Paul R. Ehrlich

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Lore & Background

Karrer's early research concerned complex metal compounds, but his most important work focused on plant pigments, particularly the yellow carotenoids. He elucidated their chemical structure and showed that some of these substances are transformed in the body into vitamin A. His work led to the establishment of the correct constitutional formula for β-carotene, the chief precursor of vitamin A — the first time the structure of a vitamin or provitamin had been established. George Wald worked briefly in Karrer's lab while studying the role of vitamin A in the retina. Later, Karrer confirmed the structure of ascorbic acid (vitamin C) and extended his research into vitamins B2 and E. His important contributions to the chemistry of the flavins led to the identification of lactoflavin as part of the complex originally thought to be vitamin B2. Karrer published many papers and received many honours and awards, including the Nobel Prize in 1937. His textbook *Lehrbuch der Organischen Chemie* (Textbook of Organic Chemistry) was published in 1927, went through thirteen editions, and was published in seven languages.

Reader's Guide

Karrer married Helena Froelich in 1914 and had three sons, one of whom died in infancy. He died on 18 June 1971 at the age of 82 in Zürich. His wife died in 1972. The prestigious Paul Karrer Gold Medal and lecture were established in his honour in 1959 by a group of leading companies including CIBA AG, J.R. Geigy, F. Hoffmann-La Roche & Co. AG, Sandoz AG, Société des Produits Nestlé AG and Dr. A. Wander AG. It is awarded annually or biannually to an outstanding chemist who delivers a lecture at the University of Zurich. The Paul Karrer Lecture Foundation is based at the Chemistry Institute of the University of Zurich at Rämistrasse 71, in Zürich.

Did You Know?

• Karrer was born in Moscow, Russia to Swiss nationals Paul Karrer and Julie Lerch.
• He studied chemistry at the University of Zurich under Alfred Werner and gained his PhD in 1911.
• Karrer established the correct constitutional formula for β-carotene, the first time the structure of a vitamin or provitamin had been established.
• His textbook *Lehrbuch der Organischen Chemie* went through thirteen editions and was published in seven languages.
• The Paul Karrer Gold Medal was established in 1959 by a group of leading companies including CIBA AG, J.R. Geigy, and F. Hoffmann-La Roche & Co. AG.

Roots in Two Worlds: Early Life and Education

Paul Karrer entered the world on April 21, 1889, in Moscow, Russia—an unusual birthplace for a man who would become one of Switzerland's most celebrated chemists. His parents, Paul Karrer and Julie Lerch, were both Swiss nationals, and in 1892 the family uprooted and returned to their homeland. Young Paul grew up in Switzerland, attending school at Wildegg before matriculating at the Old Cantonal School in Aarau in 1908. His academic path led him to the University of Zurich, where he pursued chemistry under the renowned Alfred Werner. After earning his doctorate in 1911, he spent an additional year assisting in the university's Chemical Institute before accepting a position as a chemist alongside Paul Ehrlich at the Georg Speyer Haus in Frankfurt-am-Main. By 1919, Karrer had risen to become both Professor of Chemistry and Director of the Chemical Institute, a role that would anchor his decades of groundbreaking work.

Decoding Nature's Yellow Molecules

While Karrer's earliest investigations focused on complex metal compounds, it was his turn toward plant pigments that reshaped biochemistry. He devoted his career to unraveling the chemistry of yellow carotenoids, ultimately determining their precise molecular architecture. His landmark achievement came when he established the correct constitutional formula for β-carotene, the principal precursor from which the human body synthesizes vitamin A. This was the first time in scientific history that the structure of a vitamin or provitamin had been definitively mapped. His laboratory also hosted the young George Wald, who was exploring vitamin A's role in retinal function. Building on this foundation, Karrer went on to confirm the structure of ascorbic acid, better known as vitamin C, and pushed his inquiries into the chemistry of vitamins B2 and E. His work on flavins proved particularly consequential, revealing that lactoflavin was actually a component of the larger complex that had originally been mistaken for vitamin B2 itself.

Nobel Recognition and a Lasting Textbook

Karrer's body of published research attracted widespread acclaim, and his contributions were formally recognized when he and British chemist Norman Haworth were jointly awarded the Nobel Prize in Chemistry in 1937. His Nobel Lecture, delivered on December 11 of that year, bore the title "Carotenoids, Flavins and Vitamin A and B2," a concise summary of the very work that had earned him the honor. Beyond his original research, Karrer left an indelible mark on chemical education through his textbook, Lehrbuch der Organischen Chemie, first published in 1927. That single volume went through thirteen editions and was translated into seven languages, making it a standard reference for generations of students and researchers across the globe. The breadth of his influence—spanning original discovery, pedagogical writing, and international recognition—cemented his reputation as one of the defining organic chemists of the twentieth century.

A Life Beyond the Laboratory and an Enduring Legacy

In 1914, Karrer married Helena Froelich, and the couple raised three sons, though one tragically died in infancy. He lived to the age of eighty-two, passing away in Zürich on June 18, 1971. His wife survived him by just one year, dying in 1972. Yet Karrer's name continues to resonate well beyond his personal lifespan. In 1959, a consortium of major Swiss and European companies—including CIBA AG, J.R. Geigy, F. Hoffmann-La Roche & Co. AG, Sandoz AG, Société des Produits Nestlé AG, and Dr. A. Wander AG—established the Paul Karrer Gold Medal and accompanying lecture series in his honor. The award is presented annually or biannually to an outstanding chemist who then delivers a lecture at the University of Zurich. The Paul Karrer Lecture Foundation, which administers this honor, is housed at the Chemistry Institute on Rämistrasse 71 in Zürich, ensuring that his scientific spirit remains embedded in the city's academic landscape.