Converting CO2 into heterocyclic compounds under accelerated performance through Fe3O4 grafted ionic liquid catalysts

Solid supported catalysts such as amines has high demand for chemical fixation of CO2 into commodity chemicals. Here, we demonstrate an accelerated platform for 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-ionic liquids (ILs) catalyzed CO2...

Divergent Electrolysis for the Controllable Coupling of Thiols with 1,2-Dichloroethane: a Mild Approach to Sulfide and Sulfoxide

Organosulfurs are important commodity chemicals and indispensable synthetic intermediates in modern chemistry that traditionally synthesized using metal catalysts, oxidants or strong bases, which caused numerous issues of environment pollutions. The...

Heterogeneous Catalysts in Grammar School

The discovery of new catalytically active materi- als is one of the holy grails of computational chemistry as it has the potential to accelerate the adoption of renewable energy sources and reduce the energy consumption of chemical industry. Indeed, heterogeneous catalysts are essential for the production of synthetic fuels and many commodity chemicals. Consequently, novel catalysts with higher activity and selectivity, increased sustainability and longevity, or improved prospects for rejuvenation and cyclability are needed for a diverse range of processes. Unfortunately, computational catalyst discovery is a daunting task, among other reasons because it is often unclear whether a proposed material is stable or synthesizable. This perspective proposes a new approach to this challenge, namely the use of generative grammars. We outline how grammars can guide the search for stable catalysts in a large chemical space and sketch out several research directions that would make this technology applicable to real materials.

Carboxylation of alkenes and alkynes using CO2 as a reagent: an overview

: CO2 fixation reactions are of paramount interest both from economical and environmental perspectives. As an abundant, non-toxic, and renewable C1 feedstock, CO2 can be utilized for the synthesis of fuels and commodity chemicals under elevated reaction conditions. The major challenge in the CO2 utilization reactions is its chemical inertness due to high thermodynamic stability and kinetic barrier. The carboxylation of unsaturated hydrocarbons with CO2 is an important transformation as it forms high-value reaction products having industrial as well as medicinal importance. This mini-review is mainly focused on the recent developments in the homogeneously and heterogeneously catalyzed carboxylation of alkenes and alkynes by using carbon dioxide as a reagent. We have highlighted various types of carboxylation reactions of alkenes and alkynes involving different catalytic systems, which comprise mainly C-H bond activation, hydrocarboxylation, carbocarboxylation, heterocarboxylation, and ring-closing carboxylation, including visible-light assisted synthesis processes. The mechanistic pathways of these carboxylation reactions have been described. Moreover, challenges and future perspectives of these carboxylation reactions are discussed.

Implementation of Synthetic Pathways to Foster Microbe-Based Production of Non-Naturally Occurring Carboxylic Acids and Derivatives

Microbially produced carboxylic acids (CAs) are considered key players in the implementation of more sustainable industrial processes due to their potential to replace a set of oil-derived commodity chemicals. Most CAs are intermediates of microbial central carbon metabolism, and therefore, a biochemical production pathway is described and can be transferred to a host of choice to enable/improve production at an industrial scale. However, for some CAs, the implementation of this approach is difficult, either because they do not occur naturally (as is the case for levulinic acid) or because the described production pathway cannot be easily ported (as it is the case for adipic, muconic or glucaric acids). Synthetic biology has been reshaping the range of molecules that can be produced by microbial cells by setting new-to-nature pathways that leverage on enzyme arrangements not observed in vivo, often in association with the use of substrates that are not enzymes’ natural ones. In this review, we provide an overview of how the establishment of synthetic pathways, assisted by computational tools for metabolic retrobiosynthesis, has been applied to the field of CA production. The translation of these efforts in bridging the gap between the synthesis of CAs and of their more interesting derivatives, often themselves non-naturally occurring molecules, is also reviewed using as case studies the production of methacrylic, methylmethacrylic and poly-lactic acids.

Construction of a plasmid addiction system using grpE as selection marker in Escherichia coli and its application in phloroglucinol biosynthesis

Microbial synthesis of commodity chemicals often be conducted in recombinant plasmid-based expression systems, in which plasmids play pivotal roles on productivity. The recombinant plasmids always encounter instability, leading to losses in product recovery of entire process. To maintain the stability of plasmids, several mechanisms have been evolved. Plasmid addition system, selectively killing plasmid-free cells, is regard as a useful strategy to improve the proportion of plasmid-containing cells. In this study, a novel plasmid addition system using an essential gene grpE that encodes a molecular cochaperone as selection marker, avoiding use of antibiotics, was constructed in Escherichia coli . The solo copy of grpE gene on the chromosome was knocked out and relocated on multicopy plasmids. The generated strains can maintain high ratio of plasmid-harboring cells without antibiotics supplementation in mineral salts media and exhibit improved cell growth and increased tolerance to phloroglucinol. Using this system in phloroglucinol synthesis, it could significantly increase the phloroglucinol titer from 0.75 g/L to 1.26 g/L, which was further increased to 1.78 g/L when biotin-[acetyl-CoA-carboxylase] ligase BirA was overexpressed. It can be expected that this system will be a powerful tool for microbial manufacture of important chemicals in E . coli .

Chiral Diamine in Small Molecule Biomimetic Asymmetric Catalysis

Enzymatic reaction, as an environmentally friendly approach, has made great progress producing commodity chemicals comparing to the conventional metallo/organo catalysis. However, the reaction compatibility is not satisfactory. The development of biomimetic catalysis balancing both strategies for the green and broad application in synthesis is desirable. Here, we report the design and synthesis of a chiral diamine catalyst fulfilling this requirement. Asymmetric addition reactions using this ligand in water were demonstrated and the corresponding products were produced in excellent yields and enantiomeric ratios. This pluripotent ligand has also shown good reactivity/enantioselectivity on a number of representative reactions in both green and organic solvents. We anticipate that the ligand would allow further development of other catalysts for important yet challenging green stereoselective transformations.

Computer-Aided Process Intensification of Natural gas to Methanol Process

The recent revolution in shale gas has presented opportunities for distributed manufacturing of key commodity chemicals, such as methanol, from methane. However, the conventional methane-to-methanol process is energy intensive which negatively affects the profitability and sustainability. We report an intensified process configuration that is both economically attractive and environmentally sustainable. This flowsheet is systematically discovered using the building block-based representation and optimization methodology. The new process configuration utilizes membrane-assisted reactive separations and can have as much as 190% higher total annual profit compared to a conventional configuration. Additionally, it has 57% less CO2-equivalent greenhouse gas (GHG) emission. Such drastic improvement highlights the advantages of building block-based computer-aided process intensification method.