MARKOVNIKOV RULE

in organic chemistry, a generalization, formulated by Vladimir Vasilyevich Markovnikov in 1869, stating that in addition reactions to unsymmetrical alkenes, the electron-rich component of the reagent adds to the carbon atom with fewer hydrogen atoms bonded to it, while the electron-deficient component adds to the carbon atom with more hydrogen atoms bonded to it. Thus, hydrogen chloride (HCl) adds to propylene (CH3CH=CH2) to produce 2-chloropropane (CH3CHClCH3) rather than the isomeric 1-chloropropane (CH3CH2CH2Cl). The rule is useful in predicting the molecular structures of products of addition reactions.