Active Hydroxy Group Research Articles

One-Pot Synthesis of Dicarbazolyl(aryl)methanols Based on α-Keto Acids

AbstractIn this work, carbazoles, one of the most important types of nitrogenous compounds, were used as substrates to synthesize dicarbazolyl(aryl)methanols in moderate to excellent yields (up to 95%). This simple and efficient strategy can regioselectively form an sp3 quaternary carbon with two large sterically hindered carbazole rings, one benzene ring, and an active hydroxy group in a one-pot reaction. The resulting triarylmethanes are all new products, and have high potential as building blocks for medicinal chemistry or materials science.

Synthetic aporphine alkaloids are potential therapeutics for Leigh syndrome

Mitochondrial diseases are mainly caused by dysfunction of mitochondrial respiratory chain complexes and have a variety of genetic variants or phenotypes. There are only a few approved treatments, and fundamental therapies are yet to be developed. Leigh syndrome (LS) is the most severe type of progressive encephalopathy. We previously reported that apomorphine, an anti- “off” agent for Parkinson’s disease, has cell-protective activity in patient-derived skin fibroblasts in addition to strong dopamine agonist effect. We obtained 26 apomorphine analogs, synthesized 20 apomorphine derivatives, and determined their anti-cell death effect, dopamine agonist activity, and effects on the mitochondrial function. We found three novel apomorphine derivatives with an active hydroxy group at position 11 of the aporphine framework, with a high anti-cell death effect without emetic dopamine agonist activity. These synthetic aporphine alkaloids are potent therapeutics for mitochondrial diseases without emetic side effects and have the potential to overcome the low bioavailability of apomorphine. Moreover, they have high anti-ferroptotic activity and therefore have potential as a therapeutic agent for diseases related to ferroptosis.

Antioxidant Activity of Diatomic Phenols

Nine compounds are studied for antioxidant activity, including those from the class of catecholamines containing 3,4-hydroxyphenyl (catechol) as a common structural fragment, which imparts antioxidant properties to the compounds in the reactions of hydrocarbon substrate oxidation. The antiradical activity is determined by the chemiluminescent method by the interception of peroxyl radicals in the model reaction of the initiated oxidation of ethylbenzene (RH). The mechanism of the inhibition of chain oxidation processes by diatomic phenol compounds is provided by the presence of two active hydroxy groups with a possible intramolecular hydrogen bond, leading to a weakening of the О–Н bond and a high rate constant of hydrogen abstraction in the reaction with peroxyl radicals (kinh). This reaction is dominant and determines the inhibitory activity of antioxidants in oxidation processes. The maximum inhibitory activity is shown by 3,5- and 3,6-di-tert-butylpyrocatechins, dopamine, and epicatechin.

A Green Technology for the Preparation of High Fatty Acid Starch Esters: Solid-Phase Synthesis of Starch Laurate Assisted by Mechanical Activation with Stirring Ball Mill as Reactor

Starch laurate, a kind of high fatty acid starch ester, was directly produced by mechanical activation (MA)-assisted solid-phase synthesis (MASPS) technology with a customized stirring ball mill as reactor. The starch laurates with different degrees of substitution (0.0148–0.0412) were obtained under different reaction conditions. Fourier transform infrared spectroscopy confirmed that starch ester had been successfully produced by MASPS attributed to active hydroxy groups induced by MA. X-ray diffractometry and scanning electron microscopy showed that MA and esterification significantly disrupted the morphology and crystal structure of starch. Water absorption of starch was increased by MA but decreased by the introduction of laurate groups. Viscosity of starch was obviously reduced after both the processes of MA pretreatment and MASPS. The successful synthesis of starch laurate without the use of solvent and additives suggested that MASPS was a fast, simple, and green method for the production of high fa...

Synthesis of twin‐tail tadpole‐shaped (cyclic polystyrene)‐ block‐[linear poly (tert‐butyl acrylate)]2 by combination of glaser coupling reaction with living anionic polymerization and atom transfer radical polymerization

AbstractThe twin‐tail tadpole‐shaped (cyclic polystyrene)‐block‐[linear poly (tert‐butyl acrylate)]2 [(c‐PS)‐b‐(l‐PtBA)2] was synthesized by combination of Glaser coupling reaction with atom transfer radical polymerization (ATRP) and living anionic polymerization (LAP). First, the telechelic PS with an active and an ethoxyethyl‐protected hydroxyl groups at both ends was prepared by LAP of St monomers using lithium naphthalenide as initiator and terminated by 1‐ethoxyethyl glycidyl ether. And the alkyne groups were introduced onto each PS end by selectively reaction of active hydroxy group with propargyl bromide in NaH/tetrahydrofuran (THF) system. Then, the intramolecular cyclization was carried out by Glaser coupling reaction in pyridine/Cu(I)Br system in air atmosphere. Finally, the macroinitiator of c‐PS with two bromine groups at the junction point was synthesized via the cleavage of ethoxyethyl group and the subsequent esterification of the deprotected hydroxyl groups with 2‐bromoisobutyryl bromide. The copolymer of (c‐PS)‐b‐(l‐PtBA)2 was obtained by ATRP of tBA monomers, and the PtBA segment was also hydrolyzed for (cyclic polystyrene)‐block‐(linear polyacrylic acid)2 [(c‐PS)‐b‐(l‐PAA)2]. The target copolymers and all intermediates were well characterized by GPC, MALDI‐TOF MS, and 1H NMR in detail. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

STUDY ON THE ADSORPTION PROPERTIES OF NOVEL CALIX[6]ARENE POLYMERS FOR HEAVY METAL CATIONS

A research has been conducted to investigate the capability of a series of novel calix[6]arenes-based polymers: poly-monoallyloxycalix[6]arene (2a), poly-monoallyloxypenta-estercalix[6]arene (2b) and poly-monoallyloxypenta-acidcalix[6]arene (2c) for trapping of heavy metal cations such as Cd(II), Cu(II) and Cr(III). The existence of active hydroxy group (-OH) and with a tunnel-like structure of the polymers, caused the polymers can be used as adsorbents for heavy metals. The adsorption process was carried out in batch method in the variation of acidity (pH), contact time and initial concentration of metal ions. The results showed that the amount of adsorbed metal increased with the increasing of the pH of metal solution. For these three polymers, the amount of metal ions Cd(II), Cu(II) and Cr(III) adsorbed was optimum at pH 7, 6 and 5 respectively. The optimum contact time for Cd(II) and Cu(II) was 120 min, while that for Cr(III) was 60 min. Study of the adsorption kinetics showed that the adsorption of Cd(II), Cu(II) and Cr(III) using polymer 2a followed kinetics model of Ho. For adsorbent 2b and 2c, the adsorption kinetics of Cd(II) and Cr(III) also followed kinetics model of Ho while for the Cu(II) followed Lagergren kinetic models. Isothermal studies showed that the adsorption of metal ions on all adsorbents tend to follow the Langmuir isotherm. The adsorption energies of the three adsorbents were higher than 23 kJ/mole and polymer 2c has the largest adsorption capacity for Cr(III).

FT-IR spectroscopic investigation of the adsorption pyridine on the raw sepiolite and Fe-pillared sepiolite from anatolia

The adsorption of pyridine on the surface of the raw sepiolite and Fe-pillared sepiolite catalysts has been studied for the determination of the Brønsted and Lewis acid sites. The data obtained showed that the catalysts have medium Lewis acidity, but are also weak Brønsted acids, having active hydroxy groups in the catalysts, which give the ability to interact with pyridine by H-bonding and by protonation. Pyridine is a suitable basic probe for the quantification of the catalysts. The intercalation of the Fe-polycation within sepiolite was shown by X-ray diffraction in order to increase the interlayer spacings.

FTIR Study of the Adsorption of Ammonia and Pyridine on V2O5/Mgo Catalysts

The adsorption of ammonia and pyridine on the surface of the V2O5/MgO catalysts has been studied for the determination of the Brønsted and Lewis acid sites. The data showed that the catalysts have medium Lewis acidity, but are also weak Brønsted acids, having active hydroxy groups able to interact with pyridine by H-bonding and by protonation. Pyridine is a suitable basic probe for the quantification of the catalysts. 32% V2O5/MgO catalyst is the most acidic catalyst.

FT-IR spectra of ethylene molecularly adsorbed on metal oxides

The FT-IR spectra of ethylene molecularly adsorbed on some oxidic surfaces at low temperature are presented and discussed both in terms of vibrational frequencies and of band intensities. A hydrogen-bonding interaction is observed between ethylene and surfaces having active hydroxy groups, like amorphous silica and HY zeolite. Strong adsorption is observed on some transition metal oxide surfaces (TiO 2, ZrO 2, Fe 2O 3, ZnO) where interaction is thought to occur on coordinatively unsaturated cationic centers. In both these cases the bands that are only Raman active in the ghas-phase molecule, become activated, some bands (namely CH stretchings and CC stretching) are shifted toward lower frequencies while some others (CH 2 out-of-plane bending) are shifted toward higher frequencies. Band intensities reveal a strong increase on the protonic charge on the ethylene hydrogens, evidencing that electron flows from the ethylene molecule to teh surface sites, the C 2H 4 moiety retaining its planar structure. On rock-salt structure metal oxides (MgO, CaO and NiO) the interaction is weaker, and is thought to occur on surface oxide anions. When incompletely reduced centers like Cu(I) are exposed, interaction dominated by backbonding from the surface to π★-type antibonding orbitals of ethylene occurs, like on typical ethylene-metal homogeneous complexes.

The structure of 2,4‐dihydroxypyridines

AbstractChemical experiments designed to give information regarding the structure of 2,4‐dihydroxypyridines indicated that one rather active hydroxy group was present, but failed to detect a keto group. Acetylation produced only monoacetates but benzoylation in two cases gave dibenzoates also. Only monoethers resulted from diazomethane reaction.Comparison of the absorption of selected compounds between the wavelengths 220 and 340 mμ indicated that this region of the spectrum is unsatisfactory as a source of structural data.