Most chemical reactions on asteroids, from which meteors and meteorites originate, are hypothesized to occur primarily
in the solid mixtures. Some secondary chemical reactions may have occurred during the periods of the aqueous alteration
of the asteroids. A myriad of organic compounds have been isolated from the meteorites, but the chemical pathways by
which they were formed are only partially elucidated. In this paper we propose that many meteoritic organic compounds
were formed in the solventless and solid-state reactions, which were only recently explored in the conjunction with the
green chemistry (environmentally friendly). A typical solventless approach exploits the phenomenon of the mixed
melting points. As the solid materials are mixed together, the melting point of the mixture becomes lower than the
melting points of its individual components. In some cases the entire mixture may melt upon mixing. The reactions
would then occur in a viscous melted state. In the traditional solid-state reactions the solids are mixed together, which
allows for the intimate contact of the reactants, but the reaction occurs without melting. Numerous examples of the
known solventless and solid-state reactions which are particularly relevant to the meteoritic chemistry are described.
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