Synthesis Of Fine Chemicals Research Articles

Asymmetric Bio-epoxidation of Unactivated Alkenes.

Optically active epoxides play important roles in pharmaceutical, agricultural and fine chemical syntheses. There are many chiral medications with pharmacodynamic activity in nature that can be synthesized by chiral epoxides. In recent years, researchers have developed a variety of biocatalysts for the asymmetric epoxidation of alkenes, which use oxygen or hydrogen peroxide as eco-friendly and low-cost oxidants, to provide better chemo-, regio- and stereoselectivity under moderate reaction conditions. In this paper, the advances, opportunities and challenges of the asymmetric epoxidation of unactive alkenes by biocatalyst are reviewed.

Opportunities from Metal Organic Frameworks to Develop Porous Carbons Catalysts Involved in Fine Chemical Synthesis

In the last decade, MOFs have been proposed as precursors of functional porous carbons with enhanced catalytic performances by comparison with other traditional carbonaceous catalysts. This area is rapidly growing mainly because of the great structural diversity of MOFs offering almost infinite possibilities. MOFs can be considered as ideal platforms to prepare porous carbons with highly dispersed metallic species or even single-metal atoms under strictly controlled thermal conditions. This review briefly summarizes synthetic strategies to prepare MOFs and MOF-derived porous carbons. The main focus relies on the application of the MOF-derived porous carbons to fine chemical synthesis. Among the most explored reactions, the oxidation and reduction reactions are highlighted, although some examples of coupling and multicomponent reactions are also presented. However, the application of this type of catalyst in the green synthesis of biologically active heterocyclic compounds through cascade reactions is still a challenge.

C−N Coupling through Hydroaminoalkylation on a Single‐Atom Rh Heterogeneous Catalyst

AbstractC−N coupling is significant for the synthesis of fine chemicals toward various applications. Hydroaminoalkylation of olefins is a tandem reaction of C−N coupling involving first the formation of an aldehyde through hydroformylation of an olefin and then the production of amine through reductive amination of the aldehyde. Here we report a stable, supported catalyst of singly dispersed Rh1 atoms anchored on TiO2 (P25) nanoparticles designated as Rh1/P25. Its high activity for C−N coupling was demonstrated by six hydroaminoalkylations of olefins and amines with selectivity of higher than 90% for producing tertiary amines. The singly dispersed Rh1O4 on P25 exhibit activity and selectivity for hydroaminoalkylation comparable or even higher than some reported molecular catalysts. In contrast to molecular catalysts, the Rh‐based single‐atom Rh heterogeneous catalysis (Rh1/P25) can be readily separated from reactants and products, reused for multiple runs of hydroaminoalkylation, and recycled with a low cost.

C-N Coupling through Hydroaminoalkylation on a Single-Atom Rh Heterogeneous Catalyst.

C-N coupling is significant for the synthesis of fine chemicals toward various applications. Hydroaminoalkylation of olefins is a tandem reaction of C-N coupling involving first the formation of an aldehyde through hydroformylation of an olefin and then the production of amine through reductive amination of the aldehyde. Here we report a stable, supported catalyst of singly dispersed Rh1 atoms anchored on TiO2 (P25) nanoparticles designated as Rh1 /P25. Its high activity for C-N coupling was demonstrated by six hydroaminoalkylations of olefins and amines with selectivity of higher than 90% for producing tertiary amines. The singly dispersed Rh1 O4 on P25 exhibit activity and selectivity for hydroaminoalkylation comparable or even higher than some reported molecular catalysts. In contrast to molecular catalysts, the Rh-based single-atom Rh heterogeneous catalysis (Rh1 /P25) can be readily separated from reactants and products, reused for multiple runs of hydroaminoalkylation, and recycled with a low cost.

Solvent-controlled selective photocatalytic oxidation of benzyl alcohol over Ni@C/TiO2

Selective photocatalysis offers an alternative green and economically competitive approach for valuable fine chemical synthesis. In this research, the Ni@C/TiO2-Z catalyst was prepared for the efficient photocatalytic oxidation of various aromatic alcohols. Interestingly, the selectivity of the reaction products is affected by the absorbance of the solvents used in the reaction. The oxidation ability of the reaction system is stronger when the absorption peaks of the solvents are closer to light source wavelengths. Therefore, the reaction tends to generate aldehyde in acetonitrile and acid in ethyl acetate, which allows for the manipulation of product selectivity by choosing the solvent.

Green and Efficient Acquirement of Unsaturated Ether from Direct and Selective Hydrogenation Coupling Unsaturated Aldehyde with Alcohol by Bi-Functional Al-Ni-P Heterogeneous Catalysts

In view of the industrial importance of high-grade unsaturated ether (UE) and the inconvenience of acquiring the compound, herein, a series of low-cost Al-Ni-P catalysts in robust AlPO4/Ni2P structure possessing novel bi-functional catalytic features (hydrogenation activation and acid catalysis) were innovated, and testified to be efficient for directly synthesizing UE with a superior yield up to 97% from the selective hydrogenation coupling carbonyl of unsaturated aldehyde (cinnamaldehyde or citral) with C1–C5 primary or secondary alcohol under 0.1 MPa H2 and 393 K. The integrated advantages of high efficiency, green manner and convenient operation of the present heterogeneous catalytic system gave the system potential for feasibly harvesting high-grade unsaturated ether in related fine chemical synthesis networks.

Organochalcogen (Se/Te) substituted Schiff bases: Syntheses and applications

Schiff base was originally proposed, synthesized by Hugo Schiff and widely used since 1864. They are synthesized by the reaction of aromatic aldehydes or ketones and the primary amines. It consists of CN functional group or azomethine. It is one of the most widely studied molecule just because of its ease to synthesize and append many functional moieties like selenium and tellurium as a part of its molecular structure. Schiff bases are mostly utilized by chemists, material scientists and the biologists. Chemists use them as catalysts and intermediates for the synthesis of fine chemicals, pigments, dyes and polymer stabilisers. Material scientists study their physical properties. However, biologists are highly fascinated by studying their biological activities such as antifungal, antibacterial, anti-malarial, anti-proliferative, anti-inflammatory, antiviral, etc. Schiff bases bearing larger Se and Te atoms are also used as sensors, light emitting diodes and solar cells. Therefore, this review article is mainly focused on the synthesis and applications of organochalcogen (Se/Te) substituted Schiff bases.

Sulfuric acid-catalyzed pyrolysis of iota-carrageenan in polyethylene glycol

The use of seaweed polysaccharides for fine chemical synthesis is a promising approach to replace fossil fuel-based feedstocks. In this work, acid-catalyzed pyrolysis of the polysaccharide iota-carrageenan from red seaweed has been studied using differential scanning calorimetry (DSC). DSC shows that sulfuric acid in a polyethylene glycol (PEG) solvent lowers the temperature of the exothermic decomposition peak by ca. 63 °C when compared with the pyrolysis of pure polysaccharide. Evolved products from the pyrolysis in a purpose-built glass tube vacuum reactor were analyzed using gas chromatography/mass spectrometry, and showed that levoglucosenone (LGO) and furfural were dominant. Yield of LGO was 12 mg/gIC or 9.0 mol% and of furfural was 2.8 mg/gIC or 2.8 mol% when 2% w/w H2SO4 was used as catalyst.

Designed Iron Catalysts for Allylic C-H Functionalization of Propylene and Simple Olefins.

Propylene gas is produced worldwide by steam cracking on million-metric-ton scale per year. It serves as a valuable starting material for π-bond functionalization but is rarely applied in transition metal-catalyzed allylic C-H functionalization for fine chemical synthesis. Herein, we report that a newly-developed cationic cyclopentadienyliron dicarbonyl complex allows for the conversion of propylene to its allylic C-C bond coupling products under catalytic conditions. This approach was also found applicable to the allylic functionalization of simple α-olefins with distinctive branched selectivity. Experimental and computational mechanistic studies supported the allylic deprotonation of the metal-coordinated alkene as the turnover-limiting step and led to insights into the multifaceted roles of the newly designed ligand in promoting allylic C-H functionalization with enhanced reactivity and stereoselectivity.

Designed Iron Catalysts for Allylic C−H Functionalization of Propylene and Simple Olefins

AbstractPropylene gas is produced worldwide by steam cracking on million‐metric‐ton scale per year. It serves as a valuable starting material for π‐bond functionalization but is rarely applied in transition metal‐catalyzed allylic C−H functionalization for fine chemical synthesis. Herein, we report that a newly‐developed cationic cyclopentadienyliron dicarbonyl complex allows for the conversion of propylene to its allylic C−C bond coupling products under catalytic conditions. This approach was also found applicable to the allylic functionalization of simple α‐olefins with distinctive branched selectivity. Experimental and computational mechanistic studies supported the allylic deprotonation of the metal‐coordinated alkene as the turnover‐limiting step and led to insights into the multifaceted roles of the newly designed ligand in promoting allylic C−H functionalization with enhanced reactivity and stereoselectivity.

Photocatalytic coupling of electron-deficient alkenes using oxalic acid as a traceless linchpin

•Oxalic acid is used as a traceless linchpin •CO2 radical anion formation via photocatalytic oxidation of oxalic acid is achieved •Homo- and cross-coupling of electron-poor alkenes is achieved Reductive alkene cross-coupling represents a straightforward strategy for the construction of C–C bonds from readily available alkene feedstocks. A one-pot protocol, utilizing oxalic acid as a traceless linchpin, has been developed to achieve direct cross-coupling of electron-deficient alkenes. The overall process is a two-step transformation involving hydrocarboxylation followed by decarboxylative cross-coupling. A dual-photocatalyst system is crucial for success and promotes the two reaction steps synergistically. This reaction supports the efficient synthesis of bioactive molecules. Photoredox catalysis provides an easy and mild pathway for the generation of a CO2 radical anion from oxalic acid, which paves the way for the broad utilization of this reactive intermediate in the synthesis of fine chemicals. Reductive alkene cross-coupling represents a straightforward strategy for the construction of C–C bonds from readily available alkene feedstocks. A one-pot protocol, utilizing oxalic acid as a traceless linchpin, has been developed to achieve direct cross-coupling of electron-deficient alkenes. The overall process is a two-step transformation involving hydrocarboxylation followed by decarboxylative cross-coupling. A dual-photocatalyst system is crucial for success and promotes the two reaction steps synergistically. This reaction supports the efficient synthesis of bioactive molecules. Photoredox catalysis provides an easy and mild pathway for the generation of a CO2 radical anion from oxalic acid, which paves the way for the broad utilization of this reactive intermediate in the synthesis of fine chemicals.

Continuous Flow Epoxidation of Alkenes Using a Homogeneous Manganese Catalyst with Peracetic Acid.

Epoxidation of alkenes is a valuable transformation in the synthesis of fine chemicals. Described herein are the design and development of a continuous flow process for carrying out the epoxidation of alkenes with a homogeneous manganese catalyst at metal loadings as low as 0.05 mol%. In this process, peracetic acid is generated in situ and telescoped directly into the epoxidation reaction, thus reducing the risks associated with its handling and storage, which often limit its use at scale. This flow process lessens the safety hazards associated with both the exothermicity of this epoxidation reaction and the use of the highly reactive peracetic acid. Controlling the speciation of manganese/2-picolinic acid mixtures by varying the ligand:manganese ratio was key to the success of the reaction. This continuous flow process offers an inexpensive, sustainable, and scalable route to epoxides.

Sustainable and Mild Catalytic Acceptorless Dehydrogenations

AbstractCatalytic acceptorless dehydrogenation of organic molecules plays a crucial role in fine-chemical synthesis as well as in energy storage and transport. In particular, the acceptorless dehydrogenation of saturated N-heteroarenes and hydrocarbons is realized by both transition-metal-free and transition-metal-catalyzed approaches. In this direction, our research group aims to develop mild catalytic acceptorless dehydrogenation protocols, in the main by using photoredox approaches. In this account, we briefly discuss the advances made by our group on the dehydrogenation of saturated N-heterocycles, aliphatic alcohols, and relatively challenging hydrocarbons.1 Introduction1.1 Challenges Associated with Catalytic Acceptorless Dehydrogenation2 Transition-Metal-Free Dehydrogenation of N-Heterocycles3 Photoinduced Hybrid-Catalysis-Enabled Dehydrogenations3.1 The Binary Catalyst System3.2 The Ternary Catalyst System3.3 The Noble-Metal-Free Catalyst System3.4 Catalytic Acceptorless Dehydrogenation of Aliphatic Alcohols4 Self-Photo-Sensitizing Hydrogen Atom Transfer Catalysis5 Summary

Zinc incorporated covalent organic framework (Zn@DBPG): an efficient catalyst for the synthesis of carbamates through CO2 and non CO2 fixation pathways under sustainable condition

Recent trends in synthesis of organic fine chemicals using metal incorporated covalent organic frameworks as heterogeneous catalyst clinching appreciable attentions towards researchers. Permanent porosity, high surface area and extremely thermal stable nature makes those covalent organic frameworks (COFs) based materials as appropriate heterogeneous catalyst. The amine-aldehyde modified covalent organic framework constructed zinc catalyst; Zn@DBPG is synthesized and characterized properly. The synthesized material is utilized as an efficient catalyst for the production of organic carbamates following two different pathways: one is carbon dioxide fixation path and another is non carbon dioxide track under mild reaction conditions. In CO2 fixation track, both alkyl halides and aryl halides produced carbamates by reacting with various aromatic amines in presence of Zn@DBPG at room temperature. The absence of a solvent makes this catalytic process more environmentally friendly and greener. Besides, organic carbamate synthesis in non CO2 pathway environmentally benign urea is employed instead of CO2. Aliphatic as well as aromatic alcohols smoothly undergo through this catalytic reaction in ambient reaction conditions. High yield of respective carbamate products are obtained through both catalytic reaction pathways. Again easily separable COF catalyst Zn@DBPG perpetuates its catalytic productivity even after usage of seven catalytic reaction cycles. Besides, feasible mechanism cycles of the catalytic reactions in both pathways established here by DFT calculations.

Spontaneous generation of singlet oxygen on microemulsion-derived manganese oxides with rich oxygen vacancies for efficient aerobic oxidation.

Developing innovative catalysts for efficiently activating O2 into singlet oxygen (1O2) is a cutting-edge field with the potential to revolutionize green chemical synthesis. Despite its potential, practical implementation remains a significant challenge. In this study, we design a series of nitrogen (N)-doped manganese oxides (Ny-MnO2, where y represents the molar amount of the N precursor used) nanocatalysts using compartmentalized-microemulsion crystallization followed by post-calcination. These nanocatalysts demonstrate the remarkable ability to directly produce 1O2 at room temperature without the external fields. By strategically incorporating defect engineering and interstitial N, the concentration of surface oxygen atoms (Os) in the vicinity of oxygen vacancy (Ov) reaches 51.1% for the N55-MnO2 nanocatalyst. This feature allows the nanocatalyst to expose a substantial number of Ov and interstitial N sites on the surface of N55-MnO2, facilitating effective chemisorption and activation of O2. Verified through electron paramagnetic resonance spectroscopy and reactive oxygen species trapping experiments, the spontaneous generation of 1O2, even in the absence of light, underscores its crucial role in aerobic oxidation. Density functional theory calculations reveal that an increased Ov content and N doping significantly reduce the adsorption energy, thereby promoting chemisorption and excitation of O2. Consequently, the optimized N55-MnO2 nanocatalyst enables room-temperature aerobic oxidation of alcohols with a yield surpassing 99%, representing a 6.7-fold activity enhancement compared to ε-MnO2 without N-doping. Furthermore, N55-MnO2 demonstrates exceptional recyclability for the aerobic oxidative conversion of benzyl alcohol over ten cycles. This study introduces an approach to spontaneously activate O2 for the green synthesis of fine chemicals.

Advanced metal oxide-based nanocatalysts for the oxidative synthesis of fine chemicals

The present review article sheds light on the fabrication of heterogeneous metal oxide-supported nanostructure-based catalysts for boosting industrially significant oxidation processes.

A supported pyridylimine-cobalt catalyst for N-formylation of amines using CO2.

N-Formylation of amines with CO2 as a cheap and non-toxic C1-feedstock and hydrosilane reducing agent is a practical and environment friendly method to synthesize formamides. This study describes an efficient and chemoselective mono-N-formylation of amines using CO2 and phenylsilane under mild conditions using a porous metal-organic framework (MOF)-supported single-site cobalt catalyst (pyrim-UiO-Co). The pyrim-UiO-Co MOF has a UiO-topology, and its organic linkers bear a pyridylimine ligated Co catalytic moiety. A wide range of aliphatic and aromatic amines are transformed into desired N-formamides in moderate to excellent yields under 1-5 bar CO2. Pyrim-UiO-Co is tolerant to various functional groups and could be recycled and reused at least 10 times. Mechanistic investigation using kinetic, spectroscopic and density functional theory studies suggests that the formylation of benzylamine proceeds sequentially via oxidative addition of PhSiH3 and CO2 insertion, followed by a turn-over limiting reaction with an amine. Our work highlights the importance of MOF-based Earth-abundant metal catalysts for the practical and eco-friendly synthesis of fine chemicals using cheap feedstocks.

Transforming carbon dioxide and carbon monoxide into value-added products: boracarboxylation and boracarbonylation

This review surveys the current state-of-the-art of catalytic difunctionalization of unsaturated substrates with easily accessible feedstocks CO2/CO and heteroelement boron for the synthesis of fine chemicals and medicinally important molecules.

Sustainable synthesis of fine chemicals using biocatalysis

Sustainable synthesis of fine chemicals using biocatalysis

Green microfluidics in microchemical engineering for carbon neutrality

• Characteristics of green microfluidics and feasibility of applying green microfluidics in microchemical engineering industry for realizing carbon neutrality are elucidated. • Development of green microfluidic systems is interpreted. • Representative low carbon applications of green microfluidics in microchemical engineering are summarized. • Challenges and perspectives for further advancing green microfluidics in microchemical engineering for carbon neutrality are proposed and discussed. The concept of “carbon neutrality” poses a huge challenge for chemical engineering and brings great opportunities for boosting the development of novel technologies to realize carbon offsetting and reduce carbon emissions. Developing high-efficient, low-cost, energy-efficient and eco-friendly microfluidic-based microchemical engineering is of great significance. Such kind of “green microfluidics” can reduce carbon emissions from the source of raw materials and facilitate controllable and intensified microchemical engineering processes, which represents the new power for the transformation and upgrading of chemical engineering industry. Here, a brief review of green microfluidics for achieving carbon neutral microchemical engineering is presented, with specific discussions about the characteristics and feasibility of applying green microfluidics in realizing carbon neutrality. Development of green microfluidic systems are categorized and reviewed, including the construction of microfluidic devices by bio-based substrate materials and by low carbon fabrication methods, and the use of more biocompatible and non-destructive fluidic systems such as aqueous two-phase systems (ATPSs). Moreover, low carbon applications benefit from green microfluidics are summarized, ranging from separation and purification of biomolecules, high-throughput screening of chemicals and drugs, rapid and cost-effective detections, to synthesis of fine chemicals and novel materials. Finally, challenges and perspectives for further advancing green microfluidics in microchemical engineering for carbon neutrality are proposed and discussed.