That's really interesting! What's the energy source that drives this reaction? (Where does the energy that becomes the additional chemical potential energy in the peroxide come from? Is it from oxidizing the plant sugars?)
Great question! The reaction is actually thermodynamically downhill and spontaneous (delta G less than zero). The current manufacturing processes use palladium catalysts that do have an activation barrier that requires heat. Enzymes are much more efficient and can catalyze this reaction even below room temperature.
That's counterintuitive to me because I know peroxides have quite a bit of potential energy (for example, because of their use in fuels). Are you starting from sugars that have even more?
yep, sugars have more internal energy than peroxide (you can just add up all the bond enthalpies for a quick estimate). Peroxide is used in fuels because 1.) it is much easier to activate than sugars because it is thermodynamically metastable and 2.) it is an oxidizer. Oxidizers help accelerate the release of internal energy from energy-dense fuels (e.g. kerosene...or even sugar). Another way to look at this is reduced vs oxidized. O2 is the most (stable) oxidized form of oxygen while H2O is a reduced form of oxygen. H2O2 is intermediate. Hexane is a very reduced C6 compound (high internal energy) whereas 6 CO2 molecules are the most oxidized (low internal energy). glucose is intermediate between hexane and 6 CO2 molecules but closer to hexane in terms of how reduced it is. Glucose is quite energy dense and it is for this reason that it is used by plants to store energy from sunlight.
