Paul Walden

Paul Walden (Latvian: Pauls Valdens; German: Paul von Walden; Russian: Павел Иванович Вальден; 26 July 1863 – 22 January 1957) was a Latvian-Baltic German chemist known for his work in stereochemistry and history of chemistry. In particular, he discovered Walden's rule, he invented the stereochemical reaction known as Walden inversion and synthesized the first room-temperature ionic liquid, ethylammonium nitrate.