|Died||26 February 1931 (aged 83)|
|Nationality||Prussia / German Empire|
|Alma mater||University of Göttingen|
|Known for||Isoprene rule|
|Institutions||University of Göttingen, |
University of Bonn
|Doctoral advisor||Hans Hübner|
|Doctoral students||Walter Haworth, Adolf Sieverts|
Wallach was born in Königsberg, the son of a Prussian civil servant. His father, Gerhard Wallach, descended from a Jewish family that had converted to Lutheranism. His mother, Otillie (Thoma), was an ethnic German of Protestant religion. Wallach's father was transferred to Stettin (Szczecin) and later to Potsdam. Otto Wallach went to school, a Gymnasium, in Potsdam, where he learned about literature and the history of art, two subjects he was interested his whole life. At this time he also started private chemical experiments at the house of his parents.
In 1867 he started studying chemistry at the University of Göttingen, where at this time Friedrich Wöhler was head of organic chemistry. After one semester at the University of Berlin with August Wilhelm von Hofmann, Wallach received his Doctoral degree from the University of Göttingen in 1869, and worked as a Professor in the University of Bonn (1870-89) and the University of Göttingen (1889-1915). Two of his doctoral students were Adolf Sieverts and Walter Haworth. Wallach died at Göttingen. In 1912, he was awarded the Davy Medal.
During his work with Friedrich Kekulé in Bonn he started a systematic analysis of the terpenes present in essential oils. Up to this time only a few had been isolated in pure form, and structural information was sparse. Melting point comparison and the measurement of mixtures was one of the methods to confirm identical substances. For this method the mostly liquid terpenes had to be transformed into crystalline compounds. With stepwise derivatisation, especially additions to the double bond present in some of the terpenes, he achieved the goal of obtaining crystalline compounds. The investigation of the rearrangement reactions of cyclic unsaturated terpenes made it possible to obtain the structure of an unknown terpene by following the rearrangement to a known structure of a terpene. With these principal methods he opened the path to systematic research on terpenes.
He wrote a book about the chemistry of terpenes, "Terpene und Campher" (1909).