Production of lactic acid mediated by compressed carbon dioxide on heterogeneous Ni(ii) catalysts: a facile approach

Abstract

Lactic acid is one of the appealing platform molecules in organic synthesis, currently in high demand after the innovation of bio-plastics. The limitations of traditional manufacturing routes (microbial process and chemical synthesis using petroleum resources) directed us to develop economically and environmentally viable catalytic strategies exploring renewable resources to meet the expected demand. In this study, we demonstrated a method of lactic acid synthesis by fixing CO₂ as a waste gas into acetaldehyde used as a biobased feedstock on a highly active, recyclable heterogeneous Ni catalyst. The significance of the developed process lies in the transformation of easily available low-cost starting materials to a high-value product without harsh reaction conditions, extra sensitive reagents, and additional steps to derive the right starting material or to remove impurities, which is advantageous in terms of sustainability. Moreover, the optimization of different reaction parameters ensures achieving high yields (>80%) and an excellent production rate of 6700 μmol g⁻¹ h⁻¹. In addition, the characterization of the catalyst by different spectroscopic techniques suggested an interaction between the substrate and the catalyst, which provides an indication of the possible reaction path, thus a mechanism would be outlined. The successful extension of this process to various aldehydes was possible to produce their corresponding hydroxycarboxylic acid with broad functional group tolerance. Altogether, this methodology opens up a promising avenue for the production of biochemicals from renewable resources, which is a key to develop a sustainable society.