Robby Vroemans

Catalysts, Vol. 14, Pages 250: Diphenyl Carbonate: Recent Progress on Its Catalytic Synthesis by Transesterification

Catalysts doi: 10.3390/catal14040250

Authors: Dong Wang Feng Shi Guochao Yang

Diphenyl carbonate is one of the raw materials used for the synthesis of polycarbonate, and its green and clean production is of great importance to the non-phosgene process for polycarbonate. The production of diphenyl carbonate by transesterification is its representative process route and is considered to be one of the typical examples of a green and sustainable process for chemicals. Since the discovery of the transesterification catalyst for diphenyl carbonate in the 1970s, researchers have been committed to improving its catalytic activity and selectivity and, correspondingly, the reaction engineering process. However, thermodynamic limitations, low activity, low selectivity, and limited stability have been bottlenecks that the transesterification catalyst has not been able to completely overcome, and the improvement of the catalyst is still ongoing. Therefore, this review takes the transesterification reaction of dimethyl carbonate and phenol as a model reaction and, based on a review of the progress in catalyst research on catalytic reaction processes, tries to clarify the structure–activity relationship between catalytic active sites and catalytic performance in homogeneous and heterogeneous catalytic processes and provides an overview of the progress in catalyst synthesis and modification.

Nature Chemistry, Published online: 28 March 2024; doi:10.1038/s41557-024-01470-8

Nature Synthesis, Published online: 27 March 2024; doi:10.1038/s44160-024-00515-7

Publication date: 13 June 2024

Source: Chem, Volume 10, Issue 6

Author(s): Qiang Wang, Haifeng Qi, Yujing Ren, Zhusong Cao, Kathrin Junge, Rajenahally V. Jagadeesh, Matthias Beller

An electrochemical dehydrative reaction of dicarboxylic acids to their cyclic anhydrides is presented. The electrochemically generated anhydrides can be directly employed for amidation reactions. The mechanism of the reaction was investigated by ¹⁸O isotope labeling, revealing the formation of sulfate during electrolysis.

Abstract

An intramolecular electrochemical dehydration reaction of dicarboxylic acids to their cyclic anhydrides is presented. This electrolysis allows dicarboxylic acids as naturally abundant, inexpensive, safe, and readily available starting materials to be transformed into carboxylic anhydrides under mild reaction conditions. No conventional dehydration reagent is required. The obtained cyclic anhydrides are highly valuable reagents in organic synthesis, and in this report, we use them in-situ for acylation reactions of amines to synthesize amides. This work is part of the recent progress in electrochemical dehydration, which – in contrast to electrochemical dehydrogenative reactions for example – is an underexplored field of research. The reaction mechanism was investigated by ¹⁸O isotope labeling, revealing the formation of sulfate by electrochemical oxidation and hydrolysis of the thiocyanate-supporting electrolyte. This transformation is not a classical Kolbe electrolysis, because it is non-decarboxylative, and all carbon atoms of the carboxylic acid starting material are contained in the carboxylic anhydride. In total, 20 examples are shown with NMR yields up to 71 %.

Nature Synthesis, Published online: 26 March 2024; doi:10.1038/s44160-024-00499-4

Publication date: 15 April 2024

Source: Molecular Catalysis, Volume 559

Author(s): Jie Xu, Qiqi Li, Tianlin Ma, Yujie Wang

Publication date: 15 June 2024

Source: Coordination Chemistry Reviews, Volume 509

Author(s): Sem Bleus, Wim Dehaen

Abstract

A Mitsunobu process performed under neat grinding conditions, using a mixer mill, is reported. It proceeds in the absence of reaction solvent and in short reactions times (10–20 min). A broad substrate scope encompassing primary and secondary alcohols, as well as oxygen, nitrogen, sulfur, and carbon-centered nucleophiles is demonstrated. Application to the functionalization of a selection of APIs is shown, also. The developed process is amenable to scale up on a planetary ball-mill, yielding over 2 grams of product. Finally, a representative alcohol is inverted with excellent stereoselectivity.

A straightforward and ligand-free manganese-catalyzed protocol for the chemo- and stereoselective hydroborylation of alkynes with HBpin is demonstrated. This atom-economical reaction is highly selective for the synthesis of (E)-alkenylboronates, and tolerates important functionalities, including halides, ether, alkenyl, silyl and thiophenyl groups. A preliminary mechanistic study supports the involvement of a metal-hydride intermediate.

Abstract

Developing simple and benign protocols for synthesizing alkenylboronates is crucial as they are synthetically valuable compounds in various organic transformations. In this work, we report a straightforward ligand-free protocol for synthesizing alkenylboronates via atom-economical hydroboration of alkynes with HBpin catalyzed by a manganese salt. The reaction shows a high level of chemo and regioselectivity for the terminal alkynes and exclusively produces E-selective alkenylboronates. The hydroboration scope is vast, with the resilience of a range of synthetically beneficial functionalities, such as halides, ether, alkenyl, silyl and thiophenyl groups. This reaction proceeds through the involvement of a metal-hydride intermediate. The developed alkenylboronate can be smoothly converted to useful C-C, C-N and C-I bond-forming reactions.

The 100/100 world of perfumes: Perfumery is currently experiencing its most radical change since the introduction of synthetic vanillin 150 years ago: The transition to 100 % renewable and 100 % biodegradable ingredients. In the Review by P. Kraft and co-workers (DOI: 10.1002/chem.202400006), the reader can learn about the impact that this has on the different fragrance families, and snoop around, from sustainable santals derived from campholenic aldehyde, via a paradisaic pear from itaconic acid, a muguet odorant from oranges, and new routes to the odor principle of ambergris, to musks from crude sulfate turpentine.