chloroatranorin noun1 •One of the most common allergens found in treemoss, along with atranorin, having the same molecular structure as atranorin but with one of the hydrogen atoms replaced by a chlorine atom.The method of purification described by St. Pfau by repeated crystallisation from chloroform, in which chloroatranorin was sparingly soluble, was laborious and incomplete over a number of stages. — 1963
