[FeS/FeS2], a redox system for the origin of life (some experiments on the pyrite-hypothesis).

The FeS/FeS, redox system, whose importance is stressed in recent theories on the origin of life, has been tested experimentally. In this paper it is demonstrated by thermodynamical calculations as well as by experiments, that cyclohexanone, which served as model compound, can be reduced by the aforementioned redox system. Reactions were carried out in methanol and DMF at 25 degrees C and at 100 degrees C. Besides products that were synthesised in both solvents, like cyclohexanethiol and dicyclohexydisulphide, special compounds were obtained in methanol and in DMF, because of the involvement of the respective solvent in the reaction. Yields of reduced compounds were lower in methanol owing to compound that hindered the reduction (cyclohexylketal). With increasing temperature and duration the amount of reduced compounds increased. Further experiments have shown that 1,1-cyclohexanedithiol is likely to be a necessary intermediate for the reduced products. The experiments give evidence to the 'pyrite hypothesis', which postulates that the FeS/FeS2, redox system was of importance for the origin of life.