Synthesis and antioxidant activity of some new thioglycoluril derivatives

ABSTRACT

A series of S-alkylated products was prepared by alkylation of thioglycoluril with various alkylation agents, i.e. ethyl bromide, ethylene dibromide and chloroacetic acid. The synthesis performed in DMF at 60°C using sodium hydroxide as a base to give the corresponding products with significant advantages such as high conversions, short reaction time, mild reaction conditions, and low cost, simple workup with moderate to excellent yields. The structures of the synthesized compounds have been deduced from their spectral (IR, ¹H-NMR and ¹³C-NMR) data. Significant antioxidant activity was observed for some members of the series.     

Highly active hydrotreatment catalysts prepared with chelating agents

Hydrotreatment catalysts (Co–Mo/Al₂O₃, Ni–Mo/Al₂O₃ and Ni–W/Al₂O₃) were prepared by an impregnation method using an aqueous solution containing a chelating agent (nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) or trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CyDTA)). Co–Mo/Al₂O₃ and Ni–W/Al₂O₃ prepared with the chelating agents showed higher hydrodesulfurization (HDS) activity as well as hydrogenation (HYD) activity under high pressure (5.1 MPa) than those prepared without the chelating agents. Co–Mo/Al₂O₃ prepared with CyDTA showed ca. 70% higher HDS activity for benzothiophene (BT) than that prepared without it. HYD activity of Ni–W/Al₂O₃ for o-xylene was promoted about 65% by the addition of CyDTA. FT-IR of nitric oxide (NO) adsorbed on the sulfided Co–Mo/Al₂O₃'s suggested that Co was highly dispersed over the catalyst surface when the catalysts were prepared with the chelating agents.     

Aggregate Formation of Glycyrrhetic Acid 3-<Emphasis Type="Italic">O</Emphasis>-Glucuronide

The molecular structure of glycyrrhetic acid 3‐O‐glucuronide consists of an aglycone and glucuronic acid as hydrophobic and hydrophilic groups, respectively. In general, this amphiphile is obtained from glycyrrhizic acid (a major component of licorice root) by hydrolysis of the terminal glucuronic acid. Glycyrrhetic acid 3‐O‐glucuronide is used as a substitute for glycyrrhizic acids, which are potent sweeteners. In this work, the surface and aggregation properties of glycyrrhetic acid 3‐O‐glucuronide were studied using general surface chemistry techniques. The surface tension of a glycyrrhetic acid 3‐O‐glucuronide solution (pH 7) gradually decreased with increasing concentration and the critical micelle concentration (CMC) was determined to be 1.6 mmol L^?1 (γ_CMC = 54 mN m^?1). Similar values of CMC were further confirmed by the pyrene fluorescent probe method and light scattering measurements. According to the dynamic light scattering method, the average radius of aggregate was 200 nm over a concentration of 3 mmol L^?1. Transmission electron microscopy showed that glycyrrhetic acid 3‐O‐glucuronide forms large spherical aggregates. These results suggested that its potential for surface activity is almost equivalent to that of glycyrrhizic acid, even though the two amphiphiles have a different number of hydrophilic groups in them. The removal of one glucuronic acid group significantly influenced the shape of the aggregate formed by glycyrrhetic acid 3‐O‐glucuronide. Furthermore, it was confirmed that glycyrrhetic acid 3‐O‐glucuronide can also be used as a plant‐derived surfactant, similar to glycyrrhetic acid.     

Synthesis of two Unique Compounds,a Ceramide and a Cerebroside,Occurring in Human Stratum Corneum

The cerebroside 1a and the ceramide 1b , both playing important roles in epidermal barrier function, were synthesized by N‐acylation of 1‐O‐glucosylated C₁₈‐sphingosine 2 and C₁₈‐sphingosine 8 , respectively, with O‐acyl fatty acid 3 . The required compound 3 was obtained from ω‐hydroxy fatty acid 6 and linoleic acid 7 by esterification. The ω‐hydroxy C₃₀‐fatty acid 6 was prepared as follows: Copper‐catalyzed coupling of ω‐hydroxy alkyl halide 11 with the Grignard reagent derived from bromo compound 13 afforded after oxidation C₁₇‐aldehyde 15 . Wittig reaction with phosphonium salt 10 , derived from ω‐bromo‐tridecanoic acid 9 , and subsequent hydrogenation and O‐deprotection furnished 6 in high yield.     

Extraction of anthocyanins from Aronia melanocarpa skin waste as a sustainable source of natural colorants

Aronia melanocarpa (Michx.) Elliott (black chokeberry) skin wastes from the production of Aronia fruit juice were extracted using a batch extraction method and a novel integrated extraction‐adsorption process. Optimum conditions for batch extraction were as follows: 60 °C, 3 h, acid (0.1% v/v hydrochloric acid), biomass‐to‐solvent ratio of 1:16, and biomass‐to‐solid phase extraction resin ratio of 1:1. The integrated extraction‐adsorption process gave improved anthocyanin yields of higher quality when the process was performed for 3 h without cooling of the circulating liquid, and with a flow rate of 1.3 ml s^?1. Overall, the new method showed better anthocyanin yield and purity compared with the batch method, increasing the extraction yield by ca. 20% (5.25→6.34 mg g^?1 dry weight of pomace) and increasing anthocyanin content by ca. 40% (19.9%→28.4% w/w dry weight of extract). This method also simplified the process as three steps were eliminated saving time and energy. Furthermore, the integrated extraction‐adsorption method is industrially scalable to produce large quantities of anthocyanins. In the batch method, anthocyanins present in A. melanocarpa skins were identified as cyanidin‐3‐O‐galactoside (38.8%), cyanidin‐3‐O‐arabinoside (6.4%), cyanidin‐3‐O‐glucoside (3.6%), cyanidin‐3‐O‐xyloside (0.5%), and the cyanidin aglycon (50.7%); in the continuous method, anthocyanin content was cyanidin‐3‐O‐galactoside (45.7%), cyanidin‐3‐O‐arabinoside (16%), cyanidin‐3‐O‐glucoside (3.6%), cyanidin‐3‐O‐xyloside (2.7%), and the cyanidin aglycon (32%). The integrated extraction‐adsorption method was shown to be substantially less susceptible to acid‐catalysed anthocyanin decomposition processes. All anthocyanins were derived from only one anthocyanidin parent structure (cyanidin), and only monosaccharide glycosides were identified, which is unusual when compared with other berries that typically have more anthocyanidins and/or greater glycosylation diversity.     

Lipase‐catalyzed alcoholysis of vegetable oils

Fatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.     

Synthesis of high‐molecular weight poly(trimethylene terephthalate) catalyzed by MoO3 supported Al2O3‐TiO2 catalysts

Poly(trimethylene terephthalate) (PTT) is an excellent fiber materials. Although it was synthesized as early as 1940s, obtaining high‐molecular weight PTT suitable for spinning is not easy due to no evident breakthrough in the catalysts for PTT synthesis. Patents and literatures disclosed a lot of the catalysts of preparing PTT, but which are more or less disadvantageous. Based on acid catalytic mechanism of PTT preparation, a series of solid acid as x% MoO₃/(50% Al₂O₃ ? 50% TiO₂) (briefly written as xM/(A ? T), x = 0, 10, 15, 20 by weight) were prepared by sol–gel coprecipitation and wetting impregnation methods, and first used for PTT synthesis in this work. When 50% Al₂O₃ ? 50% TiO₂ (briefly written as A ? T) was supported by MoO₃ using wetting impregnation technique of (NH₄)₆Mo₇O₂₄.4H₂O aqueous solution, a lot of Brφnsted acid and Lewis acid sites were formed on xM/(A ? T) catalyst surfaces, which was confirmed by the characteristics of their NH₃‐TPD (temperature programmed desorption). All the prepared catalysts were highly active ones toward synthesis of PTT. PTT with high‐intrinsic viscosity (IV) was obtained in the presence of trace amount of the catalysts. IV ranging of the PTT synthesized from 0.66 to 0.95 dL g^?1 corresponds to weight average molecular weight from 49,197 to 73,004. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Highly selective purification of ferulic acid from wheat bran using deep eutectic solvents modified magnetic nanoparticles

Fe₃O₄ nanoparticles (Fe₃O₄NPs) were prepared by chemical coprecipitation. Deep eutectic solvents (DESs) (ChCl/glycol, 1/2, n/n) were used to modify Fe₃O₄NPs. The obtained Fe₃O₄NPs and DESs–Fe₃O₄NPs were applied for purification of ferulic acid from wheat bran by magnetic solid-phase extraction (MSPE). The satisfactory extraction recoveries for ferulic acid (88.7%) were obtained by changing different washing and eluted solvents. The recovery of the proposed method at three spiked level analysis was 77.9–97.5%, with the relative standard deviation less than 4.5%. DESs–Fe₃O₄NPs showed good performance for ferulic acid and the proposed approach might offer a novel method for purifying complex samples.     

Anthranilic acid assisted preparation of Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles

Magnetic Fe₃O₄–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were prepared by a novel and simple method: anthranilic acid assisted polymerization. The synthetic strategy involved two steps. First, Fe₃O₄ nanoparticles capped by anthranilic acid were obtained by a chemical precipitation method, and then the aniline and oxidant were added to the modified Fe₃O₄ nanoparticles to prepare well‐dispersed Fe₃O₄–poly(aniline‐co‐o‐anthranilic acid) nanoparticles. Fe₃O₄–poly(aniline‐co‐o‐anthranilic acid) nanoparticles exhibited a superparamagnetic behavior (i.e., no hysteresis loop) and high‐saturated magnetization (M_s = 21.5 emu/g). The structure of the composite was characterized by Fourier‐transform infrared spectra, X‐ray powder diffraction patterns, and transmission electron microscopy, which proved that the Fe₃O₄–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were about 20 nm. Moreover, the thermal properties of the composite were evaluated by thermogravimetric analysis, and it showed excellent thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1666–1671, 2006     

Synthesis of Hetroaromatic Polyamide and Imide–Acid-Functional Fe3O4 Nanoparticle and Their Effect on Thermal Degradation of PLA

A new hetroaromatic polyamide-reinforced polylactic acid (PLA)/functional Fe₃O₄ nanocomposite system was prepared through solution casting method. The hetroaromatic polyamide (PA) was synthesized from 2,5-pyridinedicarboxylic acid and 3,3′-diaminodiphenyl sulfone by direct polycondensation reaction. An imide–acid-functional Fe₃O₄ nanoparticle was prepared using pyromellitic dianhydride and coupling agent. As a potential reinforcement, PA and imide–acid-functionalized Fe₃O₄ were used in a PLA system. Combination of the functional Fe₃O₄ with PA showed a good effect on improving the thermal properties of PLA. The temperature at 5 mass% loss (T₅) was increased from 309°C to 337°C in PLA–PA containing 5 mass% of PA (PLA–PA 5) as compared to the neat PLA. The char yield of PLA–PA–FN 10 was increased from 0.5% to 8.9% as compared to the neat PLA and it was much high as compared to the system containing only 5 mass% of PA or the functional Fe₃O₄.     

Bis(ethyl-3-oxo-butanolato-O1, O3)-bis(2-propanolato) titanium (tyzor DCR) as a reactant and catalyst in the trimerization of 2-isocyanatoethyl methacrylate (IEM)

The reaction of bis(ethyl-3-oxo-butanolato-O¹, O³)-bis(2-propanolato)titanium (Tyzor DC^R) and 2-isocyanatoethyl methacrylate (IEM) in different molar ratios, at room temperature produced the trimer of IEM in high yields with ethyl acetoacetate, isopropyl acetoacetate, and titanium dioxide, which are derived from Tyzor DC^R, as by-products. The reaction products were identified by FTIR,¹H NMR,¹³C NMR, G.C. and M.S. procedures. The study showed that Tyzor DC^R acts as a catalyst in this reaction.     

Preparation and properties ofgem-dichlorocyclopropane derivatives of long-chain fatty esters

Methyl oleate (18∶1) and linoleate (18∶2) were readily transformed to the correspondinggem-dichlorocyclopropane derivatives in high yield, using triethylbenzylammonium chloride as the phase-transfer catalyst in the presence of aqueous NaOH and CHCl₃. Reaction of dichlorocarbene with methyl 12-hydroxystearate furnished methyl 12-chlorostearate (49%) and 12-O-formylstearate (19%). The hydroxy group in methyl ricinoleate was protected (O-tetrahydropyran-2′-yl) prior to dichlorocyclopropanation of the ethylenic bond. Removal of the protecting group allowed the hydroxy group to be converted to a chloride,O-acetyl, azido orO-formyl function. Treatment of methyl ricinoleate with thionyl chloride, followed by the reaction with dichlorocarbene gave the corresponding 12-chloro-dichlorocyclopropane derivative. The dichlorocyclopropane derivative of oleic acid was transformed to a C₁₉ allenic fatty acid when treated witht-butyl lithium. However, the remaining dichlorocyclopropane derivatives, containing an additional functional group in the alkyl chain, failed to yield the corresponding allenic derivatives. All derivatives were characterized by a combination of spectroscopic and chromatographic techniques, including infrared,¹H nuclear magnetic resonance (NMR), and¹³C NMR spectroscopy.     

Production of NMSBA from the oxidation of NMST in the homogeneous Co/Mn/Br/H3PMoxW12−xO40 catalytic system

2-nitro-4-methylsulphonylbenzoic acid (NMSBA) is an important intermediate for the preparation of the highly effective herbicide mesotrione. NMSBA is produced from the oxidation of 2-nitro-4- methylsulphonyltoluene (NMST) by nitric acid commercially, which suffers from the serious problems of low yield and heavy pollution. In this paper, a homogeneous system consisting of Co/Mn/Br/ · H₃PMo_xW_12−xO₄₀ has been applied to catalyze the production of NMSBA by oxidizing NMST with oxygen in acetic acid. The experiments indicate that the best value of x in the phosphomolybdenum tungsten heteropoly acid is 3. The optimum composition of this catalyst system is 1163 ppm H₃Pmo₃W₉O₄₀ · 12.17H₂O, 247.5 ppm Co, 453.5 ppm Mn, and 1075 ppm Br. Such a catalytic system is able to achieve a NMST conversion of 94.93% and a NMSBA selectivity of 99.84%. H₃PMo₃W₉O₄₀ exceeds both H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ as a catalyst in the production of NMSBA from the oxidation of NMST by oxygen.     

Chemo-enzymatic synthesis of amino acid-based surfactants

The application of lipases to the synthesis of amino acid-based surfactants was investigated. Low yields (2–9%) were obtained in the acylation of free amino acids, such as l-serine and l-lysine, as well as their ethyl esters and amides with fatty acids, owing in part to low miscibility of the reactants. When the N-carbobenzyloxy (Cbz)-l-amino acids were used in an effort to improve miscibility of the amino acid derivatives with the acyl donor, a dramatic improvement was observed for N-Cbz-l-serine (92% yield) but not for N _α-Cbz- or N _ζ-Cbz-l-lysine (7 and 2% yield, respectively). As an alternative, and efficient synthesis of N _ζ-acyl-l-lysines was developed, based on the regiospecific chemical acylation of copper(II) lysinate. In pursuit of a general route to amino acid-fatty acid surfactants, the utility of a polyol linker was investigated. Thus, the glycerol ester of N _α′ N _ζ-di-Cbz-l-lysine was prepared and evaluated as a substrate for acylation. As expected, this and other glycer-1-yl esters of N-protected amino acids were excellent substrates for lipase-catalyzed acylation. Their reaction with myristic acid in the presence of Novozyme resulted in the regioselective acylation of the primary hydroxyl group of the glycerol moiety to afford the corresponding 1-O-(N-Cbz-l-aminoacyl)-3-O-myris-toylglycerols with conversions of 50–90%. These were readily deprotected to give a range of 1-O-(aminoacyl)-3-O-myristoyl-glycerols with overall yields of 27–71%.     

Using a polymer‐supported azide ion in [2+3] cycloaddition reaction of azide ion with nitriles

The [2+3] cycloaddition between various nitriles and crosslinked poly(4‐vinylpyridine) supported azide ion proceeds smoothly in the presence of ammonium bromide or ammonium chloride in N,N‐dimethyl formamide, to give the corresponding 5‐substituted‐1H‐tetrazoles in good to high yields. Conventional heating was used to promote reaction. It was found that using nitriles with electron‐withdrawing groups result in bout higher yields and lower reaction times. The present procedure offers advantages, such as shorter reaction time, and simple workup. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced Bactericidal Effect of O3/H2O2 Followed by Cl2

With the appearance of chlorine resistant microorganisms such as Cryptosporidium parvum and Giardia lamblia in drinking water, significant attention has been drawn to the sequential application of multiple disinfectants including ozone, chlorine dioxide, and UV as a primary disinfectant. However, few studies have reported about the inactivation behavior of ozone-based AOP (advanced oxidation process) or its sequential application combined with other disinfectants. This is especially important since ozone itself experiences difficulty in the inactivation of these pathogens, especially at low temperatures: This study investigates the enhanced inactivation of Bacillus subtilis spores by the presence of an OH radical in the O₃/H₂O₂ system and the synergistically enhanced inactivation in the application of the O₃/H₂O₂ system followed by Cl₂. The results suggest that the O₃/H₂O₂ process can be considered as one of the viable alternatives when O₃ alone does not satisfy the disinfection requirement.     

5-Pyrenylidene-hydantoin, 2-thiohydantoin derivatives: synthesis,S- and N-alkylation

5-Pyrenylidene-2-thiohydantoin derivatives 2a–d were prepared by condensation of pyrene-1-carboxaldehyde with 2-thiohydantoin derivatives. Compounds 2a,b undergo Mannich reaction with formaldehyde and morpholine to give the corresponding Mannich products 3a,b respectively. S- and N-monoalkyl-5-pyrenylidene-hydantoin derivatives 5a,b and 6a,b were prepared by reaction of 5-pyrenylidene-2-thiohydantoin sodium salts with 1,3-dioxolan-methylsulfate derivatives. Deprotection of the products afforded 5-pyrenylidene-hydantoin (7), S- and N-dihydroxy derivatives 8a,b and 9a,b respectively. Reaction of 2a with methyl iodide afforded the corresponding S-methyl derivative 10, which reacted with secondary amines such as morpholine and piperidine afforded the glycocymidine derivatives 11a,b. Reaction of 2a with (2,3,4,6-tetra-O-acetyl-α-? D-glucopyranosyl)bromide afforded a mixture of S- and N-glucoside derivatives 12 and 13 respectively. Deprotection of 12 afforded compound 7, while deprotection of 13 furnished 5-Pyrenylidene-3-? D-glucopyranosyl-2-thiohydantoin (14). Reaction of 7 with propargyl chloride in DMF afforded the monoalkynyl- and bis-alkynyl-hydantoin derivatives 15 and 16, respectively. Reaction of 15 with p-bromophenyl-ether derivative 17 yielded the bis-alkynyl derivative 18.     

Environmentally friendly liquid phase oxidation: enhanced selectivity in the aerial oxidation of alkyl aromatics,epoxidations and the Baeyer–Villiger oxidation using novel silica supported transition metal ions

Active transition metal species (Co, Cu, Cr, Ni or Mn) supported on a chemically modified silica gel are used as heterogeneous catalysts in a range of liquid phase oxidation reactions: alkyl aromatic side chain oxidations, epoxidations of alkenes and Baeyer–Villiger oxidations of linear ketones to esters and cyclic ketones to lactones. The catalyst employs metal centres bound to the silica surface via a hydrophobic spacer chain and is thus chemically robust and has a relatively high loading for a supported reagent (c 0.4 mmol g⁻¹). The Cr version of the catalyst promotes the oxidation of ethylbenzene to acetophenone in a solvent‐free system at a rate of 5.5% h⁻¹ (>370 turnover h⁻¹). It is also active for the oxidation of p‐chlorotoluene and p‐xylene to p‐chlorobenzoic acid and p‐toluic acid respectively. Cyclohexene is converted to its oxide at room temperature at a rate of c 28% h⁻¹ (c 12 turnover h⁻¹) using either the Ni or Cu versions of the catalyst. The room temperature Baeyer–Villiger oxidation of cyclohexanone is achieved at a rate of 44% h⁻¹ (49 turnover h⁻¹) using the Ni‐containing catalyst. The same material also promotes the Baeyer–Villiger oxidation of linear aliphatic ketones and aromatic side chains. All the above systems use either air or molecular oxygen as the oxidant rather than peroxides or peracids. © 1999 Society of Chemical Industry     

Synthesis and characterization of Fe3O4/poly(lactide‐co‐glycolide) composite and its coating effects on magnesium alloy

The Fe₃O₄/poly(lactide‐co‐glycolide) (PLGA) composites were prepared via a surface grafting technique. Initially, the poly(lactic acid) oligomer was synthesized and surface‐grafted to Fe₃O₄ nanoparticles. Then, the grafted Fe₃O₄ particles were compounded with PLGA matrix by a simple solution blending method. The grafted Fe₃O₄ particles presented enhanced compatibility with PLGA matrix and the composites indicated enhanced dynamic mechanical performance. Electrochemical tests showed that the Fe₃O₄/PLGA composite coating can help improve the impedance of magnesium samples by 100–300%, and the impedance of the metal may be tunable by altering the components ratio of LA/GA within PLGA matrix. The composites may have potential application for magnesium alloy used in degradable medical implants. POLYM. COMPOS., 37:1369–1374, 2016. © 2014 Society of Plastics Engineers     

A1PO4-Al2O3 catalysts with low alumina content. III. Surface basicity of catalysts obtained in aqueous ammonia

The amount of basic sites of A1PO₄-Al₂O₃ (APA1-A, 5–15 wt% Al₂O₃) catalysts at two basic strengths was measured by studying the liquid-phase adsorption of two acidic molecules (benzoic acid (BA, pK = 4.2) and phenol (PH, pKa = 9.9) from cyclohexane solutions, through the application of a spectrophotometric method. The data obtained follow the Langmuir adsorption isotherm and the monolayer coverage at equilibrium (at 298 K),X _m, is assumed as the amount of basic sites corresponding to the specific pK of the acid used as titrant. The amount of basic sites of any AlPO₄-Al₂O₃ catalyst is higher than that of AlPO₄, but lower than that of Al₂O₃. Besides, an increase in the Al₂O₃ content from 10 wt% gradually increases the basicity of the APA1-A catalyst. Moreover, calcination at increasing temperatures does not practically affect the surface basicity of APAl-A-5 and APAl-A-10 catalysts. However, for AlPO₄ content higher than 10 wt% we observe a decrease in surface basicity, this decrease depends on alumina content, i.e. it is higher as the amount of alumina increases. The basic sites of APAl-A systems catalyze the Knoevenagel condensation ofp-methoxybenzaldehyde and malononitrile at room temperature and in the absence of solvent.