after he returned to Berlin in 1858 for the completion of his doctorate on arsenic methyl chloride, or cacodylic chloride. Academic career and achievements After completing his doctorate, he followed Kekulé to the University of Ghent, when Kekulé became professor there. He became a lecturer at the (Royal Trade Academy) in 1860 and a professor at the University of Strasbourg in 1871. In 1875, he succeeded Justus von Liebig as Chemistry Professor at the University of Munich. Baeyer's chief achievements include the synthesis and description of the plant dye indigo, the discovery of the phthalein dyes, and the investigation of polyacetylenes, oxonium salts, nitroso compounds (1869) and uric acid derivatives (1860 and onwards) (including the discovery of barbituric acid (1864), the parent compound of the barbiturates). He was the first to propose the correct formula for indole in 1869, after publishing the first synthesis three years earlier. His contributions to theoretical chemistry include the 'strain' (Spannung) theory of triple bonds and strain theory in small carbon rings. In 1871 he discovered the synthesis of phenolphthalein by condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence the name). That same year he was the first to obtain synthetic fluorescein, a fluorophore pigment which is similar to naturally occurring pyoverdin that is synthesised by microorganisms (e.g., by some fluorescent strains of Pseudomonas). Baeyer named his finding "resorcinphthalein" as he had synthesised it from phthalic anhydride and resorcinol. The term fluorescein would not start to be used until 1878. In 1872 he experimented with phenol and formaldehyde; the resinous product was a precursor for Leo Baekeland's later commercialization of Bakelite. In 1881 the Royal Society of London awarded Baeyer the Davy Medal for his work with indigo. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1884. In 1905 he was awarded the Nobel Prize in Chemistry "in recognition of his services in the advancement of organic chemistry and the chemical industry, through his work on organic dyes and hydroaromatic compounds", and he continued in full active work as one of the best-known teachers in the world of organic chemistry up to within a year of his death. Honours 1881: Davy Medal of the Royal Society in London 1884: American Academy of Arts and Sciences fellow. 1884: Prussian Academy of Sciences 1885: foreign member of the Royal Society. 1885: survey in the