The major organic component in carbonaceous chondrites is a
highly aromatic macromolecular material. Aromatic organic matter and
phyllosilicates are co-located in these meteorites and it is possible that the
physical association represents a synthetic chemical relationship. To explore the
potential reactions that could take place to produce the aromatic macromolecular
material we heated various simple aromatic units in the presence of
montmorillonite with different exchanged cations. The majority of cation
exchanged montmorillonites tested, sodium-, aluminium-, iron-, nickel- and
cobalt-rich montmorillonites, do not produce polymerisation products. By contrast
Fe3+ cation exchanged montmorillonite readily facilitates addition reactions
between aromatic hydrocarbons. A feasible mechanism for the process is
oxidative coupling which involves a corresponding reduction of the Fe3+ cation to its Fe2+ counterpart. A similar reduction process for the other metal cations does not take place highlighting the importance of iron. This simple process is a feasible mechanism for the addition to the aromatic macromolecules such as those
found in carbonaceous chondrites. The search for a relationship between Fe3+-rich
phyllosilicates and aromatic organic structures (particularly dimers, trimers and more polymerised forms) in carbonaceous chondrites would represent an effective test for constraining the role of clay catalysis in the early solar system.