| Chemist Date of Birth: 23.01.1876 Country: Germany |
Otto Paul Hermann Diels was a German organic chemist. He was born in Hamburg and was the second of three sons of Herman Diels, a teacher and renowned philologist, and Bertha Diels (nee Dubel). When Otto was two years old, the family moved to Berlin, where his father was elected as a professor of classical philology at the University of Berlin. At the age of six, Diels enrolled in the Joachimsthal Gymnasium in Berlin.
In his twenties, Diels entered the University of Berlin to study chemistry. In 1900, under the guidance of Emil Fischer, he successfully defended his doctoral dissertation and became Fischer's assistant at the University's Chemical Institute. In 1904, Diels discovered an unusual compound containing three carbon atoms and two oxygen atoms, which he named carbon suboxide. That same year, he began studying the structure of the little-known substance cholesterol. Through dehydration (removal of hydrogen), he obtained a ketone called cholesterone from cholesterol.
In 1904, Diels became a lecturer and in 1906, he was appointed as a professor of organic chemistry. During this time, he expanded his research interests to other areas of chemistry and in 1907, he published a well-written and widely known textbook, "Introduction to Organic Chemistry" ("Einfuhrungen in die organische Chemie"). In 1913, he became the head of the Faculty of Organic Chemistry at the University. After a year of working as an adjunct professor at the Chemical Institute of the Royal Friedrich Wilhelm University (now Humboldt University), Diels returned to the University of Berlin as a full professor. In 1916, he accepted a position as a chemistry professor and director of the Chemical Institute at the Christian Albrecht University (later known as the University of Kiel). From 1925, he served as the rector of the university.
Diels reexamined the structural model of cholesterol proposed by other researchers, considering it to be erroneous. He resumed his study of the substance and discovered that when selenium was mixed with cholesterol, it underwent dehydration without destruction, unlike other methods. Diels was the first to use selenium for the dehydration of various compounds, and this method, discovered in 1927, was subsequently used by other chemists to obtain polyunsaturated oils. The compound he obtained turned out to be the basic molecule of many natural compounds, and it was soon used by other experimenters to explain the structure and chemical nature of cortisol, sex hormones, steroids, and vitamin D.
In 1928, Diels and one of his former students, Kurt Alder, published a paper in which they explained the Diels-Alder synthesis. This type of synthesis occurs when a diene (a molecule containing two double bonds between carbon atoms) reacts with a molecule called a dienophile (literally, "diene-loving"), which has one double bond between carbon atoms. The product of this reaction is a six-membered cyclic molecule called an adduct. Although the Diels-Alder synthesis had been discovered by other chemists, there was no scientific explanation for this phenomenon. In their paper, Diels and Alder described how they combined cyclopentadiene (the diene) with maleic anhydride (the dienophile) to form a highly stable adduct (3,6-endomethylene-4-tetrahydrophthalic anhydride) with simultaneous rearrangement of carbon bonds.
The cooperation between Diels and Alder continued until 1936 when Alder joined the staff of the I.G. Farbenindustrie plant in Leverkusen. The deprivation and destruction caused by World War II hindered further progress in Diels' research. The bombings by the Anglo-American aviation ultimately destroyed not only the Chemical Institute and its library but also Diels' home. Two of his sons were killed on the Eastern Front, and in 1944, he submitted a resignation request, which was accepted the following year. However, after the war, at the age of 70, he returned to the institute and worked on its reconstruction until his final retirement in 1948. In 1950, Diels and Alder were awarded the Nobel Prize in Chemistry "for the discovery and development of the Diels-Alder synthesis." In his speech at the presentation of the laureates, Arne Fredga, a member of the Royal Swedish Academy of Sciences, characterized carbon-containing compound chemistry as "something incomprehensible, difficult to explain and understand by humans." "The Diels-Alder synthesis," Fredga said, "has now become one of the most important working methods in organic chemistry. With the help of this method, a large number of compounds with complex structures can be easily synthesized, which would be impossible or extremely difficult to obtain by any other means." Due to illness, Diels was unable to attend the award ceremony. In his Nobel lecture, published the following year, he discussed the significance of the aromatic basis of steroid molecule structure.
Diels married Paula Geier in 1909 and had three sons and two daughters. A reserved person with a subtle sense of humor, he was highly respected for his courage and originality in scientific ideas. In his youth, he was a passionate mountaineer, and in his free time, he enjoyed painting. He died in Kiel on March 7, 1954, shortly after his 78th birthday. In addition to the Nobel Prize, Diels received the Adolf von Baeyer Medal from the German Chemical Society (1930) and an honorary medical degree from the University of Kiel. He was a member of the academies of sciences in Göttingen, Halle, and Munich.