Chlorogenic Acid Chemical Identity
Chlorogenic acid has the molecular formula C16H18O9 and a molecular weight of 354.3. It joins caffeic acid to quinic acid through an ester bond, and the free carboxyl and several hydroxyl groups make the molecule polar and acidic. In common usage the name refers to 5-O-caffeoylquinic acid, although the numbering of quinic acid has changed over time and older papers use a different locant for the same compound.
That numbering history is a real source of confusion. Neochlorogenic acid and cryptochlorogenic acid are isomers with the caffeoyl group on other positions of the quinic ring, and they share the formula and molecular weight. The natural source here is Eucommia ulmoides Oliv., the hardy rubber tree, whose leaf is rich in this ester together with iridoids and flavonoids. Related forms from the same tree are supplied as Eucommia Leaf Extract 5–50% Chlorogenic Acid, the 10:1 Eucommia Leaf Extract Powder and the iridoid Aucubin 98%. Coffee beans are the best-known source of chlorogenic acid, but they are a different material with a different impurity profile.












