Otto Wallach

Otto Wallach remained a lifelong bachelor dedicating all his time and energy to his work. He died on 26 February 1931, at the age of 83, from natural causes at Göttingen. He was buried at Göttinger Stadtfriedhof.

In organic chemistry, the rule that states, racemic crystals tend to be denser than their chiral counterparts, has been named ‘Wallach’s Rule’. Besides, there are the ‘Wallach Rearrangement’ the ‘Wallach Degradation’ and ‘the Leuckart-Wallach reaction’ all named after Otto Wallach.

Otto Wallach was born on 27 March 27 1847, in Königsberg, an ancient city located in the Kingdom of Prussia. Now, the town is part of Russia and has been renamed Kaliningrad.

His father, Gerhard Wallach, was a high ranking civil servant with transferable job. Born as a Jew, he later converted to Lutheranism. His mother, Otillie Wallach, was a Protestant German.

Soon after Otto’s birth, the family moved first to Stettin and then to Potsdam. It was at Potsdam that Otto started his education at a humanistic Gymnasium. Science subjects were hardly taught in those schools.

At that stage, he grew a liking towards literature and history of art, an interest he retained throughout his life. At the same time, he privately studied chemistry and undertook many experiments at home.

Ultimately, it was in 1867, that he enrolled at the University of Göttingen with chemistry as his main subject. At that time Friedrich Wöhler, who is best known for his synthesis of urea, was the head of the department. Young Wallach was as much influenced by him as by Professor Fittig and Professor Hübner.

After receiving his doctorate degree in 1869, Wallach joined H. Wichelhaus in Berlin. While working with him on nitration of b-naphthol, he received an invitation from Friedrich August Kekulé to join him at the University of Bonn.

Accordingly Wallach joined University of Bonn in 1870 as a lecturer of pharmacy. The same year, he was drafted into the army and joined the Franco Prussian War, which started on 19 July 1870.

Once the war ended on 10 May 1871, Wallach first went to Berlin and took up a job at Aktien-Gesellschaft für Anilin-Fabrikation, which manufactured dyes and strains. However, he could not tolerate the fumes there and in 1872, returned to the University of Bonn and remained attached to it until 1889.

Initially Wallach was appointed as an assistant at the organic laboratory. Later he became a Privatdozent and finally in 1876, he was appointed as the Professor Extraordinary of Pharmacy.

Although he was more interested in chemistry, when in 1879, the Chair of Pharmacology fell vacant, Wallach was more or less forced to take it. Sometime now, he started working on amid chlorides and phosphorus pentachloride and discovered imino-chlorides. During this period, he also worked on imide chlorides, amidines, glyoxalines etc.

Wallach is best remembered for his work on the molecular structure of the essential oils. He first separated the components of various oils by repeatedly distilling them and then studied their physical properties. Finally he came to conclusion that many of these oils are identical to one another.

In addition, he was also able to isolate a group of fragrant substance from these oils. He named it terpenes. His experimentation took almost fifteen years to complete. Finally in 1909, he published his findings in a paper titled ‘Terpene und Campher’. His work formed the basis of modern perfume industry.

Wallach is also remembered for his work on amid chlorides, on azo dyes and diazo compounds. His conversion of chloral into dichloroacetic acid is another of his important works.