THE POLYOXYPHENOLS OF WESTERN RED CEDAR (THUJA PLICATA DONN.): I. ISOLATION AND PRELIMINARY CHARACTERIZATION OF PLICATIC ACID

Abstract

An amorphous, optically active, heat and light sensitive, polyoxyphenolic acid (pKa = 3) has been isolated from the mixture of polyoxyphenols present in the aqueous extractive of western red cedar. Analyses of crystalline derivatives are consistent with a molecular formula of C20H22O10. Color tests, spectra, methylation, and alkaline nitrobenzene oxidation results indicate it to be a propylphenol dimer, a lignan acid, in which one aromatic ring is 3-methoxy-4-hydroxyphenyl and the other is 3,4-dihydroxy-5-methoxyphenyl. Acetylation results and lactone formation require the presence of three alcoholic hydroxyls, one of which is in the γ position to the carboxyl.