Real atom economy and its application for evaluation the green degree of a process

Green chemistry has attracted more attention in the past century.Among the 12 principles of green chemistry,only atom economy and E factor can be expressed quantitatively to depict the impact of a chemical process to environment.Atom economy was thought better than the traditional yield for evaluating the atom efficiency of raw materials.But it is not enough to reflect the conversion degree of raw material.In this paper,we proposed the concept of real atom economy(RAE)as a metric.RAE could combine the above two factors together to better express the green degree of a process.We further suggested an equation to correlate E factor with RAE.The concept of RAE is proved to be helpful for estimating an environmentally benign process.

Chemical Reaction Route Selection Based on Green Chemical Engineering

In the preliminary stage of chemical process design, the choice of chemical reaction route is the key design decision, and the concepts of atom utilization and environmental quotient have become extremely useful tools. However, the waste quality such as chemical toxicity and other engineering factors have not been taken into account. Therefore, a synthetic route selection index, Iroute, is proposed to determine the suitability of a chemical route in this paper. Iroute considers the effects of 'extended atom economy', material renewability, chemical characteristics and some engineering factors. The extended atom economy concept regards not only the value of the desired product but also the value of byproducts. The methodology by using Iroute to compare different routes is illustrated in case study of cyclohexanone oxime and acrylonitrile manufacture.

Atom-economic synthesis of an oligomeric P/N-containing fire retardant towards fire-retarding and mechanically robust polylactide biocomposites

Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are ef- fective in PLA, but their high addition loading usually decreases the mechanical strength of the PLA bulk. For polyphosphoramides, despite high fire-retardant efficiency, their chemical synthesis often generates chemical wastes as byproducts. Herein, we report an atom-economic and highly efficient oligomeric P/N fire retardant (APN) prepared using a mild Michael addition polymerization with no byproducts. Using only 3 wt% APN, the resulting PLA exhibits desired fire retardancy including a UL-94 V-0 rating and a limiting oxygen index of 37.6%. Furthermore, the toughness of the fire-retardant PLA increases by 85% compared to pure PLA, with both tensile strength and thermal stability preserved. This work offers an atom-economic strategy for synthesizing highly efficient P/N fire retardants for use in the creation of fire-resistant PLA with robust mechanical properties.

Catalytic C2 prenylation of unprotected indoles:Late‐stage diversification of peptides and two‐step total synthesis of tryprostatin B

C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols generally require a multi‐step procedure and stoichiometric promoters.Hereinwe develop a one‐step C2 prenylation of NH indole with cheap tert‐prenyl alcohol enabled by acidcatalysis.Salient features include good regioselectivity,step‐and atom‐economy,broad substratescope,and simple catalytic system.The mechanistic investigations demonstrate that both C2prenylation and C3 prenylation/migration pathways are engaged in the reaction.Notably,this practicalstrategy can be applied to the late‐stage diversification of tryptophan‐based peptides and concisesynthesis of tryprostatin B.

Chemoenzymatic Synthesis of Ramosetron Hydrochloride

A new method for the synthesis of ramosetron hydrochloride, the most wildly used 5-HT3 receptor antagonist, was reported. The intermediate 8 was obtained in a high e.e. value via lipase catalyzed hydrolytic kinetic resolution. Then enantiomerically pure ramosetron hydrochloride was synthesized in two steps with excellent yield （the total yield is 24.6%）. The method provides a new environment friendly and atom economy way to synthesize enantiomerically pure ramosetron.

The Technology of Green Chemistry and Its Function in Redox Response and: Environmentally Friendly Technology for Sustainable Development: Assessment of Recent Findings

Sustainability is the ability to nurture or support a process for a long time without compromising the needs of future generations. Rather, sustainable chemistry is a term that refers to the production of chemical products and processes that reduce or eliminate the use and production of hazardous substances. Green chemistry creates alternative technologies that are safer for human health and the environment to prevent further damage to human health and the environment, such as reducing the release of hazardous chemicals into the air, leading to reduced lung damage. Although sustainable and environmentally friendly technologies have evolved in other areas of science, their use in redox reactions and industry is still in its early stages. The current review aims to highlight the need for green chemistry as a sustainable chemistry and its principles and its application to produce environmentally friendly industrial products and to reduce or stop the production of harmful intermediates and products during its synthesis process.

Bimetallic Pd-Cu/Al_(2)O_(3) Catalyst for the Green Catalytic Synthesis of 2,2'-bipyridine from Pyridine

Bimetallic Pd-Cu/Al_(2)O_(3) was prepared by wetness impregnation method and its catalytic activity on coupling reaction of pyridine to 2,2'-bipyridine was assessed in view of the effects of different molar ratios of Pd:Cu.It is found that Pd-Cu/Al_(2)O_(3) has the small particle size and good dispersion through the characterization.Compared with Pd/Al_(2)O_(3),Pd-Cu(1:2)/Al_(2)O_(3) is the preferable catalyst under the optimum conditions of 1 MPa N2 pressure,310℃and 16 h.The conversion of pyridine is 35.4%,and the selectivity for 2,2'-Bipyridine is up to 99%,which is much higher activity than Pd/Al_(2)O_(3).The directly coupled synthesis meets the requirements of the atomic economy better.The addition of Cu also reduces the dosage of Pd and lowers the cost.It is worth noting that the recycled Pd-Cu/Al_(2)O_(3) catalyst still shows high activity and stability after three times.

Catalytic Cracking of Polylactic Acid to Acrylic Acid

Comprehensive Summary,As a typical type of sustainable plastic,polyesters can be recycled or upcycled into value-added chemicals in a variety of methods.However,excess reagents are required for most of the depolymerization and upcycling processes,causing the emission of environmental pollutants and the waste of chemical resources.Here we demonstrate a one-pot catalytic process to directly crack polylactic acid into acrylic acid by acid catalyst with the assistance of an ionic liquid,Bu4PBr.Polylactic acid is attacked by the Br–from Bu4PBr and the H+from acid to form oligomers containing Br or acryloyl group,and these oligomers serve as intermediates to produce acrylic acid during their mutual transformation.The acrylic acid is vaporized directly from the reactor and obtained in a collector with a selectivity around 90%when polylactic acid is fully converted.This green process shows great advantages in atom economy compared to the conventional recycling/upcycling methods for polyesters,in addition.

Electrochemical regioselective synthesis of N-substituted/unsubstituted 4-selanylisoquinolin-1(2H)-ones

A novel and efficient electro-chemical initiated radical strategy was developed for the preparation of both N-substituted and N-unsubstituted 4-selanylisoquinolin-1(2H)-ones through selenylation of isoquinolin-1(2H)-ones with organodiselenides under chemical oxidant-, additive-free and ambient conditions.

Copper-catalyzed diversified annulations betweenα-diketones and alkynylα-diketones

Copper-catalyzed divergent annulations betweenα-diketones and alkynylα-diketones have been achieved,delivering a series of highly functionalized and biologically important cis-hexahydro-2Hcyclopenta[b]furan(HCPF)and 2-hydroxydihydrofuran-3(2H)-one(HDFO)products with high levels of stereoselectivity under identical conditions.The protocol features the use of earth-abundant copper catalyst,mild conditions,shortening synthetic routes in constructing different molecular frameworks,and reducing the corresponding possible waste production.The substituents of the nucleophilicα-diketones play crucial roles in switching the reaction pathways.

1,n-Thiosulfonylation using thiosulfonates as dual functional reagents

In recent years,the direct introduction of sulfonyl and sulfenyl groups into unsaturated substrates by using thiosulfonates as unique dual functional reagents has inarguably provided chemists a new platform for the diverse synthesis of important S-containing derivatives.These 1,n-thiosulfonylation reactions usually feature simple procedures,100%atom economy,and high regioselectivity.This review focuses on the recent advancements in the transformations of thiosulfonates through 1,n-thiosulfonylation involving the formation of two distinct C-S bonds under transition-metal-catalyzed or metal-free conditions,where thiosulfonates act as both a sulfonyl and a sulfenyl component.