The crystal structures of quinolinium 3-carboxy-4-hydroxybenzenesulfonate trihydrate, C9H8N + C7H5O6S 3H2O, (I), 8-hydroxyquinolinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, C9H8NO + C7H5O6S H2O, (II), 8-aminoquinolinium 3-carboxy-4-hydroxybenzenesulfonate dihydrate, C9H9N2 + C7H5O6S 2H2O, (III), and 2-carboxyquinolinium 3-carboxy-4-hydroxybenzenesulfonate quinolinium-2-carboxylate, C1...

A series of sterically shielded pyrrolidine nitroxides were synthesized, and their reduction by ascorbate (vitamin C) indicate that nitroxide 3, a tetraethyl derivative of 3-carboxy-PROXYL, is reduced at the slowest rate among known nitroxides, i.e., at a 60-fold slower rate than that for 3-carboxy-PROXYL.