Otto Wallach was a German chemist born in the Kingdom of Prussia in the middle of nineteenth century. He received the 1910 Nobel Prize in chemistry for his work on alicyclic compounds. Educated at a gymnasium, which laid more stress on humanities than science, he started experimenting on different chemical reactions at home. Ultimately, he graduated from the University of Göttingen with chemistry and received his PhD from there at the age of twenty-two. At the age of twenty-three, he joined the University of Bonn as a Lecturer of Pharmacy; but soon was drafted into the Franco Prussian War of 1870. After the war he first tried to settle in Berlin, but circumstances were such that he had to rejoin the University of Bonn for the second time. It was at this phase that his mentor, Friedrich August Kekulé, came across an old and forgotten cupboard full of essential oils and asked him to investigate on them. Thus he began a long and detailed experimentation. Among other things, it led to the discovery of terpene and established the foundation of modern perfume industry.
Childhood & Early Life
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.
Nonetheless, very soon he left University of Göttingen to join University of Berlin. However, he rejoined Göttingen after studying one semester at Berlin with August Wilhelm von Hofmann and G. Magnus and immersed into work.
Although the gas in the laboratory was turned off after 5 pm every evening he carried on his work under candlelight. Ultimately he received his PhD in 1869 after working for five semesters only. His thesis dealt with the position isomers in the toluene series.
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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.
Meanwhile, Professor Kekulé discovered an old forgotten cupboard, in which there were rows of bottles containing essential oil. He asked Wallach to examine them. In this way, Wallach entered a field that would later establish him as a renowned chemist and earn him the Nobel Prize in Chemistry.
In 1884, he published his first paper on the essential oils. At that time, it was believed that the so called C10H16 group contained various elements called citrene, carvene, cinene, cajuputene, eucalyptine, hesperidine, etc. In this publication he raised questions about it.
In 1885, he confirmed that many of these elements were identical. However, it took him many more years to complete his studies. He published his final paper in 1909.
Meanwhile, in 1889, Wallach was appointed to the Wöhler's Chair at the Chemical Institute at Göttingen. At the same time, he also became the Director of the Institute. He retired from there in 1915.
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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.
Awards & Achievements
Wallach was awarded the 1910 Nobel Prize in Chemistry "in recognition of his services to organic chemistry and the chemical industry by his pioneer work in the field of alicyclic compounds".
In 1912, Wallach received the Davy Medal from the Royal Society of London “for his researches on the chemistry of the essential oils, and the cyclo-olefines".
He also received Honorary Fellowships of the Chemical Society in 1908 and became Honorary Member of the Verein Deutscher Chemiker in 1912.
In 1911, Wallach received the Kaiserlicher Adlerorden III Klasse (Imperial Order of the Eagle) and in 1915 the Königlicher Kronorden II Klasse (Royal Order of the Crown).
He also received Honorary Doctorates from University of Manchester, University of Leipzig and the Technological Institute of Braunschweig.
Personal Life & Legacy
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.