Otto Wallach is the German Chemist who won the Nobel Prize in Chemistry for his work on alicyclic compounds. One of his major contributions that he is known for is his isoprene rule and study of terpene which is used in turpentine today.
The early years
Wallach was the son of a high-ranking German civil servant. His father became the Auditor General at Potsdam. Born in Königsberg, Germany, Wallach spent his early years studying in a school at Potsdam. In his young age he had more liking for subjects like history and art as chemistry was hardly taught at secondary-school level.
In 1867 he went to Göttingen. There he studied chemistry with Wöhler, Fittig and Hübner. However it was not long after, that Wallach left for Berlin to study for one semester under A.W. Hofmann and G. Magnus. In 1869 and 1870 he assisted H. Wichelhaus in Berlin, while they working on the nitration of b-naphthol.
Wallach spent his time in the military during the Franco-Prussian war. After the war he spent a brief period working for "Aktien-Gesellschaft für Anilin-Fabrikation”. His ill health however prevented him from staying there for long. He could not stand the noxious fumes that were being produced in the factory. Due to this he returned to Bonn to become an assistant in an organic laboratory followed by holding the position of Professor Extraordinary and holding the Chair of Pharmacology in 1879.
Using common reagents like hydrogen chloride and hydrogen bromide, Wallach was able to characterize the differences between the structures of compounds like camphene, citrene, carvene. These were terpenes that were present in essential oils. You get terpenes biosynthetically from units of isoprene. He was able to identify which of these compounds were identical. He published the results of these findings in his book ‘Terpene und Campher’, which he dedicated to his pupils.
One of the important findings of his research is the isoprene rule. Isoprene has the molecular formula of C5H8 while the molecular formulae of terpenes are derived from the formula (C5H8)n . Here ‘n’ stands for the number of linked isoprene units; this is what is known as the isoprene rule.