Weber argued based on kinetic and thermodynamic principles that under mild aqueous reaction conditions, the FR may in fact be the only one-carbon condensation reaction capable of generating complex organic compounds for the origin of life. Under neutral pH conditions, HCHO solutions can also produce a series of low molecular weight polyoxymethylene (POM) polymers (of formula HO(CH 2 O) n H) . A five-weight percent (~1.3 M) aqueous HCHO solution contains ∼14% POM dimer, 3% trimer, and 0.5% tetramer , and such compounds are suspected to be major components of comets . Under the basic conditions which allow the FR to proceed, a complex mixture of carbohydrates can arise even at concentrations as low as 10 -3 M 3 . Nevertheless, it may only be possible to reach such concentrations in specialized early Earth environments .