ISSN:
1432-1432
Schlagwort(e):
Hydrogen sulfide
;
Thiols
;
Primitive atmosphere
;
Prebiotic syntheses
;
Iminothioester
;
Energy converter
;
Chemical evolution
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Summary Sulphur may have played an important role, mainly as an energy converter, during the initial steps of Chemical Evolution. In atmospheric processes, sulphur, in the form of H2S might have been a primary energy acceptor and a source of hot hydrogen atoms. The presence of H2S in the primeval earth atmosphere with a molar ratio of about 10−2 could have allowed the formation of several volatile S-containing compounds without inhibiting the synthesis of the reactive products which are formed in the absence of H2S. An evaluation of the quantity of H2S which could have been included in the primeval atmosphere suggests that such a molar ratio may have been reached. In the primitive soup, the thiols and sulphides formed in the gaseous phase may have evolved, giving rise to various prebiotic syntheses. Studies on the addition reaction of alkanethiols on malonic nitriles in aqueous solutions show two different condensation processes: the formation of thioethers and the formation of iminothioesters. Taking into account the values of the specific rate constants for the two reactions, it is shown that these reactions may have taken place in the primitive earth conditions. These two compounds may have played an important role in the prebiochemical evolution. In particular, iminothioesters can be considered as the immediate precursors of thioesters.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01796095
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