Regeneration and recovery of hydriodic acid after reduction of polyols to fuels

Polyols such as sorbitol, now directly available from biomass carbohydrates , are reduced by hydriodic acid (HI) to hydrocarbon fuels (80%) with some a lkyl halide (20%) according to a new process (eq 1). Incipient iodine (I-2) is reduced and returned to hydriodic acid (HI) in situ by the simultaneous use of either phosphorous acid (H3PO3) Or hypophosphorous acid (H3PO2) rat her than elemental red phosphorus. The acid mixture can be reused many time s. Eventually, HI must be recovered from the ever-increasing amount of phos phoric acid and water in the mixture. The recovery process consists of two to three distillation steps but for safety reasons combines an initial air oxidation of any excess H3PO3 to H3PO4 P-31 NMR conveniently monitors phosp horus moieties, Less than a mmol/L of HI remains in the final phosphoric ac id pot residue. This coupled redox combination of reducing acids may allow other industrial uses of otherwise expensive HI at the lesser expense of H3 PO3 or H3PO2, either of which also provide the benefit of a homogeneous sys tem.