The Nobel Prize in Chemistry 1910 was awarded to Otto Wallach "in recognition of his services to organic chemistry and the chemical industry by his pioneer work in the field of alicyclic compounds".
 

From apples to ylang-ylang, the range of scents and flavours that fill Nature's vast garden of plants are formed chiefly from specific combinations of volatile organic compounds, known collectively as essential oils. For decades the tools used in chemistry were deemed ill-equipped to untangle these complex and unstable mixtures, until Otto Wallach devised ways in which to reveal the essential virtues of plants. Through a carefully controlled series of reactions with common laboratory reagents (such as hydrogen chloride and hydrogen bromide), Wallach successfully characterised the key components from a wide range of essential oils and deduced their structures. The ease with which different terpenes can transform into each other made them especially tricky and fragile to study, but Wallach's methods for isolating pure essential oils from natural plant mixtures opened up a new field of research in organic chemistry.