Johann Karl Wilhelm Ferdinand Tiemann (June 10, 1848 – November 14, 1899) was a German chemist and together with Karl Reimer discoverer of the Reimer-Tiemann reaction. Beginning in 1866, Tiemann studied pharmacy at the TU Braunschweig where he graduated in 1869. His professor in Brunswick wrote a letter of recommendation to August Wilhelm von Hofmann at the University of Berlin where Tiemann started as assistant of von Hofmann in 1869. In 1874 Wilhelm Haarmann and Tiemann started a company, after they discovered the synthesis of vanillin from coniferyl alcohol. The vanillin plant Holzminden was not very successful before discovered the Reimer-Tiemann reaction which opened an alternative synthesis route to vanillin. In 1882 Tiemann became professor at the University of Berlin.