Nobel Prize in Chemistry · 1981
Roald Hoffmann
A child who hid from the Nazis in an attic grew up to show chemists how to predict which way a reaction will go.
The Nobel citation: “for their theories, developed independently, concerning the course of chemical reactions”
- Born
- July 18, 1937, Zloczov, Poland (now Ukraine)
- Shared with
- Kenichi Fukui
- Affiliation at the time
- Cornell University, USA
Chemistry prize
1981
Shared with 1 other laureate.
Age that year
44years
Born in 1937.
Sources cited
23
Fact-checked September 24, 2026.
- He was born Roald Safran and named after the polar explorer Roald Amundsen. Leaving Poland, his family bought the papers of a dead German named Hoffmann.
- From 1943 to 1944 he and his mother hid for about 15 months in a village schoolhouse attic, protected by a Ukrainian teacher. His father was killed by the Nazis in 1943.
- Of the roughly 4,000 Jews of his hometown, he says, perhaps 200 survived the war, and only five of them were children.
- He arrived in New York at 11, and English was his sixth language. Nine years later he graduated from Columbia summa cum laude in chemistry.
- He heard he had won the Nobel Prize on the radio while fixing his bicycle in his garage. Even after the prize he kept teaching first-year chemistry at Cornell.
The breakthrough
The Woodward-Hoffmann rules: orbital symmetry decides how reactions run (1965)
Chemical reactions happen when electrons move: old bonds between atoms break and new ones form. In the early 1960s chemists knew of reactions that seemed to follow strange rules. In one family of reactions, a chain of carbon atoms closes into a ring in a single smooth step. Heat it and you get one three-dimensional product; shine ultraviolet light on it and you get a different one. Robert Burns Woodward hit such a puzzle while making vitamin B12 at Harvard, when a key step gave a product he had not predicted. In spring 1964 he brought his questions to Hoffmann, a 26-year-old theorist. Their answer, first published in January 1965, became the Woodward-Hoffmann rules. Electrons in a molecule occupy orbitals, regions of space with a particular shape and symmetry. Woodward and Hoffmann showed that this symmetry is conserved, kept intact, all the way through such a reaction. If the orbitals of the starting molecule line up smoothly with those of the product, the reaction is 'allowed' and runs easily. If they clash, it faces a high energy barrier and in practice does not go that way. Heat and light put electrons into different orbitals, which is why they open different paths. Think of two gears: they turn together only when their teeth mesh. The rules let chemists predict from a pencil sketch what a reaction will make before they go into the lab. In Japan, Kenichi Fukui reached the same predictions independently with his frontier orbital theory.[1],[3],[4],[10],[14],[16],[17]
“I knew from our experience that people were not simply good or evil. They made choices.”
What it meant for humanity
Before the 1960s, chemists often found out by trial and error which reactions would work and what shape their products would take. Hoffmann helped turn part of that guesswork into prediction. The Woodward-Hoffmann rules, first published in 1965, tell a chemist from a simple drawing whether a whole family of one-step reactions will go with heat, with light or not at all, and which three-dimensional product will form. The Nobel presenter linked this to a practical problem. Many molecules come in right- and left-handed forms, the body makes only one of them, and so vitamins and drugs often have to be made in a single form. He credited the rules with helping to complete the Woodward-Eschenmoser synthesis of vitamin B12. The Royal Swedish Academy of Sciences said chemists who study life processes and chemists who make new drugs use these models, and that good theory saves experimenters time. Hoffmann's other tools spread just as widely. The extended Hückel method, written as computers were just coming into use, gave rough pictures of the electrons and shapes of molecules. His isolobal analogy showed hidden likenesses between metal-containing and carbon-based building blocks, giving chemists a bridge between inorganic and organic chemistry. He also spent his career opening chemistry to others. He taught first-year general chemistry at Cornell almost every year from 1966 and has said he cannot separate his teaching from his research. He presented The World of Chemistry, a 26-part television course that began airing on PBS in 1990 and was used in hundreds of US classrooms. He wrote poetry, essays and plays about science, and for fifteen years co-hosted a monthly science cabaret in Greenwich Village. As a survivor, he helped bring about a 2009 memorial at a village near his hometown where more than 3,000 Jews were killed.
- The 1981 Nobel press release said chemists who study life processes and chemists who make new drugs use Fukui's and Hoffmann's way of thinking about reactions.[3]
- The Nobel presentation speech credited the orbital symmetry rules with helping to complete the Woodward-Eschenmoser synthesis of vitamin B12.[4],[10]
- By Crossref's count, his 1963 extended Hückel paper has about 4,400 citations, the 1969 Woodward-Hoffmann review The Conservation of Orbital Symmetry about 2,600, and his Nobel lecture about 1,100.[15],[17],[23]
- His Nobel lecture set out the isolobal analogy, which maps the building blocks of inorganic chemistry onto those of organic chemistry and helps chemists spot unexpected structural cousins.[5],[9]
- The World of Chemistry, 26 half-hour episodes he presented, began airing on PBS in 1990 and was used in hundreds of US classrooms. All 26 episodes are now free on YouTube, linked from his website.[1],[9],[20]
- In 2009 a memorial was dedicated in Yelykhovychi, near his hometown, where more than 3,000 Jews were killed. JTA reported it was built on the initiative of American and Israeli groups and of Hoffmann personally.[12],[13]
Impact in numbers
We make no quantified claims for Hoffmann. His work is theory: the Woodward-Hoffmann rules, the extended Hückel method and the isolobal analogy are ways of thinking that let chemists predict how molecules will react and what shapes they will take. The Royal Swedish Academy of Sciences said such models save experimenters time and are used by chemists who study life processes and make new drugs. But no drug, material or process can be traced to these ideas alone, and any count of lives saved or dollars earned would be invented. His influence is better measured in use: by Crossref's count his 1963 extended Hückel paper has been cited about 4,400 times, the 1969 Woodward-Hoffmann review about 2,600 times and his Nobel lecture about 1,100 times. His second legacy is public: decades of first-year teaching, a 26-part television chemistry course, poetry, plays, and his work to mark where his town's Jews were murdered.
Fundamental scienceEducationCulture
No number is given here on purpose. Some contributions cannot be counted honestly, and we would rather describe them than invent a figure.
The double edge
No harm has been traced to Hoffmann's work. It is theory that explains and predicts reactions rather than a product or a weapon. The main controversy is about credit. In the weeks after the 1981 prize announcement, E. J. Corey, a Harvard colleague who won his own Nobel Prize in 1990, wrote to Hoffmann that on 4 May 1964 he had given Woodward the key idea behind the rules and that Woodward took it without credit. Corey made the claim public in his 2004 Priestley Medal address, and Hoffmann answered with a five-page article in Angewandte Chemie. Woodward had died in 1979 and could not respond. Many scientists the Boston Globe interviewed in 2005 believed Corey, though some noted that Woodward liked to ask questions he already knew the answers to. Hoffmann told the Globe he did not believe Corey, but would apologize and give him credit if hard evidence appeared. The Globe concluded the truth would likely stay unknown, and quoted Yale chemist Jerome Berson noting that the Dutch chemist L. J. Oosterhoff had proposed a similar idea in 1961.
- Minor
Credit dispute with E. J. Corey
Corey says he suggested the core idea to Woodward in May 1964 and was never credited. Hoffmann, who says he heard of the idea secondhand and then offered to work with Woodward, does not believe the claim and replied in print in 2004. Woodward died in 1979. Many colleagues the Boston Globe interviewed believed Corey, but none could settle it, and L. J. Oosterhoff had proposed a similar idea in 1961.[14],[18]
Against the odds
Hoffmann was born in one of the most dangerous places in Europe for a Jewish child. In 1921 Jews were just over half of the 11,000 people of Zloczow, a town in Polish Galicia, and antisemitic leaflets, a desecrated cemetery and the firing of Jewish clerks marked the mid-1930s. The Soviet Union occupied the town in 1939. When the Germans arrived in July 1941, local Ukrainians and German soldiers murdered 3,000 to 4,000 Jews in three days. In 1942 about 5,000 more were deported to the Belzec death camp, and in April 1943 the ghetto was emptied and about 6,000 people were shot at a pit outside town. Hoffmann's family went to the ghetto and then a labor camp. Early in 1943 his father smuggled five-year-old Roald and his mother out. A Ukrainian schoolteacher hid them in a village schoolhouse attic for about 15 months, at great risk, while, as Hoffmann says, many neighbors helped the Nazis. His father stayed in the camp, organized a breakout attempt and was killed in June 1943. Three of his four grandparents also died. Hoffmann estimates that perhaps 200 of the town's 4,000 Jews survived. After years in displaced persons' camps, he reached New York in 1949, aged 11.
1935
Discrimination
In the mid-1930s antisemitism grew in Zloczow: leaflets against Jews circulated in Polish and Ukrainian, a Jewish family was murdered in a nearby village, Jewish clerks were fired and the Jewish cemetery was desecrated.[12]
1941
Persecution
Germany occupied Zloczow on 2 July 1941. In a pogrom starting 4 July, local Ukrainians and German soldiers killed 3,000 to 4,000 Jews in three days. Deportations to Belzec followed in 1942, and the ghetto was destroyed in April 1943. Hoffmann's family was held in the ghetto and then a labor camp.[1],[12]
1943
Holocaust survivor
Early in 1943 his father smuggled him and his mother out of the labor camp. A Ukrainian teacher, Mikola Dyuk, hid them with a few relatives in the attic of a village schoolhouse for about 15 months, until the Red Army arrived in 1944.[1],[2],[7]
1943
Family killed
His father, Hillel Safran, stayed in the camp and organized a breakout. Yad Vashem's encyclopedia of Jewish communities says he led an underground group gathering weapons, and fought back when caught. He was killed in June 1943. Three of Roald's four grandparents and several aunts and uncles were also murdered.[1],[7],[8],[12]
1946
Exile
In 1946 the family left Poland for Czechoslovakia, then lived in displaced persons' camps near Linz in Austria and in Germany before reaching the United States on 22 February 1949.[1],[9]
Jewish background
Hoffmann was born into a Polish Jewish family in Zloczow: his father, Hillel Safran, was a civil engineer, and his mother, Clara (née Rosen), a teacher. His father, three of his four grandparents and several aunts and uncles were murdered in the Holocaust. At the Nobel banquet he described himself as a child of wartime Europe with Jewish roots and an American dream. He calls himself an atheist who is moved by religion, and says he responds to the synagogue ritual of his Jewish background. He co-wrote Old Wine, New Flasks (1997), a book on science and Jewish tradition, and wrote a play drawn from his own years in hiding.[1],[2],[6],[8],[9],[10],[19]
Key dates
July 18, 1937
Born Roald Safran in Zloczow, Poland (now Zolochiv, Ukraine), to Hillel Safran, a civil engineer, and Clara Rosen, a teacher. He is named after Roald Amundsen.[1],[2],[8]
July 2, 1941
German troops occupy Zloczow. A pogrom beginning two days later kills thousands of the town's Jews.[12]
1943
After a ghetto and a labor camp, his father smuggles him and his mother out; they hide in a schoolhouse attic. His father is killed in June.[1],[7]
1944
Freed by the Red Army. The family moves to Przemysl and then Krakow, where he finally goes to school.[1]
1946
Leaves Poland with his mother and stepfather, and spends the next years in displaced persons' camps in Austria and Germany.[1],[9]
February 22, 1949
Arrives in the United States, aged 11. He goes on to Stuyvesant High School in New York.[1],[9]
1958
Graduates summa cum laude in chemistry from Columbia, which he entered as a premed student because his parents hoped he would be a doctor. He then starts graduate study at Harvard.[1],[9],[22]
1962
Earns his Harvard PhD. With L. L. Lohr and William Lipscomb he has built the extended Hückel method, published in 1963.[1],[9],[15]
January 1965
The first Woodward-Hoffmann paper, on the stereochemistry of ring-closing reactions, appears. Later that year he joins Cornell University.[1],[16]
October 19, 1981
Learns from the radio that he has won the Nobel Prize in Chemistry, shared with Kenichi Fukui.[2],[14]
1990
The World of Chemistry, his 26-part television course, begins airing on PBS. He receives the Priestley Medal, the American Chemical Society's highest honor.[1],[9]
2001
Oxygen, his play with Carl Djerassi, premieres in San Diego. From 2002 to 2017 he also co-hosts Entertaining Science, a monthly science cabaret in Greenwich Village.[9],[10],[21]
July 15, 2009
A Holocaust memorial built partly on his initiative is dedicated in Yelykhovychi, near Zolochiv, where more than 3,000 Jews were killed.[13]
2023
Carnegie Corporation of New York names him one of its Great Immigrants.[11]
Sources
- 1.Roald Hoffmann – Biographical · NobelPrize.org (Nobel Foundation), 1981
- 2.Roald Hoffmann – Facts · NobelPrize.org (Nobel Prize Outreach)
- 3.The Nobel Prize in Chemistry 1981 – Press release · Royal Swedish Academy of Sciences / NobelPrize.org, 1981
- 4.The Nobel Prize in Chemistry 1981 – Award ceremony speech · NobelPrize.org (Nobel Foundation), 1981
- 5.Building Bridges between Inorganic and Organic Chemistry (Nobel lecture, 8 December 1981) · NobelPrize.org (Nobel Foundation), 1981
- 6.Roald Hoffmann – Banquet speech · NobelPrize.org (Nobel Foundation), 1981
- 7.The Tense Middle (This I Believe essay by Roald Hoffmann) · NPR, Morning Edition, 2006
- 8.Looking for Connections: An Interview with Roald Hoffmann (Liberato Cardellini, Journal of Chemical Education 84:1631) · Journal of Chemical Education (archived copy from roaldhoffmann.com), 2007
- 9.Roald Hoffmann – Long Biography · roaldhoffmann.com (Cornell University)
- 10.Roald Hoffmann (Scientific Biographies) · Science History Institute
- 11.Roald Hoffmann – 2023 Great Immigrants honoree · Carnegie Corporation of New York, 2023
- 12.Zloczow – Pinkas Hakehillot Polin: Encyclopedia of Jewish Communities in Poland, Volume II (English translation) · Yad Vashem, via JewishGen Yizkor Book Project
- 13.Holocaust monument dedicated in western Ukraine · JTA (archived copy), 2009
- 14.Whose idea was it? Dispute over Nobel-winning theory shows how hard it is to trace origins of scientific discoveries (Carolyn Y. Johnson) · The Boston Globe (archived copy), 2005
- 15.An Extended Hückel Theory. I. Hydrocarbons (R. Hoffmann, J. Chem. Phys. 39:1397), Crossref metadata record · The Journal of Chemical Physics, via Crossref, 1963
- 16.Stereochemistry of Electrocyclic Reactions (R. B. Woodward and R. Hoffmann, J. Am. Chem. Soc. 87), Crossref metadata record · Journal of the American Chemical Society, via Crossref, 1965
- 17.The Conservation of Orbital Symmetry (R. B. Woodward and R. Hoffmann, Angew. Chem. Int. Ed.), Crossref metadata record · Angewandte Chemie International Edition, via Crossref, 1969
- 18.A Claim on the Development of the Frontier Orbital Explanation of Electrocyclic Reactions (R. Hoffmann, Angew. Chem. Int. Ed. 43:6586-6590), Crossref metadata record · Angewandte Chemie International Edition, via Crossref, 2004
- 19.Something That Belongs To You: a play in two acts by Roald Hoffmann · roaldhoffmann.com (Cornell University)
- 20.World of Chemistry · roaldhoffmann.com (Cornell University)
- 21.Entertaining Science · roaldhoffmann.com (Cornell University)
- 22.Scientist at Work: Roald Hoffmann; Seeking Beauty in Atoms (Malcolm W. Browne) · The New York Times (archived copy), 1993
- 23.Building Bridges Between Inorganic and Organic Chemistry (Nobel Lecture) (R. Hoffmann, Angew. Chem. Int. Ed. 21:711), Crossref metadata record · Angewandte Chemie International Edition, via Crossref, 1982
Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 6 corrections made. How we check
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