AQUEOUS HIGH-TEMPERATURE CHEMISTRY OF CARBOCYCLES AND HETEROCYCLES .4. 4-SUBSTITUTED PYRIDINES

In aquathermolysis, 4-methylpyridine and 1, 2-bis(4-pyridyl)ethane are stable, but pyridine-4-carboxaldehyde, 4-pyridylmethanol, and 1, 2-bis(4-pyridyl)ethene are all more reactive than the corresponding 3- and 2-isomers. Pyridine-4-carboxylic acid is as reactive as pyridine-3-carboxylic acid but less so than the 2-acid, being only partially decarboxylated. The aldehyde yields pyridine, 4-methylpyridine, 1, 2-bis(4-pyridyl)ethane, and, for reactions carried out in cyclohexane, also 1, 2-bis(4-pyridyl)ethene. The alcohol forms similar products in water, but in cyclohexane these simple products are accompanied by more complex molecules containing three pyridine rings. With one exception, the structures of all products have been elucidated, reaction sequences for their formation suggested, and the sequences tested by the study of two of the bimolecular derivatives implicated. The implications of this chemistry for diagenesis and catagenesis of kerogens, under aquathermolysis conditions, are outlined in part 1 of this series. © 1990, American Chemical Society. All rights reserved.