Illustrated Glossary of Organic Chemistry

Starting material: A reactant in a chemical reaction or mechanism step. This term is usually reserved for the reactant that contributes the greatest number of carbon atoms to the product, or the reactant that is considered most 'precious' because of availability, cost, effort to synthesize, etc. The starting material for an enzyme reaction is usually called the substrate.

In this catalytic hydrogenation reaction, 1,2-dimethylcyclohexene is the starting material (or substrate), molecular hydrogen is a reactant, ethanol is the solvent, and platinum is a catalyst. The product is cis-1,2-dimethylcyclohexane.

	+		+		Mix together --------------->
Dry pasta (a starting material.)		Boiling water (a starting material).		Spaghetti sauce (a starting material).		A yummy dinner (the product).

When making spaghetti, the starting materials are dry pasta, boiling water, and spaghetti sauce. The product is yummy dinner.