-3-cyclohexene-1-one) to resorcinol occurred during a 24-h extraction of an acidic (pH 2.0) aqueous dihydrophloroglucinol preparation into ethyl acetate. This conversion did not occur at neutral pH, nor did phloroglucinol (1,3,5-trihydroxybenzene)-induced or succinate-induced Penicillium simplicissimum enzyme extracts convert the dihydrophloroglucinol preparation to resorcinol at pH values of 5.5–8.0. The chemical structure of the dihydrophloroglucinol preparation was determined by gas chromatography - mass spectrometry, high resolution 13C and 1H nuclear magnetic resonance, Fourier-transformed infrared spectrometry, and ultraviolet spectrophotometry. Resorcinol (1,2-dihydroxybenzene) was detected by gas chromatography - mass spectrometry or thin-layer chromatography and ultraviolet spectrophotometry. A chemical mechanism for the conversion of the dihydrophloroglucinol preparation to resorcinol is proposed.