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The hygroexpansion of paper was significantly reduced, up to 28% lower amplitude of change when the paper was subjected to a change in relative humidity from 20 to 85% RH, by oxidation of the fibre wall. Never-dried bleached kraft fibres were oxidised with sodium periodate, which specifically oxidises the C2–C3 bond of 1,4-glucans so that the cellulose is partly converted into dialdehyde cellulose. Since both the dry and wet strength of laboratory sheets were significantly improved, the dry tensile strength increased from 24 kNm/kg up to 66 kNm/kg and the relative wet tensile strength increased from 1.5% up to 40%, it is suggested that the aldehydes form hemiacetal linkages within the fibre wall during the consolidation and drying of the sheets. The mechanical, hygroexpansive and moisture sorptive properties of the sheets made from the oxidised fibres were studied. The results showed that the main reason for the reduced hygroexpansion was a decrease in moisture sorptivity, i.e. when the sheets made of fibres with different degrees of cross-linking were subjected to the same change in relative humidity, the more cross-linked fibres showed a smaller change in moisture content. It was also shown that the hygroexpansion coefficient, i.e. the moisture-normalised dimensional change, was not significantly changed by the periodate oxidation, i.e. indicating that there are no improvement in dimensional stability if the paper is subjected to a specific amount of water. [ABSTRACT FROM AUTHOR]

A facile route for the large scale production of graphene oxide (GO) papers and their mechanical enhancement has been presented in this work. The novel paper-like GO made from individual GO sheets in aqueous suspension can be achieved in large scale by a simple drop casting method on hydrophobic substrates. Significant enhancement in mechanical stiffness (341%) and fracture strength (234%) of GO paper have been achieved upon modification with a small amount (less than 10 wt%) of glutaraldehyde (GA). The cross-linking reaction takes place between hydroxyl groups on the surface of GO and aldehyde groups of GA, through forming hemiacetal structure, which can result in distinct mechanical enhancement of the GO papers. [ABSTRACT FROM AUTHOR]

For more cost-effective and/or value-added utilization of cellulosic fibers in pulp and paper industry, fiber engineering is an important concept. Essentially, fibers can be engineered via various mechanical, chemical, and biological processes. In the current study, the combined use of laccase and TEMPO was applied to introduce carboxyl and aldehyde groups to softwood-derived cellulosic fibers (bleached softwood kraft pulp). The process conditions in preparation of the engineered fibers were optimized. Under the conditions studied, the maximum increases in carboxyl and aldehyde contents were 360 % and 225 %, respectively. The effectiveness of the laccase/TEMPO system could be well explained by the reaction cycles in catalytic oxidation pathways. The findings of the current work may provide useful insights into the enzymatic modification of cellulosic fibers for papermaking applications. [ABSTRACT FROM AUTHOR]

Proper reaction conditions have been found for the conversion of geraniol, citronellol, trans-2-penten-1-ol and 1-pentanol to the corresponding aldehydes with good chemo-selectivity (>70%) by photochemical excitation of suspensions of P25-TiO2. It is demonstrated that adsorption of the alcohol on the surface as an alcoholate is necessary for its oxidation. ESR-spin trapping experiments point out that oxidation of alcohols starts with the formation of alkoxide radicals. Water content in the dispersing medium strongly inhibits alcohol adsorption and subsequent oxidation. In fact, water increases the polarity of the dispersing medium favouring the affinity between the polar alcohol and the CH3CN–H2O mixture itself; moreover, water competitive adsorption with the alcohol causes the removal of the latter from the photocatalytic surface with consequent difficult oxidation, as evidenced by ESR-spin trapping investigation. The reactivity of the alcohol on the surface of photoexcited P25-TiO2is also affected by the nature of its hydrophobic aliphatic chain: geraniol and citronellol are more susceptible to the water content than their short analogues trans-2-penten-1-ol and 1-pentanol. Moreover, in anhydrous CH3CN, specific interaction between the surface and the OH group enhances the reactivity of the primary aliphatic alcohols towards their partial oxidation to aldehyde, which can be accumulated in the reaction environment. [ABSTRACT FROM AUTHOR]

The paper presents the results of a theoretical analysis of the low-frequency region of the vibrational spectrum and calculations of the internal rotation of model molecules containing a four-membered carbocyclic fragment and a CHO formyl group bonded with it in the anharmonic approximation. The influence of the form of the potential energy surface (PES) and the behavior of kinematic factors on the values of torsion frequencies is considered. The possibility of a pronounced kinematic relationship between the internal rotation and other low-frequency modes is examined. [ABSTRACT FROM AUTHOR]

The article cites a study which reports on the removal of fluoride contents from water bodies using a submerged plant, Hydrilla verticillata Royle under laboratory and field conditions. The effect of fluoride on chlorophyll, protein, cysteine and malondialdehyde contents has been studied under laboratory conditions. The plants of Hydrilla verticillata Royle were collected from unpolluted water bodies in and around Lucknow, India and acclimatized for 6 months in laboratory campus. In laboratory experiments, part of the harvested plants were blotted using blotting paper to remove excess water and used for the estimation of chlorophyll, protein, cysteine and malondialdehyde contents.

The article reports on turning acetaldehyde as a substrate for organic synthesis. At the Max Planck Institute for Coal Research, Benjamin List and his group managed to use acetaldehyde in the Mannich reaction that allows an opportunity to a range of applications in drug design. List's group combined acetaldehyde with N-Boc-imines in Mannich reaction that formed a single enantiomer. They have tried to improve the yield wherein they successfully optimized the reaction and synthesize a new anti-AIDS drug and other active substances.

Formaldehyde (FA) is frequently used to embalm human cadavers that are employed to teach gross anatomy to medical and dental students. However, exposure to FA is harmful to both students and educators. The aim of this study was to reduce the FA levels in the anatomy dissection hall by spraying an FA scavenger solution. We measured the changes in FA levels after administering FA scavenger solutions to liquid, wet paper towels, organs, and cadavers containing FA. Among L-cysteine, N-ethyl urea, and urea, the latter was found to have the strongest scavenging power towards the FA in the liquid. The molar concentration of urea that most efficiently reduced the levels of volatilized FA from the wet paper towels was the same as that of the FA. After spraying the urea solution, the volatilized FA levels immediately decreased, reaching their minimum at 60 min, and remained low even after 240 min. Spraying the urea solution onto the organs reduced the levels of FA volatilized from the surfaces of organs but not those from the insides of the organs. In the dissection hall used for the gross anatomy course at Tokyo Medical University, the FA levels were significantly decreased after spraying the urea solution onto the cadavers. Moreover, dissection could be performed without the cadavers putrefying during the 4-month course. These results indicate that various institutes could use urea solution spray to effectively reduce the FA levels in the dissection hall and thus ensure the safety of students and educators. [ABSTRACT FROM AUTHOR]

In this paper, a novel and efficient method for the preparation of new indeno[1,2-b]chromene derivatives is reported. This synthetic method comprises one-pot and three-component condensation reaction between various aryl aldehydes, indane-1,3-dione and 4-hydroxychromen-2-one in the presence of Fe3O4@SiO2@(CH2)3OPO3H2 as novel solid acid nanocatalyst. The structures of the synthesized products were identified by MR and elemental analysis. [ABSTRACT FROM AUTHOR]

Enhancing the effectiveness of a laccase-TEMPO treatment on sisal pulp by increasing pulp consistency was for the first time found to increase the biorefining potential of this enzyme-mediator system. The operating conditions used were those previously found to maximize oxidative functionalization and paper strength. Prior to the enzyme treatment, the pulp was refined at a variable intensity (0, 3,000 and 4,500 revolutions) in order to ascertain whether the increased surface area would lead to enhanced functionalization and boost the refining effect as a result. Increasing pulp consistency increased the contents in aldehyde and carboxyl groups by 130% and 94%, respectively. Also, it resulted in more marked reduction of pulp viscosity during the enzyme treatment, especially at a high refining intensity; this had a detrimental effect on fibre strength and significantly reduced tear strength in the refined pulp. Oxidized pulp exhibited a considerably increased water retention value with respect to the initial pulp, particularly after refining. Dry tensile index was increased by 21, 18 and 12%, and burst index by 23, 16 and 13% at 0, 3,000 and 4,500 rev, respectively, by the laccase-TEMPO treatment as a result of increased inter-fibre hydrogen bonding offsetting the loss of fibre strength, an effect that can provide substantial savings in refining energy. Based on the results, a laccase-TEMPO treatment is an enzymatic booster of mechanical refining with the added advantages of providing unaltered drainability and increased air permeability. The most salient effect of the laccase-TEMPO treatment was an increase in wet tensile strength (by 160, 553 and 588% at 0, 3,000 and 4,500 rev, respectively) that can be ascribed to inter-fibre covalent bonding through hemiacetal linkages promoted by aldehyde groups. The improvement was much greater than that obtained at a lower consistency under identical conditions. [ABSTRACT FROM AUTHOR]

The two major aldehydes ( E)-2-hexenal and ( E)-2-octenal emitted as defensive secretions by bed bugs Cimex lectularius L. (Hemiptera: Cimicidae), inhibit the in vitro growth of an isolate of Metarhizium anisopliae sensu lato ( s.l.) (Metsch.) Sokorin (Hypocreales: Clavicipitaceae) (ARSEF 1548). These chemicals inhibit fungal growth by direct contact and via indirect exposure ('fumigation'). Fumigation with ( E)-2-octenal for as little as 0.5 h was sufficient to inhibit all fungal growth. Bed bugs placed on filter paper treated with an isolate of M. anisopliae s.l. conidia in the absence of ( E)-2-octenal exhibited 99 % mortality after one week. However, bed bugs placed on fungal-treated filter paper and exposed to ( E)-2-octenal at 1 h experienced 10 % mortality. The inhibition of fungal growth by bed bug aldehydes is discussed in the context of other biotic and abiotic barriers to infection. [ABSTRACT FROM AUTHOR]

Due to their enhanced reactivity, metal and metal-oxide nanoscale zero-valent iron (nZVI) nanomaterials have been introduced into remediation practice. To ensure that environmental applications of nanomaterials are safe, their possible toxic effects should be described. However, there is still a lack of suitable toxicity tests that address the specific mode of action of nanoparticles, especially for nZVI. This contribution presents a novel approach for monitoring one of the most discussed adverse effects of nanoparticles, i.e., oxidative stress (OS). We optimized and developed an assay based on headspace-SPME-GC-MS analysis that enables the direct determination of volatile oxidative damage products (aldehydes) of lipids and proteins in microbial cultures after exposure to commercial types of nZVI. The method employs PDMS/DVB SPME fibers and pentafluorobenzyl derivatization, and the protocol was successfully tested using representatives of bacteria, fungi, and algae. Six aldehydes, namely, formaldehyde, acrolein, methional, benzaldehyde, glyoxal, and methylglyoxal, were detected in the cultures, and all of them exhibited dose-dependent sigmoidal responses. The presence of methional, which was detected in all cultures except those including an algal strain, documents that nZVI also caused oxidative damage to proteins in addition to lipids. The most sensitive toward nZVI exposure in terms of aldehyde production was the yeast strain Saccharomyces cerevisiae, which had an EC50 value of 0.08 g/L nZVI. To the best of our knowledge, this paper is the first to document the production of aldehydes resulting from lipids and proteins as a result of OS in microorganisms from different kingdoms after exposure to iron nanoparticles. [ABSTRACT FROM AUTHOR]

Periodate oxycellulose was subjected to alkaline hydrolysis at room temperature in both homogeneous (cupriethylenediamine) and heterogeneous (sodium hydroxide) medium, and the degradation kinetics was followed for nearly three months. By comparing the obtained results with the degradation kinetics of both hydrocellulose and periodate oxycellulose reduced with tert-butylamine borane, it was demonstrated that the β-alkoxy fragmentation of oxidised sites is a very fast reaction, which reaches completeness during the preparation of samples for viscometric analyses. The subsequent degradation is due to other mechanisms, such as autoxidation and peeling. A comparison between the degrees of polymerisation of periodate oxycellulose before and after its reduction allows the quantitative determination of dialdehyde groups, without the interference of reducing end groups. Although this technique might not be valid for other kinds of oxycellulose, it supplies a simple and fast method for the analysis of mildly oxidised cellulose. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study to perform low temperature spray coating polymer dielectric process with good conformal deposition on aspect ratio features (2:1) through silicon via (TSV) CMOS image sensor (CIS) wafer-level-packaging. In this study, one kind of phenolic aldehyde polymer is deposited on the sidewall of though silicon via by spray coating process. Individual conditions that affect the weak-point of polymer dielectric on the TSV sidewall and step coverage such as nitrogen gas pressure, polymer so lution flow rate and temperature are investigated. The optimal condition is used to deposit into TSVs by spray coating process. The results turn to give excellent step coverage and satisfied weak-point (>2 µm) on the sidewall of though silicon via with the diameter of 65 µm and depth of 130 µm. [ABSTRACT FROM AUTHOR]

The composition and nature of changes in the low-molecular-weight metabolome (LMWM) of Potamogeton perfoliatus L. growing in six biotopes of Lake Ladoga with different types of anthropogenic load have been analyzed. According to the results, it is found that the total number of low-molecular-weight organic compounds (LMWOCs) in the P. perfoliatus LMWM composition is directly dependent on anthropogenic load, which is well marked by the development of cyanobacteria. The greater the intensity of pollution or eutrophication of waters, or the higher the number of cyanobacteria, the lower the total number of LMWOCs and their concentration. A strongly pronounced dependence of the total concentrations of groups of LMWM compounds on the anthropogenic disturbance of the biotope and the concentration of cyanobacteria is revealed. A decrease in the number, relative amount, total concentration of carboxylic acids, and number and content of unsaturated fatty acids and an increase in the composition and content of phenols and the total content of aldehydes and ketones depends on an increase in anthropogenic pressure. The specific composition of the LMWM of claspingleaf pondweed depends on its response to biotic and abiotic factors of the aquatic (including anthropogenic) environment. The features of the change in the composition of the P. perfoliatus LMWM make it possible to use it as an integral indicator of the anthropogenic impact on the littoral biotopes of water bodies and the deterioration of their ecological state. [ABSTRACT FROM AUTHOR]

Fungicidal effect of 2-amino-4-nitrophenol and its derivates, prepared by replacing the hydrogen atom in its amino group by different organic radicals was studied. Evaluation of the biological activity of studied substances by сomputational chemistry methods was performed. Toxicity of 2-amino-4-nitrophenol and synthesized N-(2-hydroxy-5-nitrophenyl)formamide and N-(2-hydroxy-5-nitrophenyl)acetamide to six species of phytophatogen fungi were tested in the experiment. The results of the study demonstrate that replacement of the hydrogen atom in the amino group by a aldehyde group leads to an increase in fungicidal activity with respect to Rhizoctonia solani and Bipolaris sorokiniana. A replacement of the hydrogen atom by a ketone group increases the inhibitory effect on Sclerotinia sclerotiorum and Venturia inaequalis. The paper contains comparative data on the fungicide effect of commercial preparation for studied fungi also. [ABSTRACT FROM AUTHOR]

This paper presents an ecological protocol for Knoevenagel condensation using a catalytic amount of 4,4′-trimethylenedipiperidine as a versatile, efficient, safe, commercially available, inexpensive, and recyclable organocatalyst by a ball-milling process at room temperature. The scope of the present protocol was explored and demonstrated for Knoevenagel condensation of the active methylene, such as Meldrum's acid with various aryl and heteroaryl aldehydes. The developed protocol provides a good to excellent conversion of various aldehydes to respective Knoevenagel products in an environmentally friendly process. Furthermore, this efficient process displays a combination of the synthetic virtues of conventional Knoevenagel condensation with ecological benefits and the convenience of a facile mechanochemistry procedure. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a series of catalysts of (0.5-10 wt%) Ce2(MoO4)3 supported on SiO2 gel were synthesized via a precipitation assisted impregnation method. The original and calcined catalysts were extensively characterized by TG-DTA, TEM, XRD, FTIR, N2 sorption analysis and acidity measurements. The catalytic activity successfully tested for the direct dehydrogenation of methanol into formaldehyde. Results revealed that, the complete conversion of methanol, with selectively of 100%, to formaldehyde was achieved at 350 °C and about 95% conversion obtained at 325 °C. In addition, a strong correlation between the catalytic activity and acidity was observed. Moreover, the moderate strength of Brønsted acid sites created on the surface of catalyst plays the main role in the production of formaldehyde. Finally, the catalyst exhibited a unique stability towards anhydrous formaldehyde formation up to a duration time of 200 h.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Functional group interconversion is an important asset in organic synthesis. Phenols/anilines being naturally abundant and the carbonyl being the most common in a wide range of bioactive molecules, an efficient conversion is of prime interest. The reported methods require transition metal catalyzed cross coupling which limits its applicability. Here we have described a method for synthesizing various aldehydes and ketones, starting from phenol and protected anilines via Csp2-O/N bond cleavage in a one-pot/stepwise manner. Our synthetic method is found to be compatible with a diverse range of phenols and anilines carrying sensitive functional groups including halides, esters, ketal, hydroxyl, alkenes, and terminal alkynes as well as the substitution on the aryl cores. A short-step synthesis of bioactive molecules and their functionalization have been executed. Starting from BINOL, a photocatalyst has been designed. Here, we have developed a transition metal-free protocol for the conversion of phenols and anilines to aldehydes and ketones. For the carbonylation reactions to synthesize aldehyde, ester, amide, and other carbonyl derivatives, a transition metal-free and CO- free reaction was challenging but highly demanded. Here, the authors report a transition metal-free and CO- free method for deoxygenetive/denitrogenetive conversion of phenols and anilines to aldehydes and ketones. [ABSTRACT FROM AUTHOR]

The present paper reports on the use of CeO2 materials supported palladium chloride catalyst for selectively oxidising organic alcohols into aldehydes. Spherical, microsized rod-shaped and spindle-like CeO2 particles are synthesised and characterised by SEM. The catalysts are prepared by loading palladium chloride onto the CeO2 support matrix. A complete characterization of the catalysts is performed. The activity of catalysts is studied by the selective oxidation of various alcohols. The results show that (1) the catalytic activities prepared by spherical cerium are superior to the catalysts prepared by spindle-like or rod-shaped cerium and (2) the catalyst PdCl2/CeO2 (nanospheres) show good activity, high yield, and good stability. [ABSTRACT FROM AUTHOR]

Abstract  X-ray Photoelectron Spectroscopy (XPS) was used to characterize the functional groups present on regenerated cellulose films after mild oxidation with TEMPO–NaBr–NaClO and the results were correlated with the adhesion forces holding together two wet cellulose films laminated with a thin (i.e. less than 10 mg/m2) layer of polyvinylamine (PVAm). There was no correlation between adhesion and carboxyl content, whereas wet adhesion was proportional to the total content of aldehyde and hemiacetal groups on the cellulose. It is proposed that aldehyde groups react with neighboring cellulose chains to form hemiacetals which serve as crosslinks strengthening the cellulose surface. The hemiacetals can also be attacked by primary amines to give imine and aminal covalent linkages to the PVAm adhesive layer. [ABSTRACT FROM AUTHOR]

10-Methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives are significant class of compounds and this is critical to develop methods in water using commercially available and non-toxic catalysts. In this paper, an efficient method is introduced for the synthesis of 10-methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives. For the synthesis of the desired products, a multicomponent reaction was designed and performed between 4-hydroxycoumarin, an aldehyde, 6-methyl-2H-pyran-2,4(3H)-dione, and ammonium acetate. The products are obtained under green conditions in water in the presence of a catalytic amount of L-proline (10 mol%). The advantage of this method is no need to any toxic solvent, which is critical from the environmental viewpoint. A possible mechanism was suggested, which confirms the role of L-proline in the reaction as the catalyst. [ABSTRACT FROM AUTHOR]

Advanced glycation end products (AGEs) are a group of proteins and lipids becoming glycated and oxidized after persistent contact with reducing sugars or short-chain aldehydes with amino group and/or high degree of oxidative stress. The accumulation of AGEs in the body is a natural process that occurs with senescence, when the turnover rate of proteins is reduced. However, increased circulating AGEs have been described to arise at early lifetime and are associated with adverse outcome and survival, in particular in settings of cardiovascular diseases. AGEs contribute to the development of cardiac dysfunction by two major mechanisms: cross-linking of proteins or binding to their cell surface receptor. Recently, growing evidence shows that high-molecular weight AGEs (HMW-AGEs) might be as important as the characterized low-molecular weight AGEs (LMW-AGEs). Here, we point out the targets of AGEs in the heart and the mechanisms that lead to heart failure with focus on the difference between LMW-AGEs and the less characterized HMW-AGEs. As such, this review is a compilation of relevant papers in the form of a useful resource tool for researchers who want to further investigate the role of HMW-AGEs on cardiac disorders and need a solid base to start on this specific topic. [ABSTRACT FROM AUTHOR]

Static headspace is an easy to perform, convenient, and usually automated method for extraction of volatiles from various food matrices. Among other applications, it is used also for monitoring of volatile lipid oxidation products. However, the biggest disadvantage of this method is its low sensitivity especially when compared to such techniques as solid-phase microextraction or dynamic headspace. This paper focuses on the comparison of static headspace analysis of volatile lipid oxidation products with a modification of this technique, where volatiles extracted multiple times from oil matrix in a headspace vial are trapped on Tenax trap and subsequently desorbed into gas chromatograph. Twenty volatile compounds (mainly alkanals, 2-alkenals, ketones, and alcohols being volatile lipid oxidation products) in rapeseed oil were used for method comparison. For all compounds, a significant increase in method sensitivity and improvement of limits of detection (10 to 33 times) depending on the compound were noted; however, the repeatability was worse (for 16 out of 20 compounds) and carry-over values (also 16/20) were higher for combined headspace/trapping method. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to compare the role of UV light and of electric discharges, the two most important sources of energy on the primitive earth, in the synthesis of organic compounds out of a reducing model of that atmosphere. Since Miller's experiments in 1953, most of the experimental simulations have been performed with electric discharges, and it has been assumed that UV radiations would give similar results. In order to check this assumption we have performed both experimental simulations in our laboratory. Experimental results indicate that this assumption was wrong in a large extent. Our four main conclusions are: [ABSTRACT FROM AUTHOR]

In contemporary drug discovery, enhancing the sp3-hybridized character of molecular structures is paramount, necessitating innovative synthetic methods. Herein, we introduce a deoxygenative cross-electrophile coupling technique that pairs easily accessible carboxylic acid-derived redox-active esters with aldehyde sulfonyl hydrazones, employing Eosin Y as an organophotocatalyst under visible light irradiation. This approach serves as a versatile, metal-free C(sp3)−C(sp3) cross-coupling platform. We demonstrate its synthetic value as a safer, broadly applicable C1 homologation of carboxylic acids, offering an alternative to the traditional Arndt-Eistert reaction. Additionally, our method provides direct access to cyclic and acyclic β-arylethylamines using diverse aldehyde-derived sulfonyl hydrazones. Notably, the methodology proves to be compatible with the late-stage functionalization of peptides on solid-phase, streamlining the modification of intricate peptides without the need for exhaustive de-novo synthesis. Enhancing the sp3-hybridized character of molecular structures in drug discovery is paramount. Here, the authors introduce a deoxygenative cross-electrophile coupling technique that pairs easily accessible carboxylic acid-derived redox-active esters with aldehyde sulfonyl hydrazones, employing Eosin Y as an organophotocatalyst under visible light irradiation. [ABSTRACT FROM AUTHOR]

Upgrading ethanol to long-chain alcohols (LAS, C6+OH) offers an attractive and sustainable approach to carbon neutrality. Yet it remains a grand challenge to achieve efficient carbon chain propagation, particularly with noble metal-free catalysts in aqueous phase, toward LAS production. Here we report an unconventional but effective strategy for designing highly efficient catalysts for ethanol upgrading to LAS, in which Ni catalytic sites are controllably exposed on surface through sulfur modification. The optimal catalyst exhibits the performance well exceeding previous reports, achieving ultrahigh LAS selectivity (15.2% C6OH and 59.0% C8+OH) at nearly complete ethanol conversion (99.1%). Our in situ characterizations, together with theoretical simulation, reveal that the selectively exposed Ni sites which offer strong adsorption for aldehydes but are inert for side reactions can effectively stabilize and enrich aldehyde intermediates, dramatically improving direct-growth probability toward LAS production. This work opens a new paradigm for designing high-performance non-noble metal catalysts for upgrading aqueous EtOH to LAS. Achieving efficient carbon chain propagation remains a grand challenge for ethanol upgrading. Here, the authors report sulfur doped Ni@C-Sx catalysts with controllably exposed nickel sites that can dramatically improve direct-growth probability towards long-chain alcohols production. [ABSTRACT FROM AUTHOR]

The formal C–C bond insertion into aldehydes is an attractive methodology for the assembly of homologated carbonyl compounds. However, the homologation of aldehydes has been limited to diazo approach and the enantioselective reaction was rarely developed. Herein, we report an asymmetric formal C–C bond insertion into aldehydes through diyne cyclization strategy. In the presence of Cu(I)/SaBOX catalyst, this method leads to the efficient construction of versatile axially chiral naphthylpyrroles in moderate to excellent yields with good to excellent enantioselectivities. This protocol represents a rare example of asymmetric formal C–C bond insertion into aldehydes using non-diazo approach. The combined experimental and computational mechanistic studies reveal the reaction mechanism, origin of regioselectivity and stereoselectivity. Notably, the chiral phosphine ligand derived from synthesized axially chiral skeleton was proven to be applicable to asymmetric catalysis. The formal C–C bond insertion into aldehydes is an attractive methodology for the assembly of homologated carbonyl compounds but the homologation of aldehydes has been limited to diazo approach and the enantioselective reaction was rarely developed. Here, the authors report an asymmetric formal C–C bond insertion into aldehydes through diyne cyclization strategy [ABSTRACT FROM AUTHOR]

TS-1 with different Ti/Si molar ratios (0.02 for TS-1a, 0.025 for TS-1b, 0.03 for TS-1c), and Ti–K (TiO2-SiO2) catalysts were prepared through a hydrothermal procedure and characterized by the XRD, BET, SEM/TEM, XPS/ICP, Raman, UV–Vis, FT-IR/Py–IR, and NH3–TPD for gas-glycerol value-added conversion. The acidic [(Ti, Si)O4] sites were considered to be the reactive centers for acetaldehyde production with the selectivity closely related to the concentration of [(Ti, Si)O4] and Smicro/SBET values but not the PyB/PyL value or surface acid density. The [(Ti, Si)O4] in MFI micro-structure promoted acetaldehyde production by 1–2 dehydration and subsequent cracking of gas-glycerol, better than the [(Ti, Si)O4] without MFI micro-structure. Over the TS-1c, gas-glycerol conversion reached 91.5%, with the selectivity towards acetaldehyde and acrolein reaching 34.4% and 29.5%, respectively. Significantly, the catalytic stability of the TS-1c can be obviously improved by using liquid feed of a glycerol-methanol solution. TS-1c (3.3%) showed glycerol catalytic conversion reached 91.5 % with the selectivity of acetaldehyde and acrolein reaching about 34.4 %, and 29.5 %, respectively. The acidic [(Ti, Si)O4] was confirmed to be the reactive centers for acetaldehyde production, especially for the [(Ti, Si)O4] in MFI micro-structure (with b-axis 300 nm, micro-pores 5.8 Å) promoted acetaldehyde production from 1 to 2 and 1–3 dehydration of glycerol. It was new found the catalytic stability of TS-1c can be obviously improved as using liquid feed of glycerol-methanol solution. [ABSTRACT FROM AUTHOR]

The paper presents results concerning the changes in the content of aldehydes in samples of lake water collected near the lake surface. The study of lake waters was undertaken to explain which physicochemical parameters of the environment have the greatest influence on the level of aldehydes, which of the aldehydes are most often met in surface water and in what concentrations. We observed that formaldehyde, acetaldehyde, propanal, glyoxal, methylglyoxal and acetone were commonly present in surface water samples, while semi-volatile and poorly soluble aldehydes such as nonanal and decanal were observed seasonally. The contents of total aldehydes varied in a wide range, from 55 to 670 μg/l, and the concentration of total organic carbon varied significantly from 3 to 18 mg /l, but there was no evident correlation between them in all of samples. The total content of aldehydes did not depend on the meteorological parameters such as air temperature, UV radiation and ozone concentration; however, it was noted that the level of carbonyl concentration is related to the period of intense precipitation: in the period of very low precipitations, the highest contents of total aldehydes were determined in all of the water samples, and in the periods of intense precipitations, the content of total aldehydes was drastically smaller. [ABSTRACT FROM AUTHOR]

Unsaturated alcohols, usually produced from selective hydrogenation of unsaturated aldehydes, are important fine chemical intermediates used to synthesize pharmaceuticals and flavoring materials. Acrolein, the smallest member in α, β-unsaturated aldehydes, is the model system for studying selective hydrogenation of α, β-unsaturated aldehydes. So far most theoretical work is about adsorption and reactions of acrolein and its related species on surfaces. In the present paper we systematically studied the geometries, electronic structures, stability and transformation of various species derived from stepwise hydrogenation of acrolein in the gas phases. We identified the most stable intermediates for each system and determined the energy barrier for intermolecular conversion between isomers for various species with different content of hydrogen. All these results are valuable and informative for understanding the surface chemistry of hydrogenation of α, β-unsaturated aldehydes. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Baylis-Hillman reaction between an aldehyde and an activated alkene, such as alkyl vinyl ketones, acrylates, acrylonitrile, and vinylsulfones, giving the β-hydroxy-α-methylene carbonyl compounds, is a versatile and atom-economical carbon-carbon bond-forming reaction. This reaction usually is catalyzed by strong Lewis bases such as tertiary amines and suffers from slow reaction rate. In this paper the Baylis-Hillman reaction between arylaldehydes and methyl vinyl ketone was successfully realized by a catalytic amount of l-proline and l-histidine system to give the corresponding normal Baylis-Hillman adducts in moderate to high yields for the first time. The effects of solvent and reagent electro property on the yields of this reaction were also investigated. Proline and histidine are naturally widely present amino acids in food system; furthermore, aldehydes and activated alkenes can also be easily produced in food processing, so proline and histidine co-catalyzed Baylis-Hillman reaction may find application in explaining some phenomena in food processing. [ABSTRACT FROM AUTHOR]

The ultimate goal in this paper has been developed for the synthesis of structurally various bromomethyl cyclopropane via an α-bromoketone and/or aldehydes with ethyl cyanoacetate or malononitrile and cyanogen bromide (BrCN) in the presence of Et3N to give products in excellent yields within about 3 s. All structures were characterized by IR, 1H-NMR, 13C-NMR, and Mass spectroscopy techniques. The reaction mechanism was discussed. [ABSTRACT FROM AUTHOR]

Trifluoroacetic acid as an efficient catalyst promoting the Dakin-West reaction at ambient temperature is reported for the first time in this paper. A few efficacious auxiliary catalysts were also developed for the Dakin-West reaction. A variety of substituted aryl aldehydes and aryl ketones were found to be applicable to the preparation of some new β-acetamido-β-arylpropiophenones. This procedure has several advantages such as high yields, short reaction time, and smaller amount (0.30 mol%) of catalyst. [ABSTRACT FROM AUTHOR]

The title compounds (bis(alkenoyl) ketene dithioacetals) were prepared starting from the cyclic acyl ketene dithioacetal and aromatic aldehydes. These compounds were characterized by IR, H NMR, mass spectral studies and X-ray crystal structure analysis. The bis(furyl) ketene dithioacetal crystallized in the space group $$ P{\bar{\text{1}}} $$ with unit cell dimensions a = 7.7626(12) Å, b = 9.0217(13) Å, c = 26.827(5) Å, α = 86.271(14)°, β = 87.643(14)°, γ = 66.286(11)° and the structure was refined to an R-factor of 0.0528 while bis(thienyl) ketene dithioacetal crystallized in the space group P2/c with unit cell dimensions a = 10.2433(9) Å, b = 10.4142(6) Å, c = 18.0973(18) Å, β = 106.0° and the structure was refined to an R-factor of 0.0446. The ketenedithioacetal functionality present between the carbonyl groups prevents the possibility of keto-enol tautomerization in these compounds. In both the crystal structures, the crystal packing is stabilized by C-H···O hydrogen bonds as well as van der Waals interactions. Graphical Abstract: The details regarding the synthesis, spectroscopic analysis and crystal structures of the title compounds are reported in this paper.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Following gradual shift of primary resources from fossil towards renewable ones in chemical industry, biomass based ethanol has been attracting growing interests as a fuel to replace gasoline and as a chemical feed stock to replace ethylene. This paper reviews major work reported in the last 10 years for the production of acetaldehyde, acetic acid, and other related compounds from ethanol. At present acetic acid can be industrially produced more economically from methanol than from ethylene, the production of acetic acid from ethanol is not profitable. Acetaldehyde, which is more expensive than ethanol, can be selectively produced in gas phase by dehydrogenation over supported Cu catalysts and by oxidation with O over V and Mo based oxides. It is noteworthy that gold nanoparticles deposited on basic and acidic metal oxides are highly selective to acetaldehyde by oxidation with O. Acetic acid can be produced in water solvent over Au catalysts supported on MgAlO or on Cu doped NiO, while in gas phase over Mo-V-Nb mixed oxides combined with TiO colloids. [ABSTRACT FROM AUTHOR]

Triazolaminoquinoleine is rapidly formed in formulations of alprazolam tablets in presence of excipients, and its generation is speeded up with increasing temperature and humidity. The present paper deals with detailed quantitative and qualitative studies into the nonactive constituents of the formulation in order to determine the excipient (or the mixture) responsible for the degradation. Our studies have demonstrated that reducing carbohydrate excipients play a fundamental role in the generation of triazolaminoquinoleine, with lactose as the main one responsible, through a Maillard reaction. In order to demonstrate the validity of the proposed degradation mechanism, p-nitrobenzaldehyde has been employed as a model of reaction of the nucleophylic attack of amino-opened structure of alprazolam to an aldehyde to generate the first intermediate involved in Maillard reaction, a Schiff base. This model enables the identification of all the intermediates by mass spectrometry and/or nuclear magnetic resonance techniques, with the outcome of this experiment leading to a full understanding of the generation pathway. Calcium carbonate has been proposed as a possible tablet diluent replacing lactose in the pharmaceutical formulation. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl4·4H2O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant. [ABSTRACT FROM AUTHOR]

Branched aldehydes, such as 2-methyl propanal and 2- and 3-methyl butanal, are important flavour compounds in many food products, both fermented and non-fermented (heat-treated) products. The production and degradation of these aldehydes from amino acids is described and reviewed extensively in literature. This paper reviews aspects influencing the formation of these aldehydes at the level of metabolic conversions, microbial and food composition. Special emphasis was on 3-methyl butanal and its presence in various food products. Knowledge gained about the generation pathways of these flavour compounds is essential for being able to control the formation of desired levels of these aldehydes. [ABSTRACT FROM AUTHOR]

Abstract  This paper describes an hybrid procedure for mechanical characterization of biological membranes. The in-plane displacement field of a glutaraldehyde treated bovine pericardium patch obtained with an equi-biaxial tension test is measured with intrinsic moiré and then compared with finite element predictions. Preliminary analysis of moiré patterns observed in the experiments justifies the assumption of the constitutive model based on transversely isotropic hyperelasticity. In order to determine the 16 hyperelastic constants included in the constitutive model and the fiber orientation, the difference Ω between displacement values measured with moiré and their counterpart determined numerically is minimized by means of multi-level and multi-point simulated annealing. Results clearly demonstrate the efficiency of the identification procedure presented in this research: in fact, residual difference between experimental data and numerical values of in-plane displacements is less than 2%. In order to validate the entire identification process, another experimental test is conducted by inflating the same specimen. Out-of-plane displacements, now measured with projection moiré, are compared with predictions of a new finite element model reproducing the experimental test. The 16 hyper-elastic constants previously determined are given in input to the inflation test FE model. Remarkably, experimental and numerical results are again in excellent agreement: maximum percent error on w-displacement is less than 3%. [ABSTRACT FROM AUTHOR]

Zinc alloy offers superior sacrificial protection to steel as the alloy dissolves more slowly than pure zinc. The degree of protection and the rate of dissolution depend on the alloying metal and its composition. Zinc-nickel alloy may also serve as at less toxic substitute for cadmium. In this paper the physico-chemical characterization of zinc-nickel electrodeposits obtained from sulphamate bath containing substituted aldehydes was carried out using hardness testing, X-ray diffraction, and corrosion resistance measurements. The corrosion behaviour of these samples in a 3⋅5% NaCl solution was examined. The decrease in Icorr and high charge transfer resistance indicated the improved corrosion resistance of these deposits. [ABSTRACT FROM AUTHOR]

To apply the approach of forward genetics (e.g., gene identification with mutagenesis and screening, followed by positional cloning) to the mouse, it is necessary to have available screening tests that can be applied rapidly to individual mice and that give a reliable assessment of visual function. This paper reviews the strengths and limitations of two anatomical tests related to visual function, fundus examination and retinal histological examination. Two tests that do not depend on behavior of a conscious animal are reviewed: the electroretinogram and the visual evoked potentials of the cortex. Eight behavioral tests are also summarized: maze-based tests, cued fear conditioning, tests based on conditioned suppression, visual placing, optokinetic nystagmus, pupillary reflex, and light-induced shifts in circadian phase. It is recommended that retinal histology, the electroretinogram, and visual-evoked potentials be used at the present time for screening because they assess the function and structure of the visual system rapidly and reliably. In fact, the electroretinogram (or visually evoked potentials) can be recorded from several animals simultaneously in response to the same stimulus. It is also recommended that efforts be made to develop more appropriate, automated, behavioral tests of visual perception than are now available, particularly tests that rely solely on rewarding visually evoked behavior. Two other promising behavioral tests are cued fear conditioning and variants of maze tests. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective introduction of a propargyl group constitutes one of the most important carbon–carbon forming reactions, as it is versatile to be transformed into diverse functional groups and frequently used in the synthesis of natural products and biologically active molecules. Stereoconvergent transformations of racemic propargyl precursors to a single enantiomer of products via propargyl radicals represent a powerful strategy and provide new reactivity. However, only few Cu- or Ni-catalyzed protocols have been developed with limited reaction modes. Herein, a photoredox/cobalt-catalyzed regio-, diastereo- and enantioselective propargyl addition to aldehydes via propargyl radicals is presented, enabling construction of a broad scope of homopropargyl alcohols that are otherwise difficult to access in high efficiency and stereoselectivity from racemic propargyl carbonates. Mechanistic studies and DFT calculations provided evidence for the involvement of propargyl radicals, the origin of the stereoconvergent process and the stereochemical models. Catalytic enantioselective introduction of a propargyl group is an important carbon–carbon forming reactions but only few Cu- or Ni-catalyzed protocols with limited reaction modes are known. Here, the authors describe a photoredox/cobalt-catalyzed propargyl addition to aldehydes via propargyl radicals which enables the construction of a broad scope of homopropargyl alcohols. [ABSTRACT FROM AUTHOR]

The commercially available 4,4ʹ-trimethylenedipiperidine (TMDP) was used in the solid state to activate various aldehydes and controlled the libration of methyl amine for preparing the corresponding N-methyl imines. It was indicated that TMDP could play multiple roles simultaneously in this reaction, including (a) a bifunctional base with a predicted pKa ~ 11 and a good scavenger of acid, (b) a catalyst able to form strong hydrogen bonding and chemical interactions with aldehyde functional group through hemiaminal and/or iminium intermediate, and (c) liberating methyl amine from its salt viz. methylammonium chloride. TMDP could be regenerated by neutralization. It was also regenerated by heating at 70 °C, which is reported for the first time according to the best of our knowledge. The regenerated reagent was stable regarding its chemical structure, and there was no significant loss in the catalytic efficiency even after several runs. The mechanism was investigated by performing several control reactions and studying the FTIR and NMR spectra in the solid-state synthesis. The current work demonstrated TMDP as a safe and greener promoter-acid scavenger for organic transformations compared with toxic, flammable, volatile liquid secondary amines such as piperidine. [ABSTRACT FROM AUTHOR]

Dark and photolysis reactions in solution were investigated for 9-acridinecarboxaldehyde (ACL). ACL reacts in the dark at T = 20 °C and pH = 7.0 in an air saturated solution to the main product 9-acridinecarboxylic acid (ACA) and to the minor product 9-acridinemethanol (ACM) with a lifetime of τ = 4.3 days. The dissociation constant of the base ACLH+ was determined to be pKa±σ = 4.38 ± 0.04. The photolysis of ACL was investigated using a polychromatic Xe-light source. The quantum yield in aqueous solution at T = 20 °C in a concentration range of c0(ACL) = 0.18–16.6 μM for pH ＞ pKa and for nitrogen, air and oxygen aerated solutions was found to be Φ±σ = (0.015 ± 0.003) mol/mol, independent from concentration. The quantum yield of ACLH+, i.e. for pH < pKa, is by a factor of 2 higher (Φ = 0.029 mol/mol). Quantum yields in methanol and isopropanol are slightly lower compared to water and in acetone lower by about a factor of 20. In acetonitrile ACL was found to be practically photostable. Minimum lifetimes in sunlight for a measurement on September 5, 2017 were in the range of τ = 5–10 minutes. The diurnal photolysis of ACL in sunlight was satisfactory explained using the mean quantum yield, the absorption spectrum and photon fluxes with suitable corrections for cloudiness and the dimensions of the setup. For low concentrations ACR is formed with a yield of practically 100% in the photolysis reaction. However, with increasing concentration of ACL yields of ACR decrease and yields of ACA increase. 9(10H)-Acridinone and ACM were always detected as minor products with yields below 2%. 9-Methylacridine was never detected in any reaction of ACL. Strong indications are presented of a photolysis reaction of ACL in a river located in Lower Saxony (Germany) with a corresponding equimolar formation of ACR. ACL is therefore a direct precursor of ACR in natural surface water. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the toxic effect of allyl isothiocyanate (AIT) and cinnamic aldehyde on human KB cells and yeast Saccharomyces cervisiae. The study uses ethyl alcohol, cell culture system and long-probit paper to test the toxicity of the substances. Results show that AIT is more toxic than CA to human KB cells while CA inhibits the growth of Saccharomyces cervisiae.

This paper describes a novel method for the sensitive determination of the volatile aliphatic aldehydes formed by autoxidation in fats and oils. In a solution of fats, the aldehydes are derivatized to the O-pentafluorobenzyloximes (PFBOs) without any isolation procedure. From the mixture, the lipids are removed by silica gel column chromatography using pentane/dichloromethane (4+1) as the eluant. The eluate is evaporated to dryness and the PFBOs are extracted from the residue with a small volume of acetonitrile. They are separated by capillary column gas chromatography and are determined with high selectivity and sensitivity by using an electron-capture detector. The determination limit was as low as 0.01 mg/kg for hexanal. Analysis of a series of corn oil samples yielded high recoveries for 14 aldehydes added at the 1 mg/kg level, with low relative standard deviations of between 3 and 17%. [ABSTRACT FROM AUTHOR]

The commonly used phenolic resin vulcanizing agents for rubber processing technology have some limitations. In this study, a new aldehyde teroctyl phenolic resin vulcanizing agent was synthesized from SP-1055 through a series of chemical reactions and tested for its efficiency in vulcanizing isoprene rubber (IR) at low dosages. The structure of the new phenolic resin was confirmed using infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The results showed that the new phenolic resin exhibited excellent vulcanization properties and environmental protection characteristics, and the IR blended with the new phenolic resin vulcanizing agent showed higher tensile strength, elongation at break, and better recovery from prolonged extension than those of IR with traditional phenolic resin vulcanizing agents. The improvement is attributed to the replacement of the chain end hydroxyl with an aldehyde group in the new phenolic resin vulcanizing agent. The new phenolic resin vulcanizing agent has significant potential for future research and development and could be a promising alternative for medical rubber products. [ABSTRACT FROM AUTHOR]

We herein describe an asymmetric α-allylic allenylation of β-ketocarbonyls and aldehydes with 1,3-enynes. A synergistic chiral primary amine/Pd catalyst was identified to facilitate the utilization of 1,3-enynes as atom-economic and achiral allene precursors. The synergistic catalysis enables the construction of all-carbon quaternary centers-tethered allenes bearing non-adjacent 1,3-axial central stereogenic centers in high level of diastereo- and enantio-selectivity. By switching the configurations of ligands and aminocatalysts, diastereodivergence can be achieved and any of the four diastereoisomers can be accessed in high diastereo- and enantio- selectivity. Enantioselective α-allylic allenylation of carbonyls is a straightforward approach to access chiral allenes that are of significant relevance as synthons and bio-active products. Here, the Luo group describe an asymmetric α-allylic allenylation of β-ketocarbonyls and aldehydes with 1,3-enynes, via a combined chiral primary amine and palladium catalyst system. [ABSTRACT FROM AUTHOR]

Guayule (Parthenium argentatum Gray) is a semi-arid shrub, native from the Chihuahan desert. This plant produces polyisoprene and resin. Polyisoprene is the main focal point of many researches, from structure to properties. Today, some processes are used to extract polyisoprene under its dry form, using solvent extraction, to produce rubber (used in truck or airplane tires) or as an emulsion, to make latex products by dipping (used in medical gloves, condoms, etc.). This article focuses on guayule resin which has some interesting applications in adhesives, coatings, pharmaceuticals, etc. In order to better know the resin composition and to be able to perform comparisons between varieties or seasons, liquid and gas chromatographic analysis methods have been described, for the groups of molecules composing the resin (polyphenols, guayulins, free fatty acids, di and triacylglycerols, argentatins, alkanes, alkanals, sugars, organic acids). Unlike other articles, this study aims to analyze all components of the same resin; the average composition of a guayule resin is given. [ABSTRACT FROM AUTHOR]