Selective chemo-catalytic routes for the preparation of β-hydroxypyruvic acid Original Research Article

β-Hydroxypyruvic acid was prepared by heterogeneous catalytic liquid phase oxidation of glycerol and derivatives over a bismuth-modified platinum catalyst using air as terminal oxidant. A convenient preparative method is described using sodium glycerate as the starting material under weakly acidic conditions (pH 5–6). A selectivity of 93% towards β-hydroxypyruvic acid at a conversion of sodium glycerate of 95% could be achieved. Dihydroxyacetone as well as glycerol, however, were found to be not a suitable starting material for the preparation of the title compound. Oxidation of these two substrates under the above conditions yields mainly oxalic acid. Glyceric acid may be prepared by oxidation of glycerol with oxygen over PdC catalyst under alkaline conditions (pH 10), or by liquid phase catalytic oxidation of solketal with oxygen over PtC catalyst and subsequent removal of the protecting isopropylidene group in acidic medium.