If alkane reacts with iodine to form alkyl iodide then HI is also produced as given by the equation.
RH+I_2rightleftharpoonsRI+HI
This reaction is reversible one since HI possesses reducing property.As a result the alkane is reproduced again and the yield of alkyl iodide is negligible,
But presence of of an oxidizing agent eg HIO_3 in the reaction mixture oxidizes the HI produced to I_2and prevents the reaction to occur in backward direction and thus may help the production of RI
Oxidation Of HI
HIO_3+5HI->3I_2+3H_2O