A review that highlights water as the logical reaction medium in which organic chemistry can be practiced. The key roles that water can play in directing reaction outcomes, including impacting mechanistic features, are discussed using selected examples.

Iron lends power to traces of palladium: Palladium (Pd) is a mainstay of chemical catalysis. The precious metal has a knack for forging carbon-carbon (C-C) bonds. Handa et al. now report that when mixed in a specific preparation with iron, just parts per million of Pd suffice to catalyze the C-C bond–forming Suzuki coupling reaction. The addition of surfactants allowed the reaction to proceed in water. The protocol bodes well for conserving Pd in pharmaceutical and agrochemical synthesis. Science , this issue p. 1087