Hydroxymethyl hydroperoxide and bis(hydroxymethyl) peroxide fom gas-phase ozonolysis of naturally occurring alkenes.

Ozonolysis is one of the main pathways for degradation of alkenes in the atmosphere, where the reaction is associated with smog formation1 and the haze that often occurs over forests2,3. In recent decades, ground-level ozone concentrations have greatly increased4,5. The possibility of significant damage to plants by ozone and its products has consequently been raised in discussions of ‘waldsterben’, the large-scale dying of trees in northern Europe and North America6–9. With particular regard to the formation of peroxides, we have used 13C- nuclear magnetic resonance (NMR) to investigate the water-soluble products of the gas-phase ozonolysis of isoprene and several terpenes, which are emitted into the atmosphere in large quantities (108–109 tonnes yr−1 globally) by trees3,10,11. All these alkenes yield bis(hydroxymethyl)peroxide (BHMP; HOCH2OOCH2OH). The apparent precursor of BHMP is hydroxymethyl hydroperoxide (HMP; HOCH2OOH), which results from addition of water to the ozonolysis intermediate. As both HMP and BHMP have various toxic effects on plant cells and enzymes12–14, we point out here an indirect way by which ozone may adversely affect forests