Hence, from both environmental and economic aspects, it is vital and urgent to develop more efficient, sustainable, and environmentally friendly selective oxidation methods. First, the ideal newly developed oxidation processes are expected to be carried out selectively with green, cheap, sustainable, and non-toxic oxidants, to replace the above-mentioned oxidants. Hydrogen peroxide (H2O2) and molecular oxygen (O2) have become the ideal oxidants since they not only meet the abovementioned ideal oxidants' requirements but also with the advantage of being safe, atomefficient, and producing water as a byproduct. Based on these, several groups have developed highly efficient selective oxidation of alcohols with O2 and H2O2 under homogenous catalytic systems. Bäckvall and co-workers had established the use of a triple catalytic system consisting of RuCI (OAc)(PPh3)3-hydroquinone-Co(salophen)(PPh3), for the oxidation of benzyl alcohol, geraniol, cinnamyl alcohol, and 2-naphthylmethanol by multistep electron transfer at 20 °C under 1 atm of O2. The Marko group has also made a great contribution to develop efficient selective oxidation of alcohols using O2. They have developed homogenous Copper-catalyzed, Ruthenium-Catalyzed oxidation systems. They used the homogenous copper complex CuCl-Phen (5 mol %), with 2 equiv. K2CO3, and 1,2-bis(ethoxycarbonyl)hydrazine (DEADH2; 25 mol %), under the following conditions (O2 or air, toluene, 70° to 90°C), and a wide range of alcohols including primary, secondary, allylic, and benzylic alcohols can be oxidized to the corresponding carbonyl compounds in 71-97% yield.