Abstract: Alkali metal salts of polymeric acetal carboxylate are stable detergent builders under laundry use conditions but depolymerize in acid media, making the polymer fragments more readily biodegradable in waste streams. According to the improved process of the present invention, an ester of a polymeric acetal carboxylate is brought together in a reaction zone with a sufficient amount of an alkali metal base having a normality of at least 5 normal, and preferably at least 10 normal, to saponify at least 50 percent of the ester groups. In the preferred embodiment, the ester is contacted with a solvent to remove color-producing impurities.