Related Carbonyl Compounds Research Articles

Oxidation of alcohols to carbonyl compounds with H2O2 in water catalyzed by polyoxometalate-based hyper-crosslinked ionic polymer

The oxidation reaction involving hydrogen peroxide (H2O2) in water is of great attraction in fundamental research and industrial application, but there is still a long way to go. Herein, a new hybrid catalyst PW@Py-HIP was successfully synthesized by immobilization of phosphotungstic anions onto/into the pyridinium-based hyper-crosslinked ionic polymer using a post-synthetic strategy. This facile synthetic method afforded heterogeneous catalyst with a large specific surface area of 428.7 m2·g−1 and stable polymeric skeleton. The amphiphilic PW@Py-HIP exhibited remarkable catalytic activity and quantitative selectivity for the oxidation of alcohols into carbonyl compounds with H2O2 in water. The turnover frequency (TOF) and turnover number (TON) values reached 1088.9 h−1 and 4083.3, respectively. Owing to its good heterogeneous nature, PW@Py-HIP can be recycled for six times without significant loss of activity. The developed catalytic system confirmed to be beneficial toward the synthesis of related carbonyl compounds from various alcohols with appreciable conversions.

Synthesis of N-Trifluoromethyl Thiocarbamates and Ureas from 3-Aminopyridine-Derived Carbamates

AbstractThe synthesis of N-trifluoromethyl thiocarbamates and ureas from 3-pyridyl isothiocyanates via the nucleophilic substitution reaction of perfluorophenyl pyridin-3-yl(trifluoromethyl)carbamate is described. Recently, Schoenebeck’s group reported a straightforward method to access N-trifluoromethyl analogues of amides and related carbonyl compounds. However, N-trifluoromethyl thiocarbamates and ureas derived from pyridine-containing amines remain a synthetic challenge. In this paper, the strategy relies on the operationally simple preparation of perfluorophenyl pyridin-3-yl(trifluoromethyl)carbamates, which can smoothly undergo nucleophilic substitution reactions with thiophenol, sodium mercaptide, and amine. Various functional groups such as amide, halogen, ether, and ester were tolerated under these reaction conditions. Notably, alkylamine structures containing pyridine heterocyclic rings are also compatible to access N-trifluoromethyl thiocarbamates.

Recognition of acrolein-specific epitopes by B cell receptors triggers an innate immune response

Natural antibodies, predominantly immunoglobulin M (IgM), play an important role in the defense against pathogens and in maintaining homeostasis against oxidized molecules known as oxidation-specific epitopes, such as those contained in oxidized low-density lipoproteins. However, owing to the complexity of the oxidized products, very few individual epitopes have been characterized in detail. In the present study, to identify endogenous sources of oxidation-specific epitopes, we stimulated mouse spleen and peritoneal cavity (PerC) cells in vitro with bovine serum albumin modified with a variety of lipid peroxidation–related carbonyl compounds and identified the acrolein-modified bovine serum albumin as the most efficient trigger studied for the production of IgM in PerC cells. The acrolein-specific epitopes accelerated the differentiation of B-1a cells, a fetal-derived B cell lineage, to plasma cells. In addition, acrolein-modified bovine serum albumin was specifically bound to B-1a cells, suggesting the presence of an acrolein-specific IgM–B cell receptor (BCR). A hybridoma, RE-G25, producing an acrolein-specific IgM, was established from the PerC cells and was indeed identified as a population of B cells expressing a specific IgM–BCR. In addition, we analyzed the BCR repertoire of acrolein-specific B cells and identified the most frequent IgM heavy chain gene segments of the B cells. These data established the presence of innate B cells expressing the acrolein-specific BCR and suggested that in addition to our understanding of acrolein as a toxic aldehyde, it may play a role as a trigger of the innate immune response.

4-Hydroxynonenal (HNE), a Toxic Aldehyde in Fried Chicken from Fast Food Restaurants and a Grocery Store

The lipid oxidation product, the toxic 4-hydroxynonenal, was measured for fried chicken in commercial samples from two fast food restaurants and one commercial establishment. The fried chicken samples were breasts, thighs, chicken nuggets and popcorn chicken. Fried chicken samples were separated to breast skin and meat, and thigh skin and meat. Chicken nuggets and popcorn chicken were not separated from the coating materials and the meat was analyzed together. Samples were analyzed for total fat, fatty acid distribution, reactivity with thiobarbituric acid (TBAR), measuring the secondary lipid peroxidation products such as aldehydes, ketones and related carbonyl compounds. Samples were analyzed for HNE, a toxic aldehyde using high performance liquid chromatography (HPLC). Fatty acid distribution showed in breast and thigh meats, a higher level of palmitic acid, compared to the breast and thigh skins. TBAR values were significantly higher in all breast meats compared to skins. TBAR values were significantly higher in thigh meat than in skin samples. HNE concentrations (μg HNE/g fat) were significantly very low in breast skins compared to breast meat. HNE concentration was generally higher in thigh meat than skin but not in every sample. In chicken nuggets, both the TBAR value and HNE concentration were much higher from one establishment than from the two others. Chicken nuggets TBAR and HNE concentrations resembled one of the chicken nugget samples. The average toxic HNE concentration for 100 g fried chicken breast (skins + meat) was 12.55 μg and for thighs (skin + meat) was 26.76 μg. The average total HNE concentration was 2.1 times higher in the fried chicken thighs than in the breasts. It is clear that HNE is produced during the heating process of oils and incorporated into the fried meat and skin samples during the frying process. If HNE, a toxic aldehyde, is consumed with the food, over long periods of time it could be related to a number of pathological conditions.

Straightforward access to N-trifluoromethyl amides, carbamates, thiocarbamates and ureas.

Amides and related carbonyl derivatives are of central importance across the physical and life sciences1,2. As a key biological building block, the stability and conformation of amides affect the structures of peptides and proteins as well as their biological function. In addition, amide-bond formation is one of the most frequently used chemical transformations3,4. Given their ubiquity, a technology that is capable of modifying the fundamental properties of amides without compromising on stability may have considerable potential in pharmaceutical, agrochemical and materials science. In order to influence the physical properties of organic molecules-such as solubility, lipophilicity, conformation, pKa and (metabolic) stability-fluorination approaches have been widely adopted5-7. Similarly, site-specific modification with isosteres and peptidomimetics8, or in particular by N-methylation9, has been used to improve the stability, physical properties, bioactivities and cellular permeabilities of compounds. However, the N-trifluoromethyl carbonyl motif-which combines both N-methylation and fluorination approaches-has not yet been explored, owing to a lack of efficient methodology to synthesize it. Here we report a straightforward method to access N-trifluoromethyl analogues of amides and related carbonyl compounds. The strategy relies on the operationally simple preparation of bench-stable carbamoyl fluoride building blocks, which can be readily diversified to the corresponding N-CF3 amides, carbamates, thiocarbamates and ureas. This method tolerates rich functionality and stereochemistry, and we present numerous examples of highly functionalized compounds-including analogues of widely used drugs, antibiotics, hormones and polymer units.

The in Vivo Antioxidant Effects of (-)-Epigallocatechin-3-Gallate Consumption in Healthy Postmenopausal Women Measured by Urinary Excretion of Secondary Lipid Peroxidation Products.

The present study was carried out to determine whether the consumption of epigallocatechin (EGCG), the major bioactive green tea catechin, exerts a positive effect on lowering in vivo lipid peroxidation, a measure of oxidative stress, in healthy postmenopausal women. Urinary excretion of secondary lipid peroxidation products, a measure of in vivo lipid peroxidation, was determined in 40 participants randomly assigned to consume a green tea catechin extract (843.0 ± 44.0 mg EGCG/d) or placebo capsules for 12 months. Urine samples were analyzed for individual polar and nonpolar lipophilic aldehydes and related carbonyl compounds by high-performance liquid chromatography (HPLC) at the beginning and at the end of the 12-month intervention period. Results show that two nonpolar aldehydes, nonanal and decatrienal, were both 48% lower (p < 0.005) following consumption of EGCG. These results indicate that a modest degree of in vivo antioxidant activity exists with long-term EGCG consumption, which could slightly limit oxidative damage associated with lipid peroxidation and the onset and progression of chronic diseases.

Effects of Temperature and Heating Time on the Formation of Four Toxic α,β‐Unsaturated‐4‐Hydroxyaldehydes in Vegetable Oils

AbstractThe formation of four α,β‐unsaturated hydroxyaldehydes, 4‐hydroxy‐2‐trans‐hexenal (HHE), 4‐hydroxy‐2‐trans‐octenal (HOE), 4‐hydroxy‐2‐trans‐nonenal (HNE), and 4‐hydroxy‐2‐trans‐decenal (HDE), was detected in commercial corn, soybean, peanut, and canola oils heated for 1, 3, and 5 hours at 145, 165, and 185 °C. These four toxic aldehydes were investigated using high‐performance liquid chromatography (HPLC). These oils were selected based upon different degrees of unsaturations, especially their linoleic and linolenic acid concentrations. To select the appropriate conditions of temperatures and heating times, preliminary experiments were conducted using the thiobarbituric acid assay, which detects the formation of secondary‐oxidation products such as aldehydes and related carbonyl compounds. After various heat treatments, the formation of HHE, HOE, HNE, and HDE was detected as 2,4‐dinitrophenyl hydrazine derivatives using HPLC. In general, HHE, HOE, HNE, and HDE formation increased in all four oils with higher temperatures, longer heating times, and higher concentrations of linoleic and linolenic acids in the oils. The formation of HNE in the oils was mostly much higher than the other three 4‐hydroxyaldehyde isomers under the same conditions.

Recent advances in the synthesis of functionalised monofluorinated compounds.

Over the past few years, we have tackled the synthesis of interesting monofluorinated organic molecules, such as: dihydronaphthalene derivatives, β-fluoro sulfones and related carbonyl compounds, fluorohydrins and allylic alcohols. Overall, a wide range of modern synthetic techniques are covered in this feature article including transition-metal, photo- and organocatalysis, nucleophilic and electrophilic fluorinations, chiral auxiliaries and enantioselective catalysis.

Starch-coated maghemite nanoparticles functionalized by a novel cobalt Schiff base complex catalyzes selective aerobic benzylic C–H oxidation

The CoL2@SMNP nanocatalyst catalyzed heterogeneous aerobic oxidation of benzylic C–H bonds of saturated hydrocarbons and alcohols to the related carbonyl compounds.

A methodological approach to screen diverse cheese-related bacteria for their ability to produce aroma compounds

Microorganisms play an important role in the development of cheese flavor. The aim of this study was to develop an approach to facilitate screening of various cheese-related bacteria for their ability to produce aroma compounds. We combined i) curd-based slurry medium incubated under conditions mimicking cheese manufacturing and ripening, ii) powerful method of extraction of volatiles, headspace trap, coupled to gas chromatography-mass spectrometry (HS-trap-GC-MS), and iii) metabolomics-based method of data processing using the XCMS package of R software and multivariate analysis. This approach was applied to eleven species: five lactic acid bacteria (Leuconostoc lactis, Lactobacillus sakei, Lactobacillus paracasei, Lactobacillus fermentum, and Lactobacillus helveticus), four actinobacteria (Brachybacterium articum, Brachybacterium tyrofermentans, Brevibacterium aurantiacum, and Microbacterium gubbeenense), Propionibacterium freudenreichii, and Hafnia alvei. All the strains grew, with maximal populations ranging from 7.4 to 9.2 log (CFU/mL). In total, 52 volatile aroma compounds were identified, of which 49 varied significantly in abundance between bacteria. Principal component analysis of volatile profiles differentiated species by their ability to produce ethyl esters (associated with Brachybacteria), sulfur compounds and branched-chain alcohols (H. alvei), branched-chain acids (H. alvei, P. freudenreichii and L. paracasei), diacetyl and related carbonyl compounds (M. gubbeenense and L. paracasei), among others.

β-Carbon activation of saturated carboxylic esters through N-heterocyclic carbene organocatalysis

The activation of the α-carbons of carboxylic esters and related carbonyl compounds to generate enolate equivalents as nucleophiles is one of the most powerful strategies in organic synthesis. We reasoned that the horizons of chemical synthesis could be greatly expanded if the typically inert β-carbons of saturated esters could be used as nucleophiles. However, despite the rather significant fundamental and practical values, direct use of the β-carbons of saturated carbonyl compounds as nucleophiles remains elusive. Here we report the catalytic activation of simple saturated ester β-carbons as nucleophiles (β-carbon activation) using N-heterocyclic carbene organocatalysts. The catalytically generated nucleophilic β-carbons undergo enantioselective reactions with electrophiles such as enones and imines. Given the proven rich chemistry of ester α-carbons, we expect this catalytic activation mode for saturated ester β-carbons to open a valuable new arena for new and useful reactions and synthetic strategies.

ChemInform Abstract: Positional Chemoselectivity in the Zn(II)‐Mediated Removal of Phenol Protecting Groups.

AbstractReaction conditions involving ZnCl2 are developed for the selective ortho‐deprotection of aldehydes or related carbonyl compounds.

Efficient Selective Oxidation of Organic Substrates Using Pyridinum Sulfonate Halochromate Under Solvent-Free Conditions and Microwave Irradiation: Experimental and Theoretical Study

A convenient and rapid method has been developed for the selective oxidation of several types of alcohols to related carbonyl compounds under solvent-free conditions. In this study, the authors report the microwave-assisted selective oxidation of alcohols and a number of organic compounds with pyridinum sulfonate chlorochromate (PSCC) and pyridinum sulfonate fluorochromate (PSFC). The density functional theory calculations were made at B3LYP/6–31G* levels of theory and thermodynamic data supported the proposed mechanism involving formation of a halochromate ester, which showed that PSFC should be a more capable oxidant than PSCC. The oxidation products are easily obtained in short reaction time with good yields.

Fluorescent Studies of Salicylaldehyde and Other Related Carbonyl Compounds for the Selective and Sensitive Detection of Zinc(II) Ions in Aqueous Solution

Salicylaldehyde was found to have a high selectivity for zinc ions with simultaneous enhancement of fluorescence in aqueous buffer solution at optimum pH 8.5. The stoichiometry of the complex was determined to be 1:1 with a K(a) value of 3.4 × 10(4) M(-1) at 298 K. The fluorescence of the complex is not affected by common anions and Zn(2+) binds preferentially to salicylaldehyde in the presence of alkali, alkaline earth and heavy metal cations (Hg(2+), Cd(2+), Cr(3+) and Ni(2+)). This property is not observed with related phenolic compounds bearing a carbonyl group such as esters, amides, carboxylic acids and ketones.

ChemInform Abstract: Ruthenium Carboxylate Complexes as Easily Prepared and Efficient Catalysts for the Synthesis of β‐Oxopropyl Esters.

Abstract The easily prepared complex cis-[Ru(κ2-O2CMe)2(PPh3)2] is an effective catalyst for the addition of carboxylic acids to propargyl alcohols to afford β-oxopropyl esters. The reaction is tolerant to a range of functional groups on the propargyl alcohol and is effective in the case of the steroid ethisterone. An investigation into the ruthenium-containing products from the reaction involving benzoic acid revealed that rapid exchange between coordinated acetate and benzoate ligands occurs. The synthesis of crystallographically characterised cis-[Ru(κ2-O2CPh)2(PPh3)2] was developed. This benzoate-substituted complex was shown to react with HC CPh and HC CC(OH)PhH to give [Ru(κ2-O2CPh)(κ1-O2CPh)( C CPhH)(PPh3)2] and [Ru(κ2-O2CPh)(κ1-O2CPh)( C CC{OH}PhH)(PPh3)2] respectively. Reaction of cis-[Ru(κ2-O2CPh)2(PPh3)2] with CO affords [Ru(κ2-O2CPh)(κ1-O2CPh)(CO)(PPh3)2] or [Ru(κ2-O2CPh)2(CO)2(PPh3)2] depending on the conditions employed. Related carbonyl compounds are thought to be the ruthenium-containing products from the catalytic reactions and [Ru(κ2-O2CMe)(κ1-O2CMe)(CO)(PPh3)2] was also shown to be a competent catalyst.

Ruthenium carboxylate complexes as easily prepared and efficient catalysts for the synthesis of β-oxopropyl esters

The easily prepared complex cis-[Ru(κ 2-O 2CMe) 2(PPh 3) 2] is an effective catalyst for the addition of carboxylic acids to propargyl alcohols to afford β-oxopropyl esters. The reaction is tolerant to a range of functional groups on the propargyl alcohol and is effective in the case of the steroid ethisterone. An investigation into the ruthenium-containing products from the reaction involving benzoic acid revealed that rapid exchange between coordinated acetate and benzoate ligands occurs. The synthesis of crystallographically characterised cis-[Ru(κ 2-O 2CPh) 2(PPh 3) 2] was developed. This benzoate-substituted complex was shown to react with HC CPh and HC CC(OH)PhH to give [Ru(κ 2-O 2CPh)(κ 1-O 2CPh)( C CPhH)(PPh 3) 2] and [Ru(κ 2-O 2CPh)(κ 1-O 2CPh)( C CC{OH}PhH)(PPh 3) 2] respectively. Reaction of cis-[Ru(κ 2-O 2CPh) 2(PPh 3) 2] with CO affords [Ru(κ 2-O 2CPh)(κ 1-O 2CPh)(CO)(PPh 3) 2] or [Ru(κ 2-O 2CPh) 2(CO) 2(PPh 3) 2] depending on the conditions employed. Related carbonyl compounds are thought to be the ruthenium-containing products from the catalytic reactions and [Ru(κ 2-O 2CMe)(κ 1-O 2CMe)(CO)(PPh 3) 2] was also shown to be a competent catalyst.

Synthesis and kinetic resolution of furyl substituted secondary carbinols by porcine pancreatic lipase under solvent free conditions

Chiral furyl substituted carbinols were prepared from the related carbonyl compounds and their enzymatic kinetic resolution was studied by using porcine pancreatic lipase (PPL) in transesterification reaction under solvent free condition. This study revealed that carbinols having one less bulky group on the chiral center are good substrates for PPL and the resolution proceeds with higher ee,s and less reaction time.

Nitroxide Radicals as Probes for Exploring the Binding Properties of the Cucurbit[7]uril Host

EPR spectroscopy was used for the first time to explore the binding properties of cucurbit[7]uril (CB7), a representative member of the cucurbituril family. Evidence for the formation of a complex between nitroxide radicals and the host system in an aqueous solution was provided by large changes in the nitrogen hyperfine splitting, attributed to the different polar environments experienced by the included radical. In the presence of alkali cations, the EPR spectra of benzyl tert-butyl nitroxide were characterised by new signals attributed to the radical hosted in the CB7 cavity in which one metal cation is in close contact with the nitroxidic oxygen. The formation of the coordination complex results in a substantial increase in the electron spin density on the nitrogen in inverse order with respect to the size of the cation owing to increased localisation of negative charge on the oxygen atom from bonding to the alkali cation. The EPR spectra showed selective line-broadening effects as a result of metal exchange between bulk water and the coordination complex. Analysis of the EPR linewidth variations allowed us to measure the corresponding kinetic rate constants for the first time. NMR spectroscopy showed that this behaviour is not peculiar to nitroxides but is also exhibited by the related carbonyl compounds. These data allowed us to quantify the template effect and to reach the conclusion that, in the presence of a guest having a coordinating lone pair, the formation of ternary metal-guest-CB complexes must be taken into account when discussing the complexation behaviour of cucurbituril derivatives in the presence of salts.

Formation of the Salt-like Complexes [Co{S2CC(PPh3)2}3][Co(CO)4]3 and [(CO)4Mn{S2CC(PPh3)2}][Mn(CO)5] from the Reaction of the Related Carbonyl Compounds with S2CC(PPh3)2

The betain-like compound S2CC(PPh3)2 (1), which is obtained from CS2 and the double ylide C(PPh3)2, reacts with [Co2(CO)8] and [Mn2(CO)10] in THF to afford the salt-like complexes [Co{S2CC(PPh3)2}3][Co(CO)4]3 (2) and [(CO)4Mn{S2CC(PPh3)2}][Mn(CO)5] (3), respectively, in good yields. At both d6 cations 1 acts as a chelating ligand. Disproportionation reactions from formal Co0 into CoIII and Co−I and from Mn0 into MnI and Mn−I occurred with the removal of four or one carbonyl groups, respectively. The crystal structures of 2·5.5THF and 3·2THF are reported, which show a shortening of the C–C bond in the ligand upon complex formation. The compounds are further characterized by 31P NMR and IR spectroscopy.

Aerosol characterisation at the FEBUKO upwind station Goldlauter (II): Detailed organic chemical characterisation

Abstract An extensive set of gaseous and particulate organic compounds was quantified before an orographic cloud passage at the upwind site of the research region in Thuringer Wald. Samples were collected with two different time resolutions, 2 h for gaseous species and spray absorber samples and the whole cloud event duration to determine the concentrations of ketones, aldehydes, monocarboxylic acids, dicarboxylic acids (DCA), hydrocarbons, biogenic sugars and alcohols in both the gas and particle phase. The measurement of different groups of organic compounds delivered size-segregated concentrations at the upwind site of a cloud experiment. The size distribution of DCA showed a peak in the mass-rich impactor stage 3 (0.42–1.2 μm). The concentrations of DCA from the filters, the impactor foils as well as the spray absorber samples decreased with increasing C-number. The time resolved measurements revealed an increasing mixing ratio from night time to midday for carboxylic and DCA, and related carbonyl compounds. The biogenic compounds xylitol (up to 103 ng m−3), levoglucosan (up to 62 ng m−3) and pinonaldehyde (up to 34 ng m−3) were the compounds found in highest concentrations in the particle phase beside the oxalate (up to 104 ng m−3). The organic trace gases with the highest mixing ratios identified were formaldehyde (up to 1.47 ppbv), acetaldehyde (up to 0.84 ppbv) and acetone (up to 0.65 ppbv), acetic acid (up to 0.43 ppbv) and formic acid (up to 0.41 ppbv).