Sodium amalgam or zinc and hydrochloric acid reduce it to lactic acid, whilst hydriodic acid gives propionic acid.
Boron and iodine do not combine directly, but gaseous hydriodic acid reacts with amorphous boron to form the iodide, BI 31 which can also be obtained by passing boron chloride and hydriodic acid through a red-hot porcelain tube.
Hydriodic acid and phosphorus at high temperature give a dihydro-compound, whilst sodium and alcohol give hexaand octo-hydro derivatives.
They are not decomposed by boiling alkalis, but on heating with hydriodic acid they split into their components.
Thus by transposition we may write the last equation as follows 2HI =H2+12+12200 cal., and thus express that hydriodic acid when decomposed into its elements evolves 12200 cal.