<P> Vitalism survived for a while even after the rise of modern ideas about the atomic theory and chemical elements . It first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen . A more decisive experiment was Wöhler's 1828 synthesis of urea from the inorganic salts potassium cyanate and ammonium sulfate . Urea had long been considered an "organic" compound, as it was known to occur only in the urine of living organisms . Wöhler's experiments were followed by many others, in which increasingly complex "organic" substances were produced from "inorganic" ones without the involvement of any living organism . </P> <P> Even though vitalism has been discredited, scientific nomenclature retains the distinction between organic and inorganic compounds . The modern meaning of organic compound is any compound that contains a significant amount of carbon--even though many of the organic compounds known today have no connection to any substance found in living organisms . </P> <P> The organic compound L - isoleucine molecule presents some features typical of organic compounds: carbon--carbon bonds, carbon--hydrogen bonds, as well as covalent bonds from carbon to oxygen and to nitrogen . </P> <P> Still, even the broadest definition (of "carbon - containing molecules" as organic) requires excluding alloys that contain carbon, including steel . Other' excluded' materials are: compounds such as carbonates and carbonyls, simple oxides, halides and sulfides of carbon, the allotropes of carbon, and cyanides not containing the − C ≡ N functional group--all which are considered inorganic . </P>

Classification of organic compounds based on their structure