Selective Acceptorless Conversion of Primary Alcohols to Acetals and Dihydrogen Catalyzed by the Ruthenium(II) Complex Ru(PPh3)2(NCCH3)2(SO4)

The complex bis(acetonitrile)bis(triphenylphosphine)ruthenium(II) sulfate [Ru(PPh3)2(NCCH3)2(SO4)], fully characterized spectroscopically and by a single crystal X-ray study, catalyzes at 110 degrees C the direct transformation of primary alcohols to the corresponding acetals with liberation of molecular hydrogen. The formation of acetals proceeds via direct substitution of the hydroxy group of the hemiacetal intermediate by an alcohol molecule. The closely related bis(triphenylphosphine)ruthenium(II) acetate [Ru(PPh3)2(OAc)2] catalyzes the conversion of primary alcohols to the corresponding esters rather than acetals.