Conversion of lignin into well-defined aromatic chemicals is a highly attractive goal but is often hampered by recondensation of the formed fragments, especially in acidolysis. Here, we describe new strategies that markedly suppress such undesired pathways to result in diverse aromatic compounds previously not systematically targeted from lignin. Model studies established that a catalytic amount of triflic acid is very effective in cleaving the β-O-4 linkage, most abundant in lignin. An aldehyde product was identified as the main cause of side reactions under cleavage conditions. Capturing this unstable compound by reaction with diols and by in situ catalytic hydrogenation or decarbonylation lead to three distinct groups of aromatic compounds in high yields acetals, ethanol and ethyl aromatics, and methyl aromatics. Notably, the same product groups were obtained when these approaches were successfully extended to lignin. In addition, the formation of higher molecular weight side products was markedly suppressed, indicating that the aldehyde intermediates play a significant role in these processes. The described strategy has the potential to be generally applicable for the production of interesting aromatic compounds from lignin.

The major antimicrobial products of neutrophilic myeloperoxidase (MPO) in physiologic fluids are hypochlorous acid (HOCl) and hypothiocyanite (OSCN-), and the former is generally believed to be the killing agent. However, we have determined that HOCl oxidizes SCN- in a facile nonenzymic reaction. The observed kinetics and computational models substantiate the hypothesis that SCN- serves to moderate the potential autotoxicity of HOCl by restricting its lifetime in physiologic fluids. Furthermore, the oxidizing equivalents of HOCl are preserved in OSCN-, a more discriminate biocide that is not lethal to mammalian cells.

Aqueous biphasic systems were investigated for the production of formate–amine adducts by metal‐catalyzed CO2 hydrogenation, including typical scrubbing solutions as feedstocks. Different hydrophobic organic solvents and ionic liquids could be employed as the stationary phase for cis‐[Ru(dppm)2Cl2] (dppm=bis‐diphenylphosphinomethane) as prototypical catalyst without any modification or tagging of the complex. The amines were found to partition between the two phases depending on their structure, whereas the formate–amine adducts were nearly quantitatively extracted into the aqueous phase, providing a favorable phase behavior for the envisaged integrated reaction/separation sequence. The solvent pair of methyl isobutyl carbinol (MIBC) and water led to the most practical and productive system and repeated use of the catalyst phase was demonstrated. The highest single batch activity with a TOFav of approximately 35 000 h−1 and an initial TOF of approximately 180 000 h−1 was achieved in the presence of NEt3. Owing to higher stability, the highest productivities were obtained with methyl diethanolamine (Aminosol CST 115) and monoethanolamine (MEA), which are used in commercial scale CO2‐scrubbing processes. Saturated aqueous solutions (CO2 overpressure 5–10 bar) of MEA could be converted into the corresponding formate adducts with average turnover frequencies up to 14×103 h−1 with an overall yield of 70 % based on the amine, corresponding to a total turnover number of 150 000 over eleven recycling experiments. This opens the possibility for integrated approaches to carbon capture and utilization.

Lewis superacid with higher fluoride ion affinity than SbF5.

a Ionic liquids are attractive reaction media for the solubilisation and depolymerisation of lignin into valueadded products. However, mechanistic insight related to the cleavage of specific linkages relevant to efficient lignin depolymerisation in such solvents is still lacking. This study presents important insight into the scission of the most abundant lignin β-O-4 motif in Brønsted acidic ionic liquids. Using relevant model compounds, cleavage products were identified and undesired side reactions examined carefully. Stabilization of reactive intermediates was achieved in ionic liquids comprising both Brønsted acidic function and stabilized nanoparticles that comprise hydrogenation activity in order to suppress undesired side reactions. Especially, the in situ hydrogenation of the aldehyde intermediate originating from the acid-catalysed cleavage of lignin beta-O-4 model compounds into more stable alcohols was investigated. This is the first time that such products have been systematically targeted in these multifunctional reaction media in relation to lignin depolymerization.