5-Sulfosalicylic acid catalyzed direct Mannich reaction in pure water

•A green system for metal- and surfactant-free Mannich reactions was established.•5-Sulfosalicylic acid is superior recyclable water-soluble organocatalyst.•The catalytic Mannich reactions afforded β-amino ketones with excellent yields.•The catalyst can be recycled in water whereas the product isolated by filtration.•A new single crystal confirmed the anti-conguration of products.