Search

Selective hydrogenation of cinnamaldehyde (CAL) toward cinnamyl alcohol (COL) is an extremely important and challenging reaction. Herein, a series of PtxFey-Al2O3 bimetallic catalysts with varied Pt to Fe ratios were prepared by incipient wetness impregnation method. The introduction of Fe significantly modifies the electronic and surface properties of Pt, which clearly enhances the C=O hydrogenation selectivity. Among all the catalysts, Pt3Fe-Al2O3 displays the best catalytic performance and the conversion of CAL is 96.6% with 77.2% selectivity of COL within 1 h. In addition, Pt3Fe-Al2O3 had excellent reusability with 76% COL selectivity after five runs of the recycle process. Further characterization of the fresh, used and cycled catalysts revealed that the structure and electronic state of the synthesized PtxFey-Al2O3 are unchanged after hydrogenation reaction. The identical-location transmission electron microscopy (IL-TEM) results revealed that the interaction between the nanoparticles and the supports was strong and the catalyst was relatively stable.

Hydrogenation of aldehydes (RHO) is one of the frequently used reactions in organic synthesis and pharmaceuticals industries. In this contribution, we have synthesized control shaped and nano-sized tetragonal zirconia (t-ZrO2), palladium supported on zirconia (Pd/t-ZrO2) and nickel promoted palladium supported on zirconia (Ni-Pd/t-ZrO2) though modified microwave irradiation method. All the prepared samples were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Diffractometry (XRD), Thermal Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) surface area and pore size analysis, and Fourier Transform Infrared Spectroscopy (FT-IR). Theoretical calculation (DFT) revealed high interaction of Pd with t-ZrO2(101) surface. Furthermore, adsorption energy, support relaxation and charge transfer studies confirmed the stability of Pd on t-ZrO2(101) surface. The catalytic activity of catalysts was tested for cinnamaldehyde (CAL) hydrogenation in a modified microwave reactor. The comparative study of microwave irradiated (MW) and conventional heating (C-Heating) systems show supremacy of MW over C-Heating by a factor of 46% under optimal reaction parameters for Pd/t-ZrO2 catalyst. The stability, life span, conversion and selectivity of Pd/t-ZrO2 under MW system suggest the applicability of the catalysts for a variety of organic hydrogenation reactions.

Cinnamon is a natural spice with a wide range of pharmacological functions, including anti-microbial, antioxidant, and anti-tumor activities. The aim of this study is to investigate the effects of cinnamaldehyde-rich cinnamon extract (CRCE) on the colorectal cancer cell lines HCT 116 and HT-29. The gas chromatography mass spectrometry analysis of a lipophilic extract of cinnamon revealed the dominance of trans-cinnamaldehyde. Cells treated with CRCE (10–60 µg/mL) showed significantly decreased cell viability in a time- and dose-dependent manner. We also observed that cell proliferation and migration capacity were inhibited in CRCE-treated cells. In addition, a remarkable increase in the number of sub-G1-phase cells was observed with arrest at the G2 phase by CRCE treatment. CRCE also induced mitochondrial stress, and finally, CRCE treatment resulted in activation of apoptotic proteins Caspase-3, -9, and PARP and decreased levels of mu-2-related death-inducing gene protein expression with BH3-interacting domain death agonist (BID) activation.

It is a challenging task for selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HCAL) without additional by-product formation. In this work, a La2O3 supported high Ni content nanoparticle catalyst was prepared for CAL selective hydrogenation. Meanwhile, Co-La2O3 catalysts were used as a reference catalyst. XRD, TEM, STEM-HAADF, XPS, and H2-TPR measurements were used to investigate the physicochemical properties of Ni-La2O3 catalysts. The experimental results confirmed that the CAL conversion and HCAL selectivity were effectively promoted with the increase of Ni loading amounts. At a Ni/La molar ratio of four, a high HCAL selectivity of 87.4% was obtained at a CAL conversion of 88.1% under mild reaction conditions. The catalyst was recycled five times without activity loss. Combined with various characterizations, it could be inferred that the good hydrogen adsorption and dissociation capacity of Ni and the presence of a certain amount of oxygen vacancies on the La2O3 support have a positive effect on the improvement of HCAL selectivity. This work provided an effective path to design transition-metal-based supported oxide catalyst for the cinnamaldehyde hydrogenation to hydrocinnamaldehyde.

Eugenol, cinnamaldehyde and D-limonene, the main components of natural essential oils, are endowed with antioxidant and anti-inflammatory properties which allow them to induce beneficial effects on intestinal, cardiac and neuronal levels. In order to characterize their pharmacokinetic profiles and aptitude to permeate in the central nervous system after intravenous and oral administration to rats, new analytical procedures, easily achievable with HPLC-UV techniques, were developed. The terminal half-lives of these compounds range from 12.4 ± 0.9 (D-limonene) and 23.1 ± 1.6 min (cinnamaldehyde); their oral bioavailability appears relatively poor, ranging from 4.25 ± 0.11% (eugenol) to 7.33 ± 0.37% (cinnamaldehyde). Eugenol evidences a marked aptitude to permeate in the cerebrospinal fluid (CSF) of rats following both intravenous and oral administrations, whereas cinnamaldehyde appears able to reach the CSF only after intravenous administration; limonene is totally unable to permeate in the CSF. Eugenol was therefore recruited for in vitro studies of viability and time-/dose-dependent dopamine release in neuronal differentiated PC12 cells (a recognized cellular model mimicking dopaminergic neurons), evidencing its ability to increase cell viability and to induce dopamine release according to a U-shaped time-course curve. Moreover, concentration-response data suggest that eugenol may induce beneficial effects against Parkinson’s disease after oral administration.

The hydrogenation of cinnamaldehyde is usually performed in the liquid phase in batch mode. In this study, a vapour phase flow system has been used to evaluate the use of cobalt catalysts supported inside and outside hollow carbon spheres (HCSs). The influence of temperature, hydrogen flow rate, and catalyst mass on the hydrogenation reaction was investigated. The catalysts generally showed modest conversion to the required products, hydrocinnamaldehyde, 3-phenyl propanol, cinnamyl alcohol, together with formation of various decomposition products. The data revealed that the Co@HCS showed better conversion and product selectivity compared with the Co/HCS. The catalysts with smaller particle sizes (ca. 6 nm) were more efficient than those with larger particles (30–40 nm). An increase in reaction temperature (200–300 °C) resulted in a lower cinnamaldehyde conversion and a poor product selectivity. TPR studies revealed that the Co@HCSs had a stronger metal-support interaction than the Co/HCSs catalysts. Catalyst recycling studies revealed that only the Co/HCSs could be regenerated (four cycles) and post reaction analysis of the catalysts revealed that this was due to HCS pore blockage and not Co sintering.

Differences in the activity of Pd/WO3 and Pd/MoO3 (Pd loading 0.4–4 wt%) catalysts in competitive hydrogenations of the C C and C O groups in polyfunctional reagents have been studied as a function of two effects: (1) the in situ formation of hydrogen bronzes, HxWO3 and HxMoO3, and (2) the electronic interaction between the supports and the metallic Pd. The cinnamaldehyde (CAL), furfural (FU) and 5-hydroxymethylfurfural (HMF) were hydrogenated under mild reaction conditions. The formation of hydrogen bronzes in Pd/WO3 and physical mixture of Pd/WO3 with supporting WO3 oxide upon exposure to H2 was also studied using the gas flow-through microcalorimetry. In both Pd/MoO3 and Pd/WO3 catalysts, the electronic interactions contributed to the promotion of selectivity toward the C O hydrogenation in CAL and FU, yet in Pd/MoO3 this effect was much more pronounced. On the other hand, apart from increasing the overall reaction rate, the formation of hydrogen bronzes remarkably enhances the C C hydrogenation in CAL, as well as the decarbonylation of FU to furan and hydrogenolysis of C–OH in HMF to 5-methylfurfural. The bronze effects are significantly stronger in HxWO3, compared to HxMoO3, which may be related to higher H-species mobility and weaker H-bonding in the W–O–H (54 kJ/mol H2) than in the Mo–O–H (100 kJ/mol H2). This may also explain very high tendency of Pd/WO3 to furan ring hydrogenation in FU and HMF as well as almost selective (>98%) hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol.

The number of synthetic strategies used to functionalize MOFs with polymers is rapidly growing; this stems from the knowledge that non-native polymeric guests can significantly boost MOF performance in a number of desirable applications. The current work presents a scalable and solid-state method for MOF/polymer composite production. This simple method constitutes mixing a MOF powder, namely, Fe-BTC (BTC = 1,3,5-benzenetricarboxylate), with a biomass-derived solid monomer, 5-hydroxymethylfurfural (HMF), and subsequently heating the solids; the latter promotes both solid-state diffusion of HMF into the MOF and the formation of polymeric humin species with a high density of accessible hydroxyl functionality within the MOF pore. The resulting composite, Fe-BTC/humin, was found to selectively extract Ag+ ions from laundry wastewater. Subsequent reduction of the Ag+ species yields a novel catalyst, Fe-BTC/humin/Ag, that is able to drive the organic transformation of cinnamaldehyde in a highly selective manner. Moreover, the catalyst exhibited recyclability up to five cycles, which is in contrast to the Fe-BTC/Ag catalyst without the humin-based polymer. It is envisioned that MOF/polymer composites that are able to selectively extract precious metals from liquid waste streams can be used for the future production of sustainable catalysts; this work was aimed at demonstrating a proof of concept in this regard. Moreover, this study brings more understanding of the impact that MOFs can have on polymer functionalities. Understanding the polymer structure and how it can be manipulated will help us realize the high degree of future potential of this distinct class of composite materials.

Several supported gold metal catalysts with different Au nanoparticles sizes were prepared and evaluated for the chemoselective hydrogenation of cinnamaldehyde (CA) to cinnamyl alcohol (CAL). To investigate the structure-activity relationship, stability of catalyst, heterogeneity and recyclability, the structural characteristics of materials and Au catalysts (fresh and spent catalysts) were studied by employing variety of physico-chemical techniques. The interrelationship among Au nanoparticles size (nm) with turnover frequency (h-1 ) of Au catalysts has also been explored. Among the various Au catalysts tested, nitrogen-doped mesoporous carbon (NMC) supported Au catalyst having homogeneously dispersed (78.8%) Au nanoparticles (1.6 nm) synthesized by sol-immobilization method (Au-NMC-SI) demonstrated improved catalytic activity affording 78% CAL selectivity and 94.2% CA conversion without using any promoter. Moreover, Au-NMC-SI catalyst exhibited good recyclability and stability. The catalyst synthesis approach described in this investigation opens up a novel strategy for the design of highly efficient metal nano-catalysts supported on NMC materials.

In recent years, infections caused by multidrug-resistant (MDR) bacteria have greatly threatened human health and imposed a burden on global public health. To overcome this crisis, there is an urgent need to seek effective alternatives to single antibiotic therapy to circumvent drug resistance and prevent MDR bacteria. According to previous reports, cinnamaldehyde exerts antibacterial activity against drug-resistant Salmonella spp. This study was conducted to investigate whether cinnamaldehyde has a synergistic effect on antibiotics when used in combination, we found that cinnamaldehyde enhanced the antibacterial activity of ceftriaxone sodium against MDR Salmonella in vitro by significantly reduced the expression of extended-spectrum beta-lactamase, inhibiting the development of drug resistance under ceftriaxone selective pressure in vitro, damaging the cell membrane, and affecting its basic metabolism. In addition, it restored the activity of ceftriaxone sodium against MDR Salmonella in vivo and inhibited peritonitis caused by ceftriaxone resistant strain of Salmonella in mice. Collectively, these results revealed that cinnamaldehyde can be used as a novel ceftriaxone adjuvant to prevent and treat infections caused by MDR Salmonella, mitigating the possibility of producing further mutant strains.

Surface states—the electronic states emerging as a solid material terminates at a surface—are usually vulnerable to contaminations and defects. This fundamental limitation has prohibited systematic studies of the potential role of surface states in surface reactions and catalysis, especially in more realistic environments. Herein, we use selective hydrogenation of cinnamaldehyde (CAL) on platinum-covered titanium oxide (Pt@P25) as a prototype reaction, and show that the competitive exchange of extra-introduced species (sodium hydroxide and sodium formate) with spontaneously formed weak bound carbonate and bicarbonate anions at Pt NPs can reconstruct the surface states, which directs the preferred adsorption of the conjugated C=O and C=C double bonds of CAL, and consequently, results in highly efficient synthesis of unsaturated alcohol cinnamyl alcohol (COL) and saturated aldehyde hydrocinnamaldehyde (HCAL) with high selectivity of 98.9% and 99.5%, respectively. Our concept of restructured surface states to tune the chemoselectivity of α, β-unsaturated aldehydes triggered by the selective adsorption of alien molecules may lead to new design principles of heterogeneous catalysts, beyond the conventional d-band theory.

The conversion of cinnamaldehyde (CALD) to Cinnamyl alcohol (CALC) over a Pt/SiO2 catalyst was investigated. To achieve maximum CALC production, the historical data design of using a response surfa...

Herein, we report a rapid catalyst-free three-component reaction of 2-hydroxy-1,4-naphthoquinone, cinnamaldehydes and 3-aminopyrazoles in ethanol medium under reflux conditions for the easy access of styryl-linked dihydropyridines fused with naphthoquinone and pyrazole moiety. A wide variety of cinnamaldehyde derivatives and 3-aminopyrazoles were found suitable for this three-component reaction. All the products were fully characterized by spectroscopic tools and by recording single crystal XRD of one of the product. Catalyst-free reaction conditions, short reaction time, good yields of the products, easy purification process, formation of three new bonds (Two C-C and one C-N) in one-pot and products having four different bioactive moieties are the notable features of this methodology.

Au-Pd bimetallic nanoparticles (NPs) supported on SnNb2O6 ultrathin nanosheets (SN) were developed as multifunctional photocatalysts for the selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HCAL) under visible light irradiation. A representative catalyst (Au6-Pd1/SN) exhibits optimum performances with 99.8% conversion and 91.0% selectivity. The structure and surface properties of the prepared samples were revealed by SEM, TEM, BET, TPD, XPS, and EPR. The results of in situ FTIR spectra and NH3-TPD reveal that the rich surface Lewis acid sites on SN can chemisorb and activate CAL via the C = C…Nb coordination. EPR experiments indicate that H2 would dissociate to activated H atoms on Pd NPs following a photopromoted surface catalytic process. Experimental results suggest that Au NPs reduce the over hydrogenation of HCAL by inhibiting the formation of Pd-H species. The superior catalytic performance is attributed to a synergistic effect of Au, Pd NPs and SN. Finally, a possible synergetic mechanism for Au-Pd/SN is proposed to illustrate the photocatalytic process. This work offers a reference to guide a novel and more effective photocatalyst design for precise organic synthesis driven by sunlight.

Developing efficient, robust, and highly recyclable catalysts with the ability to separate products conveniently for industrially important hydrogenation reactions is a major challenge. Edges of na...

The catalytic activity of the size-selected gold clusters Au38(SCH2CH2Ph)24 (abbreviated with Au38) in 3-D nanoporous Ce-metal–organic framework (Ce–UiO-66) was studied. The Au38 nanoclusters were in situ immersed in Ce–UiO-66 with a loading percentage of 1 wt%. The Au38@Ce–UiO-66 catalyst demonstrated excellent catalytic activity for aerobic oxidation of cinnamyl alcohol. The oxidation reaction was tested from 40 to 100 °C utilizing O2 gas (30 ml min−1) as an oxidizing agent in atmospheric pressure. 0.1 mol% of the Au38@Ce–UiO-66 catalyst achieved 65% cinnamyl alcohol conversion at 100 °C within an hour with 100% selectivity toward cinnamaldehyde in toluene. In the case of using an aqueous solvent instead of an organic solvent (toluene), the conversion was increased to 75% under the same reaction condition. The cinnamyl alcohol conversion was increased gradually by increasing the reaction time over Au38@Ce–UiO-66 catalyst, where the conversion was enhanced to 93% after 5 h of heating at 100 °C in water. The catalytic activity of the Au38@Ce–UiO-66 catalyst was largely enhanced after oxygen thermal pretreatment at 100–200 °C, where the catalyst achieved 990 h−1 turnover frequency (TOF) after O2-pretreatment at 175 °C with 92% cinnamaldehyde and 8% cinnamic acid selectivity. The unique atomic packing structure and electronic properties of the size-selected gold nanoclusters (Au38) are responsible for their extraordinary catalytic activity. Moreover, the support (Ce–UiO-66) has a big role in the catalyst activity, since it has a high ability to absorb large quantities from oxygen on the Ce(III)/Ce(IV) centers and generate active oxygen species such as superoxo and peroxo species on the catalyst surface, which help in oxidation of cinnamyl alcohol. For comparison, gold nanoparticles were loaded over the same support, where the Au(III) ions were reduced by two different reduction methods utilizing NaBH4 in the absence of the ligand and hydrogen reduction at 200 °C, 4 h. The particle size of the Au38 clusters and gold nanoparticles over Ce–UiO-66 was investigated by a high-resolution transmission electron microscope (HR-TEM). The charge of the gold clusters and nanoparticles was zero as confirmed by X-ray photoelectron spectroscopy (XPS). The crystallinity and surface texture properties of the prepared catalysts and the pure support were measured by powder X-ray diffraction analysis and N2 gas sorption isotherm at − 196 °C, respectively.

Chemoselective hydrogenation of unsaturated aldehyde to unsaturated alcohol has attracted growing interests in recent years due to its widespread applications in fine chemicals. However, the hydrogenation of the C=O bond was thermodynamically and kinetically unfavorable over the hydrogenation of the C=C bond. Thus, to obtain the unsaturated alcohol from the unsaturated aldehyde is very difficult in most of the catalytic systems. In this work, ZnAl-hydrotalcite-supported cysteine-capped Au25 nanoclusters were used as the precatalysts for chemoselective hydrogenation of cinnamaldehyde to cinnamyl alcohol. The catalyst showed stable high selectivity (~ 95%) at prolonged reaction time and complete conversion of the substrate. According to the results of the control experiments, the in-situ DRIFTS of the substrate under high pressure of hydrogen and the 27Al MAS-NMR spectroscopy, we proposed that the difference of the preferential adsorption of the C=O bond to that of the C=C bond was derived from the nature of the support of the gold catalysts.

Mesoporous TS-1 microspheres (MTS-1-MS) were applied to load Pt-Fe bimetallic components with different Fe/Pt molar ratios for the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to produce cinnamyl alcohol (COL). Combining the XRD and XPS characterization results, Fe dopant co-existed as PtFe fcc alloy or FeOx species, which modified the electronic properties of Pt active sites through the electron transfer from Fe to Pt, therefore, the catalytic performance was improved remarkably with the Fe-doped Pt/MTS-1-MS catalyst. As a result, the PtFe0.25/MTS-1-MS-350 catalyst, which contains Fe amount with a Fe/Pt molar ratio of 0.25 and was calcined at 350 °C before reduction in hydrogen at 400 °C, furnished 95.7% CAL conversion and 89.2% COL selectivity with an initial activity (in terms of TOF value) reaching 19440 h−1, much better than its analogue Pt/MTS-1-MS-350, which only showed 56.6% CAL conversion and 74.4% COL selectivity under the same conditions. To the best of our knowledge, it is one of the most active Pt-Fe bimetallic catalysts up to now. Moreover, the PtFe0.25/MTS-1-MS-350 catalyst can also be cycled for at least 9 times without obvious loss in activity or COL selectivity. Furthermore, theoretical calculations based on several simplified surface models were conducted using the density-functional theory (DFT) to reveal the differences in electronic structures and geometric properties caused by Fe dopant and to explain the reason why C O hydrogenation was preferential on the PtFe0.25/MTS-1-MS-350 catalyst from the perspective of CAL adsorption and COL desorption on/from Pt-Fe surface.

A first catalytic asymmetric reaction of acetone with cinnamaldehyde for the synthesis of disubstituted 4-oxocyclohexanecarbaldehyde is developed. A variety of substituted cinnamaldehydes are successfully tested under the optimized reaction conditions. Both the enantiomers of the same diastereomeric products are achieved in good yield and diastereoselectivity with an excellent enantioselectivity by changing the enantiomer of one of the two chiral catalysts. The practicality of this methodology is demonstrated by the gram-scale synthesis.

Selective hydrogenation of the carbonyl functional group of α,β-unsaturated carbonyl compounds affords industrially important allylic alcohols. However, achieving the selective reduction of the carbonyl group in the presence of the activated olefinic group is challenging. Therefore, the development of a highly chemoselective, efficient, and recyclable catalyst for this transformation is greatly desirable from the industrial and environmental viewpoints. In this study, a Ru-immobilized bisphosphine-based porous organic polymer (Ru@PP-POP) was used as an efficient heterogeneous catalyst for chemoselective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol with high chemoselectivity (98%) and excellent recyclability. To the best of our knowledge, the catalyst, Ru@PP-POP showed a high turnover number (970) and a high turnover frequency (240 h−1) which is the best activity obtained using a phosphine based heterogeneous Ru-catalyst in this transformation.

Engineering the interface plays a vital role in tuning the catalytic properties of supported metal nanocatalysts. Herein the 0.73%Au-4.13%FeOx@SBA-15 catalyst was constructed with SBA-15 as support and FeOx as modifier by interface engineering. It exhibited better catalytic activity than 0.71%Au/SiO2, 0.69%Au@SBA-15 and 0.71%Au/bulk-FeOx under identical conditions as well as higher selectivity towards cinnamyl alcohol for selective hydrogenation of cinnamaldehyde. It was found that the introduction of FeOx fabricated the interfacial area between Au and FeOx for H2 dissociation and consequently led to higher catalytic activity of 0.73%Au-4.13%FeOx@SBA-15. Meanwhile, both the channel of the SBA-15 support and the presence of small-sized FeOx promoted the selectivity for hydrogenation of C = O bond. It demonstrated for the first time that the interface engineering provided an efficient and facile avenue to design Au catalysts of excellent performances for selective hydrogenations.

In the present study, cinnamaldehyde (CNAD) was loaded onto magnetic (Fe3O4) nanoparticles (NPs) that were functionalized with FITC and folic acid (FiCF NPs) for imaging and active drug targeting in breast cancer cells. The particle size of the NPs was ∼10 nm while TGA analysis revealed 20% loading of CNAD onto the NPs. Folic acid conjugation resulted in an increased uptake of NPs in breast cancer cells with their localization in both the cytoplasm and the nucleus. FiCF NPs induced apoptosis in the cells and increased the expression of generic caspases. Acute toxicity study demonstrated safety of the NPs in Swiss albino mice. Interestingly, FiCF NPs reduced the tumor burden in the mouse breast cancer model compared to those treated with free CNAD and FiC functionalized NPs. Furthermore, pharmacokinetic studies in Wistar rats revealed prolonged circulation time and slower plasma elimination of CNAD in animals treated with FiCF NPs. Thus, FiCF NPs exhibited promising potential against breast cancer and warrant further safety studies in the future before exploring their potential at the clinical level.

Selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde is captivating due to its industrial relevance. Herein, a two-step synthesis method was adopted to develop oxygen vacancies in Pd@ZrO2 catalysts. The oxygen vacancies were developed in Pd@ZrO2 catalysts during impregnation of Pd which was confirmed by XPS and HR-TEM analyses. The characterization results revealed that there was a synergistic role of oxygen vacancies and nano-sized active Pd metals in Pd@ZrO2 catalysts that assisted in achieving selectivity for hydrocinnamaldehyde which has been discussed in this study. We also studied the effects of different reaction parameters which revealed that 4 wt% Pd loading in a Pd@ZrO2 catalyst provided enough active sites for complete conversion of CAL. Additionally, 100 °C temperature and 10 bar H2 pressure provided enough energy for effective collisions and activation of reactants and catalysts to form the desired product in a reaction time of 9 h. Therefore, a defect-rich 4-Pd@ZrO2 catalyst demonstrated complete CAL conversion with 86% yield towards HCAL which is the best result amongst various Pd@ZrO2 catalysts with different Pd loading investigated for the hydrogenation of cinnamaldehyde. Moreover, a plausible mechanism was proposed to support the chemoselective hydrogenation of cinnamaldehyde over a 4-Pd@ZrO2 catalyst. Along with high catalytic performance, the 4-Pd@ZrO2 catalyst also showed impressive recyclability performance for up to six recycles. Thus, the oxygen-vacancy-rich Pd@ZrO2 can be considered as an efficient catalyst for the chemoselective hydrogenation of cinnamaldehyde.

Functional group hydrogenation of α-β unsaturated aldehydes to fine chemicals is a potential process in organic synthesis. In this study, we demonstrate the complete functional group hydrogenation of cinnamaldehyde (CAL) to hydrocinnamyl alcohol (HCOL) over magnesium aluminium hydrotalcite (MAHT) having bimetallic nickel/ruthenium (1.3% Ni and 0.74% Ru) species (MANR–HT). The catalyst shows complete conversion of CAL with 97.5% selectivity of HCOL at 150 °C and 1 MPa H2 pressure. The synergic effect of bimetallic Ni/Ru and basicity of the HT material facilitated the high catalytic activity of MANR–HT in the CAL hydrogenation. The catalyst also demonstrated comparable activity even after several runs.

The preparation of composite gels through the hydrothermal reaction of a mixture of chitosan (CH), malonic acid (MLA), urea (UR) and cinnamaldehyde (CA), all of which are sustainable materials, is reported. The new material, CHMLAUR-CA, was characterized by 13C solid-state NMR (SS NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The properties of the material were evaluated by rheometry and thermogravimetric analysis (TGA), while its morphology was assessed by SEM and AFM. The release of cinnamaldehyde by the composite gels displayed sustained release behavior. Also, the antibacterial study proves that composite gels exhibit a commendable and long-standing antibacterial activity against Escherichia coli (Gram-negative) bacteria and Staphylococcus aureus (Gram-positive). The outcome of the studies revealed that the prepared composite gels could be considered to be efficient long-term antibacterial materials.

Precious metals have been shown to play a vital role in the selective hydrogenation of α,β-unsaturated aldehydes, but still suffer from challenges to control selectivity. Herein, we have advanced the design of catalysts made out of Pt–Co intermetallic nanoparticles (IMNs) supported on a MIL-101(Cr) MOF (3%Pty%Co/MIL-101(Cr)), prepared by using a polyol reduction method, as an effective approach to enhance selectivity toward the production of α,β-unsaturated alcohol, the desired product. XRD, N2 adsorption–desorption, FTIR spectroscopy, SEM, TEM, XPS, CO adsorption, NH3-TPD, XANES and EXAFS measurements were used to investigate the structure and surface properties of our 3%Pty%Co/MIL-101(Cr) catalysts. It was found that the Co-modified 3%Pty%Co/MIL-101(Cr) catalysts can indeed improve the hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL), reaching a higher selectivity under mild conditions than the monometallic Pt/MIL-101(Cr) catalysts: 95% conversion of CAL with 91% selectivity to COL can be reached with 3%Pt3%Co/MIL-101(Cr). Additionally, high conversion of furfural (97%) along with high selectivity to furfural alcohol (94%) was also attained with the 3%Pt3%Co/MIL-101(Cr) catalyst. The enhanced activity and selectivity toward the unsaturated alcohols are attributed to the electronic and geometric effects derived from the partial charge transfer between Co and Pt through the formation of uniformly dispersed Pt–Co IMNs. Moreover, various characterization results revealed that the addition of Co to the IMPs can promote the Lewis acid sites that facilitate the polarization of the charge-rich CO bonds and their adsorption via their oxygen atom, and also generate new interfacial acid sites.

Due to coexistence of two conjugated unsaturated functional groups in cinnamaldehyde (CAL), exploring efficient catalysts with desirable selectivity to highly value-added products is still challengeable for the selective hydrogenation of CAL. Herein, NixFe1-xAl2O4+δ spinel composite metal oxides (SCMOs) supported Pt catalysts were developed and proved to be active and selective for the selective hydrogenation of CAL. Moreover, the selectivity switch can be realized just by changing the Ni/(Fe + Ni) molar ratios in NixFe1-xAl2O4+δ SCMOs. As a result, the excellent cinnamyl alcohol (COL) selectivity (~92.2%) and hydrocinnamaldehyde (HCAL) selectivity (~80.7%) were achieved on Pt/FeAl2O4+δ and Pt/NiAl2O4+δ, respectively. Based on the kinetic investigation of further hydrogenation of semi-hydrogenated product, the reason for the selectivity switch with Pt/NixFe1-xAl2O4+δ was revealed. In combination with detailed characterization, the excellent COL selectivity on Pt/FeAl2O4+δ can be attributed to more Pt(1 1 1) facets and FeOx species which can facilitate the preferential activation of C O bonds; while the high HCAL selectivity on Pt/NiAl2O4+δ is owing to the fact that there are more low coordinated active sites and two neighbouring Pt sites.

Selective preparation of unsaturated alcohols via the hydrogenation of C═O in α,β-unsaturated aldehydes is a challenging reaction. In this work, a nanoscale material Pt/UiO-66 catalyst with homogen...

Selective hydrogenation of C=O against the conjugated C=C in cinnamaldehyde (CAL) is indispensable to produce cinnamyl alcohol (COL). Nonetheless, it is challenged by the low selectivity and the need to use organic solvents. Herein, for the first time, we report the use of Fe-Co alloy nanoparticles (NPs) on N-doped carbon support as a selective hydrogenation catalyst to efficiently convert CAL to COL. The resultant catalyst with the optimized Fe/Co ratio of 0.5 can achieve an exceptional COL selectivity of 91.7 % at a CAL conversion of 95.1 % in pure water medium under mild reaction conditions, ranking it the best performed catalyst reported to date. The experimental results confirm that the COL selectivity and CAL conversion efficiency are, respectively promoted by the presence of Fe and Co, while the synergism of the alloyed Fe-Co is the key to concurrently achieve high COL selectivity and CAL conversion efficiency.

The effect of the reduction temperature (300 °C, 400 °C, 500 °C and 600 °C) in cobalt SiO2 core-shell catalysts for chemoselective hydrogenation of cinnamaldehyde is reported. The Co-CoO@SiO2 catalysts structures were synthesized starting from a calcined Co3O4@SiO2 nanostructure obtained using a solvothermal method for the core (Co3O4) and a modified Stober method for the porous shell (SiO2) submitted to different reduction temperatures. The initial Co3O4@SiO2 structure and the derived Co-CoO@SiO2 catalysts were characterized by AAS, TG/DTG, TPR, TEM, XRD, XPS and SBET. The increase in the metallic Co content along with the reduction temperature increased the total conversion of cinnamaldehyde in the liquid-phase hydrogenation reaction. The highest selectivity towards the unsaturated alcohol over Co-CoO@SiO2-500 °C catalyst was attributed to an optimum Co/CoO surface ratio. A large chemical and mechanical stability of the Co-CoO@SiO2 structure was evidenced after five consecutive reaction cycles, revealing the beneficial effect of the core-shell architecture towards cobalt leaching in liquid-phase reactions.

Chemoselective catalytic oxidation of olefin derivatives containing alcoholic and olefinic groups is important in organic synthesis. In the present study, Co–Salen immobilized on SBA-15 was synthesized and characterized to study its chemoselective catalytic activity towards the oxidation of cinnamyl alcohol and cinnamaldehyde, with tert-butyl hydroperoxide as the oxidant at 60, 70 and 80 oC. Cinnamyl alcohol selectively yielded cinnamaldehyde at the reactant ratio of cinnamyl alcohol tert-butyl hydroperoxide equal to 1:0.5. Cinnamaldehyde selectively yielded 2,3-epoxy-cinnamaldehyde at the ratio of cinnamaldehyde tert-butyl hydroperoxide equal to 1:0.5. The catalyst yielded epoxide with many styrene derivatives and benzaldehyde with benzyl alcohol, but only cinnamaldehyde with cinnamyl alcohol, thus proving its applicability for chemoselective catalytic oxidation of olefin derivatives. The cinnamaldehyde conversion and selectivity to 2,3-epoxy-cinnamaldehyde increased with the increase in the content of tert-butyl hydroperoxide. So, this study establishes that the catalyst can be applied to selective oxidation of primary alcoholic function without affecting olefinic double bonds. The conversion was maximum at 70 oC. The conversion and product selectivity remained the same for 5 cycles thus endorsing stability of the catalysts. Based on the activity and selectivity of the catalysts, it is inferred that the same catalyst can be exploited for selective oxidation of multifunctional olefin derivatives.

In this work, an alloy catalyst with C@PtGa interface structure was synthesized under H2/CO2 atmosphere by using PtCl62−/MgAlGa-LDHs as precursor. Cs-corrected STEM, EELS and CO chemisorption clearly confirmed the PtGa alloy particles were well covered by amorphous carbon thin layer with the characteristics of porous and permeable. In selective cinnamaldehyde hydrogenation, the C@PtGa catalyst showed a higher selectivity than both bare PtGa catalyst and Ga2O3@PtGa catalyst. The enhanced selectivity was attributed to the geometric decoration of carbon layer as well as the formation of electron-rich Pt sites at C@PtGa interface, which optimized the adsorption mode of cinnamaldehyde. More importantly, the permeable characteristic of carbon layer which maintained the accessibility of reactants to the Pt sites, contributed to the higher conversion compared to Ga2O3@PtGa catalysts with traditional oxide interface layer. Additionally, C@PtGa catalyst exhibited a good reusability with conversion of 88.3% and selectivity of 91.9% after 5 cycles. This work provides an alternative way to realize the boost of activity and selectivity in selective hydrogenation of C=O bonds by intelligently fabricating non-oxides@metal interface.

The selective hydrogenation of cinnamaldehyde (CAL) is an extremely important transformation. Herein, oxygen functionalized carbon nanotubes (oCNTs) supported a series of PtxCoy bimetallic nanoparticles (NPs) with varied Pt to Co ratios were synthesized. The introduction of Co significantly affects the electronic structure of Pt NPs, which clearly promotes the selectivity to cinnamyl alcohol (COL). Among all PtxCoy-oCNTs catalysts, PtCo3-oCNTs exhibited the best catalytic performance and a selectivity of over 76% towards COL at a CAL conversion of 99% was obtained. Further characterization of the fresh, used and cycled catalysts revealed that the NP structures were stable and did no change. The structural evolutions during the catalytic reaction were also investigated by identical location transmission electron microscopy (IL-TEM) method in detail, which found that the deactivation of PtCo3-oCNTs catalyst during the cycle experiment results from the agglomeration and detachment of PtCo3 NPs.

Two series of catalysts, i.e., [Ni/C, Cu/C and CuNi/C] and [Pt–Ni/C, Pt–Cu/C and Pt–CuNi/C] were prepared by liquid phase chemical reduction and galvanic replacement, respectively. Pt/C was synthesized via an impregnation method. The nanostructures of these catalysts were tuned by being reduced in N2 + H2. Their nanostructures were characterized by TG, XPS, XRD, TEM, HRTEM and STEM–EDS elemental analysis techniques. The catalysts, which had unique nanostructures resulted from the loading of platinum islands on the transition metal related nanoparticles (i.e., Pt–Ni/C with Pt-on-Ni/Ni(OH)2, Pt–Cu/C-reduced with Pt-on-Cu/CuO, Pt–CuNi/C-reduced with Pt-on-CuNi alloy), exhibited much more excellent catalytic performance (conversion of cinnamaldehyde: 100.0%, selectivity to cinnamyl alcohol: 62.9%, 64.6% and 72.6%, respectively) than the catalysts with platinum–transition metal alloy structure (e.g. Pt–Ni/C-reduced with PtNi alloy) and transition metal/carbon for the selective hydrogenation of cinnamaldehyde (80 °C, 5.0 MPa H2, 1 h). The Pt–CuNi/C-reduced catalyst also showed superior stability in cinnamaldehyde hydrogenation. The outstanding performance of Pt–Ni/C, Pt–Cu/C-reduced and Pt–CuNi/C-reduced catalysts for cinnamaldehyde hydrogenation was attributed to the synergistic effect and interaction of platinum and non-noble metal related nanoparticles.

An efficient one-pot multicomponent reaction for the synthesis of novel tetrasubstituted hexahydroimidazo[1,2-a]pyridines starting from readily available cinnamaldehydes, ethylenediamines, and 1,3-dicarbonyl compounds catalyzed by AcOH is described. Two new cycles and four new bonds are constructed with all reactants being efficiently utilized in this transformation. The products could be obtained in 1-3 h under ambient conditions exclusively as a single isomer (trans). Single-crystal X-ray analysis confirmed the trans derivative as the only isomer.

The bimetallic core–shell nanostructures of galvanic metals have gained considerable scientific interest in improving the TiO2 photocatalysis under solar radiations over the monometallic analogues. In the present research work, Pd@Au core–shell supported TiO2 nanostructures were synthesized via galvanic replacement reaction and were examined for their catalytic/ photocatalytic hydrogenation. Three different types of bimetallic Pd@Au nanostructure were synthesized by varying Pd:Au weight ratio i.e. (1:1), (1:2) and (1:3). DLS measurements revealed that with increasing Au weight ratio, the hydrodynamic size increases from 126 to 157 nm. The optical studies showed a considerable blue shift in the absorption band of Au nanoparticles from 529 to 518 nm in the case of Pd@Au (1:1). The co-existence of absorption characteristic of Pd and Au suggests the successful synthesis of bimetallic nanostructure. STEM and EDS mapping further confirmed the formation of Pd@Au nanostructure with inner Pd core and outer Au shell. Bimetallic Pd@Au nanocatalyst displayed superior activity and selectivity towards hydrogenation of cinnamaldehyde in comparison to monometallic analogues. However, when Pd@Au nanostructures were impregnated on the surface of TiO2, a significant improvement in the hydrogenation reaction was observed under solar radiations relative to catalytic conditions. The photocatalytic performance of Pd@Au-TiO2 was found to be varied as a function of shell thickness and the optimized APT-2 (Pd1@Au2-TiO2) photocatalyst exhibited higher rate constant (2.3 × 10−1 h−1) for cinnamaldehyde hydrogenation. Hence, the plasmonic Pd@Au-TiO2 hetero-junction could be a promising greener photocatalyst for selective hydrogenation of unsaturated carbonyls for large scale industrial applications.

Ceria-zirconia oxide materials with a specific surface area ranging from 160 to 240 m2/g and different meso- and micropores ratio were obtained by a simple deposition-precipitation method with urea (DPU), which allows preparation of ceria-zirconia oxides directly in one-step while avoiding the formation of oxo-hydroxo species and further thermal treatment to obtain oxide phases. Moreover, a microwave-assisted DPU method allowed the decrease of the synthesis time from 24 to 3.5 h. The prepared samples were studied by TG-DTA, BET, N2 adsorption, XRD, SEM, and TEM methods. Pt-containing catalysts based on synthesized oxides have shown a high catalytic activity in selective hydrogenation of benzaldehyde, citral, and cinnamaldehyde at room temperature and atmospheric pressure.

Allylic alcohols produced from α,β-unsaturated aldehydes by selective hydrogenation are useful intermediates and additives in the fine chemicals industry. An efficient process for the catalytic tra...

Pt@MAF-6 was designed as a highly selective catalyst for cinnamaldehyde hydrogenation. The aperture of Pt@MAF-6 acted to sterically confine cinnamaldehyde, and 94% selectivity to cinnamic alcohol was obtained at a high conversion of 95%. Steric confinement was inefficient in trans-2-pentenal hydrogenation, showing that encapsulating active sites within a commensurate porous support is important for a steric effect catalyst.

A catalyst in which Pd nanoparticles are supported on triangle-shaped La2 O2 CO3 nanosheets exposing predominantly the (001) planes (Pd/La2 O2 CO3 -TNS; where TNS denotes triangular nanosheets) was prepared by a facile solvothermal method. The Pd/La2 O2 CO3 -TNS catalysts exhibited excellent catalytic activity and recycling stability for hydrogenation of cinnamaldehyde to hydrocinnamaldehyde with turnover frequency of up to 41 238 h-1 . This enhanced activity of Pd/La2 O2 CO3 -TNS results from strong metal-support interactions. Structure analysis and characterization demonstrated that surface-oxygen-enriched La2 O2 CO3 -TNS supports exposing (001) planes are beneficial to charge transfer between the Pd nanoparticles and triangle-shaped La2 O2 CO3 nanosheets and increase the electron density of Pd. Moreover, the modulated electronic states of the Pd/La2 O2 CO3 -TNS catalysts can enhance the adsorption and activation of hydrogen to enhance the hydrogenation activity.

The selective hydrogenation of α,β-unsaturated aldehydes plays a crucial role in industrial production, and an efficient non-noble metal catalyst for it has been pursued to reduce the cost. Herein, we report an amorphous nickel phosphide for the selective hydrogenation of cinnamaldehyde. Compared to crystalline nickel phosphide, amorphous nickel phosphide showed both high activity and high selectivity to target products. Its catalytic performance was also better than that of commercial Pd/C catalyst. In addition, initial P/Ni ratio was found to be an important factor to affect the activity of amorphous nickel phosphide. High initial P/Ni ratio led to high activity owing to small particles, high surface area and strong metallicity of as-synthesized catalyst. Moreover, excellent catalytic performances of amorphous nickel phosphide were observed in the selective hydrogenation of different α,β-unsaturated aldehydes and ketones.

A comprehensive study of the kinetics of the catalytic hydrogenation of unsaturated aldehydes, in particular of cinnamaldehyde, promoted by CuPtx/SBA-15 single-atom alloy catalysts was carried out ...

HPZSM-5 with hierarchical porous structure obtained via partial desilication of commercial ZSM-5 was proved to be a suitable support for Pt nanoparticles towards the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to yield cinnamyl alcohol (COL). Compared with Pt/ZSM-5, Pt/HPZSM-5 showed improved catalytic performance although the improvement seems to be very limited. After doping Fe to Pt/HPZSM-5 with a Fe/Pt molar ratio of 0.25, the PtFe/HPZSM-5 catalyst gave much further enhanced CAL conversion. Under the optimized conditions, a 97.9% CAL conversion with 87.6% selectivity to COL was achieved with the PtFe/HPZSM-5 catalyst. The initial activity (in terms of TOF value, defined as molecules of CAL converted per surface atom of Pt per second) reached about 3.41 s−1 with the PtFe/HPZSM-5 catalyst, one of the highest values up to now to our best knowledge. Moreover, the PtFe/HPZSM-5 catalyst can be recycled for at least 9 times without obvious loss in activity or selectivity to COL. The effect of partial desilication and Fe doping on the catalytic performance of PtFe/HPZSM-5 was discussed based on the characterization results using a series of techniques.