Pierre Pelletier. Portrait of Pierre Joseph Pelletier (1788-1842), French chemist. Pelletier studied and taught at the Ecole de Pharmacie until his retirement in 1842. From 1809 he and J.B. Caventou began extracting chemicals from plants by using mild solvents rather than the traditional method of destructive distillation. In 1817, they isolated chlorophyll, the green chemical used by plants in photosynthesis. They also discovered a number of useful 'vegetable bases' (alkaloids) such as strychnine, caffeine, quinine, cinchonine and veratrine. In 1823, he and Dumas proved that alkaloids contain nitrogen in a ring structure and in 1838 Pelletier and P. Walter isolated toluene.