 Saponification of triglycerides

A triglyceride contains three ester linkages joining glycerol to fatty acid-derived acyl groups. Complete saponification therefore consumes three hydroxide equivalents per triglyceride, yielding one glycerol and three fatty acid carboxylates.^[ref]

Writing the three hydrocarbon groups separately allows their compositions to differ:This is the preceding ester chemical equation applied three times: each linkage supplies one carboxylate, and each formerly esterified oxygen on the glycerol scaffold gains one hydrogen. The two sides retain the same three ${\mathrm{R}}_i$ groups and have net electric charge $-3$.

Soap consists of sodium or potassium salts of long-chain fatty acids. Its carboxylate head is hydrophilic, while its long hydrocarbon tail is hydrophobic. This makes it an amphiphile and a surfactant: the tails can associate with grease while the heads remain exposed to water, helping disperse grease for rinsing. An acetate ion is also a carboxylate, but lacks the long hydrophobic tail that gives soap this cleaning role.^[ref]