Russian organic chemist who contributed to structural theory and to the understanding of the ionic addition (Markovnikov addition) of hydrogen halides to the carbon-carbon double bond of alkenes.

After studying at the universities of Kazan and St. Petersburg, Markovnikov taught at the universities of Kazan, Odessa, and Moscow (1873–98). Through his experiments he showed that butyric and isobutyric acids have the same chemical formula but different structures; i.e., they are isomers. In 1869, while developing his theory of the mutual influence of atoms in chemical compounds, he noted that when hydrogen halides are added to an alkene, the hydrogen attaches to the carbon with more hydrogens already attached, whereas the halogen attaches to the carbon with fewer hydrogens attached. Why hydrogen bromide exhibited both Markovnikov as well as reversed-order, or anti-Markovnikov, addition, however, was not understood until Morris Selig Kharasch offered an explanation in 1933.