Pyrogallo4arenes: a synthetic investigation
Griffin, Pauline (2007) Pyrogallo4arenes: a synthetic investigation. PhD thesis, Dublin City University.
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The first part of this work involved the study of the acid condensation of pyrogallol with acataldehyde. The product formed, pyrogallolarene, is present as a mixture of two isomers, the rccc cone and the rctt flattened partial cone conformations, which could be separated using an extractiodreprecipitation procedure. A series of studies was undertaken to determine if these two isomers could be interconverted. We found that both the rctt flattened partial cone and rccc cone isomers could not be interconverted, demonstrating the high stability of the pyrogallolarene macrocycle compared to the well-documented resorcinarenes. Alkylation of the pyrogallolarene macrocyle with ethyl bromoacetate was successfully achieved and analysis of both isolated products (rccc and rctt) revealed that the original conformations are maintained and are temperature stable.
The same acidic reaction conditions were used to condense pyrogallol with a variety ofketones leading to the first ever pyrogallolarenes possessing two alkyl groups at the bridging carbons. The conformations of this new class of sterically hindered pyrogallolarene were established.
Also reported is the development of new gentle, environmentally fkiendly condensation conditions for the preparation of pyrogallolarenes. This work lead to the development of a new and novel metal catalysed condensation reaction. We found that these conditions are highly efficient for the preparation of pyrogallolarenes from aryl aldehydes possessing electron rich groups. Furthermore, the resulting cyclic tetramers prepared by this new methodology, are of higher purity than the cyclic tetramers prepared fkom the harsh acid condensation conditions that have been used to date.
The final section of this research work involved the investigation of the ion selectivity of both calixarene phthalonitriles and pyrogallolarenes using picrate extractions, mass spectral techniques and ion selective electrode based potentiometry.
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