Leopold Ruzicka Biography

Leopold Ruzicka worked in what he referred to as the "borderland" between bio-organic chemistry and biochemistry. His studies of odorous natural products led to his discovery of carbon rings with many more carbon atoms than had been originally thought possible. His research also contributed important information on how living things biosynthesize some steroids and sex hormones. For this work he shared the 1939 Nobel Prize in chemistry.

Leopold Stephen Ruzicka was born on September 13, 1887, to Stjepan and Amalija (Sever) Ruzicka. He was the first of two boys. They lived at first in Vukovar in Eastern Croatia (later part of Yugoslavia). His father, a cooper, died when Ruzicka was about four years old, and the family then moved to Osijek to live with relatives. Ruzicka attended elementary and high school in Osijek, where he received a classical education (Latin and Greek), and was initially determined to enter the Catholic priesthood. As a teenager, he changed his interests to chemistry, and upon graduation began to look for graduate schools in Germany and Switzerland. He eventually settled on the Technische Hochschule in Karlsruhe, Germany, choosing it over the Swiss Federal Institute of Technology (Eidgenossische Technische Hochschule, or ETH) in Zurich, because it provided more flexibility in courses and did not require an entrance examination in descriptive geometry.

Ruzicka obtained his doctorate in only four years, under the direction of Hermann Staudinger at Karlsruhe. He then assisted Staudinger in research on the natural products in the Chrysanthemum species; these chemicals, called pyrethrins , were of particular interest as insecticides. In September of 1912, they both moved to ETH, where Ruzicka had originally considered studying, when Staudinger replaced Richard Willstätter as professor of organic and inorganic chemistry. Reflecting on these events later in his life, Ruzicka wrote, in Annual Review of Biochemistry, "The fact that I went to Karlsruhe for my training was a very important factor in my life. If I had taken my doctorate degree with Willstätter I should have gone to Germany with him in 1912, and two years later Germany was at war.... That war ended in 1918 with the destruction of the Habsburg empire and the beginning of bad times in Germany." Instead, he had established sufficient residency in Zurich by 1917 to obtain Swiss citizenship, and avoided the devastation caused during World War I.

In 1916, Ruzicka started his own research program, supported financially by a Geneva perfume company. (His position at ETH carried no salary until 1925, two years after he was named a professor.) The University of Utrecht, in the Netherlands, offered him a job as an organic chemistry professor in 1926. After three years there, he went back to Zurich to take on the job of directing ETH. During much of his career he was also supported financially by the Rockefeller Foundation.

Ruzicka studied various organic compounds early in his career, but in 1921 his most fruitful work began--on the structure and synthesis of several natural compounds important to the fragrance industry. (His collaborations with the Swiss pharmaceutical and perfume industries was to continue throughout his working life.) Before Ruzicka's discoveries, chemists thought that ring structures containing more than eight carbons would be unstable, because no one had been able to synthesize large rings. Ruzicka's research on muscone (obtained from the male musk deer) and civetone (from both male and female civet cats), however, indicated rings with as many as seventeen carbons--a huge number. He was able to synthesize some of these very large rings with new procedures developed by his research group.

Another line of research dealt with isoprene . Biochemists are interested in how living things bio__synthesize large molecules; they had known for some time that isoprene is one of nature's favorite building blocks. Ruzicka found many more large biochemicals that were constructed from isoprene units, and he formulated a rule of thumb called the "isoprene rule " for predicting biosynthesis based on this starting material. Ruzicka also synthesized testosterone and androsterone , the male sex hormones. In recognition of these successes he was awarded the Nobel Prize in chemistry in 1939, which he shared with Adolf Butenandt.

Ruzicka conducted research in an era when instrumentation was primitive by contemporary standards. The elucidation of molecular structure, therefore, depended entirely upon the observation of chemical reactions and the purification of reaction products. In this process an unknown compound would be exposed to various well-characterized reagents; if it reacted to give certain products, the chemist knew that the original molecule contained particular arrangements of atoms. (Ruzicka, for example, frequently used dehydrogenation--the removal of hydrogen atoms--to gain information about molecular structure.) Once these arrangements had been identified, the chemist would attempt to synthesize the original compound, and then compare the original and the synthetic. If they matched, that was taken as good evidence that the perceived structure was at least partly correct. This time-consuming, "wet" chemistry often gave ambiguous results, and polite arguments frequently occurred in scientific literature as the chemistry community debated the structure of a complicated new molecule. Often old rules had to give way when new discoveries were made. In his Nobel lecture, Ruzicka said, "Experience has shown that there is no rule governing the architecture of natural compounds which is valid without exception, and which would enable us to dispense with the need to test its validity accurately for every new compound to be examined."

Ruzicka married Anna Housmann in 1912; they were divorced in 1950. In 1951, he married Gertrud Acklin. He was an avid gardener and collector of paintings, so much so that he once said his chemistry had suffered as a result of his hobbies. He established an important collection of Dutch and Flemish Masters of the seventeenth century, as well as an art library on that general period, which he later gave to the Zurich art museum. During World War II, he worked to secure the escape of several Jewish scientists from the Nazis, and founded the Swiss-Yugoslav Relief Society. He was instrumental in providing refuge in Switzerland to the future Nobel Laureate Vladimir Prelog, who succeeded Ruzicka as the director of ETH when the latter retired in 1957. Ruzicka died on September 26, 1976.