Hassel, Odd (1897–1981)

Norwegian physical chemist who was awarded the Nobel Prize for Chemistry in 1969 for establishing the technique of conformational analysis – the determination of the properties of a molecule by rotating it around a single bond. Hassel described the conformations of cyclohexane (a saturated hydrocarbon in which the carbonatoms are linked in a ring).

Conformations are different spatial rearrangements of the same molecule that are not achieved by the breaking of bonds, but by the rotation of atoms around the bonds. The cyclohexane molecule exists in two main conformations: the ‘boat’ and ‘chair’, of which the chair is the most stable.

His work was severely disrupted by World War II, when he was imprisoned by occupying Nazi troops. However, his findings came to light in the 1950s and 1960s and were further developed by Derek Barton with whom he shared the Nobel Prize.

Hassel was born in Oslo, Norway, where he went to university. He moved to Germany and studied under the guidance of Kasimir Fajans in Munich and obtained a PhD from Berlin University in 1924. He was a deep-thinking man who felt uncomfortable with the unstable political situation in Berlin and he quickly returned to Oslo, where he joined the staff at the university's school of physical chemistry. He spent the rest of his career there, becoming a professor, and a director in 1934.