Naruto Masayuki, Saito Susumu
Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Institute for Advanced Research, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Nat Commun. 2015 Aug 28;6:8140. doi: 10.1038/ncomms9140.
Carboxylic acids are ubiquitous in bio-renewable and petrochemical sources of carbon. Hydrogenation of carboxylic acids to yield alcohols produces water as the only byproduct, and thus represents a possible next generation, sustainable method for the production of these alternative energy carriers/platform chemicals on a large scale. Reported herein are molecular insights into cationic mononuclear ruthenium carboxylates (Ru(OCOR)) as prototypical catalysts for the hydrogenation of carboxylic acids. The substrate-derived coordinated carboxylate was found to function initially as a proton acceptor for the heterolytic cleavage of dihydrogen, and subsequently also as an acceptor for the hydride from Ru-H, which was generated in the first step (self-induced catalysis). The hydrogenation proceeded selectively and at high levels of functional group tolerance, a feature that is challenging to achieve with existing heterogeneous/homogeneous catalyst systems. These fundamental insights are expected to significantly benefit the future development of metal carboxylate-catalysed hydrogenation processes of bio-renewable resources.
羧酸在生物可再生和石化碳源中广泛存在。将羧酸加氢生成醇类仅产生水作为唯一副产物，因此代表了一种可能的大规模生产这些替代能源载体/平台化学品的下一代可持续方法。本文报道了对羧酸加氢的典型催化剂——阳离子单核钌羧酸盐（[Ru(OCOR)]⁺）的分子见解。发现底物衍生的配位羧酸盐最初作为质子受体用于氢气的异裂，随后也作为第一步中生成的[Ru-H]⁺中氢化物的受体（自诱导催化）。加氢反应具有选择性且对官能团具有高度耐受性，这一特性对于现有的多相/均相催化剂体系来说难以实现。这些基本见解有望极大地促进金属羧酸盐催化的生物可再生资源加氢过程的未来发展。
