Typical Aldehydes Research Articles

Ozone Chemistry on Greasy Glass Surfaces Affects the Levels of Volatile Organic Compounds in Indoor Environments.

The chemistry of ozone (O3) on indoor surfaces leads to secondary pollution, aggravating the air quality in indoor environments. Here, we assess the heterogeneous chemistry of gaseous O3 with glass plates after being 1 month in two different kitchens where Chinese and Western styles of cooking were applied, respectively. The uptake coefficients of O3 on the authentic glass plates were measured in the dark and under UV light irradiation typical for indoor environments (320 nm < λ < 400 nm) at different relative humidities. The gas-phase product compounds formed upon reactions of O3 with the glass plates were evaluated in real time by a proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometer. We observed typical aldehydes formed by the O3 reactions with the unsaturated fatty acid constituents of cooking oils. The formation of decanal, 6-methyl-5-hepten-2-one (6-MHO), and 4-oxopentanal (4-OPA) was also observed. The employed dynamic mass balance model shows that the estimated mixing ratios of hexanal, octanal, nonanal, decanal, undecanal, 6-MHO, and 4-OPA due to O3 chemistry with authentic grime-coated kitchen glass surfaces are higher in the kitchen where Chinese food was cooked compared to that where Western food was cooked. These results show that O3 chemistry on greasy glass surfaces leads to enhanced VOC levels in indoor environments.

P(V)-bis(amidophenolate) ligand cooperation: stoichiometric CO-bond cleavage in aldehydes and ketones.

The cooperation between a geometrically constrained, highly electrophilic phosphorus(V) center, and an electronically rich tetradentate bis(amidophenolate) ligand enables the cleavage of the CO bond from typical aldehydes and ketones delivering iminio phosphoramidate species. The amphiphilic nature of these products, which is demonstrated through their reaction with typical Lewis acids and bases, enables their use as a mild source of silylium cations from silanes, allowing the selective reductive coupling of aldehydes to ethers under catalytic conditions.

Naphthalimide-Based Fluorescent Probe for Profiling of Aldehydes during Oxidation of Unsaturated Lipids.

A lipophilic naphthalimide hydrazine fluorescent probe was successfully developed in this study for profiling aldehyde oxidation products. Dodecyl amine was applied to afford lipophilicity of the fluorescent probe for lipids. Investigation of fluorescence properties of the probe and condensation products with typical aldehydes including MDA and hexanal revealed significant enhancement of fluorescence intensity after condensation due to the inhibition of photo-induced electron transfer. MDA and hexanal could be differentiated by the probe through emission of different fluorescence colors (blue, MDA; green, hexanal). Eight major oxidation components including seven aldehydes were detected by the fluorescent probe coupled with high-performance liquid chromatography-mass spectrometry during aerobic oxidation of typical unsaturated lipids. Formation of these aldehyde oxidation products was rationalized through the radical oxidation mechanism. Detection of representative aldehyde products demonstrated the generality in the application of this fluorescent probe for profiling of aldehydes after lipid oxidation.

A nanoporous 3D zinc(II) metal–organic framework for selective absorption of benzaldehyde and formaldehyde

A new 3D nanoporous metal–organic framework (MOF), [[Zn4O(C24H15N6O6)2(H2O)2]·6H2O·DMF]n (1) based on 4,4′,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB) ligand was solvothermally synthesized and characterized by single–crystal X-ray diffraction, Powder X-ray diffraction (PXRD), infrared spectroscopy (IR) and Brunauer–Emmett–Teller (BET) analyses. X-ray single crystal diffraction analysis reveals that 1 exhibits a 3D network with new kvh1 topology. Semi-empirical (AM1) calculations were carried out to obtain stable conformers for TATAB ligand. In addition, the absorption of two typical aldehydes (benzaldehyde and formaldehyde) in the presence of 1 was investigated and the effect of the aldehyde concentration, exposure time and temperature was studied. It was found that compound 1 has a potential for the absorption of aldehydes under mild conditions.

Evaluation of the Volatile Composition and Sensory Properties of Five Species of Microalgae

Due to their high content of polyunsaturated fatty acids, antioxidants, and proteins, microalgae hold a lot of potential for nutritional applications. When microalgae are integrated into foodstuffs, the aroma is an important aspect to consider. In this study the aroma properties of microalgae were studied by correlating data on the volatile composition with sensory evaluations. Four species of marine microalgae ( Botryococcus braunii, , Rhodomonas , Tetraselmis species, and Nannochloropsis oculata ) and one fresh water microalga ( Chlorella vulgaris ) were investigated. Multivariate data processing revealed that microalgal samples having a seafood-like odor character contain high levels of sulfuric compounds (dimethyl disulfide, dimethyl trisulfide, and methional), diketones, α-ionone, and β-ionone. Fresh green, fruity flavors were linked with typical aldehydes such as 2,4-alkadienals and 2,4,6-alkatrienals. The presence of these compounds in fresh microalga pastes is explained by aroma formation mechanisms such as enzymatic lipid oxidation, enzymatic and chemical degradation of dimethylsulfoniopropionate (generating dimethyl sulfide), phenylalanine (generating benzaldehyde), and carotenoids (generating ionones).

The X-ray Crystal Structure of a Cuprate-Carbonyl π-Complex

Complexes between copper reagents and double-bonds have been proposed as intermediates in a number of synthetically important reactions. Many h-complexes between organocuprates and carbon–carbon double-bonds, which are intermediates in 1,4-addition reactions of a,b-unsaturated carbonyl compounds, have been observed by using NMR spectroscopy. Moreover, h-O,C-complexes between organocopper compounds and carbon–oxygen double-bonds have been proposed as intermediates in 1,2-additions to carbonyl compounds, for example, copper-catalyzed asymmetric induction reactions. Carbophilic additions to thiocarbonyl compounds, mediated by organocuprates, have been explained in terms of h-S,C-complexes of carbon–sulfur double-bonds. However, there has been no report of an X-ray structure for any of these p-complexes. Therefore, we applied our rapid-injection techniques, which were previously used to prepare several important intermediates, to screen a number of typical aldehydes and ketones for complex formation with Me2CuLi, [9] and we discovered such a species with unusual stability, which has allowed us to prepare it on a larger scale and grow highquality crystals (see the Supporting Information). We now report the first X-ray crystal structure of a cuprate– carbonyl p-complex, 1 (Scheme 1 and Figure 1).

Aldehydes and Ketones Form Intermediate π Complexes with the Gilman Reagent, Me2CuLi, at Low Temperatures in Tetrahydrofuran

Typical aldehydes and ketones form π complexes with Me2CuLi at low temperatures in tetrahydrofuran. They range in stability from fleeting intermediates at -100 °C to entities that persist up to -20 °C. Three subsequent reaction pathways have been identified.

Headspace solid‐phase microextraction with on‐fiber derivatization for the determination of aldehydes in algae by gas chromatography–mass spectrometry

A simple, fast, sensitive and cost-effective method based on headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed for the determination of six typical aldehydes, 2E-hexenal, heptanal, 2E-heptenal, 2E,4E-heptadienal, 2E-decenal and 2E,4E-decadienal in laboratory algae cultures. As derivatization reagent, O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride, was loaded onto the poly(dimethylsiloxane)/divinylbenzene fiber for aldehydes on-fiber derivatization prior to HS-SPME. Various influence factors of extraction efficiency were systematically investigated. Under optimized extraction conditions, excellent method performances for all the six aldehydes were attained, such as satisfactory extraction recoveries ranging from 67.1 to 117%, with the precision (relative standard deviation) within 5.3-11.1%, and low detection limits in the range of 0.026-0.044 μg/L. The validated method was successfully applied for the analysis of the aldehydes in two diatoms (Skeletonema costatum and Chaetoceros muelleri), two pyrrophytas (Prorocentrum micans and Scrippsiella trochoidea) and Calanus sinicus eggs (feeding on the two diatoms above).

Determination of Hydride Affinities of Various Aldehydes and Ketones in Acetonitrile

The hydride affinities of 21 typical aldehydes and ketones in acetonitrile were determined by using an experimental method, which is valuable for chemists choosing suitable reducing agents to reduce them. The focus of this paper is to introduce a very facile experimental method, which can be used to determine the hydride affinities of various carbonyl compounds in solution.

Synthesis of Novel Angularly Fused Pentacyclic Heterocycles of Pharmacological Interest.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Changes in the Phenolic Composition of Maize Stovers after Blooming

The phenolic composition of 10 samples of maize stovers collected every 7 days after blooming was determined by high-performance liquid chromatography with electrochemical detection (HPLC-ED) and pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS). An increase of the p-hydroxycinnamic acids (i.e., p-coumaric acid and ferulic acid) with maturation was observed by HPLC-ED of mild alkaline extracts. Likewise, vanillin and syringaldehyde, i.e., the typical aldehydes constituting lignin, showed an increase with maturation in the alkali-soluble lignin fraction, as determined by HPLC-ED after nitrobenzene oxidation. As to PY/GC/MS, a less marked variation in the typical lignin units was observed with ripening. The ratios between syringyl and guaiacyl lignin units as determined by both analytical techniques were higher, but of the same order, than those determined previously in a set of maize stovers sampled over a wider range of maturation. Keywords: Maize stover; phenolics; lignin; high-performance liquid...

Stereospecific synthesis of Z olefins bearing an ω-azido group

Ylides derived from ω-azidoalkyltriphenylphosphonium salts were generated at low temperature. They are stable at −80°C for several hours and react smoothly and stereospecifically with typical aldehydes to form Z-ω-azido olefins which are the precursors of ω-unsaturated primary and secondary amines.

Reductions with sulfurated borohydrides. II. Reduction of typical aldehydes

Aromatic and aliphatic aldehydes can be reduced by sulfurated sodium borohydride to the corresponding alcohols. The reduction gives a quantitative yield of alcohol, without secondary products, if the reaction is performed at 0–10 °C. At higher temperatures (60°), the reduction is accompanied by the formation of disulfide. A good selection of the two possible reactions is obtained by adjusting the operating temperature. A mechanism explaining the reduction and the formation of sulfurated product is presented.