Ecgonine (tropane derivative) is a tropane alkaloid found naturally in coca leaves. It has a close structural relation to cocaine: it is both a metabolite and a precursor, and as such, it is a controlled substance in many jurisdictions, as are some substances which can be used as precursors to ecgonine itself. Structurally, ecgonine is a cycloheptane derivative with a nitrogen bridge. It is obtained by hydrolysis of cocaine with acids or alkalis, and crystallizes with one molecule of water, the crystals melting at 198–199 °C.