Dicyclohexylammonium salts for the isolation and characterization of aldonic acids

Abstract Dicyclohexylammonium salts of aldonic acids may be prepared from aldonolactones, as well as from metal aldonates and the free acids. Although accompanied by decomposition, their melting points are usually sharp, and these salts appear to have some potential utility for the isolation and characterization of aldonic acids. Dicyclohexylammonium 2-acetamido-2-deoxy- d -gluconate (1) has recently been described; in the course of the present investigation, it was converted into 2-acetamido-2-deoxy- d -glucose (3) , confirming the configuration previously assigned to it. With aqueous dicyclohexylamine, 2-acetamido-2-deoxy- d -mannono-1,4-lactone (2 ) gives 1 . The configuration of 2 was reconfirmed through reduction to 2-acetamido-2-deoxy- d -mannitol (4) , and the optical rotations of this compound and its d - gluco isomer in acidified ammonium molybdate solution were found to be useful physical constants for distinguishing these alditols. 2-Acetamido-2-deoxy- d -galactono-1,4-lactone affords a crystalline dicyclohexylammonium salt of the corresponding acid, from which the lactone may be regenerated.