Deep Eutectic Solvents- a New Additive in the Encapsulation of Lipase B from Candida antarctica: Biocatalytic Applications

The enzymes encapsulation in sol-gel matrix can be improved using some additive acting on enzyme activity and/or stability. Ionic liquids, poly-hydroxy compounds, sugars, etc. have been previously reported as additives....

Hidden Reactivity of Barbituric and Meldrum’s Acids: Atom-Efficient Free Radical C–O Coupling with N-Hydroxy Compounds

The reactivity of CH-acidic and structurally related enol-containing heterocycles towards N-oxyl radicals was disclosed. Traditionally, these substrates were considered as reactants for ionic transformations. Highly selective and efficient N-oxyl radical mediated C–O coupling of substituted barbituric or Meldrum’s acids with N-hydroxy compounds (N-hydroxyimides, hydroxamic acids, oximes, and N-hydroxybenzotriazole) was achieved using inexpensive manganese-containing salts as oxidants. Metal-free C–O coupling was demonstrated using diacetyliminoxyl as both the oxidant (hydrogen atom acceptor) and the coupling partner.

1H NMR Study of the In Vitro Digestion of Highly Oxidized Soybean Oil and the Effect of the Presence of Ovalbumin

Oxidized lipids containing a wide variety of potentially toxic compounds can be ingested through diet. However, their transformations during digestion are little known, despite this knowledge being essential in understanding their impact on human health. Considering this, the in vitro digestion process of highly oxidized soybean oil, containing compounds bearing hydroperoxy, aldehyde, epoxy, keto- and hydroxy groups, among others, is studied by 1H nuclear magnetic resonance. Lipolysis extent, oxidation occurrence and the fate of oxidation products both present in the undigested oil and formed during digestion are analyzed. Furthermore, the effect during digestion of two different ovalbumin proportions on all the aforementioned issues is also addressed. It is proved that polyunsaturated group bioaccessibility is affected by both a decrease in lipolysis and oxidation occurrence during digestion. While hydroperoxide level declines throughout this process, epoxy-compounds, keto-dienes, hydroxy-compounds, furan-derivatives and n-alkanals persist to a great extent or even increase. Conversely, a,b-unsaturated aldehydes, especially the very reactive and toxic oxygenated ones, diminish, although part of them remains in the digestates. While a low ovalbumin proportion hardly affects oil evolution during digestion, at a high level it diminishes oxidation and reduces the concentration of potentially bioaccessible toxic oxidation compounds.

Visible Light-Induced Aerobic Dioxygenation of α,β-unsaturated amides/Alkenes toward Selective Synthesis of β-Oxy Alcohols Using Rose Bengal as a Photosensitizer

The first visible light-induced dioxygenation of α,β-unsaturated amides with N-hydroxy compounds under air atmosphere was developed with the use of non-toxic organic dye rose bengal as the photoredox catalyst. This...

INFLUENCE OF CONDITIONS OF SYNTHESIS OF COBALT AND MANGANESE OXIDES ON THEIR ABILITY TO CATALYTIC DECOMPOSITION OF HYDROGEN PEROXIDE

Cobalt and manganese oxides and their complex oxide compositions were obtained by the sol-gel method using various precipitators(ammonia solution and HMTA). It was determined by X-ray diffraction method that both individual and co-precipitated hydroxo compounds after calcination at 400 °С form oxide phases of Co3O4 and Mn3O4 composition. Samples obtained by sedimentation with ammonia solution have a larger specific surface area than synthesized in HMTA solution. When calcined at 400 °C, the specific surface area for cobalt-containing samples sedimentated with ammonia solution decreases, and for samples sedimentated from HMTA solution - increases. The pore volume depends on the precipitator and changes little during calcination. For co-sedimentated and calcined at 400 °C samples, the specific surface area plays a significant role: the higher it is, the greater the catalytic ability of the sample to decompose hydrogen peroxide. On the SEM image of samples driedat 100 °C, sedimentated with ammonia solution, agglomeration of flat particles of gitrated oxides of cobalt and/or manganese of globular form is observed. For samples deposited in HMTA solution, SEM images are represented by agglomeration of particles in the form of planar layers. Calcination at 400 °C partially destroys the structure. Kinetic studies of the decomposition of hydrogen peroxide with theparticipation of the obtained samples indicate the first order of the reaction. Samples of cobalt hydroxide and co-sedimentated cobalt and manganese hydroxy compounds synthesized in HMTA solution showed the best ability to catalyze. The highest productivity (dm3 H2O2 of decomposed 1 g of catalyst) is inherent in samples of cobalt hydroxy compounds and its composition with manganese compounds synthesized by HMTA, after heat treatment at 100 °C. The ability of such samples to catalytic decomposition of hydrogen peroxide is estimated to be not less than 2.4 dm3 H2O2 (14 days). Compared to compounds synthesizedwith ammonia solution, they retain their activity for a longer time.

Synthesis of N-substituted 3-(2-aryl-2-oxoethyl)-3-hydroxyindolin-2-ones and their conversion to N-substituted (E)-3-(2-aryl-2-oxoethylidene)indolin-2-ones: synthetic sequence, spectroscopic characterization and structures of four 3-hydroxy compounds and five oxoethylidene products

An operationally simple and time-efficient approach has been developed for the synthesis of racemic N-substituted 3-(2-aryl-2-oxoethyl)-3-hydroxyindolin-2-ones by a piperidine-catalysed aldol reaction between aryl methyl ketones and N-alkylisatins. These aldol products were used successfully as strategic intermediates for the preparation of N-substituted (E)-3-(2-hetaryl-2-oxoethylidene)indolin-2-ones by a stereoselective dehydration reaction under acidic conditions. The products have all been fully characterized by 1H and 13C NMR spectroscopy, by mass spectrometry and, for a representative selection, by crystal structure analysis. In each of (RS)-1-benzyl-3-hydroxy-3-[2-(4-methoxyphenyl)-2-oxoethyl]indolin-2-one, C24H21NO4, (Ic), and (RS)-1-benzyl-3-{2-[4-(dimethylamino)phenyl]-2-oxoethyl}-3-hydroxyindolin-2-one, C25H24N2O3, (Id), inversion-related pairs of molecules are linked by O—H...O hydrogen bonds to form R 2 2(10) rings, which are further linked into chains of rings by a combination of C—H...O and C—H...π(arene) hydrogen bonds in (Ic) and by C—H...π(arene) hydrogen bonds in (Id). The molecules of (RS)-1-benzyl-3-hydroxy-3-[2-oxo-2-(pyridin-4-yl)ethyl]indolin-2-one, C22H18N2O3, (Ie), are linked into a three-dimensional framework structure by a combination of O—H...N, C—H...O and C—H...π(arene) hydrogen bonds. (RS)-3-[2-(Benzo[d][1,3]dioxol-5-yl)-2-oxoethyl]-1-benzyl-3-hydroxyindolin-2-one, C24H19NO5, (If), crystallizes with Z′ = 2 in the space group P\overline{1} and the molecules are linked into complex sheets by a combination of O—H...O, C—H...O and C—H...π(arene) hydrogen bonds. In each of (E)-1-benzyl-3-[2-(4-fluorophenyl)-2-oxoethylidene]indolin-2-one, C23H16FNO2, (IIa), and (E)-1-benzyl-3-[2-oxo-2-(thiophen-2-yl)ethylidene]indolin-2-one, C21H15NO2S, (IIg), the molecules are linked into simple chains by a single C—H...O hydrogen bond, while those of (E)-1-benzyl-3-[2-oxo-2-(pyridin-4-yl)ethylidene]indolin-2-one, C22H16N2O2, (IIe), are linked by three C—H...O hydrogen bonds to form sheets which are further linked into a three-dimensional structure by C—H...π(arene) hydrogen bonds. There are no hydrogen bonds in the structures of either (E)-1-benzyl-3-[2-(4-methoxyphenyl)-2-oxoethylidene]indolin-2-one, C24H19NO3, (IIc), or (E)-1-benzyl-5-chloro-3-[2-(4-chlorophenyl)-2-oxoethylidene]indolin-2-one, C23H15Cl2NO2, (IIh), but the molecules of (IIh) are linked into chains of π-stacked dimers by a combination of C—Cl...π(arene) and aromatic π–π stacking interactions.

Palladium-catalyzed synthesis of β-hydroxy compounds via a strained 6,4-palladacycle from directed C–H activation of anilines and C–O insertion of epoxides

The combined experimental and computational study on palladium-catalyzed regioselective C–H functionalization of O-coordinating directing groups with epoxides is described.

Electrochemically induced oxidative S–O coupling: synthesis of sulfonates from sulfonyl hydrazides and N-hydroxyimides or N-hydroxybenzotriazoles

A variety of sulfonates were synthesized from sulfonyl hydrazides and N-hydroxy compounds via electrochemically induced oxidative S–O bond formation.