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Quantifying reactive aldehyde biomarkers, such as malondialdehyde, acrolein, and crotonaldehyde, is the most preferred approach to determine oxidative stress. However, reported analytical methods lack specificity for accurately quantifying these aldehydes as certain methodologies may produce false positive results due to harsh experimental conditions. Thus, in this research work, a novel HILIC-MS/MS method with endogenous histidine derivatization is developed, which proves to have higher specificity and reproducibility in quantifying these aldehydes from the biological matrix. To overcome the reactivity of aldehyde, endogenous histidine is used for its derivatization. The generated adduct is orthogonally characterized by NMR and LC-HRMS. The method employed a hydrophilic HILIC column and multiple reaction monitoring (MRM) to accurately quantify these reactive aldehydes. The developed method is an unequivocal solution for quantifying stress in in vivo and in vitro studies. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

"Heptil" (unsymmetrical dimethylhydrazine—UDMH) is extensively employed worldwide as a propellant for rocket engines. However, UDMH constantly loses its properties as a result of its continuous and uncontrolled absorption of moisture, which cannot be rectified. This situation threatens its long-term usability. UDMH is an exceedingly toxic compound (Hazard Class 1), which complicates its transportation and disposal. Incineration is currently the only method used for its disposal, but this process generates oxidation by-products that are even more toxic than the original UDMH. A more benign approach involves its immediate reaction with a formalin solution to form 1,1–dimethyl-2-methylene hydrazone (MDH), which is significantly less toxic by an order of magnitude. MDH can then be polymerized under acidic conditions, and the resulting product can be burned, yielding substantial amounts of nitrogen oxides. This review seeks to shift the focus of MDH from incineration towards its application in the synthesis of relatively non-toxic and readily available analogs of various pharmaceutical substances. We aim to bring the attention of the international chemical community to the distinctive properties of MDH, as well as other hydrazones (such as glyoxal, acrolein, crotonal, and meta-crolyl), wherein each structural fragment can initiate unique transformations that have potential applications in molecular design, pharmaceutical research, and medicinal chemistry. [ABSTRACT FROM AUTHOR]

Crotonaldehyde is typical inhibitory compound of wastewater discharged in the petrochemical industry. To resolve the inhibition of crotonaldehyde on microorganism, electron donors (cellose, glucose and ethanol) were dosed to accelerate the biodegradation of crotonaldehyde by semi-continuous operation experiments. The results indicated that crotonyl alcohol was the most dominant biodegradable product of crotonaldehyde, and its conversion rates dosing ethanol, glucose and cellose as electron donors (2000 mgCOD/L) were 1.84, 1.46 and 1.21 times higher than that in control test when the initial concentrations of crotonaldehyde was 500 mg/L, respectively. Furthermore, the ethanol as electron donor was superior to cellose and glucose in relieving the inhibition of crotonaldehyde on the processes of acidogenesis, acetogenesis, and methanogenesis duo to the more electron release, faster electron transfer efficiency, less electron competition. Last, the enrichment of electro-active bacteria such as Syntrophobacter , Geobacter and the bacteria associated with reverse β-oxidation pathway (RBO) such as Clostridium_sensu_stricto_12 also proved that higher electron transfer system (ETS) activity was obtained in the reactor dosed ethanol as electron donor. This study suggests that dosing electron donors is an efficient strategy to accelerate the biodegradation of crotonaldehyde, and the results could be referred to pretreat wastewater containing aldehyde pollutants. [ABSTRACT FROM AUTHOR]

The effects of acrolein and crotonaldehyde on the health of Russian smokers upon switching to heated tobacco product use were analyzed in a five-day randomized clinical trial. The findings suggest that heated tobacco products significantly reduce exposure to these toxicants, with the adverse effects becoming less pronounced in just one day and comparable to complete cessation of smoking. The dynamics of nicotine intake and metabolism in the smokers who switched to heated tobacco products remained stable throughout the study and was similar to that in the group of regular cigarette smokers.Therefore, our study, which has been performed for the first time among the Russian population, shows that smokers switching to heated tobacco products are less exposed to harmful chemicals like acrolein and crotonaldehyde and thus may be protected against some of the negative health effects often associated with regular cigarettes.

[Display omitted] • Ir – TiO 2 interaction was dependent on Ir sizes and crystal plane of TiO 2. • Both activity and selectivity of the catalysts increased as the Ir size grew from single atom to nanoparticle. • End-on C O adsorption of crotonaldehyde was favored at the Ir-TiO x interface for Ir nanoparticles. • Crotonaldehyde adsorption geometry depends on H coverage on the catalyst surface. For the supported catalysts for the selective hydrogenation of α, β - unsaturated aldehyde with H 2 , tailoring of metal - support interfacial effect to improve reaction performance is a significant but challenging subject. In this work, we regulated both the size regimes of the Ir deposits (single atom, nanocluster and nanoparticle) and the crystal plane of anatase TiO 2 (TiO 2 (1 0 1), TiO 2 (1 0 0) and TiO 2 (0 0 1)) so as to alter the Ir-TiO x interfacial properties, in order to unravel reaction mechanism of selective hydrogenation of crotonaldehyde over the Ir/TiO 2 catalysts. Both the activity and selectivity to crotyl alcohol increased as the Ir size grew from single atom to nanoparticle, ascribed to high Ir0 content, high concentration of surface defects and prominent H-spillover effect on the Ir nanoparticles. Moreover, the in situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations demonstrated that an end-on C O adsorption mode for crotonaldehyde molecule was favored at the Ir-TiO x interface particularly at high H coverage, which thus facilitated the hydrogenation of C O bond to form crotyl alcohol. Moreover, the highest reactivity of the Ir nanoparticles was evidenced by the lowest reaction barrier. These results explicitly demonstrate that larger metal nanoparticles and adsorption geometry of the reactant at the metal - support interface are vital for improved catalytic performance, which would shed light on the ingenious catalyst design. [ABSTRACT FROM AUTHOR]

The thermal chemistry of crotonaldehyde on the surface of a polished polycrystalline copper disk was characterized by temperature-programmed desorption (TPD) and reflection–absorption infrared spectroscopy (RAIRS) and contrasted with previous data obtained on a Pt(111) single crystal substrate. A clear difference in the adsorption mode was identified between the two surfaces, highlighted by the prevalence of RAIRS peaks for the C=C bond on Cu vs for C=O on Pt. Adsorption was also determined to be much weaker on Cu vs Pt, with an adsorption energy on the former ranging from −50 kJ/mol to −65 kJ/mol depending on the surface coverage. The experimental data were complemented by extensive quantum mechanics calculations using density functional theory (DFT) to determine the most stable adsorption configurations on both metals. It was established that crotonaldehyde adsorption on Cu occurs via the oxygen atom in the carbonyl group, in a mono-coordinated fashion, whereas on Pt multi-coordination is preferred, centered around the C=C bond. The contrasting surface adsorption modes seen on these two metals are discussed in terms of the possible relevance to selectivity in single-atom alloy hydrogenation catalysis. [ABSTRACT FROM AUTHOR]

The chemical stability of zeolitic imidazolate framework-8 (ZIF-8) in water, acid, base and organic solvent has been widely investigated. However, whether it is stable in aldehydes, which are common reactants, has rarely been considered. Herein, the partial or whole dissolution of ZIF-8 with 50 nm and 1000 nm sizes was observed in crotonaldehyde under air conditions. More importantly, the residual ZIF-8 gradually evolved from the original rhombic dodecahedra into a new octahedron morphology and still preserved the ZIF-8 phase structure. A series of experiments revealed that the essence of ZIF-8 degradation in crotonaldehyde is the presence of H+, derived from the autoxidation of crotonaldehyde exposing in the air to the corresponding acids. H+ could preferentially attack the Zn–N coordination bond located at the {211} edge and {111} vertices with {110} facet shrinkage of the rhombic dodecahedra, leading to the morphological reconstruction of ZIF-8. A further dynamic track showed that the dissolved ratio of ZIF-8 highly depended on the acidic value of crotonaldehyde, temperature and contact time. The dissolution process followed a shrinking core model and was controlled by the diffusion of the H+ step. [ABSTRACT FROM AUTHOR]

Recyclable PdCu single atom alloys supported on Al2O3 were applied to the selective hydrogenation of crotonaldehyde to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. It was found that, by diluting the Pd content of the alloy, the reaction activity of Cu nanoparticles can be accelerated, enabling more time for the cascade conversion of butanal to butanol. In addition, a significant increase in the conversion rate was observed, compared to bulk Cu/Al2O3 and Pd/Al2O3 catalysts when normalising for Cu and Pd content, respectively. The reaction selectivity over the single atom alloy catalysts was found to be primarily controlled by the Cu host surface, mainly leading to the formation of butanal but at a significantly higher rate than the monometallic Cu catalyst. Low quantities of crotyl alcohol were observed over all Cu-based catalysts but not for the Pd monometallic catalyst, suggesting that it may be a transient species converted immediately to butanol and or isomerized to butanal. These results demonstrate that fine-tuning the dilution of PdCu single atom alloy catalysts can leverage the activity and selectivity enhancement, and lead to cost-effective, sustainable, and atom-efficient alternatives to monometallic catalysts. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of crotonaldehyde to crotyl alcohol over PDA (polydopamine) modified Co3O4 supported Pt catalysts was investigated in liquid phase. The catalysts which contain PDA and Co3O4 lead to the formation of two kinds of interfaces: Pt-PDA and Pt-Co3O4, which greatly improves the performance in the hydrogenation of crotonaldehyde. TEM results reveal that the Pt nanoparticles of Pt/Co3O4@PDA have a smaller size and better dispersion than Pt/Co3O4. XPS, FT-IR and CO-DRIFTs results indicate that the addition of PDA decreases the electron density of Pt which is favor to the hydrogenation of C=O in crotonaldehyde. The characterization results demonstrate that the interaction between Pt and PDA creates new active interfacial sites and the synergy of Pt-PDA and Pt-Co3O4 is responsible for the excellent performance. [ABSTRACT FROM AUTHOR]

The adsorption of crotonaldehyde on Cu-Pt alloy surfaces was characterized by density functional theory (DFT). Two surfaces were considered: Cu2Pt/Cu(111) and Cu3Pt/Cu(111). It was determined that the presence of Pt on the surface, even when isolated as single atoms fully surrounded by Cu, provides additional stability for the adsorbates, increasing the magnitude of the adsorption energy by as much as 40 kJ/mol. The preferred bonding on both surfaces is via multiple coordination, with the most stable configuration being a cis arrangement with di-σ bonding of the C=O bond across a Cu–Cu bridge and an additional π bonding to a Pt atom. The fact that Pt significantly affects the adsorption of unsaturated aldehydes such as crotonaldehyde explains why the kinetics of their hydrogenation using single-atom alloy (SAA) catalysts vary with alloy composition, as we previously reported, and brings into question the simple model in which the role of Pt is only to promote the dissociation of H2. [ABSTRACT FROM AUTHOR]

A new rotationally hindered diphosphoramidite ligand has been applied to the Rh-catalyzed hydroformylation of various olefins. Good activity as well as excellent regioselectivity toward the formation of linear aldehydes were achieved. Remarkable performances were also observed in the hydroformylation of functionalized olefins, including methyl acrylate, allyl acetate, crotonaldehyde ethylene acetal and styrene. [ABSTRACT FROM AUTHOR]

SiO2-supported NiIr alloy acted as an effective heterogeneous catalyst for the hydrogenation of benzonitrile, crotonaldehyde and benzylideneacetone, showing much higher activity than monometallic Ni/SiO2 and Ir/SiO2 catalysts and superior selectivity to benzyl-benzylidene-amine, butanal and 4-Phenyl-butan-2-one at high conversion. Furthermore, the main active sites were investigated on the basis of the relationship of TOFs and the alloy composition for the hydrogenation of crotonaldehyde, benzonitrile and benzylideneacetone, and the active site was the isolated Ni atom surrounded by Ir atoms for the hydrogenation of crotonaldehyde and related to the structure of substrate in selective hydrogenation.

The selective hydrogenation of crotonaldehyde has gained considerable attention owing to its industrial applications for producing fine chemicals. Understanding the hydrogenation mechanism from density functional theory (DFT) calculations can provide insights for designing catalysts with high selectivities toward the target products. Among contemporary theoretical investigations of the hydrogenation, the calculated selectivities are not in agreement with the experimental results. Herein, a SiO2‐supported Pt nanocluster is developed, and it is used to investigate the selective hydrogenation of crotonaldehyde. The nanocluster model is used to obtain free energy barriers from DFT calculations, and these are used to build a microkinetic model. The theoretical selectivity values for the products are in agreement with the experimental results. According to the density of state analysis, this is directly attributed to the more accurate d‐band width from the Pt cluster. The contribution of each step to the final product is identified and can be used to intensify the process of generating the target product. [ABSTRACT FROM AUTHOR]

Background. To create sealing materials, polysulfide oligomers with functional groups of phosphorus and sulfur are used, which is explained by the invariance of curing methods and functional properties. The study of the process of their synthesis, production technology is relevant. Purpose: development of methods for obtaining thiokol sealants with improved properties, modified on the basis of crotonaldehyde and metal oxides. Methodology. The physical and mechanical properties of the sealants were evaluated on an AGS-X "AGS-X SHMADZU" testing machine, and the viscometry method was used. Originality. The new oligomer was obtained by modifying thiokol oligomers with unsaturated compounds and metal oxides. Findings. Thiokol oligomers were obtained by modification with crotonaldehyde and metal oxides: ZnO and MnO2. The optimal mass ratio of metal oxides and modified thiokol oligomers has been found. [ABSTRACT FROM AUTHOR]

Crotonaldehyde (CRA)—one of the major environmental pollutants from tobacco smoke and industrial pollution—is associated with vascular injury (VI). We used proteomics to systematically characterize the presently unclear molecular mechanism of VI and to identify new related targets or signaling pathways after exposure to CRA. Cell survival assays were used to assess DNA damage, whereas oxidative stress was determined using colorimetric assays and by quantitative fluorescence study; additionally, cyclooxygenase-2, mitogen-activated protein kinase pathways, Wnt3a, β-catenin, phospho-ErbB2, and phospho-ErbB4 were assessed using ELISA. Proteins were quantitated via tandem mass tag-based liquid chromatography-mass spectrometry and bioinformatics analyses, and 34 differentially expressed proteins were confirmed using parallel reaction monitoring, which were defined as new indicators related to the mechanism underlying DNA damage; glutathione perturbation; mitogen-activated protein kinase; and the Wnt and ErbB signaling pathways in VI based on Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein–protein interaction network analyses. Parallel reaction monitoring confirmed significant (p < 0.05) upregulation (> 1.5-fold change) of 23 proteins and downregulation (< 0.667-fold change) of 11. The mechanisms of DNA interstrand crosslinks; glutathione perturbation; mitogen-activated protein kinase; cyclooxygenase-2; and the Wnt and ErbB signaling pathways may contribute to VI through their roles in DNA damage, oxidative stress, inflammation, vascular dysfunction, endothelial dysfunction, vascular remodeling, coagulation cascade, and the newly determined signaling pathways. Moreover, the Wnt and ErbB signaling pathways were identified as new disease pathways involved in VI. Taken together, the elucidated underlying mechanisms may help broaden existing understanding of the molecular mechanisms of VI induced by CRA. [ABSTRACT FROM AUTHOR]

Recyclable PdCu single atom alloys supported on Al2O3 were applied to the selective hydrogenation of crotonaldehyde to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. It was found that, by diluting the Pd content of the alloy, the reaction activity of Cu nanoparticles can be accelerated, enabling more time for the cascade conversion of butanal to butanol. In addition, a significant increase in the conversion rate was observed, compared to bulk Cu/Al2O3 and Pd/Al2O3 catalysts when normalising for Cu and Pd content, respectively. The reaction selectivity over the single atom alloy catalysts was found to be primarily controlled by the Cu host surface, mainly leading to the formation of butanal but at a significantly higher rate than the monometallic Cu catalyst. Low quantities of crotyl alcohol were observed over all Cu-based catalysts but not for the Pd monometallic catalyst, suggesting that it may be a transient species converted immediately to butanol and or isomerized to butanal. These results demonstrate that fine-tuning the dilution of PdCu single atom alloy catalysts can leverage the activity and selectivity enhancement, and lead to cost-effective, sustainable, and atom-efficient alternatives to monometallic catalysts.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine and a white blood cell growth factor that has found usage as a therapeutic protein. During analysis of different fermentation batches of GM-CSF recombinantly expressed in E. coli, a covalent modification was identified on the protein by intact mass spectrometry. The modification gave a mass shift of + 70 Da and peptide mapping analysis demonstrated that it located to the protein N-terminus and lysine side chains. The chemical composition of C4H6O was found to be the best candidate by peptide fragmentation using tandem mass spectrometry. The modification likely contains a carbonyl group, since the mass of the modification increased by 2 Da by reduction with borane pyridine complex and it reacted with 2,4-dinitrophenylhydrazine. On the basis of chemical and tandem mass spectrometry fragmentation behavior, the modification could be attributed to crotonaldehyde, a reactive compound formed during lipid peroxidation. A low recorded oxygen pressure in the reactor during protein expression could be linked to the formation of this compound. This study shows the importance of maintaining full control over all reaction parameters during recombinant protein production. [ABSTRACT FROM AUTHOR]

• A scheme for mechanical pressurisation of reaction products followed by partial condensation in a thermally coupled manner is proposed. • A scheme for the evaporation of MCP from the top of the column was proposed for the discharge of impurities. • The heat transfer network of the whole process was optimised using pinch point analysis technique. • Processes with different feed concentrations of acetaldehyde were investigated. As an essential raw material of chemical industry, crotonaldehyde is mainly used to produce sorbic acid, which is a kind of safe food preservative. The nowadays production process of crotonaldehyde adopts sodium hydroxide solution and acetic acid in series as catalysis, which cause serious problems such as salinity waste water and equipment corrosion. Therefore, Zr-β zeolite was developed to catalyze the production of crotonaldehyde from acetaldehyde gas–solid reaction process in our group. This catalyst showed the potential of industrial application for its 94 % selectivity and stability. This paper aims to develop a technological process to produce crotonaldehyde from acetaldehyde based on the newely-researched-out Zr-β zeolite catalyst. According to experimental results of reaction condition and product distribution, a technological process consisting of (1) aldol condensation reaction and raw material recovery section, (2) crotonaldehyde concentration and refinement section, (3) 2-methyl-2-cyclopenten-1-one (MCP) and acidic impurity removal section was established. Mechanical supercharging was employed in section (1) to elevate the heat grade of reactor effluent to heat the reactor feed. Pre-concentration followed by azeotropic distillation was proposed to purify croton aldehyde product. The removal of little MCP in the re-used water was accomplished by evaporating MCP at the top of the column based on our previous finding that MCP-water could form minimum azeotrope. As a result, the purity of crotonaldehyde reached 99.92 wt% and water content reduced below 10 ppm in product, which is much better than the product standard required crotonaldehyde purity 99.5 % and water content 2000 ppm. Based on optimum process, heat exchange network was further optimized with pitch point method, and at last the required heat load was 2.25 Gcal per ton of crotonaldehyde product. The problem of generating salinity waste water in the traditional process was solved thoroughly, which meant that this is a more environmentally friendly process to produce crotonaldehyde. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs) have been applied to stabilize metal nanoparticles due to their excellent properties, but there are many different viewpoints about the interaction between MOFs and nanoparticles, which is important for catalyst activity and selectivity. Herein, Pt nanoparticles supported on ZIF-8 and ZIF-67 with the same topological structure other than the metal joint were synthesized, and crotonaldehyde hydrogenation was chosen to investigate their catalytic performance. The results indicated that both the activity and crotyl alcohol selectivity over ZIF-67 were much higher than those over ZIF-8, in which the TOF was 188.3 h−1 for Pt@ZIF-67 and 7.5 h−1 for Pt@ZIF-8. More importantly, the selective hydrogenation product of the C＝O bond (crotyl alcohol) was not detected regardless of whether Pt nanoparticles were located in the interior or exterior of ZIF-8. A series of characterizations were carried out to explore the essential difference between the two supported ZIF catalysts, such as H2-spillover property tests, TEM, XPS, CO-DRIFTS, and operando-FTIR reaction. These results suggested that the H2-spillover of the ZIFs could play an important role in hydrogenation, besides the electron transfer between Pt and the metals in the ZIFs. [ABSTRACT FROM AUTHOR]

An effective synthetic approach was proposed to partially and fully hydrogenated imidazo[1,2‐a]pyridines based on cyclizations of polyfluoroalkyl‐3‐oxo esters and ethylenediamine with aldehydes. It was found that acetic and propionic aldehydes react similar to the α,β‐unsaturated crotonic and cinnamic aldehydes. The cyclizations of trifluoroacetoacetic ester with ethylenediamine and aldehydes led to the formation of ethyl 5‐hydroxy‐5‐trifluoromethyloctahydroimidazo[1,2‐a]pyridin‐6‐carboxylates, except for the reaction with acetaldehyde, where the main product was 7‐hydroxy‐7‐trifluoromethylhexahydroimidazo[1,2‐a]pyridin‐5(1H)‐one. The cyclizations of polyfluoroalkyl‐3‐oxo esters resulted in 6‐(polyfluoroalkyl‐1‐hydroxyalkyl)‐tetrahydroimidazo[1,2‐a]pyridin‐5(3H)‐ones, except for transformations with cinnamaldehyde, from which ethyl 5‐hydroxy‐7‐phenyl‐5‐polyfluoroalkyloctahydroimidazo‐[1,2‐a]pyridin‐6‐carboxylates were isolated as by‐products. These bicycles containing long polyfluoroalkyl substituents (RF>C2F5) underwent haloform cleavage to form ethyl 7‐phenyl‐5‐oxooctahydroimidazo[1,2‐a]pyridin‐6‐carboxylate. The regio‐ and stereoisomeric structure of the synthesized bicycles was determined using 1H, 19F, 13C NMR spectroscopy and X‐ray. The domino mechanism was proposed for the formation of new tetra‐, hexa‐ and octahydroimidazo[1,2‐a]pyridines. [ABSTRACT FROM AUTHOR]

New DABCO‐based chiral ionic liquids were synthesized and evaluated in asymmetric Diels–Alder reaction of cyclopentadiene with α,β‐unsaturated aldehydes or 4‐phenyl‐3‐buten‐2‐one. Chiral ionic liquid of modified MacMillan catalyst having a DABCO cation and hexafluorophosphate anion acts as organocatalyst (5 mol%) for the Diels–Alder reaction of crotonaldehyde and cyclopentadiene producing 98% of the product and 87% ee (endo) in CH3CN/H2O (95/5) at 25°C in 2 h. The scope and limitations of the catalysis were also studied by using cyclopentadiene and α,β‐unsaturated aldehydes, and the Diels–Alder products were obtained in 18%–92% yields with 68%–93% ee. The catalyst was recycled and reused up to 6 cycles with a slight drop in ee and conversion of the product. [ABSTRACT FROM AUTHOR]

The electroreduction of crotonaldehyde, which can be derived from the aldol condensation of acetaldehyde (sustainably produced from CO2 reduction or from biomass ethanol), is potentially a carbon‐neutral route for generating high‐value C4 chemicals such as crotyl alcohol and 1‐butanol. Developing functional catalysts is necessary toward this end. Herein, the electrocatalytic conversion of crotonaldehyde to crotyl alcohol and 1‐butanol was achieved in 0.1 m potassium phosphate buffer electrolyte (pH=7). More importantly, the mechanisms and structure‐activity relationships of these transformations were elucidated. Crotyl alcohol was formed on oxide‐derived Ag at −0.75 V versus the reversible hydrogen electrode (RHE) with a faradaic efficiency (FE) of 84.3 % (reactant conversion after 75 min electrolysis=9.8 %), which is 1.6 times higher than that on polished Ag foils. The coordinatively‐unsaturated sites on oxide‐derived Ag surfaces were proposed to facilitate crotonaldehyde adsorption via its oxygen atom in order to promote crotyl alcohol formation. On electrodeposited Fe nanoflakes, crotonaldehyde could be reduced to 1‐butanol with an outstanding FE of 60.6 % (reactant conversion after 75 min electrolysis=9.4 %) at −0.70 V vs. RHE. This is nearly 3 times higher than the FE of 1‐butanol observed on polished Fe foils at the same potential. More strikingly, the corresponding partial current density of 1‐butanol was −9.19 mA cm−2, which is 43 times higher than that on Fe foils. The presence of tensile strains and grain boundaries on the Fe nanoflakes were elucidated and suggested to activate a concerted reduction of the C=O and C=C bonds in crotonaldehyde to produce 1‐butanol selectively. [ABSTRACT FROM AUTHOR]

Crotonaldehyde is a highly toxic pollutant, widely present in tobacco smoke and automobile exhaust. Exposure to crotonaldehyde can cause hepatotoxicity and induce liver tumors in rats; however, the underlying mechanism is unclear. Liver cells contain many mitochondria, which serve to maintain energy levels in the body. We hypothesized that the energy metabolism disorder caused by mitochondrial dysfunction is an important cause of liver injury in rats exposed to crotonaldehyde. To test this, we randomly divided 40 male Wistar rats into four groups, and provided crotonaldehyde at 0, 2.5, 4.5, and 8.5 mg/kg for 90 days by intragastric administration. The results showed that crotonaldehyde exposure caused damage to liver mitochondrial structure, reduced electron-transport chain activity and ATP levels, and interfered with mitochondrial DNA transcription. In response to increased crotonaldehyde exposure, rats exhibited increased reactive oxygen species levels, decreased superoxide dismutase and glutathione activity, and activation of the caspase-mediated apoptosis pathway, as well as elevated levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin, and histopathological damage. Our findings, together with those of previous reports, should help elucidate the underlying mechanism of crotonaldehyde-induced mitochondrial dysfunction and energy metabolism disorder, and provide an important direction for the prevention and clinical intervention of liver diseases caused by crotonaldehyde and aldehydes with similar structures. [ABSTRACT FROM AUTHOR]

Selective activation of carbon‐oxygen bonds (like C−O and C=O) represents an essential part of the biomass conversion, but it is difficult to selectively activating the inert carbon‐oxygen bonds. We report 2D MoS2 edges confined single Pt atoms efficiently catalyze biomass‐derived crotonaldehyde to crotyl alcohol with selectivity from 90 to 100 %. The Pt1/MoS2 single‐atom catalysts have a unique HO−Mo−S−Pt1−S−Mo−OH configuration, reminiscent of an enzyme pocket‐like active site, which restricts the adsorption configuration of crotonaldehyde by a steric hindrance effect. The Pt1 atoms possess unique electronic structures due to the Pt1‐S4 configuration, which easily dissociates H2 to H species and boosts the activity. The activated H species spillover and react with O atoms on edges, forming OH and creating the HO−Mo−S−Pt1−S−Mo−OH configuration, which restricts the adsorption configuration of crotonaldehyde and yields high selectivity. The tactics of fabricating pocket‐like active sites with metal single atoms and 2D nanosheet edges shed a light on developing highly selective catalysts for biomass conversion reactions. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel thermolytic distillation process was developed to depolymerize polyhydroxybutyrate (PHB) for the selective production of crotonic acid. The conditions adopted (170 °C, 150 mbar) were applied to pure PHB and PHB-enriched bacteria containing 60 and 30% of PHB, giving a recovery of crotonic acid of 92, 78 and 58%, respectively. The high efficiency of the developed process poses the basis for a drop-in production of bio-based crotonic acid, whose versatility as a platform chemical has been investigated through a photochemical approach. The photocatalytic addition (promoted by tetrabutylammonium decatungstate – TBADT) of aliphatic and aromatic aldehydes to crotonic acid took place under solar-simulated light irradiation. TBADT triggered the in situ formation of valuable acyl radicals from the corresponding aldehydes, thus inducing the desired hydroacylation via radical conjugate addition. Notably, the functionalization took place in a satisfactory yield quite independently of the adopted sample of crotonic acid (whether commercial or bio-based). [ABSTRACT FROM AUTHOR]

Schematic diagram of the differences in crotonaldehyde adsorption/hydrogenation on Ir NPs and IrFe alloy and thus the catalytic performance. [Display omitted] • IrFe alloy was more active and selective than Ir NPs in the hydrogenation of crotonaldehyde. • Catalytic performance of the IrFe alloy was related to its electronic structure. • Ir-Fe pair provided adsorption site for C = O group in crotonaldehyde. • Adsorption of crotonaldehyde was much enhanced on IrFe alloy and thus improved activity. • Hydrogenation of C = O bond was easier on IrFe alloy and thus improved selectivity. IrFe alloy nanoparticles with different Ir/Fe molar ratios were synthesized and exhibited good performance in the gas phase selective hydrogenation of crotonaldehyde (CRAL). The IrFe alloy with an Ir/Fe ratio of 19/1 gave a turnover frequency (TOF) of 0.022 s−1 at 80 °C and a crotyl alcohol (CROL) selectivity of 91 %, while the bare Ir/BN catalyst gave a TOF of 0.0014 s−1 and a CROL selectivity of 74 %. Detailed characterizations, kinetic investigation, and in situ spectroscopic study revealed that the altered electronic structure of the IrFe alloy with transfer from Fe to Ir species was essential for its improved performance. Also, density functional theory calculations indicated that such an electronic structure resulted in strong CRAL interaction with the Ir-Fe entity, thus higher adsorption capacity and lower reaction barrier than that on the Ir-Ir counterpart, which accounted for the higher activity. Moreover, the hydrogenation of C = O bond required lower barrier on the Ir-Fe site than that on the Ir-Ir, which well explained the higher selectivity to CROL. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low density lipoprotein modified by crotonaldehyde shows loss of α-helix and gain in β content. • Oxidation of low density lipoprotein generates non fibrillar and amorphous aggregates. • Oxidized low density lipoprotein is highly immunogenic and generates specific immune response in immunized rabbits. • Immunological studies confirm the presence of circulating antibodies in cancer patients. Crotonaldehyde (CA), a prominent component of cigarette smoke (CS) is a pervasive environmental pollutant that is a highly toxic, unsaturated aldehyde. Exposure to CA-rich pollutants has been linked to the emergence of many malignancies in humans. To better understand the role of CA in biomolecule modification, this study investigated the detailed structural alterations in low-density lipoprotein (LDL) modified by CA, as well as the immunogenicity of the modified protein in experimental animals and the search for autoantibodies in various cancers patients. In vitro , results indicated alterations in secondary and tertiary structures; examined using UV–visible, fluorescence, far-UV circular dichroism, and Fourier transform infrared spectroscopy techniques. Changes in the oxidation status of LDL were studied by carbonyl content assay and NBT assay. ThT binding assay, scanning, and transmission electron microscopy were used to study aggregate formation. The findings revealed significant structural damage in LDL modified by CA. The modification resulted in the unmasking of hydrophobic clusters, the loss of the protein α-helix, and the formation of β-pleated sheet structure. The amyloid aggregate formation was confirmed through ThT microscopy and electron spectroscopy. Rabbits immunized with crotonaldehyde; lead to structural changes in the LDL; that acted as extra antigenic determinants, eliciting strong antibody response. Immunoglobulin response is highly specific for modified LDL as demonstrated by the ELISA. The presence of antibodies against CA-modified LDL was confirmed by the immunoglobulin content of blood sera from human subjects with lung cancer, and competitive ELISA demonstrated the specificity of these antibodies. This study offers insights into the CA-mediated LDL modification and immunogenicity in lung cancer that will have diagnostic importance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic performance of Ir/TiO 2 catalysts depended on the crystal plane of TiO 2. • Ir/TiO 2 -{1 0 1} catalyst gave 4-fold higher activity than that of Ir/TiO 2 -{0 0 1} catalyst. • The defects sites of TiO x support were responsible for the formation of crotyl alcohol. • Ir-TiO x interfacial sites may account for the formation of 1-butanol. Supported Ir/TiO 2 catalysts with the anatase TiO 2 nanocrystals exposing {1 0 1}, {1 0 0} and {0 0 1} planes were tested for selective hydrogenation of crotonaldehyde. The Ir/TiO 2 -{1 0 1} catalyst dominantly exposing {1 0 1} plane gave a initial reaction rate of 166.1 μmol g Ir -1 s−1 at 80 °C and a turnover frequency of crotyl alcohol formation of 0.022 s−1, which is 5 and 7 times respectively higher than those obtained on the Ir/TiO 2 -{0 0 1} catalyst dominantly exposing {0 0 1} plane even though they have similar Ir particle sizes (ca. 1.3 nm). The reaction behaviors were related to the surface oxygen vacancy, which served as surface acid sites and provide adsorption sites for C O bond in the CRAL molecule. Therefore, the higher concentration of oxygen vacancy in the Ir/TiO 2 -{1 0 1} accounted for the improved performance compared to the Ir/TiO 2 -{0 0 1}. However, strong adsorption of crotonaldehyde and/or products on the catalyst surface, as well as the CO poisoning via decarbonylation of crotonaldehyde, were the main reasons for the catalyst deactivation. [ABSTRACT FROM AUTHOR]

Lignocellulosic waste is a potential feedstock for the generation of fuels and commodity chemicals, but existing conversion methods are too cost-intensive to be viable long-term solutions. Electrochemical reductions are promising for decentralized biomass valorization due to their modular scaling and capacity to run intermittently and without high temperatures or pressures. Using crotonaldehyde as a multi-functional model compound for the many partially unsaturated oxygenates found in processed biomass, we here demonstrate the production of butanal, butanol, butene, and butane (variously useful as commodity chemicals and major components of liquified petroleum gas) under ambient conditions by reductive bulk electrolysis with a copper mesh working electrode. We identify an optimum potential for reduced organic production under the reaction conditions and compare product distributions from reductions of intermediate species to further propose branching reaction pathways. Though butanal is typically the most abundant product from crotonaldehyde reduction, most of the butene and butane appear to result from a pathway involving initial reduction of the aldehyde group. We discuss evidence that selectivity is driven by interplay between crotonaldehyde reduction, local pH shifts due to the hydrogen evolution reaction, and changes in site reactivity and availability due to electrode fouling. This demonstration of model electrochemical biomass valorization also serves to inform further exploration into reduction of multi-functional molecules and electrochemical biomass processing in general. [ABSTRACT FROM AUTHOR]

Crotonaldehyde, a highly toxic α, β‐unsaturated aldehyde, is a ubiquitous hazardous pollutant. Because of its extreme toxicity and ubiquity in all types of smoke, most current research focuses on the lung toxicity of such air pollutants. However, the specific mechanism of pulmonary toxicity caused by crotonaldehyde remains unclear, especially after long‐term exposure to crotonaldehyde at low dose. Therefore, the aim of the present study is to determine whether crotonaldehyde‐induced oxidative damage and inflammation promote apoptosis in rats via the mitochondrial pathway using histopathology, immunohistochemistry, biochemistry analysis and Western blot analysis. The results show that crotonaldehyde elicited oxidative damage and inflammation in rats in a concentration‐dependent manner. Crotonaldehyde‐induced lung injury which was confirmed by H&E, Masson's trichrome staining and TUNEL. And crotonaldehyde‐induced lung cell apoptosis showed a concentration‐response relationship. Immunohistochemistry and Western blot results showed that apoptotic mitochondrial signaling pathway is abnormally activated in crotonaldehyde‐induced lung injury. Collectively, this study demonstrates that exposure of rats to crotonaldehyde induces lung injury by inducing apoptosis, which is related to oxidative damage and inflammation through mitochondrial pathway. [ABSTRACT FROM AUTHOR]

Various supported Ir/TiO2 catalysts were prepared using different Ir precursors (i.e., H2IrCl6, (NH4)2IrCl6 and Ir(acac)3) and tested for vapor phase selective hydrogenation of crotonaldehyde. The choice of Ir precursor significantly altered the Ir-TiOx interaction in the catalyst, which thus had essential influences on the geometric and electronic properties of the Ir species, reducibility, and surface acidity, and, consequently, their reaction behaviors. The Ir/TiO2-N catalyst using (NH4)2IrCl6 as the precursor gave the highest initial reaction rates and turnover frequencies of crotyl alcohol formation. Such high performance was ascribed to the high Ir dispersion and high surface concentration of Ir0 species, as well as a higher surface acidity, in the Ir/TiO2-N catalyst compared to its counterparts, indicating the synergistic roles of the Ir-TiOx interface in the reaction, as the interfacial sites were responsible for the adsorption/activation of H2 and the C=O bond in the crotonaldehyde molecule.

3-Formyl substituted indoles or pyrroles can form HOMO-raised dearomative aza-dienamine-type intermediates with secondary amines, which can undergo direct aza-Michael addition to β-trifluoromethyl enones to afford N-alkylated products efficiently, albeit with low to fair enantioselectivity. In addition, similar asymmetric aza-Michael additions of these heteroarenes and crotonaldehyde are realized under dual catalysis of chiral amines, and the adducts are obtained with moderate to good enantioselectivity. [ABSTRACT FROM AUTHOR]

Bio-ethanol is a liquid organic compound mainly produced from the fermentation of renewable sources such as sugar, starch, and lignocellulose. It can be used as a feedstock for the production of several bulk chemicals, including hydrocarbon and oxygenate compounds. 1,3-butadiene is one of the most important chemicals that can also be produced from the catalytic conversion of bio-ethanol. The conversion of bio-ethanol to 1,3-butadiene is a series of continuous reactions that require different active sites for each step. In this work, a FeMgAl-Layered double oxide (LDO) catalyst was selected as a catalyst for 1,3-butadiene production using bioethanol as a feedstock. The effect of ZrO2, grafted on the FeMgAl-LDO catalyst, on 1,3-butadiene production is also investigated. The physical and chemical properties of catalysts were studied using various characterization techniques, including XRD, XRF, NH3-TPD, CO2-TPD, and BET. It was found that the 1,3-butadiene yield was enhanced (8.4 %) with using ZrO2/FeMgAl-LDO as a catalyst. The total basicity of the catalyst was also increased (0.780 mmol/g) with the addition of the grafted-ZrO2. The presence of grafted ZrO2 on the catalyst helped promote the condensation reaction of acetaldehyde to crotonaldehyde and Meerwein-Ponndorf-Verley (MPV) reduction of crotonaldehyde to crotyl alcohol, which are the important steps for 1,3-butadiene production. It also promoted the side reaction that is ethanol dehydration to ethylene and other hydrocarbon gasses. [ABSTRACT FROM AUTHOR]

A new example of the reactivity of enals with benzoylnitromethane was studied in a Michael-Michael-Aldol-Dehydration quadruple organocascade reaction. The reaction unexpectedly yielded a tetrasubstituted cyclohexene carbaldehyde with excellent enantiomeric excess when crotonaldehyde was used as the Michael-acceptor, whereas using (E)-Hex-2-enal as the Michael-acceptor formed a cyclic hemiacetal by steering the reaction into the intramolecular formation of the same intermediate via a Michael-Heterocyclization domino reaction. [ABSTRACT FROM AUTHOR]

To develop functional materials with high retention ability for hydrogen cyanide (HCN) and crotonaldehyde in cigarette smoke, 20 tetrabutyl ammonium hydroxide-amino acid ionic liquids (TBAILs) were prepared. The structures of TBAILs were characterized, and their toxicant-reducing performance in smoke was evaluated. The effects and stability of TBAILs on reducing the releases of HCN and crotonaldehyde in mainstream cigarette smoke were evaluated in the form of paper-cellulose acetate dual composite filter. The results showed that: 1) The structures of TBAILs were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy. In addition, thermogravimetric analysis indicated that TBAILs had good thermal stability under 150 °C . 2) The adsorption performance tested on a bespoke device revealed that all of the 20 TBAILs had substantial reductions for HCN (>80% ), wherein 13 TBAILs also showed a high efficiency for crotonaldehyde (>60% ). 3) When tetrabutyl ammonium-threonine ionic liquid ([N4444][Thr]) was applied to cigarette filters at 10 mg/cig., compared with the control cigarettes, the releases of HCN and crotonaldehyde in mainstream smoke were reduced by 50.8% and 27.7%, respectively, and the smoke sensory quality did not change obviously. The toxicant-reducing performance of [N4444] [Thr] was maintained after storing for 3 months. [ABSTRACT FROM AUTHOR]

A diffusion denuder apparatus has been used to investigate the gas-particle partitioning of formaldehyde, acetaldehyde, acrolein and crotonaldehyde in cigarette mainstream smoke (MS), compounds that are of interest owing to their toxicity and near quantitative retention in the body during cigarette smoking. Formaldehyde showed the best performance in denuder experiments with simple aldehyde-air mixtures owing to the relatively fast rate of the heterogeneous reaction formaldehyde(g) + dinitrophenylhydrazine(s) 6 hydrazone(s). Analysis with the GORMLEY-KENNEDY equation revealed that formaldehyde denuder removal approached, but did not attain, complete efficiency even under optimized operational conditions. Acetaldehyde, acrolein and crotonaldehyde were trapped with considerably lower efficiency than formaldehyde under the denuder conditions used, and more effective denuder wall coatings would be required to examine gas-particle partitioning of these other carbonyls. The proportion of form-aldehyde in the smoke particulate phase initially entering the denuder was > 99%, but loss of formaldehyde from the smoke particles was relatively rapid leading to 35%–61% deposition over the denuder length. The temperature dependence of formaldehyde deposition in the denuder was well predicted using Henry's law constant for aqueous formaldehyde solutions. These observed properties of form-aldehyde are primarily due to reversible reactions of formaldehyde with water in cigarette smoke leading to the much less volatile species methanediol, its oligomers and hydrate. These data suggest that cigarette smoke inhalation is likely to expose the deeper-lung generations of smokers to greater relative formaldehyde exposure, and greater genotoxic risk at those generations than might occur through inhalation of formaldehyde vapour alone. Risk assessments of formaldehyde in cigarette smoke should be updated to recognise this modified risk profile. [Beitr. Tabakforsch. Int. 29 (2020) 2–20] [ABSTRACT FROM AUTHOR]

Imidazolidin‐4‐one is used as a recoverable organocatalyst for the asymmetric Diels‐Alder reaction in the presence of catalytic amount of dicationic ionic liquid and trifluoroacetic acid as a co‐catalyst. The Diels‐Alder reaction between model substrate cyclopentadiene and crotonaldehyde gave the product in 95% conversion and 87% ee of the endo‐product. The catalyst was shown better reusability when the 20 mol% of dicationic ionic liquid was used and catalyst was reused upto 5 cycles, conversion remains upto 3 recycles but ee of endo‐9 was slightly droped. [ABSTRACT FROM AUTHOR]

Crotonaldehyde is a hazardous pollutant present in cigarette smoke and automobile exhausts that is generated by lipid peroxidation, and harmful to reproductive organs. Although we are often exposed to low doses of crotonaldehyde daily, its adverse effects on the reproductive organs have not been fully elucidated. To elucidate them, we administered crotonaldehyde (0, 2.5, 4.5, and 8.5 mg/kg) by gavage for 150 days to male Wister rats, and evaluated its effect on their testicular tissues. Body weight, testis coefficient, sperm count, and motility decreased. Reactive oxygen species and malondialdehyde levels in the 8.5 and 4.5 mg/kg groups significantly increased as antioxidant enzyme activity decreased. Testicular cell apoptosis rate in the exposed groups increased. Testicular enzyme activity and reproductive hormone levels were significantly altered in the 8.5 and 4.5 mg/kg groups. Therefore, long-term exposure to crotonaldehyde may induce oxidative stress, resulting in testicular cell apoptosis, and testicular enzyme and hormone level alteration. [ABSTRACT FROM AUTHOR]

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A series of five alumina-supported palladium catalysts have previously been prepared and characterised by a combination of CO chemisorption and infrared spectroscopy. The reactive attributes of these catalysts are examined using the hydrogenation of crotonaldehyde as a test reaction, using a modified infrared gas cell as a batch reactor. Periodic scanning of the infrared spectrum of the gaseous phase present over the Pd/Al2O3 catalysts was used to construct reaction profiles. Four of the catalysts were able to facilitate a 2-stage hydrogenation process (crotonaldehyde → butanal → butanol), whilst one catalyst was totally selective for the first stage hydrogenation process (crotonaldehyde → butanal). Rate coefficients for the first and second stage hydrogenation processes are normalised to the number of surface palladium atoms for the particular catalyst. Correlation of these kinetic parameters as a function of mean particle size indicates the first stage process to be structure insensitive, whilst the second stage hydrogenation is structure sensitive. Chlorine residues associated with the preparative process of one of the catalysts is seen to selectively poison the second stage hydrogenation process for that catalyst. Structure/activity relationships are considered to explain the observed trends. [ABSTRACT FROM AUTHOR]

Herein, we synthesized PtCo/CNTs, Pt/CNTs, and Co/CNTs nanocatalysts at room temperature by chemical reduction method. The synergistic effect in PtCo/CNTs for crotonaldehyde (CAL) hydrogenation is investigated. The nanostructures, morphologies, electronic property, Pt–Co interaction, surface characteristic and composition of the catalysts are examined by XRD, BET, SEM, XPS, HRTEM, STEM, STEM-EDX elemental maps and line profiles and H 2 -TPD. It is found that Pt and Co forms PtCo bimetallic nanoparticles in the PtCo/CNTs catalyst and the PtCo bimetallic nanoparticles are coated on multi-walled carbon nanotubes. And PtCo/CNTs achieves 83.5% CAL conversion, 91.3% crotyl alcohol (COL) selectivity, and 647.4 h−1 turnover frequency (TOF) at 60 °C within 2 h under 3 MPa hydrogen, and its catalytic performance remains basically unchanged after five recycles. According to the analysis, the presence of PtCo bimetallic particles lead to electron transferring from Co to Pt (synergy effect), which improves their activation ability of hydrogen and desorption of C C in COL and thus enhances its selectivity to COL. [Display omitted] • PtCo/CNTs, Pt/CNTs and Co/CNTs are acquired via liquid reduction method. • PtCo/CNTs exhibits 83.5% conversion and 91.3% selectivity to crotyl alcohol for crotonaldehyde hydrogenation at 60 °C. • PtCo/CNTs has much higher catalytic performance than other as-obtained catalysts due to electron synergy effect of Pt and Co. • PtCo/CNTs also shows good stability. [ABSTRACT FROM AUTHOR]

• Heterocyclic aromatic amine (HAA) formation was inhibited by phenolics. • Phloroglucinol was the phenolic that most inhibited HAA formation. • Inhibition was due to the trapping of the carbonyls responsible for HAA formation. • Produced phloroglucinol/carbonyl adducts were determined in beef patties. • Foods rich in phloroglucinol analogues (i.e. apple juice) were good HAA inhibitors. Carcinogenic heterocyclic aromatic amines (HAAs) with the structure of aminoimidazoazaarene (PhIP, MeIQx, IQ, and MeIQ) are produced by reaction of creatin(in)e, ammonia, and reactive carbonyls (phenylacetaldehyde, acrolein, and crotonaldehyde). In an attempt to provide efficient methodologies for HAA reduction in beef patties, this study: identified phloroglucinol as the most efficient phenolic to reduce HAA formation (76–96% inhibition); isolated and characterized by NMR and MS phloroglucinol/phenylcetaldehyde and phloroglucinol/acrolein adducts; and determined by LC-MS/MS adduct formation in beef patties treated with phloroglucinol. Obtained results suggested that addition of trihydroxyphenols (including phloroglucinol) to beef patties should decrease HAA formation. This was confirmed by both immersing beef patties in apple (or pear) juice before cooking (>90% inhibition) and including wheat bran in patty recipe. All these results confirm the key role of reactive carbonyls in the formation of carcinogenic HAAs and propose carbonyl-trapping as a way for controlling HAA formation in food products. [ABSTRACT FROM AUTHOR]

Reactive carbonyl species (RCS) are generated during thermal food processing, and their accumulation in the body increases the risk of various chronic diseases. Herein, the RCS-scavenging ability of theanine, a unique nonproteinogenic amino acid, was evaluated in terms of the scavenging rate, reaction kinetics, and reaction pathway using LC-MS/MS. Three major products of theanine conjugated with acrolein (ACR) and glyoxal (GO) were prepared and identified using nuclear magnetic resonance. Thereafter, the simultaneous reactions of four types of RCS (namely, ACR, crotonaldehyde, methylglyoxal, and GO) with theanine were discussed in RCS-theanine and RCS-tea models. Under different reaction ratios, theanine could nonspecifically scavenge the four coexisting RCS by forming adducts with them. The amount of theanine-RCS adducts in green and black tea was more than that of catechin (epigallocatechin gallate, epigallocatechin, epicatechin gallate, and epicatechin)-RCS adducts despite the lower content of theanine than catechins. Thus, theanine, as a food additive and dietary supplement, could demonstrate new bioactivity as a promising RCS scavenger in food processing.

Oxidation of crotonaldehyde to crotonic acid is an important chemical reaction process because crotonic acid, its derivative and copolymer are ubiquitous in the productions of chemical, cosmetic, and medicines. However, the reactor safety and process efficiency are still not satisfactory. In order to solve such problems, a novel reactor of gas-liquid-solid mini-fluidized bed with bed inner diameter of 3 mm was developed to carry out the selective catalytic oxidation reaction. The effects of operation conditions and solid particle properties on the conversion rate of reactant crotonaldehyde and the selectivity of product crotonic acid were investigated. The causes of these effects are explained from the standpoint of residence time and gas-liquid mass transfer flux. Moreover, the comparison of reactor performance between the three-phase mini-fluidized bed and the batch stirred tank reactor as a traditional one was made to evaluate the performance of such a reactor. Experimental results show that the average reaction or conversion rate of the mini-fluidized bed is about 30 times much higher than that of batch stirred tank reactor to evaluate the improved performance. But the selectivity is less affected by the operation conditions and solid particle bed properties. The size reduction of three-phase mini-fluidized bed decreases the mass transfer distance of molecular diffusion, and the solid particles and mini-bubbles not only provide the higher specific interface area but also cause hydrodynamics changes that is to intensify the interface disturbance, which effectively accelerate the mass transfer. Unlabelled Image • The performance of a novel gas-liquid-solid mini-fluidized bed was studied. • The comparison of reactor performance with batch stirred tank reactors was made. • The explanation standpoints are residence time and gas-liquid mass transfer flux. • The presence of solid particles and mini-bubbles accelerate the mass transfer. [ABSTRACT FROM AUTHOR]

Stabilized Pd(0) nanoparticles by supported 12-tungstophosphoric acid (Pd(0)-TPA/ZrO2) was explored as a sustainable recyclable catalyst for selective C=C hydrogenation of cyclohexene and crotonaldehyde. The catalyst shows an outstanding performance [catalyst to substrate ratio (1:1.31 × 104)] towards high conversion as well as 100% selectivity of the desired product with high turnover number (> 10,000) and turnover frequency (> 2600 h−1) for both the systems. The use of neat water as a solvent and mild reaction conditions makes the present system environmentally benign and green. Moreover, the catalyst could be recovered and reused up to five cycles without any significant loss in their conversion as well as selectivity. The viability of the catalyst was evaluated towards different aromatic as well as aliphatic arenes and found to be excellent in all the cases. The obtained selectivity, especially butyraldehyde, was correlated with the nature of the catalyst as well as solvent and based on the study, a plausible mechanism for both the reactions was also proposed. [ABSTRACT FROM AUTHOR]