Insight into alcohol reduction by saccharides and their homologues in supercritical water via aldehyde-mediated radical formation

• Benzhydrol was reduced to diphenylmethane by α-hydroxyaldehydes and 1,2-dialdehyde.
• Supercritical water at 400 °C afforded diphenylmethane.
• Subcritical water at 300 °C resulted in 1,1,2,2-tetraphenylethane.
• A plausible reaction pathway involving radical formation was proposed.

Benzhydrol was directly reduced to diphenylmethane by α-hydroxyaldehydes and dialdehyde, being saccharide degradates, without using a hydride reagent, in supercritical water at 400 °C for 10 min. A lower-temperature reaction in subcritical water at 300 °C primarily generated 1,1,2,2-tetraphenylethane. A plausible reaction pathway was proposed, involving radical formation via the degradation of hemiacetal intermediates derived from benzhydrol and aldehydes.

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