Selective aerobic oxidation of aliphatic aldehydes: the critical role of percarboxylate anion on the selectivity

Abstract

During the aerobic oxidation of aldehydes, peracids accumulate in the reaction mixture. From a safety and selectivity perspective, the quantification and transformation of the peracids into the corresponding carboxylic acids...

Light-induced autoxidation of aldehydes to peracids and carboxylic acids

“…Following a mechanism similar to Baeyer–Villiger oxidation, 20 the corresponding carboxylic acid 3a can be formed via a Criegee intermediate at rate k b . Another pathway for the rearrangement of the Criegee intermediate has been reported, 17,21 which can afford a mixture of formate 4a and carboxylic acid 3a . Luckily, formate byproduct 4a was not observed under our conditions for substrate 1a .…”

“…14 Favre-Réguillon et al investigated these pathways and the key factors that favored one pathway over another. 14,21,22 Lehtinen et al and Jin, Peng, Zhao et al have demonstrated the effect of the solvent on the rearrangement of peracid-aldehyde adducts during the aerobic autoxidation of aldehydes via experimental and computational efforts. 17 However, most of these mechanistic investigations have focused on the competition between the two pathways governing the rearrangement of the Criegee intermediate ( k b vs. k d ) and used an aliphatic aldehyde (2-ethylhexanal) to conduct their investigation.…”

“…2), and related reports. 11 e ,13 e – g ,21,22 b Under light irradiation, aldehyde 1 is excited to form a highly reactive triplet radical pair ( I and II ), which undergoes a radical-mediated pathway with molecular oxygen to generate the corresponding peroxy radicals ( III and IV ). Peroxy radical III subsequently engages in a hydrogen atom transfer (HAT) reaction to form peracid 2 and benzoyl radical I .…”

Comment on “CO2 as oxidant: an unusual light-assisted catalyst free oxidation of aldehydes to acids under mild conditions” by S. R. Khan, S. Saini, K. Naresh, A. Kumari, V. Aniya, P. K. Khatri, A. Ray and S. L. Jain, Chem. Commun., 2022, 58, 2208

“…In particular, intermediates ( i.e. , peroxybenzoic acid) could accumulate in the reaction mixture and are later transformed into the corresponding benzoic acid during work-up, 17,18 which makes the standard Gibbs free energy change determination more challenging.…”

Ultrafast Solid-Phase Oxidation of Aldehydes to Carboxylic Acids by Atmosphseric Plasma Treatment

“…Despite the development of improved metal-catalyzed synthetic methods from the past decade, − more sustainable and efficient catalyst ligand- and metal-free strategies for aerobic oxidation are highly desired, especially the ones using only a small amount of solvent to reduce the environmental impact. , Apart from the triviality of this chemical reaction, many efforts were made, even very recently, to overcome the drawbacks and to tailor novel methods for today’s requirements. These recent methods are mainly designed alongside sustainability and green chemistry-oriented considerations. − However, many of them still suffer from the need of additional catalysts, − even if these catalysts are considered environmentally friendly ones.…”