Meteorites as catalysts for prebiotic chemistry.

Meteorite late heavy bombardment was a major event after the accretion of the earth. The relevance of organic syntheses driven by impact shocks was first proposed by Chyba and Sagan in 1992, based on the scanty indications available at the time. How would the contribution by meteorites to an early earth organic pool compare with the syntheses these meteorites might have induced after their impact? Here, we report the catalytic effect of several types of meteorites, iron, stony-iron, chondrites, and achondrites (entreis 1–12 in Table 1) in the syntheses of organic molecules of prebiotic interest using the model reaction of the thermal condensation of formamide (NH2CHO). [6] NH2CHO is a ubiquitous molecule in the universe that has been observed in the comet Hale-Bopp, in the stellar objects W33A, NGC7538, and W3 ACHTUNGTRENNUNG(H2O), [9] in the interstellar medium, in Europa and Orion-KL, in the dense cloud SgrB2, and in carbonaceous chondrites. Recently, NH2CHO was identified as a common constituent of starforming regions that foster planetary systems within the galactic habitable zone, with abundances comparable to that found in comet Hale-Bopp and a potential influx of exogenous delivery to Earth as high as 0.1 molkm 2 yr 1 or 0.18 mmolm 12 per single impact. From a synthetic point of view, NH2CHO could be either an alternative to hydrogen cyanide (HCN), or a possible nonvolatile source of HCN. Unlike HCN, NH2CHO has a boiling point of 210 8C without any azeotropic effect. Regardless of its initial concentration, physical phenomena were described that concentrate 1000-fold organic molecules in capillary spaces. Additional concentration processes by eutectics, clays absorption and evaporation have been reviewed.