Science, Tech, Math › Science Substitution Reaction Definition What Is a Substitution Reaction in Chemistry? Share Flipboard Email Print Witthaya Prasongsin / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry in Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Updated January 08, 2019 A substitution reaction is a type of chemical reaction where an atom or functional group of a molecule is replaced by another atom or functional group. A substitution reaction is also called a single displacement reaction, single replacement reaction, or single substitution reaction. Examples: CH3Cl reacted with a hydroxy ion (OH-) will produce CH3OH and chlorine. This substitution reaction replaces the chlorine atom on the original molecule with the hydroxy ion. Sources Imyanitov, Naum S. (1993). "Is This Reaction a Substitution, Oxidation-Reduction, or Transfer?". J. Chem. Educ. 70 (1): 14–16. doi:10.1021/ed070p14March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN 0-471-85472-7. Continue Reading