Oxidative decarboxylation of aldonolactones by ceric sulphate in aqueous sulphuric acid. Part II. Mechanism and kinetics. Synthesis of D-xylose, D-erythrose and D-threose.

L. SALA; A, FERNÁNDEZ CIRELLI; R. MUCHNIK DE LEDERKREMER

Anales Asociación Química Argentina

Asociación Química Argentina

Lugar: Buenos Aires; Año: 1978 vol. 66 p. 57 - 63

0365-7124

Oxidation of calcium D-galactonate, D-galactono-1,4-lactone, D-manono-1,4-lactone and D-glycero-D-gulo-heptono-1,4-lactone by cerium (IV) sulphate in M sulphuric acid at 37º was studied. The agreement for k (true rate constant) and K (complex formation) values indicates that the C-1 and C-2 of aldonic acid are involved in a coordination complex with cerium (IV), which then undergoes unimolecular decomposition to a free radical in the slow step of the reaction, as already proposed for D-glucono-1,5-lactone. Activation parameters for the reaction were calculated for D-galactono-1,4-lactone and the values found are in accordance with the mechamnism. D-lyxose, D-erythrose and D-threose were synthethysed from D-galactono-1,4-lactone, potassium D-arabinonate for D-glucono-1,5-lactone.