TRANSFORMATION OF 1,3-DIOL, 1,4-DIOL AND 1,5-DIOL OVER PERFLUORINATED RESINSULFONIC ACIDS (NAFION-H)

The transformations of 1,3-, 1,4- and 1,5-diols over perfluorinated resinsulfonic acids (Nafion-H) were studied and correlations were examined between the structure of the investigated diols, the possible transformation directions and the catalytic properties of Nafion-H. Comparisons were also made between the catalytic properties of Nafion-H and zeolites. The characteristic transformations of 1,3-diols depend on their structure. 1,3-Propanediol undergoes dehydration via 1,2-elimination and yields oligomers via intermolecular dehydration. 1,3-Diols with an alkyl substituent on the carbon between those bearing the OH groups undergo 1,2-elimination yielding unsaturated alcohols and dienes, and give carbonyl compounds via the loss of water and hydride shifts analogous to the pinacol rearrangement. The strong acidity of Nafion-H and the lack of strong basic sites are advantageous for the latter reaction. 1,3-Diols with two substituents at this position mainly yield fragmentation products. Stereoselective cyclodehydration to the corresponding oxacycloalkanes is the characteristic transformation of 1,4- and 1,5-diols over Nafion-H.