The catalytic conversion of dihydroxyacetone (DHA) to lactic acid (LA) via pyruvaldehyde (PA) in an aqueous medium was studied using different homogeneous metal salts. A kinetic model was developed and the parameters corresponding to each reaction step were estimated. Agreement between experiments and simulated results was excellent and the performance of the different catalysts was consistent with previous studies described in the literature. Aluminium salts, which show the best performance, were tested in a whole range of concentrations and at different pH values in order to identify the catalytically active ionic species. It was confirmed that the DHA to pyruvaldehyde (PA) dehydration step is catalyzed by both Brønsted and Lewis acids, whereas the consecutive reaction of PA to LA is catalyzed solely by Lewis acids. Moreover, a comparison of the thermodynamic analysis of the reaction medium and the kinetic parameters demonstrated that cationic hydroxyl-aluminium complexes [Al(OH)_h]^(3−h)+ formed in situ by the hydrolysis of aluminium aqua complexes like [Al(OH₂)₆]³⁺ are the most active Lewis acids.

中文翻译：

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在金属盐存在下在水性介质中将二羟基丙酮转化为乳酸：离子热力学平衡对反应性能的影响†

二羟基丙酮（DHA）通过以下方式催化转化为乳酸（LA）使用不同的均相金属盐研究了水性介质中的丙酮醛（PA）。建立了动力学模型，并估算了与每个反应步骤相对应的参数。实验和模拟结果之间的一致性非常好，并且不同催化剂的性能与文献中描述的先前研究一致。在整个浓度范围和不同pH值下测试了表现出最佳性能的铝盐，以鉴定具有催化活性的离子物质。证实了布朗斯台德酸和路易斯酸都催化DHA到丙酮醛（PA）的脱水步骤，而PA与LA的连续反应仅由路易斯酸催化。而且，由铝水合物如[Al（OH ₂） ₆ ] ³⁺水解而原位形成的_h ]^{（3- h）+}是最具活性的路易斯酸。