Voltammetric studies on free radicals of lower fatty alcohols

In this work, both generation and reduction processes of the α-radicals of lower fatty alcohols were studied by voltammetry in lower fatty alcohols/peroxydisulfate/phosphate buffer system. Experimental results showed that such three reactions were successively completed at negative potential on mercury electrode surface: (i) sulfate radical anion SO₄^? was generated electrochemically from one-electron reduction of peroxydisulfate ion S₂O₈^2?, (ii) the SO₄^? oxidized lower fatty alcohols to the corresponding α-radicals and (iii) the α-radicals were reduced in one-electron and one-proton addition to produce their own reduction waves. The apparent free energy Δ_rG_m of the α-radicals of lower straight-chain fatty alcohols such as methanol, ethanol, propanol, butanol and pentanol obtained were 107.09, 116.74, 122.53, 126.39 and 129.28 kJ · mol/L, respectively. The proposed method is more simple and convenient than the current approaches based on the radical-chain reaction for studying alcohol oxidation.