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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]

Humans are ubiquitously exposed to crotonaldehyde (CRA) endogenously and exogenously. Deeper knowledge of the pharmacological and toxicological characteristics and the mechanisms of CRA on vasculature is urgently needed for prevention of its harmfulness. The effects of acute and prolonged exposure to CRA were studied in rat isolated arteries and arterial smooth muscle cells (ASMCs). Instant exposure to CRA (1–300 μM) concentration-dependently declined the tension of pre-constricted arteries with an irreversible depression on the contractility. Prolonged exposure of rat coronary arteries (RCAs) to CRA concentration- and time-dependently depressed the arterial contractile responsiveness to various vasoconstrictors including depolarization, U46619, serotonin and Bay K8644 (an agonist of voltage-gated Ca2+ channels (VGCCs)). In fresh RCA ASMCs, CRA abated depolarization-induced elevation of intracellular Ca2+ ([Ca2+]i). Electrophysiological study revealed that acute exposure to CRA depressed the functions of Ca2+-activated Cl- channels (CaCCs), voltage-gated K+ (Kv) channels and inward rectifier K+ (Kir) channels in RCA ASMCs. Prolonged exposure of RCAs to CRA reduced the expressions of these ion channels in RCA ASMCs, disordered tissue frames, injured arterial cells, and increased autophagosomes in both ASMCs and endothelial cells. In rat aortic smooth muscle cells (A7r5), CRA exposure decreased the cell viability, elevated the intracellular levels of reactive oxygen species, reduced the mitochondrial membrane potential, and enhanced autophagy. Taken together, the present study for the first time portrays a clearer panoramic outline of the vascular effects and the mechanisms of CRA on arteries, demonstrates that CRA impairs arterial contractility, depresses VGCCs, CaCCs, Kv channels and Kir channels, reduces cell viability, and destroys the arterial histiocytes, and suggests that excessive oxidative stress, mitochondrial dysfunction and autophagy underlie these vascular damages. These findings are significant for the comprehensive evaluation of the vicious effects of CRA on arteries and suggest potential preventive strategies.

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"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]

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.

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]

[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 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]

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.

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]

Humans are ubiquitously exposed to crotonaldehyde (CRA) endogenously and exogenously. Deeper knowledge of the pharmacological and toxicological characteristics and the mechanisms of CRA on vasculature is urgently needed for prevention of its harmfulness. The effects of acute and prolonged exposure to CRA were studied in rat isolated arteries and arterial smooth muscle cells (ASMCs). Instant exposure to CRA (1–300 μM) concentration-dependently declined the tension of pre-constricted arteries with an irreversible depression on the contractility. Prolonged exposure of rat coronary arteries (RCAs) to CRA concentration- and time-dependently depressed the arterial contractile responsiveness to various vasoconstrictors including depolarization, U46619, serotonin and Bay K8644 (an agonist of voltage-gated Ca2+ channels (VGCCs)). In fresh RCA ASMCs, CRA abated depolarization-induced elevation of intracellular Ca2+ ([Ca2+] i). Electrophysiological study revealed that acute exposure to CRA depressed the functions of Ca2+-activated Cl- channels (CaCCs), voltage-gated K+ (Kv) channels and inward rectifier K+ (Kir) channels in RCA ASMCs. Prolonged exposure of RCAs to CRA reduced the expressions of these ion channels in RCA ASMCs, disordered tissue frames, injured arterial cells, and increased autophagosomes in both ASMCs and endothelial cells. In rat aortic smooth muscle cells (A7r5), CRA exposure decreased the cell viability, elevated the intracellular levels of reactive oxygen species, reduced the mitochondrial membrane potential, and enhanced autophagy. Taken together, the present study for the first time portrays a clearer panoramic outline of the vascular effects and the mechanisms of CRA on arteries, demonstrates that CRA impairs arterial contractility, depresses VGCCs, CaCCs, Kv channels and Kir channels, reduces cell viability, and destroys the arterial histiocytes, and suggests that excessive oxidative stress, mitochondrial dysfunction and autophagy underlie these vascular damages. These findings are significant for the comprehensive evaluation of the vicious effects of CRA on arteries and suggest potential preventive strategies. [Display omitted] • Crotonaldehyde collapses the arterial contractile responsiveness to various agonists. • Crotonaldehyde impaires Ca2+, Cl- and K+ channels in the arterial smooth muscles. • Crotonaldehyde induces extensive histocytological injuries in rat coronary arteries. • Overoxidation, mitochondrial damage and autophagy underlie the arterial paralysis. [ABSTRACT FROM AUTHOR]

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]

We report a significantly more rapid method for quantitation of the urinary mercapturic acids of the isomeric toxicants crotonaldehyde, methacrolein, and methyl vinyl ketone. The major innovation of this novel method is detection by liquid chromatography-negative atmospheric pressure chemical ionization-tandem mass spectrometry-selected reaction monitoring as opposed to detection by negative electrospray ionization in our previously reported method. The new method also uses an improved Raptor Biphenyl HPLC column. The total chromatographic analysis time was reduced to about 8 min compared to 35 min in our previously published method. Accuracy, precision, and ruggedness of the new method were established, and its suitability for the analysis of urine samples from 2500 cigarette smokers and non-smokers was confirmed. The improved method is practical for quantitation of these important toxicants in clinical studies requiring analysis of thousands of urine samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

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]

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]

• 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]

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]

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.

[Display omitted] • Series of morpholine/acid catalysts were prepared for MAL production at mild condition. • The roles of protonated morpholine species and acidic environment were demonstrated. • The optimal catalytic pathway was confirmed by mechanistic DFT calculations. • The cause of morpholine/acid catalyst deactivation was confirmed. Synthesis of methylacrolein (MAL) from formaldehyde and propanal via Mannich reaction receives significant attention considering the gradual depletion of petroleum resource. Herein, series of morpholine/acid catalyst with different acid type and molar ratio were prepared to catalyze the propanal-formaldehyde reactions for MAL production. The catalytic performance of morpholine/acid was significantly affected by the morpholine/acid ratio, acid type, and initial pH value of reactant mixture. While the addition sequence of reactants and formaldehyde source would influence the yield and selectivity of MAL. As a result, the propanal conversion and MAL yield could reach 99.8 % and 89.7 % with catalysis of morpholine/acetic acid having the molar ratio of 1/3 under weak acidic environment (pH = 5.30) at 50 °C. It was revealed that the protonation of morpholine under weak acidic environment could effectively inhibit the deactivation of morpholine/acetic acid catalyst and promote the production of MAL, however, both basic and strong acidic environment would suppress the formation of MAL. Mechanistic DFT calculations also indicated the protonated morpholine species could not only interact with formaldehyde in the form of morpholine but also act as proton donor. The kinetic studies showed that the formation rate of MAL was first-order dependent on the concentrations of both propanal and formaldehyde with the activation barrier of 30.1 kJ/mol. Undesirably, the optimal morpholine/acetic acid catalyst would be gradually deactivated due to the side reactions of morpholine with formaldehyde, propanal and MAL. [ABSTRACT FROM AUTHOR]

Blue emissive N, S co-doped carbon dots (NSCDs) (quantum yield = 12%) have been synthesized via one-pot microwave-assisted pyrolysis of optimal mole ratios of tartaric acid and thioacetamide and they are devised as a novel fluorescent probe for assessing the sensitive and selective detection of Crotonaldehyde (C H 3 C H = C H C H O , CT) in aqueous and ethanol solution. In the presence of CT, the fluorescence of NSCDs was observed to switch between static and dynamic quenching in the two solvents – water and ethanol, although both exhibited a positive deviation from the linearity in the Stern-Volmer (SV) plots. The positive deviation in the SV plots in the aqueous medium has been attributed to a combination of static and dynamic quenching mechanisms, while the deviation in the ethanol medium followed the static quenching model. The LOD values in water and ethanol medium are estimated to be 50 μM and 30.8 μM in the CT concentration range of 0–6 mM and 0–8 mM respectively. The fluorescence quenching mechanism in the two solvents have been differentiated and validated through fluorescence lifetime measurement using time-resolved fluorescence spectroscopy, shifting in absorption maxima using UV–Vis spectroscopy and energy level calculations. The energy level calculations of NSCDs have been carried out using cyclic voltammetry (CV) measurement and that of CT from density functional theory (DFT) calculations. [Display omitted] • N, S co-doped Carbon Dots were synthesized using tartaric acid and thioacetamide. • NSCDs are sensitive and selective to detect Crotonaldehyde (CT), a potent irritant. • Solvent induced switching between static and dynamic fluorescence quenching of NSCDs in the sensing of CT. • Fluorescence quenching mechanism of NSCDs in both aqueous and ethanol medium was established through time-resolve fluorescence spectroscopy, energy levels of NSCDs through cyclic voltammetry (CV) and energy levels of CT by density functional theory studies. [ABSTRACT FROM AUTHOR]

SiO 2 -supported Ni Ir alloy acted as an effective heterogeneous catalyst for the hydrogenation of benzonitrile, crotonaldehyde and benzylideneacetone, showing much higher activity than monometallic Ni/SiO 2 and Ir/SiO 2 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. • Ni-Ir/SiO 2 showed much higher activity than monometallic Ni/SiO 2 and Ir/SiO 2 catalysts for the selective hydrogenation reactions. • Ni-Ir/SiO 2 showed high selectivity to benzyl-benzylidene-amine, butanal and 4-Phenyl-butan-2-one for the hydrogenation reactions. • The main active sites were different for the hydrogenation of benzonitrile, crotonaldehyde and benzylideneacetone. [ABSTRACT FROM AUTHOR]

The 2-amino-3-methyl-imidazole [4,5-f] quinoline (IQ) is a compound generated during the Maillard reaction while heating protein-rich foods and has been classified as a class 2A possible human carcinogen that has attracted ongoing public concern. However, the formation mechanism of IQ remains unknown. Herein, we investigated the formation mechanism of IQ in the Maillard reaction model system under various reaction conditions (temperature, time, and pH). The results showed that various conditions significantly influenced the precursors, reactive carbonyl species, and IQ formation (P < 0.05). There was regularity between IQ and various conditions, and the R 2 in the fitting curves were between 0.90 and 0.99. To further explore the relationship between IQ and various conditions, a partial least squares (PLS) prediction model was constructed. The model indicates that temperature is a significant contributor to the formation of IQ during the Maillard reaction. Further analysis indicated that crotonaldehyde plays a vital role. Crotonaldehyde could promote IQ formation at low addition levels but inhibit its formation at high addition levels. Possible effects of crotonaldehyde on the formation of IQ were proposed. Overall, this research will help to identify more effective ways to reduce the formation of IQ in meat products, which can improve their safety for human consumption. [Display omitted] • The formation of IQ in the Maillard reaction model system was studied. • The regularity between the formation of IQ and various conditions was proposed. • The partial least squares (PLS) model was constructed for the prediction of IQ formation. • The effects of crotonaldehyde during the formation of IQ were illustrated. [ABSTRACT FROM AUTHOR]

Herein, a series of the Pt-based bimetallic catalysts (PtM x /SBA-15) are gained by using ultrasonic incipient wetness impregnation method (M = Co, Cu, Ni or Zn). The experimental results show that the catalytic performance (including catalytic activity (turnover frequency-TOF), selectivity to crotyl alcohol) of PtCo x /SBA-15 for catalyzing crotonaldehyde selective hydrogenation is the best among PtM x /SBA-15. Additionally, the ratio of Pt/Co in the PtCo x /SBA-15 catalysts is changed to successfully synthesize PtCo/SBA-15, PtCo 2 /SBA-15, PtCo 5 /SBA-15. It demonstrates that the selectivity of the PtCo x /SBA-15 catalysts for crotonaldehyde selective hydrogenation to crotyl alcohol is significantly improved with the increase of the Co content. The PtCo 5 /SBA-15 catalyst provides 83.8% conversion of crotonaldehyde, 94.3% selectivity to crotyl alcohol and TOF of 910.5 h−1 under mild reaction conditions (3.0 MPa H 2 , 80 °C and 2.0 h). And PtCo 5 /SBA-15 has much better catalytic performance (higher catalytic activity and selectivity to crotyl alcohol) than PtCu 5 /SBA-15, PtNi 5 /SBA-15 and PtZn 5 /SBA-15. The reasons are as follows: (1) PtCo alloy forms, which is conducive to crotonaldehyde adsorption and activation; (2) there is an appropriate synergy effect between Pt and Co, greatly improving the capacity of the catalyst activating hydrogen under mild conditions; (3) the electron transfers from Co to Pt, resulting in the increase of Pt electron density and decrease of Co electron density, then the Co sites are advantageous to C O group adsorption and activation and Pt sites for H 2 adsorbing and activating; (4) with the increase of the Co proportion in PtCo x /SBA-15, the synergy effect between Pt and Co in PtCo alloy strengthens and thus increases the selectivity of C O group hydrogenation. [Display omitted] • The PtM x /SBA-15 catalysts are successfully prepared by incipient wetness impregnation method (M = Co, Cu, Ni or Zn). • PtCo 5 /SBA-15 has ∼94.3% (91.5%) selectivity to crotyl alcohol at 83.8% (100%) conversion for crotonaldehyde hydrogenation. • PtCo 5 /SBA-15 shows much better catalytic performance than PtM 5 /SBA-15 and Pt/SBA-15 due to the electron synergy effect. • PtCo 5 /SBA-15 is also very stable. [ABSTRACT FROM AUTHOR]

[Display omitted] • The relaxation process detected for both liquids is assigned to rotational isomerism. • The energy difference between isomers for both aldehydes is comparable. • The activation energies for rotational isomerism differ significantly for both systems. • The viscosity dependence of rate constants follows a fractional-power dependence (non-TST regime) The goal of the present work was to evaluate the viscosity effect on the constants of rotational isomerism exhibited by acrolein and crotonaldehyde unsaturated aldehydes in various frequencies and temperatures by means of ultrasonic relaxation spectroscopy. Only one relaxation process has been detected in a wide frequency range for both liquids, which is assigned to a unimolecular reaction due to rotational isomerism of the corresponding molecules. The rate constants attributed to these conformational changes were determined by analyzing in detail the ultrasonic absorption coefficient as a function of temperature. Temperature rise induces increase of the relaxation frequency with a parallel reduction of the relaxation amplitude for both systems. Quantum mechanical calculations have been performed in an effort to confirm the assignment of the relaxation process to rotational isomerism and to evaluate theoretically the energetics of the optimized isomeric structures of the aldehyde molecules. From the temperature dependence of the acoustic parameters, the experimental activation energy and the energy difference between isomeric forms have been evaluated for both aldehydes in the liquid state. The behavior of the rate constants as a function of viscosity is interpreted and analyzed in the context of stochastic and phenomenological models of the field. [ABSTRACT FROM AUTHOR]

The effect of Pd-decoration on the performance of a GaN nanotube (GaNNT) was investigated in detecting crotonaldehyde (CA) via density functional theory method. The interaction of the pure GaNNT with CA was weak, and the sensing response (SR) was approximately 4.2. The adsorption energy (E ad) of CA changed from −5.4 to −23.2 kcal/mol when a Pd atom was decorated onto the surface of the GaNNT and the SR increased to 94.3 as well. At 298 K, the recovery time for the desorption of CA from the Pd-decorated GaNNT surface was 8.0 s. Finally, the Pd-decorated GaNNT was found to be a promising sensor for CA with high sensitivity. • Pd-decorated GaN nanotube may be highly sensitive crotonaldehyde molecule sensor. • The sensing response significantly rises from 4.2 to 94.3 by Pd-decoration. • A short recovery time of 8.0 s is found for the crotonaldehyde desorption. [ABSTRACT FROM AUTHOR]

Biological acidification is an effective method in the treatment or pretreatment of industrial wastewater. Crotonaldehyde is a typical characteristic organic pollutant in petrochemical wastewater, but its effect on biological acidification is unclear. To investigate the inhibitory characteristic of crotonaldehyde on biological acidification and the mechanism of crotonaldehyde removal, variations in volatile fatty acid (VFA) yields, enzyme activities, biodegradation products, and microbial community structures were investigated by batch experiments in the presence of crotonaldehyde. The results showed that crotonaldehyde caused a 50% effect concentration (EC 50) on the specific acidogenic activity (SAA) of 204.17 mg/L before 24 h, and then, the inhibitory effect was removed after 48 h as the dosage of crotonaldehyde was less than 1000 mg/L. Accordingly, crotonaldehyde was completely reduced to crotonyl alcohol by nicotinamide adenine dinucleotide (NADH) or oxidized to (E)-crotonic acid by aldehyde dehydrogenase (DHO) after 48 h. Next, 1-buanol and n -butyric acid were further metabolites, while the n-hexanoic acid detected with high-concentration crotonaldehyde might be due to the ORB pathway with 1-buanol as an electron donor. The dominant bacterial communities were Clostridium_sensu_stricto_1 , Clostridium_sensu_stricto_11 , Clostridium_sensu_stricto_12 , which were related to the biodegradation process of crotonaldehyde. The findings of this research could provide a theoretical underpinning for developing the biological technologies to pretreat crotonaldehyde wastewater. [Display omitted] • High-strength crotonaldehyde could inhibit acidogenesis process. • Anaerobic biodegradable pathway of crotonaldehyde was demonstrated. • Crotonaldehyde cloud was removed by aldehyde dehydrogenase and NADH. • Phylum Firmicutes was the dominant bacterial community in this system. [ABSTRACT FROM AUTHOR]