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The high entropy oxides are widely studied as the potential catalytic materials owing to their unique structure and excellent properties. In this work, a new high entropy oxide catalyst MnFeCoNiCuO x was successfully prepared and used for the oxidative condensation reaction of furfural (FUR) and aliphatic alcohol, where the carbon-chain length can be selectively increased under the mild conditions. For the selective oxidative transformation of FUR with n-butanol, a more than 99.0 % conversion of FUR and 91.5 % selectivity of 2-(furanyl-2-methylene) butanal was obtained at 80 ºC for 2 h. In addition, the oxidative condensation of FUR with ethanol, n-propanol, n-pentanol, n-hexanol and n-heptanol was also carried out with the MnFeCoNiCuO x - LiOH as catalyst system in the presence of molecular oxygen, where a moderate to high product yields were acquired. Furthermore, the characterizations of catalyst showed that the existence of abundant oxygen vacancy and high specific area was greatly important to the catalytic reactions. [Display omitted] • The efficient oxidative condensation of furfural with n-butanol is achieved. • High entropy oxides-LiOH system exhibits a prominent catalytic activity. • The fuel precursors of C7-C12 can be synthesized with this approach. • Catalytic mechanism of oxidative condensation reaction is studied. [ABSTRACT FROM AUTHOR]

An air quality monitoring campaign for gaseous pollutants using passive sampling techniques was carried out, for the first time, at 25 locations in the metropolitan area of Luanda, Angola, in June 2023. Concentrations of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes, SO 2 and NO 2 were generally higher in locations more impacted by traffic. Benzene, SO 2 and NO 2 levels did not exceed the World Health Organisation guidelines. Ozone concentrations surpassed those documented for other African regions. Higher O 3 formation potential values were recorded at heavy-trafficked roads. The top 5 species with potential for ozone formation were m,p-xylene, toluene, formaldehyde, propionaldehyde and butyraldehyde. The Mulenvos landfill presented a distinctive behaviour with a very low toluene/benzene ratio (0.47), while values close to 5 were obtained at traffic sites. The maximum levels of α-pinene, D-limonene, formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, hexaldehyde and crotonaldehyde were recorded at the landfill. The formaldehyde/acetaldehyde ratio ranged from 0.40 at the Mulenvos landfill to 3.0, averaging 1.8, which is a typical value for urban atmospheres. Acetaldehyde/propionaldehyde ratios around 0.4–0.6 were found in locations heavily impacted by traffic, whereas values between 0.7 and 1.2 were observed in green residential areas and in places with more rural characteristics. All hazard quotient (HQ) values were in the range from 1 to 10, indicating moderate risk of developing non-cancer diseases. The exception was the Mulenvos landfill for which a HQ of 11 was obtained (high risk). The cancer risks exceeded the tolerable level of 1 × 10−4, with special concern for the landfill and sites most impacted by traffic. A mean lifetime cancer risk of 9 × 10−4 was obtained. The cancer risk was mainly due to naphthalene, which accounted, on average, for 94.6% of the total. [Display omitted] • First air quality campaign in Luanda using passive sampling in 25 locations. • In general, benzene, SO 2 and NO 2 within WHO guidelines, while O 3 exceeded. • Top O 3 forming species: m,p-xylene, toluene, formaldehyde, propionaldehyde, butyraldehyde. • Mulenvos landfill with distinct profile: much higher aldehyde and hydrocarbon levels. • Hazard quotient moderate to high; 900 new cancer cases per million people. [ABSTRACT FROM AUTHOR]

In this study, a hydroxyl radical oxidation system was established to simulate the oxidation process in fermented meat products. This system was employed to examine the structural changes in myofibrillar proteins (MPs) resulting from tryptic hydrolysis after a hydroxyl radical oxidative regime. The effect of these changes on the ability of MPs to bind selected aldehydes (3-methyl butanal, pentanal, hexanal, and heptanal) was also investigated. Moderate oxidation (H 2 O 2 ≤ 1.0 mM) unfolded the structure of MPs, facilitating trypsin-mediated hydrolysis and increasing their binding capacity for the four selected aldehydes. However, excessive oxidation (H 2 O 2 ≥ 2.5 mM) led to cross-linking and aggregation of MPs, inhibiting trypsin-mediated hydrolysis. The oxidised MPs had the best binding capacity for heptanal. The interaction of the oxidised trypsin-hydrolysed MPs with heptanal was driven by hydrophobic interactions. The binding of heptanal affected the structure of the oxidised trypsin-hydrolysed MPs and reduced their α-helix content. • Moderate oxidation unfolds MPs structures, promoting trypsin hydrolysis. • Excessive oxidation cross-links and aggregates MPs, inhibiting trypsin hydrolysis. • Oxidised MPs had the best binding capacity for heptanal. • Trypsin hydrolysis increased the binding of oxidised MPs to aldehydes. • Binding of heptanal alters the structure of oxidised trypsin-hydrolysed MPs. [ABSTRACT FROM AUTHOR]

Hydroformylation reactions promoted by Rh single-atom catalysts typically exhibit a negative reaction order for CO and a positive reaction order for H 2 and alkenes. To enhance the catalytic activity, efforts have been concentrated on reducing the CO adsorption strength and/or enhancing the hydrogenation capacity at Rh sites. This report introduces an optimized Rh single-atom catalyst, utilizing positively charged Mn species to weaken the CO adsorption strength. Our strategy involves placing MnOx clusters in the proximity to the Rh single atom. This arrangement allows the reduction of Rh3+ to produce electronically deficient Rhδ+ species (1 < δ < 2), rather than the usual formation of the lower valence state Rh+ species. The weakened CO adsorption strength on the more positively charged Rhδ+ results in reduced CO coverage on the Rh active site, and enhanced adsorption of propylene. Our mechanistic study reveals that H 2 and CO adsorption on Rh catalyzes the reduction of adjacent Mn(IV) species, inducing the formation of a Rh-MnOx paired active site. The neighboring MnOx clusters hinder the extensive reduction of Rh3+ to Rh+. This study presents MnOx as an inorganic ligand in Rh-MnOx pair site modifies the electronic properties of Rh sites to modulate the hydroformylation activity of Rh single-atom catalysts. [Display omitted] • H 2 and CO on Rh catalyzes the reduction of adjacent Mn(IV) to form Rh-MnOx pair site. • The neighboring MnOx hinder the reduction of Rh3+ to Rh+, forming Rhδ+ (1 < δ < 2). • Rhδ+ shows weakened CO adsorption strength than Rh+ species • Weakened CO adsorption strength on Rhδ+ benefits high hydroformylation activity. [ABSTRACT FROM AUTHOR]

Highlights • The optimal condition of roasted sweet potato was determined by RSM. • 38 kinds of volatile compounds in roasted sweet potato were determined by GC–MS. • 2-Methyl butanal was the main aromatic compound in roasted sweet potato. • Low-field NMR showed that the proportion of free water increased after roast process. • The total phenolic content and antioxidant activity increased after roast process. Abstract The study evaluated the optimal condition for roasting sweet potato using response surface methodology. Proximate composition, antioxidant activity, volatile compounds, and water migration of roasted sweet potato were also determined. The results revealed that the optimal roasting condition included a roasting time of 40 min, a roasting temperature of 235 °C, and a roasting speed of 40 rad/min, the reducing sugar and vitamin C of roasted sweet potato obtained under optimal condition was 47.79 g/100 g (DW) and 60.25 mg/100 g (DW), respectively. After roasting, starch, protein and vitamin C content of sweet potato were significantly decreased, while total phenolic content and antioxidant activity were increased. 2-Methyl butanal was the main aromatic compound. Low-field NMR indicated that the proportion of free water increased and relaxation times (T 2) were decreased after roast process, indicated that the bound water in sweet potato was diffused from inside to outside, thus the texture became softer. [ABSTRACT FROM AUTHOR]

The trade-off between gas permeance and filtration accuracy in SiC ceramic membranes has constrained their utilization in gas/solid filtration. Herein, a polyvinyl butyraldehyde (PVB) solution was introduced as a prefilling layer to impede membrane particles from penetrating the macroporous SiC support (average pore size: 23 μm). The PVB layer could be removed postsintering, thereby producing a ceramic membrane devoid of any intermediate layer, which showed great potential in enhancing the gas permeance. Initially, the PVB concentration was optimized to ensure membrane integrity and strong adhesion between the support and separation layer. Thereafter, suitable dispersants and drying conditions were investigated in detail. The resultant asymmetric SiC membranes fabricated under these optimized conditions had a thickness ranging between 50 and 60 μm. These membranes demonstrated exceptional gas permeance, varying from 71.1 to 178.1 m3 m−2 h−1 kPa−1 by tuning the membrane pore size from 1.02 to 3.03 μm. Additionally, the membranes achieved 99.94 % dust rejection for particles approximately 0.3 μm in size. When compared to traditional ceramic membranes with several intermediate layers, the prefilling approach employed herein circumvents the ceramic intermediate layer. This method resolves the mismatch between particle sizes of the ceramic support and the membrane layer, offering an effective strategy for developing high-permeance SiC membranes suited for gas/solid filtration applications. [Display omitted] • SiC membranes without the middle layer were produced by using prefilling method. • The prefilling layer prevented the particle penetration completely. • The membranes exhibited great gas permeance compared with the literature. • The membranes showed above 99.94 % rejection towards PM 0.3 nanoparticles. [ABSTRACT FROM AUTHOR]

Cordyceps Sinensis, renowned for its diverse pharmacological properties and the rarity of its natural species, faces significant challenges due to rampant adulteration by counterfeit products. Consequently, there is a crucial need to reliably identify Cordyceps species to ensure their quality and efficacy. While current analytical techniques predominantly rely on LC–MS, there remains a notable deficiency and substantial demand for the development of a unified, reproducible, and fast method suitable for commercial applications. In this study, we employed a cost-effective and straightforward approach utilizing headspace GC–MS to authenticate Cordyceps sinensis. This method enables the comprehensive analysis of the chemical profile, facilitating the identification of quality and authenticity in Cordyceps samples. Through a comparative analysis of the chemical profiles of seven authentic Cordyceps samples with seven other Cordyceps samples, we propose a Quality Assessment System for Authentic Cordyceps, encompassing the following criteria: 1) the presence of 29 compounds commonly found in authentic Cordyceps within the chemical profile, and 2) the area ratio of 3-methylbutanal to 2-methylbutanal falling within the range of 2.09–3.01. This method exhibits considerable promise as a standardized, reproducible, and expeditious technique for the quality assessment and authentication of Cordyceps. ● An authenticate assessment method for cordyceps sinensis was proposed. ● chemical profiling were investigated by headspace GC–MS analyses. ● Total 176 compounds were being identified. ● 29 compounds commonly found in authentic Cordyceps. ● The area ratio of 3-methyl butanal and 2-methyl butanal were identified as marker. [ABSTRACT FROM AUTHOR]

Abstract Due to liquid electrolyte limitation in dye sensitized solar cells (DSSCs), GPEs were prepared and optimized. Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), P(VB-co-VA-co-VAc) acted as host polymer and tetrapropylammonium iodide, TPAI as dopant salt. The prepared gel polymer electrolytes (GPEs) with different TPAI salt content were characterized using electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy and X ray diffractogram. An optimum ionic conductivity of 1.93 mS cm−1 was obtained with 40 wt% of TPAI salt added along with the lowest activation energy of 0.064 eV. Temperature dependence ionic conductivity behaviour of GPEs were studied and found that the systems obeyed the Arrhenius behaviour in the temperature range of 303–373 K. The dielectric results studies showed typical behaviour of both ε ′ and ε ′ ′ inversely proportional to frequency and directly proportional to temperature. Structural studies of GPEs were performed using XRD and FTIR and confirmed the existence of complexation of P(VB-co-VA-co-VAc) and TPAI salt. GPEs were used to assemble dye sensitized solar cells (DSSCs). The power conversion efficiency of 4.615% achieved with a maximum short circuit current density (J sc) of 13.585 mA cm−2, open circuit voltage (V oc) of 0.678 V and fill factor of 50.1% at 40 wt% TPAI salt under A.M 1.5 (100 mW cm−2) illumination. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • C 4 H 8 O removal using (UV-TiO 2 /plasma) + catalytic-bed system is studied. • Specific catalysts are tested for C 4 H 8 O/O 3 removal at pilot scale. • Impacts of operating parameters on process performance are defined. • Highly efficient synergetic association was obtained. • Better performance in mineralization rate via ozone valorization. Abstract This study focuses on Butyraldehyde (C 4 H 8 O) degradation using catalytic ozonation oriented to the optimization of non-thermal plasma/photocatalytic coupled processes. After the first oxidation by non-thermal plasma coupled photocatalytic processes, a second oxidative step leading to the decomposition of the residual Butyraldehyde by Ozone is catalyzed by Mordenite, ZSM-5 and γ-alumina. The Butyraldehyde degradation in the presence of Ozone under operational parameters such as plasma energy, Butyraldehyde inlet concentration, relative humidity and the height of the catalytic bed are reported in detail. The optimum operating conditions found were: Q air = 1 m3 h-1, [C 4 H 8 O] = 100 mg m-3, SIE plasma = 18 JL-1, for Butyraldehyde degradation mediated by ZSM-5. The formation of intermediate by-products was monitored during the degradation of Butyraldehyde in the presence of Ozone and ZSM-5 catalyst to suggest a degradation pathway. The coupling of catalytic ozonation by non-thermal plasma/photocatalysis lead to the total decomposition of Ozone when catalyzed by ZSM-5and presents a positive effect on the mineralization capacity. The pollutants degradation intermediates were identified by GC-MS and the oxidative states on the catalytic bed were characterized by XPS. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • SiO 2 with weak acidity exhibited stable catalytic activity in the aldol condensation of butanal. • Both large pore size and large surface area of SiO 2 efficiently promoted the catalytic activity. • 2-Ethyl-2-hexenal selectivity of 90% with 48.3% conversion was obtaiend over SiO 2 at 240 °C. • Silanol groups on SiO 2 surface were suggested to be the active sites for the reaction. Abstract Vapor-phase aldol condensation of butanal to form 2-ethyl-2-hexenal was carried out over several oxide catalysts such as SiO 2 -Al 2 O 3 , Al 2 O 3 , ZrO 2 , and SiO 2. Catalysts with moderate and strong acid sites such as Al 2 O 3 and SiO 2 -Al 2 O 3 were active for the reaction in the initial period, whereas they deactivated rapidly. In contrast, SiO 2 with weak acidity showed a low but a stable catalytic activity for the formation of 2-ethyl-2-hexenal. Thermogravimetric analyses of the samples used after the reactions indicate that SiO 2 has the smallest amount of carbonaceous species that contributed to its stable activity among the tested catalysts. SiO 2 catalysts with different pore sizes and specific surface areas were examined: SiO 2 with a mean pore diameter of 10 nm and a surface area of 295 m2 g−1 showed the best catalytic performance and gave a 2-ethyl-2-hexenal selectivity of 90% at a conversion of 48% at 240 °C. In the catalytic test using deuterated SiO 2 , which was prepared by contacting SiO 2 with deuterated water before the reaction, it was confirmed by a mass spectrometer that the deuterium atom of SiOD was transferred to a 2-ethyl-2-hexenal molecule during the reaction. It is indicated that silanol groups on the SiO 2 surface played a role as an active site. [ABSTRACT FROM AUTHOR]

Highlights • 2-Methyl-4-phenylbutyraldehyde, safety assessment based on RIFM's criteria. • Safety assessment based on 7 human health endpoints plus environmental. • All endpoints were cleared using target data, read-across, and/or TTC. [ABSTRACT FROM AUTHOR]

Residential indoor exposure to volatile organic compounds (VOCs) is a major public health concern. However, the relevant pollution sources have not been well characterized in China. In this study, the 24-h integrated concentrations of 55 VOC species in 27 urban residences, Beijing were measured in the summer. The sources were characterized with positive matrix factorization (PMF) and general linear model (GLM). The most abundant species in terms of geometric mean concentration were formaldehyde (55.1 μg/m 3 ), acetaldehyde (18.7 μg/m 3 ), acetone (14.8 μg/m 3 ), toluene (14.1 μg/m 3 ), hexanal (13.8 μg/m 3 ), n -hexadecane (8.9 μg/m 3 ) and n -pentadecane (8.5 μg/m 3 ). PMF generated 7 factors associated with VOC sources, including aldehydes from ozone-initiated secondary reactions, butyraldehyde from hydrolysis of building materials and furniture, wood flooring emission, wooden furniture emission, wall coverings emission, mobile emission and halogenated hydrocarbons of miscellaneous outdoor origin. GLM identified leather sofa as another source of indoor terpenes and formaldehyde. GLM also found composite wood flooring had stronger emission of VOCs than solid wood flooring, except 1,4-dichlorobenzene. A comparison with multiple studies across the world suggested that: (1) more intensive ozone-initiated secondary reactions resulted in the significantly higher indoor carbonyl concentrations in Beijing than in Japan and USA in the summer; (2) the indoor concentrations of benzene and C 12 -C 17 alkanes were much higher in Beijing, due to the traffic conditions and prevalent use of wood flooring varnishing. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge DBD-plasma based technologies have been widely investigated for the abatement of air pollutants. More recently, photocatalysis (TiO 2 /UV-lamp) has also showed promising results for air pollution abatement. In this work, these two methods were used separately and combined (TiO 2 /UV-lamp/DBD-plasma) in order to enhance the performance of the process for air pollutants degradation/mineralization. Ammonia (NH 3 ) and butyraldehyde (C 4 H 8 O) have been firstly treated alone and then an equimolar mixture (NH 3 /C 4 H 8 O) was monitored in a continuous reactor. Effect of operational parameters such as pollutants inlet concentration, flowrate, humidity and specific energy of plasma were thoroughly determined. Results showed that coupling both methods in the same reactor improves removal efficiency for single pollutant or a mixture of two pollutants. This processes combination showed a synergy between DBD-plasma and photocatalytic oxidation. Moreover, pollutant mineralization and potential intermediate byproducts have been characterized and discussed. Coupling both processes contributes to enhanced mineralization in comparison with DBD-plasma alone regarding the CO 2 selectivity. As for selectivity of byproducts: (i) Relative Humidity (RH), (ii) mixture effect and (iii) (TiO 2 /UV-lamp/DBD-plasma) combined processes inhibit ozone production during the pollutants removal/oxidation. [ABSTRACT FROM AUTHOR]

Oil derived from fast pyrolysis of biomass (or bio-oil) is a candidate renewable feedstock for producing hydrogen (H 2 ). In this work, the steam reforming of model oxygenates present in the bio-oil aqueous fraction was studied in a fixed-bed reactor. Using Ni/Al 2 O 3 catalyst, the reactions with 2-butanone, 1-methoxy-2-propanol, ethyl acetate and butyraldehyde were studied. To study the efficacy of the chosen catalyst for H 2 production, experiments were performed in the 623–773 K range using varying steam/carbon ratios in feed (15–25 mol/mol). The conversion of the various feeds was of the order: butyraldehyde > ethyl acetate > 1-methoxy-2-propanol > 2-butanone. The catalyst was characterized using SEM, XRD, TPR/TPD and TGA methods. It showed high stability for 7 h of time-on-stream. [ABSTRACT FROM AUTHOR]

The polymerization of n -butyraldehyde, via a metal-free organocatalytic anionic polymerization method was successfully conducted with the phosphazene bases P 2 -t- Bu and P 4 -t- Bu. Well-defined poly( n -butyraldehdye) (PBA), with predictable molar masses and low molar mass dispersities ( Ð ) were accessed when the polymerization of n -butyraldehyde was promoted by P 2 -t- Bu. Effects of important parameters, including initiator/phosphazene base ratio and solvent polarity were assessed. The facile degradability of PBA, under benign conditions, was demonstrated, suggesting potential applications in systems requiring well-defined ‘self-immolative’ polymers, without metal ion contamination. [ABSTRACT FROM AUTHOR]

A commercial silica water selective membrane was evaluated experimentally. Additionally, its potential application in the synthesis of 1,1-diethoxybutane was studied from the process intensification point of view. The membrane performance was evaluated experimentally, at different compositions and temperatures, by measuring the flux and permeate composition of binary and ternary mixtures. The effect of composition and temperature on the species permeances was also studied. For ethanol and butyraldehyde the permeances depend only on the temperature, following an Arrhenius equation; while for the water, its permeance depends on both temperature and composition, following a modified Arrhenius equation. Altogether, the permeation data obtained in the present work combined with reaction and adsorption data from previous works allowed a comparison, by simulation, between the PermSMBR and simulated moving bed reactor (SMBR) for the synthesis of 1,1-diethoxybutane. Results showed that the PermSMBR, operating at 50°C, presents an improvement of about 7% in both productivity (34.3 k g D E B / ( d a y . L c a t a l y s t ) ) and desorbent consumption (1.73 L Eth / kg DEB ). [ABSTRACT FROM AUTHOR]

1-Deoxynojirimycin (1-DNJ) is a glycoprocessing inhibitor, and it serves as a synthetic precursor to two of three currently marketed iminosugar drugs, miglustat (N-butyl DNJ/Zavesca®) and miglitol (Glyset®). Herein a continuous flow procedure is presented that shortens a synthesis of 1-DNJ from an intermediate prepared from l -sorbose. Batch reactions involving an azide reduction, subsequent reductive amination-based cyclisation, and O -benzyl deprotection in a previous report required two steps and the use of an acid. Here, this sequence is achieved in one step using the H-Cube® MiniPlus continuous flow reactor. Subsequent reductive amination of 1-DNJ with butanal using the H-Cube® gave NB-DNJ. [Display omitted] • Continuous flow synthesis of 1-DNJ from an l -sorbose derivative. • Improved yield, reaction time and safety. • First flow synthesis of miglustat (Zavesca®). [ABSTRACT FROM AUTHOR]

• Commercial pea proteins presented large variability in sensory properties. • This study provided a sensory lexicon and volatile flavor profile of pea proteins. • Primary flavors were cereal/grainy, cardboard, green pea, and beany/yellow pea. • Key volatile aroma active compounds in pea proteins were identified and quantitated. • 25 volatiles were reported in pea proteins for the first time in this study. Pea protein is a growing plant-based protein ingredient. Pea proteins have characteristic undesirable flavors, leading to challenges in ingredient applications. The objective of this study was to characterize the flavor of pea proteins using descriptive sensory analysis and instrumental volatile compound analyses. Seven sensory attributes were identified in most pea proteins at variable intensities: cereal/grain, cardboard, green pea, beany/yellow pea, bitter, umami, and astringent. Other attributes, cheesy, doughy, sulfur, pyrazine, fecal, sweet aromatic and salty taste, were distinguishing flavors of some pea proteins (p < 0.05). The key aroma-active compounds in pea proteins were hexanal, heptanal, benzaldehyde, methional, 2-hexanone, 2-heptanone, 1-octen-3-one, 2-nonanone, 1-nonen-3-one, 1-pentanol, 2-pentyl furan, 2-isopropyl-3-methoxypyrazine, 2,5-dimethyl-3-(3-methylbutyl)-pyrazine and 2-methyl-isoborneol (present in all representative samples). Volatile compounds responsible for the majority of sample variation included 2-methyl butanal, (Z)-3-hexanal, (E,E)-2,4-decadienal, 1-octen-3-one, 2-decanone, 1-pentanol, 1-octen-3-ol, geosmin and 2,3-diethyl-5-methyl pyrazine (p < 0.05). This study can facilitate product development and flavor masking of various pea protein applications. [ABSTRACT FROM AUTHOR]

Models of increasing complexity were developed to identify and represent mechanisms affecting the evolution of the concentration of 3 aroma compounds (2-phenylethanol, isoamyl acetate and butanal) usually produced by yeasts and transferred to coffee beans during the fermentation. Model parameters were identified from simulated wet treatment performed with four media (M1: dehulled beans, M2: demucilaginated beans, M3: depulped beans, M4: depulped beans with yeast), at 25 °C using labeled aroma compounds. The transfer of 2-phenylethanol was well described by a model including evolving resistance over time (R2 = 0.98) while the accumulation of isoamyl acetate and butanal was better described by a model including two first order reactions in parallel (r2 = 0.87–0.66 and r2 = 0.80–0.67, respectively). The model development contributed to understand several mechanisms involved during fermentation such as the evolutive parchment resistance and the complex degradation reactions that take place simultaneously and have a significant impact on the compounds transfer. • Dynamic modelling of the transfer kinetics of aroma compounds in coffee beans. • Identification of complex mechanisms related to layer resistance and reactions. • Accurate prediction of the transfer of higher alcohols. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) photochemically react during the transportation from the source to the sampling site, which affects the understanding of their true characters from emissions. However, studies on the photochemical initial concentrations (PICs) of VOCs are still insufficient. Here, we propose an empirical coefficient that takes into account the combined effects of disturbances from new emissions and incomplete air mixing to calculate the PICs of non-methane hydrocarbons (NMHCs) (named "adjusted") and try to estimate the PICs of carbonyls. The relative consumption of NMHCs based on adjusted_PICs show better fits to O 3 (r = 0.56 in winter and r = 0.65 in summer) in comparison with conventional_PICs (r = 0.33 in winter and r = 0.41 in summer). The adjusted_PICs of total NMHCs are higher than conventional_PICs in winter, while lower than conventional_PICs in summer. In contrast to measured concentrations, no obvious peaks of carbonyl PICs during noon times are found for acetone, propanal, and butanal in summer. Based on the adjusted PICs, higher contributions of solvent use and printing were apportioned compared with those based on measured concentrations and conventional_PICs, and no obvious contributions from secondary formation were identified. This study provides a new perspective for analyzing PICs and facilitates a clear understanding of VOCs sources. • An empirical factor is proposed to adjust the photochemical initial concentration (PIC) of VOCs. • Relative consumption of NMHCs with adjusted_PICs correlates well with O 3. • PICs of carbonyls does not show obvious peaks during the day in summer. • Higher contributions of solvent use and printing were apportioned based on the adjusted PICs. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the butyraldehyde (Buty) conversion using dielectric barrier discharge (DBD) in a continuous reactor at pilot scale. One of the focused-on parameters in this study is relative humidity, which effect on (i) butyraldehyde removal (ii) selectivity of CO 2 and CO, and (iii) intermediate byproducts and ozone formation was investigated using a DBD reactor with planar configuration. The results showed that at pilot scale, adding a small amount of water vapor in air enhances the processes performance and 10% increase in Buty removal efficiency was observed. A kinetic degradation model was also proposed, which takes into account the relative humidity influence. Active species due to water dissociation are integrated in the model. To represent the chemical degradation pathway, we supposed, in a first step, that an equivalent intermediate compound (EI) is formed directly from Buty. Then, in a second step, this EI is oxidized by active species into CO 2 and CO in the discharge zone. This approach that also considers the competition effect between actives species improved the concordance between simulated results and experiments with a satisfactory overall description of the degradation and byproducts formation. [ABSTRACT FROM AUTHOR]

In process synthesis, it is often useful to have generic design tools to allow process designers to assess various important aspects of chemical processes. In this work, a novel graphical visualisation tool, i.e. Piper diagram is proposed to trace the changes of composition of the process streams, while establishing relationship that contributes to various strategies for process design. This tool is generic in nature, hence is applicable to all processes and various process aspects that meet the objectives of the designer. Two case studies on the production of cinnamaldehyde and butanal are used to demonstrate the novel approach, with safety, environmental and economic aspects being investigated using the Piper diagram. [ABSTRACT FROM AUTHOR]

Coupling nonthermal plasma with other processes has been studied over the past few years and promising results were obtained concerning VOCs removal for atmospheric pollution control. In this work, butyraldehyde (BUTY) removal by a dielectric barrier discharge (DBD) plasma coupled with different (photo) catalysts based on TiO 2 and MnO 2 was studied. DBD plasma system and an immobilized TiO 2 and MnO 2 at different percentages are continually and sequentially combined in order to decompose residual ozone. Indeed, different ways of combination are listed. Effects of relative humidity and initial BUTY concentration on its conversion rate and the distribution of byproducts were examined and discussed. Results with pilot scale showed that combination of plasma and photocatalysis led to an enhancement of BUTY abatement compared to the separate systems. When 100% of MnO 2 catalyst was placed in the post discharge zone, the performance of sequential DBD/MnO 2 combined system is improved in terms of decomposition and conversion rate of the pollutant. In the same way, CO was reduced and CO 2 selectivity was significantly improved when compared to the DBD plasma alone. Intermediate byproducts were identified and BUTY removal pathways are suggested. [ABSTRACT FROM AUTHOR]

Steam reforming (SR) of n -butanol and its main reaction intermediates, i.e., 1-butene, and butyraldehyde, was studied over 0,5 wt.% Rh/ZrO 2 catalyst at 500 and 700 °C, atmospheric pressure and steam to carbon (S/C) molar ratio of 4. Coke deposits on the spent catalyst samples were characterized using temperature programmed oxidation (TPO) and CHNS + O elemental analysis. Catalyst performance, i.e., conversion, product distribution and short term stability, as well as coke deposit characterization, were utilized to develop reaction networks for 1-butene, butyraldehyde and butanol. At 500 °C the individual reforming rates of the three components decrease in the order butyraldehyde > butanol > 1-butene and the initial reaction rates of butanol decrease in the order dehydration > dehydrogenation > direct reforming. The three main pathways, i.e., direct reforming of butanol and reforming via butane and butyraldehyde respectively, contributed roughly equally to the butanol reforming activity of the catalyst at 500 °C. At 700 °C, complete conversion was observed for all components, with hydrogen yields 70% of theoretical maximum for butanol and 1-butene and 60% for butyraldehyde. Deactivation of the catalyst for reforming is caused by carbon deposition on and near the Rh particles. The deposition is a side reaction of the reforming surface reaction and decreases in the order of magnitude butyraldehyde > butanol >> 1-butene. Carbon deposition elsewhere on the support proceeds mainly via the coupling products of butyraldehyde. [ABSTRACT FROM AUTHOR]

Eighteen carbonyl species in C 1 –C 10 were measured in the dining areas, kitchens and exhaust streams of six different restaurant types in Kaohsiung, southern Taiwan. Measured results in the dining areas show that Japanese barbecue (45.06 ppb) had the highest total carbonyl concentrations (sum of 18 compounds), followed by Chinese hotpot (38.21 ppb), Chinese stir-frying (8.99 ppb), Western fast-food (8.22 ppb), Chinese–Western mixed style (7.38 ppb), and Chinese buffet (3.08 ppb), due to their different arrangements for dining and cooking spaces and different cooking methods. On average, low carbon-containing species (C 1 –C 4 ), e.g. , formaldehyde, acetaldehyde, acetone and butyraldehyde were dominant and contributed 55.01%–94.52% of total carbonyls in the dining areas of all restaurants. Meanwhile, Chinese–Western mixed restaurants (45.48 ppb) had high total carbonyl concentrations in kitchens mainly because of its small kitchen and poor ventilation. However, high carbon-containing species (C 5 –C 10 ) such as hexaldehyde, heptaldehyde and nonanaldehyde (16.62%–77.00% of total carbonyls) contributed comparatively with low carbon-containing compounds (23.01%–83.39% of total carbonyls) in kitchens. Furthermore, Chinese stir-frying (132.10 ppb), Japanese barbecue (125.62 ppb), Western fast-food (122.67 ppb), and Chinese buffet (119.96 ppb) were the four restaurant types with the highest total carbonyl concentrations in exhaust streams, indicating that stir-frying and grilling are inclined to produce polluted gases. Health risk assessments indicate that Chinese hotpot and Japanese barbecue exceeded the limits of cancer risk (10 − 6 ) and hazard index (= 1), mainly due to high concentrations of formaldehyde. The other four restaurants were below both limits. [ABSTRACT FROM AUTHOR]

Glutamate decarboxylase (GAD) (EC 4.1.1.15), an enzyme responsible for the synthesis of γ-aminobutyric acid (GABA), from Synechocystis sp. PCC6803 was cloned and overexpressed in Escherichia coli BL21(DE3). The purified enzyme was expressed as a monomeric protein with a molecular mass of 53 and 55 kDa as determined by SDS-PAGE and gel filtration chromatography, respectively. The enzyme activity was pyridoxal-5′-phosphate dependent with an optimal activity at pH 6.0 and 30 °C. The catalytic properties of this enzyme were, K m = 19.6 mM; k cat = 100.7 s −1 ; and k cat /K m = 5.1 mM −1 s −1 . The transcription levels of genes involved in nitrogen metabolism were up-regulated in the Δ gad strain. The mutant showed approximately 4- and 8-fold increases in the transcript levels of kgd and gabdh encoding a novel α-ketoglutarate decarboxylase and γ-aminobutanal dehydrogenase, respectively. Overall results suggested that in Synechocystis lacking a functional GAD, the γ-aminobutanal dehydrogenase might serve as an alternative catalytic pathway for GABA synthesis. [ABSTRACT FROM AUTHOR]

Samples of butanal oxime in aqueous solution have been irradiated with the helion ( 4 He 2+ ) beam of the ARRONAX (Nantes) and the CEMHTI (Orléans) cyclotrons. The consumption yield of butanal oxime has been measured by gas-chromatography coupled with mass spectrometry. Yields of gaseous products (mainly H 2 ) have also been measured by micro-gas-chromatography. Butanal oxime can react with H ∙ radicals by abstraction mechanism to enhance H 2 production. Yields of liquid phase products (hydrogen peroxide and nitrite ion) have been measured by colorimetric methods. Butanal oxime acts as a scavenger of OH ∙ radical to inhibit the production of H 2 O 2 . The observation of the radiolytic products allows then to discuss a degradation mechanism of butanal oxime in aqueous solutions. [ABSTRACT FROM AUTHOR]

A series of polyoxometalate-based heterogeneous catalysts were prepared by immobilized transition metal mono-substituted phosphomolybdic acids (PMo 11 M, M = Fe, Co or Cu) or unsubstituted phosphomolybdic acid (PMo 12 ) on amino-functionalized SBA-15. A variety of characterization results demonstrated that the PMo 11 M units are uniformly dispersed on the surface or in the channels of mesoporous SBA-15. The catalytic properties of these hybrid materials (denoted as PMo 11 M/SBA or PMo 12 /SBA) were investigated in the epoxidation of olefins with molecular oxygen as oxidant and isobutyraldehyde as co-reagent. It has been found that PMo 11 Co/SBA and PMo 11 Cu/SBA are catalytically active for the epoxidation of cyclooctene with acetonitrile as solvent, while PMo 11 Fe/SBA and PMo 12 /SBA are nearly inactive under the same reaction conditions. Moreover, the relatively active PMo 11 Co/SBA catalyst could also efficiently convert cyclohexene and 1-octene to the corresponding epoxides, and its catalytic activity was solvent dependent. Using suitable solvent like acetonitrile could efficiently inhibit the deactivation of the catalyst, thus bringing excellent stability and recyclability for the PMo 11 Co/SBA catalyst. [ABSTRACT FROM AUTHOR]

This work investigated the performance of butyraldehyde decomposition with the help of dielectric barrier discharge (DBD) plasma coupled with photocatalysis (TiO 2 + UV) at room temperature. Effects of flow rate and initial butyraldehyde concentration on the decomposition and the distribution of byproducts were examined and discussed. The combination of these two technologies led to an enhancement of butyraldehyde abatement compared to the separate systems at pilot scale from 5 to 10 m 3 h −1 of flowrate. The synergy factor due to combination processes ranged from 1.13 to 1.27. In the same way, CO 2 selectivity was significantly improved when compared to the DBD plasma alone. In this research, DBD plasma system and an immobilized TiO 2 photocatalysis system is sequentially combined to oxidize the target pollutant. Indeed, different ways to combine sequentially DBD plasma with photocatalytic materials are listed. Results at pilot scale showed that when photocatalyst is placed in the post discharge, the performance of sequential coupling plasma–photocatalyst process is improved in term of decomposition, by-products formation and energy yield. [ABSTRACT FROM AUTHOR]

Organic inorganic hybrid catalyst synthesized by doping of cobalt phthalocyanine (CoPc) on polyaniline support (CoPc/PANI) exhibited higher activity for the oxidation of various alcohols to the corresponding carbonyl compounds in high to excellent yield using molecular oxygen as oxidant and isobutyraldehyde as a sacrificial agent. Notably, the synthesized catalyst was found to be truly heterogeneous in nature and could be easily recovered, recycled for several recycling runs without loss of catalytic activity. [ABSTRACT FROM AUTHOR]

For the controllable transformation of 1,2-propanediol (PDO) and 1,2-butanediol (BDO) in ethylene glycol (EG), the acidity of H-Beta zeolite was modified via ion exchange with NaH 2 PO 4 and Na 2 HPO 4. After the modification, the separation factors for PDO and BDO reached 7.7 and 11.6 (vs 3 on the parent H-Beta). The selectivity to butanal-derived acetal declined to 4% (vs 42% on the parent H-Beta). Therefore, EG consumption was greatly reduced. Lower temperatures were favorable to the formation of acetone, butanone, and 1,3-butadiene, while higher temperatures promoted the acetalization and oligomerization reactions. The ion-exchange treatment increased the stability of zeolite crystalline structure. Microcalorimetry and NH 3 -TPD results indicated that the strong and moderate acid sites with NH 3 adsorption heat ≥140–160 kJ/mol and of 100–110 kJ/mol were responsible for the dehydration and butanal-related acetalization reactions, respectively. In contrast, the propanal-related acetalization reactions were less sensitive to the strength and type of acid sites. On the other hand, butanal can be selectively synthesized from BDO with this catalyst. The acidity of zeolite catalysts can be modulated with this simple approach for the improvement of selectivity to desirable products. • Due to ion exchange, acetalization reactions were largely suppressed while dehydration reactions were barely affected. • Butanal was synthesized with high selectivity on this catalyst through the dehydration reaction of BDO. • The roles of different acid sites in dehydration, acetalization, and oligomerization reactions were clarified. [ABSTRACT FROM AUTHOR]

• Synthesis of grafted and co-condensated ordered mesoporous materials. • Quantification of the amount of active base sites by liquid phase NMR. • Variation of the properties of the basic centre by changing the substitution on the nitrogen atom. • Determination of the turn-over number in the aldol condensation of butyraldehyde. • Proposed reaction mechanism for heterogeneously catalysed aldol condensation. Representative ordered mesoporous silica materials MCM-41 and SBA-15 were synthesized and modified with nitrogen-containing groups by grafting and co-condensation. The created catalytic centers strongly differ in basicity depending on the degree of substitution of the nitrogen atom. Furthermore, the introduced amount also depends on the structure of the modifier as shown by quantitative liquid phase 1H NMR. This allowed to calculate the turnover number in the aldol condensation of n -butanal which changed in the sequence: secondary > primary >> tertiary >> pyridinic basic centers. Corresponding reaction mechanisms considering the special structural features of the modifier are proposed. ig. [Display omitted] [ABSTRACT FROM AUTHOR]

The synthesis of 1,1-diethoxybutane was carried out in a batch reactor from a liquid phase reaction between ethanol and butyraldehyde using Amberlyst 47 as the solid acid catalyst to obtain thermodynamic, kinetic and adsorption parameters. The reaction equilibrium constant was experimentally determined in the temperature range 293.15–323.15 K. The standard properties of the reaction at 298.15 K were also estimated. The effects of temperature, molar ratio of ethanol to butyraldehyde, stirrer speed, and catalyst loading on the reaction rate were investigated. Kinetic experiments were performed in the same temperature range at 6 bar. A two-parameter kinetic law based on a Langmuir–Hinshelwood–Hougen–Watson rate expression, using activity coefficients from the UNIFAC method, was used to predict the experimental data of the heterogeneous liquid-phase reaction. The kinetic parameters were determined based on the kinetic model. The model predicts the kinetic data very well and it will be useful for design and optimization of integrated reaction–separation processes. [ABSTRACT FROM AUTHOR]

Trivalent cation (Co 3+ , Al 3+ , Er 3+ ) containing-kenyaite and magadiite lamellar silicates were synthesized and tested as catalysts for the Knoevenagel condensation of butyraldehyde (BUT) with ethyl cyanoacetate (CAE). The as-synthesized catalysts were thoroughly characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, solid state nuclear magnetic resonance of silicon ( 29 Si NMR) and nitrogen physisorption measurements. Significant effects of the structural and textural features of kenyaite and magadiite on catalyst activity in the Knoevenagel condensation were observed. The high catalytic activity and selectivity were ascribed to the cations incorporated into silicate layers, being Co 3+ and Al 3+ leached from their structures during the reaction. Er 3+ -containing kenyaite exhibited excellent catalytic activity in the Knoevenagel condensation, suggesting that the presence of silanol groups along with trivalent cation was responsible for the exceptional activity of the catalyst at mild conditions. The effects of catalyst loading, type of solvent and temperature on the catalytic properties demonstrated that a 100 mg of catalyst mass and BUT/CAE molar ratio of 1 in the presence of toluene at 90 °C were the best conditions for testing Er 3+ -containing kenyaite and magadiite catalysts. The affinity between Si and Er took place in kenyaite structure and this could explain the better performance of Er 3+ -containing kenyaite, since Er remained in the framework during the reaction. On the contrary, leaching of the erbium in magadiite was responsible for the lesser performance of the solid. [ABSTRACT FROM AUTHOR]

In this study, pretreatment liquor of acid-stored green and yellowish barley silage was used for fermentative acetone-butanol-ethanol (ABE) production. Further, the catalytic oxidation of biobutanol over Pt catalysts was studied to investigate the behaviour of butanol as a fuel in the combustion engine. After the hydrothermal treatment of green and yellowish barley silage followed by enzymatic hydrolysis, approximately 88% and 100% of the available sugars were recovered, respectively. Batch fermentations of pretreatment barley silage liquor, supplemented with gelatinised barley grain, showed good fermentability with total ABE concentrations of 9.0 g/L and 10.9 g/L. Butanol yields of 0.20, 0.17 and ABE yields of 0.28, 0.26 (g/g monosaccharide) were obtained, respectively. In catalytic activity measurements, the conversion of biobutanol became appreciable in the 120-140°C range, whereas conversions greater than 95% were obtained over 200 °C. Selectivities were also high, although formation of by-products, such as butyraldehyde, was observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Emissions evaluation from ethanol and iso-butanol GDI and PFI vehicles. [•] THC, CO, and NOx did not show strong trends with ethanol and blends. [•] PM mass, number, and black carbon emissions were higher for the GDI vehicles. [•] Increasing ethanol and butanol content reduced PM and number emissions. [•] Butanol blends enhanced the formation of butyraldehyde emissions. [Copyright &y& Elsevier]

Highlights: [•] We achieved the highly selective hydroformylation of 3,3,3-trifluoropropene. [•] The use of Xantphos provided linear 4,4,4-trifluorobutanal in 99% selectivity. [•] DMF solvent suppressed the hydrogenation of the substrate resulting in the yield of over 80%. [•] Turnover number reached 500 for 10h reaction by the successive addition of the substrate. [Copyright &y& Elsevier]

[Display omitted] • A model was developed for binary mixture and by-products in PCO. • More than half of the converted inlet VOCs are transformed to by-products. • Aldehydes were identified as major by-products of the binary mixture. • Ratio of butyraldehyde/acetone had a great impact on efficiency and by-products. • Verified model predicted mixture performance at various operating conditions. This research reports the development of a kinetic model to predict binary mixture degradation and by-product generation in a continuous flow Photocatalytic Oxidation (PCO) reactor. Butyraldehyde and acetone were chosen as a binary VOC mixture to validate the model using experiments conducted with a photocatalyst (TiO 2 coated on silica fibers) under various concentration levels (0.1–1 ppm), concentration ratios of target compounds in the mixture (0.5–2), relative humidity levels (17–70%), irradiations (7–23.5 W/m2), and airflow rate (10–30 L/min). Formaldehyde, acetaldehyde, propionaldehyde, butyric acid, propionic acid, and acetic acid were detected as by-products, in which aldehydes had a higher quantity. Carbon balance analysis showed that butyraldehyde and binary mixtures mineralized into carbon dioxide at rates of 19% and 12.8%, respectively. Also, 24% of butyraldehyde and 10% of binary mixture were converted to by-products. Among three proposed scenarios for PCO reaction rate of butyraldehyde, the one including conversion of butyraldehyde directly towards propionaldehyde, acetaldehyde, and formaldehyde, provided the most accurate rate model (R2 = 0.98). Due to its faster reaction rate, butyraldehyde demonstrated a higher degradation efficiency than acetone in the binary mixture. At a constant butyraldehyde concentration, lowering the ratio of butyraldehyde/acetone to 0.5 resulted in the reduction of removal efficiency of butyraldehyde and an increase in concentration of acetaldehyde in air than other by-products. Conversely, enhancing this ratio to 2, led to improved removal efficiency of both butyraldehyde and acetone in the mixture and higher concentration of formaldehyde. Increases in air relative humidity level and velocity resulted in an increase in the outlet concentration of challenge compounds but reduced the formation of all by-products. However, raising the irradiation increased the degradation efficiency of butyraldehyde and binary mixture and, consequently, elevated the formation of by-products. The developed model was capable of properly predicting the concentration of the challenge compounds and their by-products in a binary mixture at different operating conditions. [ABSTRACT FROM AUTHOR]

• A UPLC-QTOF-MS/MS strategy was developed to characterize aliphatic aldehydes. • The robust strategy was based on DNPH capturing combined MDF screening. • The characteristic ions of aldehyde-DNPHs were acquired by analyzing the references. • The strategy was validated to identify aliphatic aldehydes in biological samples. • 6 and 8 aldehydes were identified in serum and supernatant of damaged rat and cell. Aliphatic aldehydes are toxic substances that correlate with the onset of many diseases. However, up to date, the methods to identify aliphatic aldehydes in biological samples are less selectivity and/or robustness. In this study, a strategy based on 2,4-dinitrophenylhydrazine (DNPH) capturing combined with mass defect filtering (MDF) was established and validated to identify aliphatic aldehydes in two biological samples (serum of immunosuppressed rats and oxidative damaged cells). Firstly, the mass spectrometric characteristic ions (m/z 163.01, 163.02 and 191.04) and fragmentation pathways of aldehyde-DNPHs were acquired through analyzing the standard references. Then, biological samples were derivatized by DNPH, a routine reagent, and subsequently assessed on an ultra-performance liquid chromatography coupled time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). Thirdly, the raw chromatogram was processed by MDF method to obtain interference-free chromatogram. Fourthly, the aldehyde-DNPHs were characterized through investigating the mass spectrometric information of each peak referred to the identified characteristic ions and fragmentation pathways. Finally, 6 and 8 aliphatic aldehydes were exclusively identified in serum of immunosuppressed rats and supernatant of oxidative damaged cells. Among which, propanal and butanal were positively correlate with immunosuppression, while formalin was more relevant to oxidative stress. The results demonstrated that the established strategy could robustly characterize the aliphatic aldehydes in biological samples, which would be helpful to evaluate the physical conditions of subjects. [ABSTRACT FROM AUTHOR]

Abstract: Primary amine-guanidines derived from trans-cyclohexane-1,2-diamines are used as organocatalysts for the enantioselective conjugate addition of isobutyraldehyde to arylated and heteroarylated nitroalkenes. The reaction was performed in the presence of imidazole as the additive in aqueous DMF as the solvent at 0°C. The corresponding Michael adducts bearing a new stereocenter were obtained in high yields and with enantioselectivities of up to 80%. Theoretical calculations are used to justify the observed sense of the stereoinduction. [Copyright &y& Elsevier]

Biphasic aldol condensation of n-butyraldehyde (nBAL), catalyzed by aqueous sodium hydroxide solution, is a part of the 2-ethyl hexanol synthesis process. In this study, the intrinsic reaction rate is obtained in the industrially relevant range 110–150°C and 0.76–1.9M NaOH, which is in the mass transfer regime dominated by the reaction in the film. A stirred cell is used to obtain stable interface between the organic and aqueous phases. The reaction dominated mass transfer regime was confirmed by the plateau region experiment and calculations of mass transfer. As a result, considering nBAL solubility and diffusivity, the rate was found to be 1st order in both nBAL and NaOH concentrations, along with 13.5±0.4kcal/mol activation energy. The kinetic parameter sensitivity using different models for solubility, diffusivity and salt effect was also studied. This work demonstrates that, using penetration theory, it is possible to determine intrinsic reaction kinetics in the mass transfer regime, governed by reaction in the film. The results of the present work will be useful for the design and optimization of reactors for the commercial biphasic aldol condensation of nBAL. [ABSTRACT FROM AUTHOR]

Highlights: [•] The mechanisms of CF3CH2CH2CHO with OH radical are studied theoretically. [•] The percentage contributions of all the reaction channels are also reported. [•] values are also reported for the first time. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the kinetics of large molecular weight aldehydes is essential in the context of both conventional and alternative fuels. For example, they are key intermediates formed during the low-temperature oxidation of hydrocarbons as well as during the high-temperature oxidation of oxygenated fuels such as alcohols. In this study, an experimental and kinetic modeling investigation of n-butanal (n-butyraldehyde) and iso-butanal (iso-butyraldehyde or 2-methylpropanal) oxidation kinetics was performed. Experiments were performed in a jet stirred reactor and in counterflow flames over a wide range of equivalence ratios, temperatures, and pressures. The jet stirred reactor was utilized to observe the evolution of stable intermediates and products for the oxidation of n- and iso-butanal at elevated pressures and low to intermediate temperatures. The counterflow configuration was utilized for the determination of laminar flame speeds. A detailed chemical kinetic interpretative model was developed and validated consisting of 244 species and 1198 reactions derived from a previous study of the oxidation of propanal (propionaldehyde). Extensive reaction pathway and sensitivity analysis was performed to provide detailed insight into the mechanisms governing low-, intermediate-, and high-temperature reactivity. The simulation results using the present model are in good agreement with the experimental laminar flame speeds and well within a factor of two of the speciation data obtained in the jet stirred reactor. [Copyright &y& Elsevier]

Abstract: n-Butanal is a key stable intermediate during the combustion of n-butanol, and as such strongly affects its chemical kinetics. In this study, ignition delay times of n-butanal/oxygen diluted with argon were measured behind reflected shock waves in the temperature range of 1100–1650K, at pressures of 1.3, 5 and 10atm, and equivalence ratios of 0.5, 1.0 and 2.0. An n-butanal sub-model was developed on the basis of literature review, and exhibits fairly good agreement with the experimental results under all test conditions. Reaction pathway and sensitivity analysis were conducted to gain an insight into the controlling reaction pathways and reaction steps. [Copyright &y& Elsevier]

Abstract: The synthesis of 2-propylquinolines, a family of antileishmanial agents, is reported. Among the pathways explored, the 3-component Povarov reaction between butyraldehyde, aromatic amines and ethyl vinyl ether in trifluoroethanol (TFE), followed by an oxidation, offers a convenient entry to 2-propylquinolines with various substituents on positions 5–8. [Copyright &y& Elsevier]

Highlights: [•] Reached results are useful for engineering process design for a sustainable glycerol valorization. [•] Mixtures of cyclic acetals are the main products obtained in acetalization reaction. [•] Amberlysts 47 acidic ion exchange resin is highly active and stable in acetals production. [Copyright &y& Elsevier]

Highlights: [•] The retardation effect in acetalization of PVA with butyraldehyde was revealed. [•] The anomalous retardation was observed in dilute polymer solutions. [•] It was explained in terms of the chain conformations. [•] Possible intramolecular cross-linking was also considered. [ABSTRACT FROM AUTHOR]

Abstract: We ever reported that benzaldehyde was more effective than isobutyraldehyde toward the Baeyer–Villiger oxidation of cyclohexanone by using meso-tetraphenylporphyrin chloride (FeTPPCl) as catalyst in the presence of molecular oxygen (96% yield of ɛ-caprolactone in the presence of benzaldehyde vs 11% in the presence of isobutyraldehyde. J. Porphyrins Phthalocyanines 2008, 12, 94–100.). In this paper, the root causes for the remarkable differences in performance have been illuminated from the investigation of kinetic and mechanism. Based on the results of in situ FTIR, UV–vis spectra, and starch/KI experiments, the differences could be attributed to the varied mechanism for the two reaction systems. In the isobutyraldehyde-mediated aerobic Baeyer–Villiger oxidation of cyclohexanone system, peroxy isobutyric acid was the oxidative species to produce ɛ-caprolactone. However, the process was via the generation of high-valent iron porphyrin, which was the active species in the benzaldehyde-mediated Baeyer–Villiger oxidation of cyclohexanone. [Copyright &y& Elsevier]

Abstract: Aldehyde dehydrogenase 1 (ALDH1A1) catalyzes the oxidation of toxic aldehydes to carboxylic acids. Physiologic levels of Mg2+ ions decrease ALDH1 activity in part by increasing NADH binding affinity to the enzyme. By using time-resolved fluorescence spectroscopy, we have resolved the fluorescent lifetimes (τ) of free NADH in solution (τ =0.4ns) and two enzyme-bound NADH states (τ =2.0ns and τ =7.7ns). We used this technique to investigate the effects of Mg2+ ions on the ALDH1A1–NADH binding characteristics and enzyme catalysis. From the resolved free and bound NADH fluorescence signatures, the K D values for both NADH conformations in ALDH1A1 ranged from about 24μM to 1μM for Mg2+ ion concentrations of 0–6000μM, respectively. The rate constants for dissociation of the enzyme–NADH complex ranged from 0.03s−1 (6000μM Mg2+) to 0.30s−1 (0μM Mg2+) as determined by addition of excess NAD+ to prevent re-association of NADH and resolving the real-time NADH fluorescence signal. During the initial reaction of enzyme with NAD+ and butyraldehyde, there was an immediate rise in the NADH fluorescence, due to the formation of bound NADH complexes, with a constant steady-state rate of production of free NADH. As the Mg2+ ion concentration was increased, there was a consistent decrease of the enzyme catalytic turnover from 0.31s−1 (0μM Mg2+) to 0.050s−1 (6000μM Mg2+) and a distinct shift in steady-state conformational population from one that favors the ALDH1–NADH complex with the shorter fluorescence lifetime (33% excess) in the absence of magnesium ion to one that favors the ALDH1–NADH complex with the longer fluorescence lifetime (13% excess) at 6000μM Mg2+. This shift in conformational population at higher Mg2+ ion concentrations and to lower enzyme activity may be due to longer residence time of the NADH in the ALDH1 pocket. The results from monitoring enzyme catalysis in the absence of magnesium suggests that the ALDH1–NADH complex with the shorter fluorescence lifetime is the form initially produced, and the complex with the longer fluorescence lifetime is produced through isomerization. [Copyright &y& Elsevier]

Abstract: A promising alternative for the production of butyraldehyde is the use of n-butanol as raw material. This alcohol can be produced via fermentation from renewable resources. n-Butanol can be converted to butyraldehyde by dehydrogenation or by partial oxidation and for both reactions Cu catalysts show activity. In this work, Cu supported on both pure ZrO2 and ZrO2 modified with CeO2 catalysts were studied in these two catalytic reactions. The catalytic performance and the catalysts characterization (ICP, N2-physisorption, XRD, TPR, and XPS) suggest that the catalyst with the best Cu dispersion was the most active and stable in n-butanol dehydrogenation. However, in n-butanol partial oxidation, the initial dispersion of Cu on the supports is deteriorated during the time on stream, being Cu sintering and oxidation the main causes of the lower butyraldehyde yield observed in this catalytic process. [Copyright &y& Elsevier]