Kinetics and Mechanisms of Hydrothermal Dehydration of Cyclic 1,2- and 1,4-Diols.

Hydrothermal dehydration is an attractive method for deoxygenation and upgrading of biofuels because it requires no reagents or catalysts other than superheated water. Although mono-alcohols cleanly deoxygenate via dehydration under many conditions, polyols such as those derived from saccharides and related structures are known to be recalcitrant with respect to dehydration. Here, we describe detailed mechanistic and kinetic studies of hydrothermal dehydration of 1,2- and 1,4-cyclohexanediols as model compounds to investigate how interactions between the hydroxyls can control the reaction.

Hydrothermal photochemistry as a mechanistic tool in organic geochemistry: the chemistry of dibenzyl ketone.

Hydrothermal organic transformations under geochemically relevant conditions can result in complex product mixtures that form via multiple reaction pathways. The hydrothermal decomposition reactions of the model ketone dibenzyl ketone form a mixture of reduction, dehydration, fragmentation, and coupling products that suggest simultaneous and competitive radical and ionic reaction pathways. Here we show how Norrish Type I photocleavage of dibenzyl ketone can be used to independently generate the benzyl radicals previously proposed as the primary intermediates for the pure hydrothermal reaction.