Johann Friedrich Wilhelm Adolf von Baeyer (German: [ˈaːdɔlf fɔn ˈbaɪɐ] ⓘ; 31 October 1835 – 20 August 1917) was a German chemist who synthesised indigo[2] and developed a nomenclature for cyclic compounds (that was subsequently extended and adopted as part of the IUPAC organic nomenclature).

[5] His mother was the daughter of Julius Eduard Hitzig and a member of the originally Jewish Itzig family, and had converted to Christianity before marrying his father, who was of non-Jewish German descent.

On his 50th birthday he was raised to the hereditary nobility by King Ludwig II of Bavaria, conferring on him the "von" distinction.

[8] Baeyer became interested in science early, performing experiments on plant nutrition at his paternal grandfather's Müggelsheim farm as a boy.

[10] 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).

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).

In 1868, Baeyer married Adelheid (Lida) Bendemann, the daughter of a family friend, and together the couple had three children: Eugenie, Hans, and Otto [de].