Applications of bio-resource based sustainable heterogeneous Pd-Nanocatalyst for Cross-Coupling and Michael addition reactions

The development of efficient and cost-effective catalysts from renewable sources is crucial for sustainable chemistry. Herein, we developed a bio-heterogeneous Pd-nanocatalyst (PdNc@PA) by incorporating palladium nanoparticles into biodegradable kenaf-cellulose modified with poly(amidoxime) ligands. The catalyst has demonstrated remarkable stability and exceptional catalytic performance in a range of cross-coupling including Mizoroki-Heck, Suzuki-Miyaura, and Tamejiro-Hiyama reactions of inactivated aryl chlorides resulting in high yields of the desired coupling products. Additionally, PdNc@PA was also found to be effective in Michael addition reactions producing N, S, O-alkylated products in high yields. Furthermore, the PdNc@PA catalyst demonstrated robustness and recoverability allowing it to be reused across successive cycles without significant loss of catalytic activity. The incorporation of renewable resources in catalyst development offers an environmentally conscious alternative to traditional synthetic approaches. This research highlights the potential of utilizing biodegradable materials as catalyst supports, which could significantly diminish environmental impact and waste production. Moreover, this study demonstrates the versatility of PdNc@PA as a proficient and reusable catalyst for a diverse array of organic reactions. These discoveries provide an encouraging pathway towards the development of sustainable and economically viable catalysts suitable for industrial applications

Poly(hydroxamic acid) functionalized copper catalyzed C–N bond formation reactions

Highly active poly(hydroxamic acid) functionalized copper catalysts were synthesized by the surface modification of khaya cellulose through graft copolymerization and subsequent hydroximation processes. The prepared catalysts were well characterized by FTIR, FESEM, HRTEM, ICP-AES, UV-vis and XPS analyses. The supported catalysts effectively promoted C–N bond formation reactions and provided excellent yields of the corresponding products under mild reaction conditions. The catalysts were easy to recover from the reaction mixture and were reused several times without any significant loss of their catalytic activity

Cellulose supported transition metal (Cu, Pd) catalysts for carbon-carbon and carbon-nitrogen bonds formation reactions

This research mainly deals with the synthesis, characterization, and applications of functionalized cellulose supported heterogeneous metal catalysts for various types of cross-coupling reactions. Cross-coupling reactions generally proceed in the presence of homogeneous metal complexes. The practical limits to perform homogeneous catalysis reactions are complicated due to the difficulty in the separation of the product from the reaction mixture, as well as the inability to reuse the metal catalysts. To overcome these problems, scientific communities have investigated the use of various heterogeneous solid supports for metal catalyst species such as carbon nanotubes, graphene, silicates, polymers, metal oxides, and various hybrid inorganic materials. Although many economic and sustainable protocols have been employed by researchers dedicated to the development of green processes for cross-coupling reactions, there is still a high demand to explore more efficient catalysts for chemical transformation reactions. Nowadays, science and technology are shifting towards environmentally friendly, sustainable resources, and processes to investigate low-cost production of fine chemicals. In this perspective, natural biopolymers (cellulose) could be considered as acceptable solid support materials because of their promising merits such as being largely abundant in nature, having low density, bio-renewability, universal availability, low-cost and interesting chemical and mechanical properties. Therefore, natural cellulose would be a perfect solid support for catalysts. In this study, corn-cob cellulose was isolated from bio-waste corn-cobs, and the backbone of the cellulose was chemically modified through polymerization. The resulting polymeric functional group was converted into suitable poly(amidoxime) chelating ligand. The cellulose-supported poly(amidoxime) readily underwent a complexation reaction by treatment with metal (Pd/Cu) salts to give the corresponding cellulose-supported heterogeneous poly(amidoxime) metal complexes. The cellulose-supported palladium complex exhibited a high catalytic activity (0.1 to 0.05 mol%) towards Mizoroki-Heck cross-coupling reactions of aryl halides with a variety of olefins to give the corresponding coupling products of up to 97% yield. The electron withdrawing aryl halides processes higher yields compare to electron donating aryl halides. The palladium complex was also applied to the synthesis of Ozagrel, a thromboxane A2-synthetase inhibitor through Mizoroki-Heck reaction with 88% yield. The cellulose-supported poly(amidoxime) copper complex was applied to the Click reaction [Cu(II) 1 to 0.05 mol%] of organic azide with terminal alkyne to afford triazole in up to 96% yield. Moreover, copper nanoparticles were prepared from the copper complex and well stabilized by the poly(amidoxime) ligands. The copper nanoparticles were efficiently promoted the chemoselective Aza-Michael reaction [Cu(0) 0.1 to 0.005 mol%] of aliphatic amines with α, β -unsaturated compounds to give addition products in up to 95% yield. Additionally, all polymeric cellulose supported catalysts were easy to recover from the reaction mixture and reused several times without significant loss of their catalytic activities

Highly Active Bio-Waste Cellulose Supported Poly(Amidoxime) Palladium(II) Complex for Heck Reactions

Corn-cob cellulose supported poly(amidoxime) Pd(II) complex was synthesized and characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses. The cellulose supported heterogeneous Pd(II) complex showed high stability and catalytic activity towards Mizoroki-Heck reaction of aryl halides and arenediazonium tetrafluoroborate with a variety of olefins to give the corresponding cross-coupling products in up to 97% yield. The Pd(II) complex was separated from the reaction mixtures and repeatedly used up to seven times without any significant decrease of its catalytic performance

Effects of additives on sonolytic degradation of azo dye molecules found in industrial wastewater

The growing number of industries is a threat to our environment, as they expose the polluted water directly into the natural water sources. Various processes have been expanded to evacuate these hazardous organic pollutants from water. Among them, advance oxidation process (AOP) is very popular, as the method is cost efficient and highly effective in the similar field. In this process ultrasound is exercised for the deterioration of these pollutants and occasionally some additives are also added to enhance the degradation. In this article, the author has reported the degradation of two azo dyes, named methyl orange (MO) and congo red (CR), in presence of some additives like, inorganic salts, charcoal, H2O2, CCl4, tert-butyl alcohol (TBA), glucose and sucrose. The total experiment was conducted at room temperature and the power of the sonication machine was fixed to 40 kHz-120W. For both of the dyes, it was found that charcoal was most effective additive, which highly enhanced the degradation rate, which was mainly due to its high adsorption capability. TBA found to be the least enhancer for MO, on the contrary, pure CR showed the lowest degradation rate. The effectiveness of additives for MO can be shown as 0.01g charcoal > 20 ml glucose > 20 ml NaCl > 100 μL CCl4 > 10 ml Na2SO4 > 400 μL H2O2 > 10 ml sucrose > pure MO > TBA, while for CR is 0.01g charcoal > combined additives > TBA > 100 μL CCl4 > pure CR, after sonication for 15 minutes in a sonicator

Anti-inflammatory, antinociceptive and antidiarrhoeal activities of methanol and ethyl acetate extract of Hemigraphis alternata leaves in mice

Abstract Background The study was designed to investigate the qualitative phytochemical constituents and evaluate the anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities of methanol (MHAL) and ethyl acetate (EAHAL) extract of Hemigraphis alternata leaves in Swiss albino mice. Methods Qualitative phytochemical constituents of MHAL and EAHAL were determined by different tests such as Molisch’s test, Fehling test, Mayer’s test, Frothing test, FeCl3 test, Alkali test, Salkowski’s test, Keller-killiani test and CuSO4 test. In addition, Xylene induced-ear edema test and Cotton pellet-induced granuloma formation test had been performed to evaluate the anti-inflammatory activity. Moreover, Formalin-induced paw licking test, Acetic acid-induced writhing tests and Castor oil induced antidiarrheal test had been performed to evaluate the anti-nociceptive and anti-diarrhoeal activities respectively. Results These crude extracts were figured the presence of carbohydrates, flavonoids, tannins, glycosides, triterpenoids, fat and fixed oils. No mortality, behavioral changes or sign of any toxicity were observed up to the dose as high as 4000 mg/kg in mice. During anti-inflammatory test, MHAL 400 mg/kg and EAHAL 200 mg/kg & 400 mg/kg were significantly reduced ear weight differences and granuloma formation in mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (35.15 ± 11.78% and 34.76 ± 11.30%) in both anti-inflammatory tests respectively. In anti-nociceptive experiments, all extracts were significantly reduced paw licking and abdominal writhing of mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (88.21 ± 2.23% and 54.00 ± 2.38%) in both anti-nociceptive tests respectively. In addition, both extracts were showed significant inhibition of percentage of diarrhea in anti-diarrhoeal models except EAHAL 200 mg/kg dose and the apex percentage inhibition is offered by MHAL 400 mg/kg dose (67.73 ± 5.77%). Conclusion These results confirm that the leaves extract of Hemigraphis alternata are nontoxic and may provide a source of plant compounds with anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities

Antiamylolytic Activityof Okra (Abelmoschus esculentusL.) Pod Glycoprotein

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century1. There has been an enormous interest in the screening of phytochemicals, specifically for the development of alternative medicines for type 2 diabetes, capable of delaying or preventingstarch hydrolysis and controllingblood glucose level. In Asian countries the okra podis consumed becauseit plays an important role in the human diet by supplying carbohydrates, proteins, vitamins, minerals and asan important source of antidiabetic compounds2. The goal of the present study was to provide in vitro evidence for potential inhibition of a-amylase and a-glucosidase activityby aqueous okra pod extract

Tapioca Cellulose Based Copper Nanoparticles for Chemoselective N-Alkylation

Biomaterials as a support for catalysts are of prime importance. Tapioca root which is an abundant biopolymer source was used to synthesize cellulose supported bio-heterogeneous poly(hydroxamic acid) copper nanoparticles (CuN@PHA) and was characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscopy (TEM) analyses. The tapioca cellulose supported CuN@PHA (50 mol ppm) effectively catalyzed N-alkylation reaction of aliphatic amines with α,β-unsaturated compounds to give the corresponding alkylated products. High yields up to 95% were achieved for the converted products. The reusability of the cellulose supported nanoparticles was found to be excellent with no significant reduction of its catalytic activity over several cycles. The catalyst showed high catalytic activity having turnover number (TON) 18000 and turnover frequency (TOF) 2250 h−1

Poly(hydroxamic acid) Functionalized Copper Catalyzed C–N Bond Formation Reactions

Highly active poly(hydroxamic acid) functionalized copper catalysts were synthesized by the surface modification of khaya cellulose through graft copolymerization and subsequent hydroximation processes. The prepared catalysts were well characterized by FTIR, FESEM, HRTEM, ICP-AES, UV-vis and XPS analyses. The supported catalysts effectively promoted C–N bond formation reactions and provided excellent yields of the corresponding products under mild reaction conditions. The catalysts were easy to recover from the reaction mixture and were reused several times without any significant loss of their catalytic activity

Mesoporous Silica-Supported Sulfonyldiamine Ligand for Microwave-Assisted Transfer Hydrogenation

N-Sulfonyl-1,2-diamine ligands, derived from 1,2-diaminocyclohexane and 1,2-diaminopropane, were immobilized onto mesoporous SBA-15 silica. The SBA-15-supported sulfonyldiamine-Ru complex was prepared in situ under microwave heating at 60 W for 3 min. The prepared sulfonyldiamine-Ru complex was used as an efficient catalyst for the transfer hydrogenation of ketones to the corresponding secondary alcohols. The heterogeneous complex showed extremely high catalytic activity with 99% conversion rate under microwave heating condition. The complexes were regenerated by simple filtration and reused two times without significant loss of activity