Introduction: Nitrile hydration reaction is considered one of the highly atom-economical and prominent green chemistry approaches for the synthesis of amides under aqueous medium. materials and methods: Materials and Methods Material Ammonium dihydrogen phosphate (S.d. fine chemicals), Calcium Carbonate (99+%, Sigma Aldrich), Nitric Acid (69-72%, S.d. fine chemicals), Urea (99%, S.d. fine chemicals), Lithium nitrate (99%, SRL Chemicals), Sodium nitrate (98%, Qualigens), Potassium nitrate (99%, S.d. fine chemicals). Preparation of β – Tricalcium phosphate by combustion method Appropriate weight of CaCO3 (2.0018g) and ammonium di hydrogen phosphate (NH4H2PO4, 3.45 g) was separately dissolved in 20 mL of 2M nitric acid and 25 mL of distilled water respectively. To the obtained Ca(NO3)2 solution and prepared NH4H2PO4 solution were mixed slowly and stirred. To the above solution mixture, 1.6016 g of urea was added and stirred until the solution becomes homogeneous. The furnace was heated to 500 °C prior to placing the sample for 15 min at 500 °C. The solid obtained was ground and calcined at two different temperatures (600 °C for 1h and 900 °C for 3 h). Preparation of Li/β-TCP by impregnation method Appropriate amount of lithium nitrate was added into 25 mL of distilled water and stirred for 5min to get homogeneous solution. To the above solution, as-prepared β-TCP powder was added with weight ratio of 1: 2 (TCP: LiNO3) and stirred for 1h and evaporated to dryness. The collected sample was subjected to heat treatment at 900 °C for 2 h. Similarly, K/β-TCP, Na /β-TCP and Li/HAP catalysts were also prepared by the procedure mentioned above. Catalytic Test The activity of as-prepared catalysts was screened in hydration of nitrile under reflux condition. To the benzonitrile (2.5 mmol), Li/β-TCP catalyst (0.1g) and water (7.5 mL) was added and refluxed under stirring condition (~550–600 rpm) at 125 °C for 3 h and cooldown to room temperature. After the reaction, ethanol was added and then, the catalyst was separated by filtration. The filtrate was placed on water bath to evaporate the solvent. The collected mass was purified using column chromatography with petroleum ether: ethyl acetate mixture as eluent. Melting point, FT-IR and 1H NMR spectrum was used to confirm the amide formation, and their corresponding data has been given in the supporting information. Characterization The structural information of as-prepared supports and catalysts was confirmed by powder X-ray diffraction (Cu Kα, Bruker, D8 Advanced) and Fourier transform infrared spectroscopy (JASCO FT-IR-4100 spectrometer). The amide formation was confirmed by their melting points, 1HNMR, (Bruker AVANCE III 400 MHz) and Fourier transform infrared spectroscopy (JASCO FT-IR-4100 spectrometer). Methods: Alkali metal nitrates (LiNO3, NaNO3, and KNO3) modified β-TCP were prepared by the impregnation method, and the catalytic activity of the prepared catalysts was screened in the nitrile hydration reaction. Results: Selective conversion of aromatic and heteroaromatic nitriles to respective amides has been achieved with alkali metal nitrate modified β-TCP catalysts under reflux conditions. Among the cat-alysts tested, LiNO3 impregnated β-TCP (Li/β-TCP) exhibits superior activity, whereas NaNO3 im-pregnated β-TCP (Na/β-TCP) and KNO3 impregnated β-TCP (K/β-TCP) catalysts exhibit relatively lower activity. Discussion: FT-IR and powder XRD analysis of Li/β-TCP confirmed the generation of CaO species as a new phase during the nitrate decomposition process, whereas CaO species were absent on both Na/β-TCP and K/β-TCP catalysts. Conclusion: The present study demonstrates that in situ generated CaO species on Li/β-TCP catalyst are responsible for its higher activity in thnitrile hydration reaction.
β-glucosidase enzymes play a pivotal role in the hydrolysis of glycosidic bonds, with bio-catalytic applications in glycoside synthesis, lignocellulosic biomass degradation, and the processing of glycosides. This review explores the engineering of β-glucosidase mutants to enhance their cata-lytic efficiency, substrate specificity, and stability for biocatalytic applications. It also considers hy-drolytic applications of glucosidases, such as lignocellulosic biomass valorisation, as well as syn-thetic applications via reverse hydrolysis, including the production of alkyl glycosides. Additionally, it examines rational design-led mutagenesis and directed evolution strategies to tailor enzyme activity, along with structural insights gained from molecular dynamics simulations and mo-lecular docking studies. These structural insights provide an understanding of the active-site archi-tecture, catalytic mechanism, and enzyme-substrate interactions, which are useful for the rational design of improved glucosidase variants. This review underscores the synergistic role of mutagenesis studies and structural analysis in optimizing glucosidases for efficient and sustainable biocatalytic applications, paving the way for innovative applications in green chemistry.
Widespread use of organic dyes and nitrophenols in paint, textile, chemi-cal, or pharmaceutical industries leads to water pollution. Reductive degradation using metal cata-lysts has emerged as an effective approach. In line with this, the current work reports the synthesis and characterization of polyaniline-supported nickel acetate (PANI-Ni), which successfully cata-lyzed the reduction of p-nitrophenol, Methylene Blue (MB), and Rhodamine B (RhB) with recovery and recyclability. PANI-Ni catalyst was prepared by adding polyaniline base (PANI) to the aqueous solu-tion of nickel acetate tetrahydrate, followed by simple filtration and washing. Finally, it was dried under vacuum to obtain the PANI-Ni. The amount of Ni loading was quantified using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The catalyst was well characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy-energy dis-persive X-ray analysis (SEM-EDX), and X-ray powder diffraction (XRD). The catalytic efficiency of the PANI-Ni was tested in the reduction of p-nitrophenol (p-NP) and reductive degradation of organic dyes like Methylene Blue (MB), and Rhodamine B (RhB) in the presence of sodium boro-hydride (SB) as the hydrogen source. The recovered catalyst was characterized using X-ray photo-electron spectroscopy (XPS) and Transmission electron microscopy (TEM). The catalytic activity of PANI-Ni was first evaluated for the reduction of p-NP, and it was found that complete reduction was achieved within 3 min., as monitored via UV absorption analysis. The scope of the catalyst was further explored for the degradation of MB and RhB. In both cases, high catalytic efficiency was observed. The catalytic degradation rate was found to be dependent on the pH of the reaction medium and on the amount of catalyst. PANI-Ni catalyst showed consistent activity over six cycles in the degradation of MB with the presence of SB. Recovered PANI-Ni showed the presence of Ni (0) as established by TEM and XPS studies. These results demonstrate that PANI-Ni is a highly effective and promising catalyst for the reductive degradation of organic dyes. The cheaper cost, high efficiency, and recyclability further underscore its potential for sustainable water remediation.
Manganese-catalyzed N-formylation of aniline using formic acid (HCOOH) represents a notable advancement in formanilide synthesis. This method offers a safer and more manageable alternative to conventional formylation methods, which rely on toxic carbon monoxide (CO) gas. The strategy utilizes HCOOH as a convenient and environmentally friendly surrogate for CO. Manganese catalysts are employed to promote selective C-N bond formation under mild con-ditions. The process achieves moderate to excellent yields across a broad range of formanilides, demonstrating good functional group tolerance and efficiency. A manganese-catalyzed protocol was developed for the efficient N-formylation of ani-lines using formic acid as a surrogate for CO. Optimization studies revealed that MnCl24H2O (5 mol%) with Na2CO3.H2O (2 equiv.) in DMF at 130°C under nitrogen for 20 h provided formanilide in 98% yield. Various reaction parameters, including catalyst type, base, solvent, temperature, and time, were systematically optimized. The method exhibited a broad substrate scope, tolerating sev-eral electron-donating and halogen-substituted groups. However, ortho-substituted anilines, nitroan-ilines, N-alkylated amines, and certain heterocycles showed low to no reactivity under the optimized conditions. This study highlights the versatility of manganese catalysts in sustainable synthesis. It marks a significant development in the production of CO-free formanilide via N-formylation of aniline using formic acid.
The organometallic chemistry associated with the metal aryloxide compounds is growing rapidly. Research has focused on the ligands'; reactivity, for example, the insertion chemistry of the M-OAr bonds, and on the organometallic reactivity that can be supported by aryloxide ligation. Species of titanium bonded to aryloxo ligands are often used as base compounds for material engineering, catalysts, or initiators for different kinds of polymerization processes, and biodegradable materials. A tetrakis(4-bromphenoxo)titanium(IV), Ti(OC6H4Br-4)4, complex has been synthesized using titanium tetrachloride with four moles of 4-bromophenol in carbon tetrachloride. Double phenoxide of composition Na2[Ti(OC6H4Br-4)6] was prepared by reacting Ti(OC6H4Br-4)4 in methanol with sodium bromophenoxide dissolved in the same solvent in a 1:2 (titanium: alkali metal) molar ratio. Reactions of Ti(OC6H4Br-4)4 with pyridine, diethylamine, and triethylamine were carried out in a 1:2 molar ratio, while with bidentate ligands, namely 1,10-phenanthroline and 2,2/-bipyridyl, reactions were carried out by mixing them in the equimolar ratio in dry benzene. The chelates with chelating agents such as benzoin, salicylaldehyde, and 2-hydroxyacetophenone were prepared with Ti(OC6H4Br-4)4 taken in methanol with a bimolar amount of chelating agent. Ti(OC6H4Br-4)4 is also characterized using elemental analysis, IR, 1H NMR, mass spectrometry, X-ray diffraction studies, and thermal analysis. The 4-bromophenol ligand binds to metal via the oxygen of the phenoxy group, and the compound has been assigned a dimeric structure bridging through phenoxy groups. Moreover, the complex Ti(OC6H4Br-4)4 forms a double phenoxide, behaves as a Lewis acid, and forms mixed chelate complexes.
