Production Of Fine Chemicals Research Articles

Mixing Performance in a Distributed-Feed Plate-Type Reactor with Multinozzle Injection for Fine Chemical Production Scale

The mixing performance of a distributed-feed plate-type reactor equipped with curved channel design and microstructured multinozzle injectors was investigated. Almost ideal plug flow behavior with ...

Consolidated production of coniferol and other high-value aromatic alcohols directly from lignocellulosic biomass

Sustainable production of fine chemicals and biofuels from renewable biomass offers a potential alternative to the continued use of finite geological oil reserves.

Polymer-Bound Triphenylphosphine and 4,4'-Dinitroazobenzene as a Coupling Reagents for Chromatography-Free Esterification Reaction.

Sustainable production of fine chemicals both in industries and pharmaceuticals heavily depends on the application of solid-phase synthesis route coupled with microwave technologies due to their environmentally benign nature. In this report, a microwave-assisted esterification reaction using polymer-bound triphenylphosphine and 4,4'-dinitroazobenzene reagent system was investigated. The solvents were obtained from Merck India. Polymer-bound triphenylphosphine (~3 mmol triphenylphosphine moiety/g) was acquired from Sigma-Aldrich. The progress of the reaction was observed by thin-layer chromatography. All the reactions were performed in Milestones StartSYNTH microwave. The NMR spectra were recorded on Bruker Avance III 300, 400, and 500 MHz FT NMR Spectrometers. Using azo compound and polymer-bound triphenyl phosphine as a coupling reagent, esterification of different carboxylic acids with alcohols was performed under microwave irradiation. Esterification of benzoic acid with 1-propanol under microwave irradiation gave a high yield of 92% propyl benzoate in 60 minutes only. Isolation of the ester products was relatively simple as both the byproducts polymer-bound triphenylphosphine oxide and hydrazine could be removed by simple filtration. The rates of reactions were found to be directly proportional to the pKa of the benzoic acids. 4,4'-Dinitroazobenzene was introduced as a novel coupling reagent, in conjugation with polymer-bound triphenylphosphine, for esterification reactions under microwave irradiation. The low moisture sensitivity of the reaction system, easy separation of the byproducts, and column chromatographyfree isolation of esters help our methods with application significance, particularly from the 'Sustainable Chemistry' perspective.

Co-catalyst and Metal-free CO2 Fixation into Cyclic Carbonates: COPs to the Rescue

The non-redox fixation of CO2 in cyclic and polymeric carbonates is regarded as one of the most promising technologies for small-scale CO2 utilization. Yet, most heterogeneous catalysts reported to date require the use of co-catalysts, harsh reaction conditions, and non-base metals. In this issue of Chem, Yavuz and coworkers report the one-step synthesis of a new covalent organic polymer that circumvents these issues.

Microbial synthesis of the type I polyketide 6-methylsalicylate with Corynebacterium glutamicum.

Type I polyketide synthases (PKSs) are large multi-domain proteins converting simple acyl-CoA thioesters such as acetyl-CoA and malonyl-CoA to a large diversity of biotechnologically interesting molecules. Such multi-step reaction cascades are of particular interest for applications in engineered microbial cell factories, as the introduction of a single protein with many enzymatic activities does not require balancing of several individual enzymatic activities. However, functional introduction of type I PKSs into heterologous hosts is very challenging as the large polypeptide chains often do not fold properly. In addition, PKS usually require post-translational activation by dedicated 4'-phosphopantetheinyl transferases (PPTases). Here, we introduce an engineered Corynebacterium glutamicum strain as a novel microbial cell factory for type I PKS-derived products. Suitability of C. glutamicum for polyketide synthesis could be demonstrated by the functional introduction of the 6-methylsalicylic acid synthase ChlB1 from Streptomyces antibioticus. Challenges related to protein folding could be overcome by translation fusion of ChlB1Sa to the C-terminus of the maltose-binding protein MalE from Escherichia coli. Surprisingly, ChlB1Sa was also active in the absence of a heterologous PPTase, which finally led to the discovery that the endogenous PPTase PptACg of C. glutamicum can also activate ChlB1Sa. The best strain, engineered to provide increased levels of acetyl-CoA and malonyl-CoA, accumulated up to 41mg/L (0.27mM) 6-methylsalicylic acid within 48h of cultivation. Further experiments showed that PptACg of C. glutamicum can also activate nonribosomal peptide synthetases (NRPSs), rendering C. glutamicum a promising microbial cell factory for the production of several fine chemicals and medicinal drugs.

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

Flow Chemistry is a revolutionary field in Organic Chemistry. By changing the conventional methods and apparatus applied in the chemical synthesis, flow chemistry emerges as a game changer for organic synthesis laboratories, in both academia and industries. Considered as a sustainable practice, flow processes play an important role in the development of fine chemical products and in drug discovery development programs. This work aims to review the recent contributions on heterocyclic synthesis under continuous‐flow conditions, focusing in heterocycle ring formation and highlighting some of the most recent examples found in the literature, as well as some synthetic strategies aiming for the flow preparation of high‐value chemical products, such as APIs and agrochemicals.

Aluminum‐Based Catalysts for Cycloaddition Reactions: Moving One Step Ahead in Sustainability

AbstractA large variety of dienes and alkenes can be derived from plants and used further for the production of fine chemicals or biologically active compounds. Herein, we have identified such dienes/alkenes, as well as their synthetic analogues, and presented a strategy for their conversion by atom‐economical cycloaddition reactions. The catalyst used for these conversions is derived from abundantly‐available aluminum metal in earth's crust, which has low toxicity, easy availability and low price in comparison to the transition metals. Astonishingly, the applications of aluminum‐based catalysts are underdeveloped in comparison to the d‐block metal analogues. Therefore, this review summarizes the developments in the field of cycloaddition reactions by using aluminum‐based catalysts, a pathway that can be pursued for developing “Sustainable Processes”.

Enhanced Hydrogenation Performance over Hollow Structured Co-CoOx@N-C Capsules.

It is desirable to design nonprecious metal nanocatalysts with high stability and catalytic performance for fine chemicals production. Here, a method is reported for the preparation of cobalt metal and cobalt oxide cores confined within nanoporous nitrogen‐doped hollow carbon capsules. Core–shell structured Zn/Co‐ZIF@polymer materials are fabricated through a facile coating polymer strategy on the surface of zeolitic imidazolate frameworks (ZIF). A series of hollow carbon capsules with cobalt metal and cobalt oxide are derived from a facile confined pyrolysis of Zn/Co‐ZIF@polymer. The hollow Co‐CoOx@N‐C capsules can prevent sintering and agglomeration of the cobalt nanoparticles and the nanoporous shell allows for efficient mass transport. The specific surface area and Co particle size are optimized through finely tuning the original Zn content in ZIF particles, thus enhancing overall catalytic activity. The yolk–shell structured Zn4Co1Ox@carbon hollow capsules are shown to be a highly active and selective catalyst (selectivity >99%) for hydrogenation of nitrobenzene to aniline. Furthermore, Zn4Co1Ox@carbon hollow particles show superior catalytic stability, and no deactivation after 8 cycles of reaction. The hollow Co‐CoOx@N‐C capsules may shed light on a green and sustainable catalytic process for fine chemicals production.

Catalytically sustainable, palladium-decorated graphene oxide monoliths for synthesis in flow

Continuous flow synthesis is an essential route towards high throughput manufacturing of fine chemical and pharmaceutical products. The mentioned chemistries are often catalyzed by solid-supported catalysts via packed beds which are characterized by multiple issues such as high pressure-drops, micro channeling through the bed, and leaching of the metallic catalyst into the product stream. These issues lower the overall process efficiency. Three dimensional (3D) structures, known as monoliths, with high porosity and mechanical robustness, offer the ideal properties to be used macroscopic supports for metallic catalyst particles. This approach has shown to alleviate several known issues with catalyst packed beds effectively.Herein centimeter-scale monolithic catalysts of palladium (Pd)-decorated, covalently-bonded graphene oxide (GO) layers have been prepared via a completely aqueous, one-pot system. These monolithic composite structures were designed for Suzuki cross-coupling reactions in flow. As highly engineered materials, monoliths’ properties such as oxygen content and Pd catalyst ionic species were tuned via microwave irradiation and ethanol vapor reduction treatments. The optimal monolithic catalysts showed over 5 h of operational longevity in flow, which was 300% higher than the conventional Pd on GO catalyst packed beds. As a proof of concept, the monolithic catalyst was successfully used as a model structure for nondestructive X-ray CT-scan elemental and porosity mapping in the centimeter scale.

Influence of the pH Value on the Hydrothermal Degradation of Fructose.

The hydrothermal treatment of sugars features a promising technology for the production of fine and platform chemicals from renewable resources. In this work the hydrothermal decomposition of fructose was studied in a buffered medium at a pH range between 2.2 and 8.0. It is demonstrated that at lower pH values mainly 5‐hydroxymethylfurfural (HMF), levulinic acid and humin are generated, while lactic acid and acetic acid are produced at higher pH values. The work shows that the use of moderate acidic conditions may have advantages for the hydrothermal HMF production over the use of strongly acidic conditions, as especially the degradation into levulinic acid is suppressed. Besides, this study deals with a rather complex reaction network, hence limitations and need for adaption of the kinetic model are discussed.

Ordered mesoporous molecular sieves as active catalyts for the synthesis of 1,4-dihydropyridine derivatives

Abstract Research on heterocyclic compounds with biological and pharmacological activity continues to arouse great interest. The study of 1,4-dihydropyridines (1,4-DHPs) is of particular interest in the pharmaceutical field due to their important applications as calcium channel antagonists for the treatment of heart diseases. The implementation of novel heterogeneous catalysts to optimize Hantzsch synthesis, such as ordered mesoporous molecular sieves, is an efficient and eco-friendly proposal that still requires a lot of work. The remarkable features of ordered mesoporous molecular sieves, such as high surface area, tailored porosity, chemical and thermal stability, among others, turn these materials into powerful solid catalysts capable of selectively leading the synthesis of 1,4-DHPs. In addition, the combination of ordered mesoporous molecular sieves and process intensification for the synthesis of 1,4-DHP derivatives is still a research field in development. Therefore, promote greener methodologies in the synthesis of 1,4-DHPs that can be extended to any organic synthesis in fine chemical production is an important goal yet to be achieved.

Chemical modification of reduced graphene oxide with sulfonic acid groups: Efficient solid acids for acetalization and esterification reactions

Surface chemical modification of reduced graphene oxide (rGO) with sulfonic acid groups produced two solid acids for acid-catalyzed reactions. One of the solid acids was prepared by covalent modification of rGO with oleum to achieve rGO-SO3H. The second solid acid obtained from the reaction of diazonium salt of para-amino benzene sulfonic acid with rGO. The prepared solid acids were characterized by various physicochemical methods which verified the successful modification of rGO with sulfonic acid groups. Catalytic activities of the obtained solid acids were evaluated and compared in the esterification of acetic acid with butanol and acetalization of benzaldehyde with ethylene glycol which indicated excellent catalytic efficiencies in both reactions. Both solid acids exhibited very high and almost identical conversion in esterification and acetalization reactions in short times, indicating the good catalytic efficiency of these solid acids for production of fine chemicals.

Synthesis of surface controlled nickel/palladium hydride nanodendrites with high performance in benzyl alcohol oxidation

Benzaldehyde byproduct is an imperative intermediate in the production of fine chemicals and additives. Tuning selectivity to benzaldehyde is therefore critical in alcohol oxidation reactions at the industrial level. Herein, we report a simple but innovative method for the synthesis of palladium hydride and nickel palladium hydride nanodendrites with controllable morphology, high stability, and excellent catalytic activity. The synthesized dendrites can maintain the palladium hydride phase even after their use in the chosen catalytic reaction. Remarkably, the high surface area morphology and unique interaction between nickel-rich surface and palladium hydride (β-phase) of these nanodendrites are translated in an enhanced catalytic activity for benzyl alcohol oxidation reaction. Our Ni/PdH0.43 nanodendrites demonstrated a high selectivity towards benzaldehyde of about 92.0% with a conversion rate of 95.4%, showing higher catalytic selectivity than their PdH0.43 counterparts and commercial Pd/C. The present study opens the door for further exploration of metal/metal-hydride nanostructures as next-generation catalytic materials.

Mechanochemical Synthesis of Ruthenium Cluster@Ordered Mesoporous Carbon Catalysts by Synergetic Dual Templates.

Ruthenium (Ru)@Ordered mesoporous carbon (OMC) is a key catalyst in fine-chemical production. In general, the OMC support is prepared by a wet self-assembly requiring excessive solvent, toxic phenol-aldehyde precursors and a long reaction time, followed by post-immobilization to load Ru species. Herein, we wish to report a solid-state, rapid, and green strategy for the synthesis of Ru@OMC with biomass tannin as the precursor. The chemistry essence of this strategy lies in the mechanical-force-driven assembly, during which tannin-metal (Zn2+ and Ru3+ ) coordination polymerization and hydrogen-bonding interactions between tannin-block copolymer (PEO-PPO-PEO, F127) simultaneously occur. After thermal treatment, Ru@OMC catalysts with mesoporous channels, narrow pore-size distribution (≈7 nm), and high surface area (up to 779 m2 g-1 ) were directed by F127 micelles. Meanwhile, the Zn2+ ions dilute Ru3+ and avoid the sintering of Ru species, resulting in Ru clusters around 1.4-1.7 nm during carbonization (800 °C). Moreover, the Ru@OMC catalyst afforded a good activity (TOF: up to 4170 h-1 ) in the selective oxidation of benzyl alcohol to benzaldehyde by molecular oxygen.

Novel Technology for Separation of Binary Eutectic-Forming Mixture by Cocrystallization into Different Sizes Combined with Particle Size Fraction

Separation of a eutectic-forming mixture is a challenge in the manufacturing process of fine chemical products. In this paper, a novel separation technology for a binary eutectic mixture by solutio...

Alternative Recovery and Valorization of Metals from Exhausted Catalytic Converters in a New Smart Polymetallic Catalyst

AbstractA new metals‐polymeric composite, Metx‐EPS (I), was prepared to be used as catalyst in water or in two‐phase aqueous conditions. The metals source was an exhausted catalytic converter that was grinded and treated with an acidic solution at room temperature. After filtration, the solution was concentrated, neutralized and added to a broth of Klebsiella oxytoca DSM 29614 to produce (I) where metals are embedded in a peculiar polysaccharide structure (EPS). The composite was easily recovered from the fermentation broth and purified. The process protocol was verified many times and was shown to be reproducible satisfactorily. The % recovery of metals, originally present in the converter, was good as determined by atomic absorption. The morphology and the chemical state of main metals in (I) were investigated by X‐ray absorption spectroscopy methods (XANES and EXAFS). No metallic alloy seems to be evident. The catalytic activity and a possible synergic effect due to the presence of the different metals was valuated in the hydrogenation of some substrates, valuable precursors for the production of fine chemicals.

Pervaporation of (R)/(S)-methyl 3-hydroxybutyrate (∑MHB) from a mixture containing an ionic liquid, methanol and Ru catalyst

Complex technologies in the production of fine chemicals bring together various connected processes, each bringing specific green chemistry challenges. A valuable mixture arises in the stereoselective hydrogenation of methyl-acetoacetate (MAA) to (R)- and (S)- methyl 3-hydroxybutyrate (∑MHB) over Ru organometallic complex (R)-Ru/BINAP, and in a “green” tetra-alkylammonium bistriflimide/methanol/water solvent phase. The reaction could be carried out in various arrangements, e.g. in a batch mode, in a continuous stirred-tank reactor, or even in a tubular microfluidic chip reactor. In either case, the valuable optically pure Ru complex has been sought to be effectively separated, and potentially recycled. The ionic liquid phase (tetra-alkylammonium bistriflimide) is intended for selective accommodation of the complex in the reaction mixture and as a green alternative to other solvents. It was the main issue of this work to design a specific separation unit, to construct it, and to optimize its performance towards the efficient separation of ∑MHB from the ionic liquid phase bearing the (R)-Ru/BINAP complex. The unit was developed to be connected with the complex preparation process, employing the microreactor fluid flow platform. The separation part of the overall technology was designed as a membrane pervaporation. The membrane separation proceeded with different feed mixtures combining ∑methyl 3-hydroxybutyrate, methanol, ionic liquid and/or the catalyst. The technique was applied at various temperatures, using the industrial composite PDMS membrane, PERVAP™ 4060 from Sulzer. The feed as well as the pervaporate were analyzed by nuclear magnetic resonance spectroscopy and infrared spectroscopy. The enrichment factor of the ∑MHB with respect to the retentate was 1.24 and the ∑MHB permeate mass flux was 61 g h−1 m−2. In addition, the membrane was characterized by scanning electron microscopy and energy dispersive X-ray microanalysis after the membrane process, showing no sorption of the catalyst into the membrane.

CFD Design of Hydrogenation Reactor for Transformation of Levulinic Acid to γ-Valerolactone (GVL) by using High Boiling Point Organic Fluids

Levulinic acid (LA) has been ranked as one of the “Top 10” building blocks for future bio-refineries as proposed by the US Department of Energy. It is considered one of the most important platform molecules for the production of fine chemicals and fuels based on its compatibility with existing processes, market economics, and industrial ability to serve as a platform for the synthesis of important derivatives. Hydrogenation of LA to produce γ-valerolactone (GVL) is an active area of research due to the potential of GVL to be used as a biofuel in its own right and for its subsequent transformation into hydrocarbon fuels. This paper contains a new design for a simple, cost effective, and safe hydrogenation reactor for the transformation of levulinic acid to γ-valerolactone (GVL) by utilizing high boiling point organic fluid. The hydrogenation reactor is composed of a heating source—organic fluid (called “DOWTHERM A” or “thermex”) and the catalytic reactor. The advantages of high boiling temperature fluids, along with advances in hydrocracking and reforming technologies driven by the oil and gas industries, make the organic concept more suitable and safer (water coming in contact with liquid metal is well understood in the metallurgical industry to be a steam explosion hazard) for heating the hydrogenation reactor. COMSOL multi-physics software version 4.3b was applied in this work and simultaneously solves the continuity, Navier-Stokes (fluid flow), energy (heat transfer), and diffusion with chemical reaction kinetics equations. It was shown that the heat flux supplied by the DOWTHERM A organic fluid could provide the necessary heat flux required for maintaining the hydrogenation process. It was found that the mass fractions of hydrogen and levulinic acid decreased along the reactor axis. The GVL mass fraction increased along the reactor axis.

Synthesis and catalytic testing of Lewis acidic nano zeolite Beta for epoxide ring opening with alcohols

Lewis acidic zeolites are robust catalytic materials that are capable of a range of important chemistry for fine chemical production, including the epoxide ring opening with alcohols. The crystalline structure imposes diffusion limitations for large molecules that are overcome through reducing the particle size to produce nano zeolite beta substituted with Lewis acidic tin (nSnBeta). nSnBeta is characterized using standard methods to demonstrate that tin is efficiently incorporated into the zeolite framework with open and closed sites similar to the micron-sized conventional Sn-Beta (cSnBeta). While nSnBeta exhibits comparable catalytic activity to cSnBeta for reactions involving small substrates such as epichlorohydrin and methanol, an improvement in catalytic performance is observed for nSnBeta relative to cSnBeta when using large substrates such as 1,2-epoxyoctane and ethanol. nSnBeta and cSnBeta convert a cyclic epoxide too large to enter the pores to similar extents, indicating that the improved performance is not associated with an increased number of catalytic sites on the external surface. Catalyst reuse experiments demonstrate that organic accumulation on the material reduces catalytic activity that can be partially restored through calcination. Overall, the results demonstrate that nano zeolite beta can be synthesized with small particle sizes (i.e., 150 nm) to help overcome diffusion limitations for bulky substrates for the alcohol ring opening of epoxides.

Direct Microdroplet Synthesis of Carboxylic Acids from Alcohols by Preparative Paper Spray Ionization without Phase Transfer Catalysts

Carboxylic acids are widely used in the production of fine chemicals. This study demonstrates rapid synthesis of carboxylic acids directly from alcohols in microdroplets by paper spray ionization u...