Reaction of 5-Amino-2,3-dicyano-1,4-naphthoquinone with Arylamines

The reaction of 5-amino-2,3-dicyano-1,4-naphthoquinone (1) with arylamines gave 5-amino-8-arylamino- (2), 5,8-bis(arylamino)- (3), and 5-hydroxy-8-arylamino-2,3-dicyano-1,4-naphthoquinone (4) together with 5-amino-2-arylamino-3-cyano- (5) and 5-amino-2-cyano-3-aryl-amino-1,4-naphthoquinone (6). It is proposed that the initial quinone-quinoneimine tautomerism of 1 to 4-hydroxy-2,3-dicyano-5-imino-1,5-naphthoquinone 7 facilitates the 8-arylamination. Some derivatives of 2 have good properties as dyes for optical information-recording media for semiconductor lasers.     

6-乙酰氧基-4(3氢)-喹唑啉酮的合成

以2-氨基-5-羟基苯甲酸为原料,与甲酰胺环合得到6-羟基-4(3氢)-喹唑啉酮,再用乙酸酐酯化得到6-乙酰氧基-4(3氢)-喹唑啉酮。研究了每步反应的投料比和反应温度对收率、纯度的影响。结果表明,①6-羟基-4(3氢)-喹唑啉酮的最佳工艺条件为:2-氨基-5-羟基苯甲酸与甲酰胺的摩尔比是1∶15,温度160℃,反应时间4 h;②6-乙酰氧基-4(3氢)-喹唑啉酮的最佳工艺条件为:6-羟基-4(3氢)-喹唑啉酮与乙酸酐的摩尔比是1∶1.2,温度80℃,反应时间3 h;两步反应的总产率达96%,产物纯度>99.0%。     

Soil transformation of wheat and corn metabolites mboa and DIM2BOA into aminophenoxazinones

The defensive cyclic hydroxamates 7-methoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIMBOA) and 7,8-dimethoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIM₂BOA) of wheat and corn are transformed in nonsterile soil, via 6-methoxy-2(3H)-benzoxazolone (MBOA) and 6,7-dimethoxy-2(3H)-benzoxazolone (M₂BOA) respectively, into 2-amino-7-methoxy-3H-phenoxazin-3-one and 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one. The soil transformation is similar of that undergone by the rye metabolite 2(3H)-benzoxazolone (BOA) into 2-amino-3H-phenoxazin-3-one. The transformations to phenoxazinones are not observed in sterile soil. The 2-amino-3H-phenoxazin-3-one inhibits barnyard grass radicle elongation, but the methoxylated aminophenoxazinones are not significantly inhibitory.     

7-氨基-6-氰基-5-(3-硝基苯基)吡喃并嘧啶-2,4-二酮的合成

报道了常温、超声辐射、水中、无催化剂条件下，以3-硝基苯甲醛、丙二腈和巴比妥酸为原料合成标题化合物的方法。考察了超声技术、反应时间及反应温度对反应的影响。最佳反应条件为：室温、超声辐射2h，收率为86．2％。     

Nano-CuFe2O4@SO3H Catalyzed Efficient One-Pot Cyclo-Dehydration of Dimedone and Synthesis of Chromeno[4,3-b]chromenes

Chlorosulfonic acid immobilized on CuFe₂O₄ nanoparticles (nano-CuFe₂O₄@SO₃H) was evaluated as a recoverable catalyst for the one-pot cyclo-dehydration of dimedone and synthesis of chromeno[4,3-b]chromene derivatives by reaction of arylaldehydes, dimedone or 1,3-cyclohexanedione, with 3-hydroxycoumarine or 4-hydroxycoumarine in good to excellent yield. Also, 2,2′-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was synthesized by the reaction of aromatic aldehyde and dimedone using nano-CuFe₂O₄ in ethanol at room temperature. The catalyst could be recycled several times without significant loss of its catalytic activity. Clean methodologies, easy work-up procedure, high yield and simple preparation of the catalyst are some advantages of this procedure.     

Melamine-(H2SO4)3/melamine-(HNO3)3 instead of H2SO4/HNO3: a safe system for the fast oxidation of thiols and sulfides under solvent-free conditions

Melamine reacted with neat sulfuric acid and fuming nitric acid readily to form two new organic solid acids, namely melamine-(H₂SO₄)₃ and melamine-(HNO₃)₃. Mixture of them acts as a unique powerful system instead of a hazardous H₂SO₄/HNO₃ system for the direct oxidation of thiols. Also, this system can oxidize the sulfides in the presence of a catalytic amount of KBr and few drops of water. This procedure offers advantages such as very low reaction time, simple work-up, excellent yield and matching with some green chemistry protocols.     

碳酸钾催化绿色合成2-氨基-3-氰基-1,4,5,6-四氢吡喃并[3,2-c]喹啉-5-酮衍生物

以4-羟基喹啉-2-酮、丙二腈、芳醛为起始原料,以碳酸钾为催化剂,在乙醇中一锅合成了2-氨基-3-氰基-1,4,5,6-四氢吡喃并[3,2-c]喹啉-5-酮衍生物。该方法具有反应条件温和、操作简单、产物易纯化、产率高等优点,是一种无毒、高效的绿色合成方法。     

微波促进碳酸钾催化一锅法合成2-氨基-3氰基-4-芳基-4H-苯并色烯衍生物

微波辐射下,乙醇溶剂中K₂CO₃催化芳甲醛、丙二腈和α-萘酚（或β-萘酚）三组分一锅法快速合成了一系列2-氨基-3-氰基-4-芳基-4H-苯并[h]色烯或苯并[f]色烯衍生物。以苯甲醛、丙二氰与α-萘酚的反应为模板反应,通过单因素实验方案优化了反应的工艺条件。结果表明：反应物各10 mmol,催化剂K₂CO₃ 1 mmol,溶剂无水乙醇15 ml,采用微波功率500 W,80℃回流反应 5 min,2-氨基-3-氰基-4-苯基-4H-苯并[h]色烯（4a）的收率83.6%。在上述最佳条件下,利用取代苯甲醛代替苯甲醛,4H-苯并[h]色烯衍生物(4)产率为65.8%~89.4%。 利用β-萘酚代替α-萘酚,4H-苯并[f]色烯衍生物(6)产率为67.5%~82.9%,合成产物通过熔点和红外光谱表征其结构。     

Metal-organic framework Cu3 (BTC)2(H2O)3 catalyzed Aldol synthesis of pyrimidine-chalcone hybrids

A typical metal organic framework, [Cu₃ (BTC)₂(H₂O)₃, BTC = 1,3,5-benzene tricarboxylate] has been used for the synthesis of pyrimidine-chalcones. We have explored a green synthesis of pyrimidine chalcones under Cu₃(BTC)₂ catalysis by Aldol condensation. Easy isolation of product, excellent yield, and recyclable catalyst makes this reaction eco-friendly. The technology was demonstrated to be applicable to the synthesis of a host of chemical hybrids.     

Reactions of ketene dithioacetal for a new versatile synthesis of 4,5-substituted 3-aminothiophene-2-carboxylate derivatives

Poly substituted 3-aminothiophenes were successfully synthesized in good yields by using a one-pot protocol via ketene S,S-acetal as an intermediate in basic medium (K₂CO₃/N,N-dimethylformamide) followed by Dieckmann condensation with ethyl bromoacetate. Further, chemistry of thiophenes was explored using active functional groups such as C₃–NH₂, C₄–CN and C₅–SCH₃ on the thiophene nucleus.

Synthesis of ethyl 3-acetamido-4-cyano-5-(methylthio)thiophene-2-carboxylate derivatives and ethyl 3-amino-4-carbamoyl-5-(methylthio)thiophene-2-carboxylate derivatives.     

Synthesis of an industrially important zinc borate, 2ZnO·3B2O3·3H2O, by a rheological phase reaction method

2ZnO·3B₂O₃·3H₂O is an industrially important zinc borate. Herein, 2ZnO·3B₂O₃·3H₂O has been prepared via a rheological phase reaction method using zinc oxide and boric acid as starting materials. This route is facile and acceptable for green chemical synthesis, producing no pollution and giving a yield of near 100% of theoretical value. And in this method, the complete conversion of the starting materials can be achieved in the presence of only 0.04 mL water (one drop of water). The products have been characterized by X-ray powder diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM) and particle size distribution. The effects of experimental conditions on the products were investigated. The main factors that affect the formation of zinc borate are water volume, sealing state, reaction time and temperature.     

Synthese substituierter 2-Aminochinolin-1-oxide durch reduktive Cyclisierung substituierter 3-(2-Nitrophenyl)acrylnitrile

Synthesis of Substituted 2-Aminoquinoline-1-oxides by Reductive Cyclization of Substituted 3-(2-Nitrophenyl)acrylonitriles An approach to the class of 2-aminoquinoline-1-oxides is given based on reductive cyclization of appropriate substituted 3-(2-nitrophenyl)acrylonitriles. Thus, 2-nitrobenzylidene compounds 1 a – d have been reductively cyclized by H₂/PtO₂ or H₂/Pd-C under normal conditions to form N-oxides 2 a – d . ¹H-NMR data show that 1 d has to be regarded as ethyl(Z)-2-cyano-3-hydroxy-3(2-nitrophenyl)acrylate. The analogous (2-nitrobenzoyl)acetonitrile 3 , however, did not cyclize under the same conditions, but yielded anthraniloylacetonitrile 4 . The results are discussed in comparison with the reaction behaviour of structural related nitronitriles under comparable conditions. A short survey of reactions leading to heterocyclic N-oxides by reductive cyclization of nitro compounds is given.     

Highly uniform Gd(OH)3 and Gd2O3:Eu hexagram-like microcrystals: glucose-assisted hydrothermal synthesis,growth mechanism and luminescence property

Monodispersed and uniform Gd(OH)₃ microcrystals with novel hexagram-like morphology have been successfully prepared through a simple and green hydrothermal process with the assistance of glucose. The results of control experiments revealed that the glucose concentration in the reaction system was an important factor, which affected the morphology of the Gd(OH)₃ microcrystals significantly. On the basis of time-dependent experiments, the growth mechanism of the Gd(OH)₃ hexagrams was discussed. Furthermore, the Gd₂O₃ and Eu³⁺-doped Gd₂O₃ hexagram-like microcrystals, inheriting the Gd(OH)₃ precursors' morphology, were obtained during a direct annealing process in air. The corresponding Gd₂O₃:Eu³⁺ hexagram-like microcrystals exhibit strong red emission pertaining to the ⁵D₀→⁷F₂ transition of the Eu³⁺ ions under UV light, which have potential applications in novel optoelectronic devices.     

Novel Brønsted acidic ionic liquids catalyzed one-pot reaction of highly green regioselective thiocyanation of N-containing aromatic and heteroaromatic compounds at room temperature

In this method, a novel Brønsted acidic ionic liquid silica-supported pyridinium sulfonic acid thiocyanate {SiO₂@[Pyridine-SO₃H]SCN} and sulfonic acid-functionalized pyridinium chloride {[PSA]Cl} were easily synthesized and characterized. In the first method, {SiO₂@[Pyridine-SO₃H]SCN as a novel and environmentally friendly catalyst with one acidic functional group and one thiocyanation agent group was ef?ciently used for the synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives in the presence of H₂O₂ as a green oxidant in EtOH:H₂O (1:1) at room temperature. In the second method, {[PSA]Cl} as a new ionic liquid and environmentally friendly catalyst with one acidic functional group was used for the simple and efficient synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives with NH₄SCN in the presence of H₂O₂ as a green oxidant in EtOH:H₂O (1:1) at room temperature. A simple experimental procedure, clean reaction profile, use of an inexpensive catalyst, and recyclability of the catalyst are some of the advantages of the procedure. Also, one of the advantages of the first method is the non-usage of NH₄SCN or KSCN in the reaction.     

Catalytic Production of Carbon Nanotubes by Decomposition of CH4 over the Pre-reduced Catalysts LaNiO3, La4Ni3O10, La3Ni2O7 and La2NiO4

A large amount of more graphitic carbon nanotubes with a narrow size distribution was produced from catalytic decomposition of CH₄ over pre-reduced LaNiO₃, La₄Ni₃O₁₀, La₃Ni₂O₇ and La₂NiO₄. The structure and component of fresh and reduced LaNiO₃, La₄Ni₃O₁₀, La₃Ni₂O₇ and La₂NiO₄ were determined by X-ray diffraction (XRD). The carbon nanotubes obtained were characterized by means of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Thermal oxidation of carbon nanotubes in air was made by thermogravimetric experiments (TG). The results revealed that the value of La/Ni in different catalyst precursors influences the diameter distribution and graphitic degree of carbon nanotubes. Lower La/Ni leads to wider diameter and higher graphitic degree of carbon nanotubes.     

Synthesis, characterization and optimum reaction conditions of oligo-2-amino-3-hydroxypyridine and its Schiff base oligomer

The oxidative polycondensation reaction conditions of 2-amino-3-hydroxypyridine (AHP) and 2-[benzilydeneimino] pyridine-3-ol (BIP) were studied by oxidants such as with air O₂, NaOCl and H₂O₂. Oligo-2-amino-3-hydroxypyridine (OAHP) was synthesized from the oxidative polycondensation of AHP with air O₂, NaOCl and H₂O₂ in an aqueous acidic and alkaline medium at 30-90 °C. BIP was synthesized from condensation of 2-amino-3-hydroxypyridine with benzaldehyde. Oligo-2-[benzilydeneimino] pyridine-3-ol (OBIP) was synthesized from the oxidative polycondensation of BIP with air O₂, NaOCl and H₂O₂ in an aqueous alkaline medium at 40-90 °C. About 95% BIP was converted to OBIP. The number average molecular weight, (M_n) weight average molecular weight (M_w) and polydispersity index (PDI) values of OAHP and OBIP (for air O₂ oxidant) were found to be 1433, 1912 g mol⁻¹, 1.33 and 2637, 5106 g mol⁻¹ and 1.94, respectively. At the optimum reaction conditions, the yield of OAHP was found to be 86.0% (for air O₂ oxidant), 43.0% (for H₂O₂ oxidant) and 85.0% (for NaOCl oxidant). At the optimum reaction conditions, the yield of OBIP was found to be 91.0% (for air O₂ oxidant), 92.0% (for H₂O₂ oxidant) and 95.0% (for NaOCl oxidant). The OHAP and OBIP were characterized by FT-IR, UV-Vis, ¹H and ¹³C-NMR elemental analysis. TG and DTA analyses were shown to be unstable of OAHP and OBIP against thermo-oxidative decomposition. According to TG analyses, the weight loss of OAHP and OBIP was found to be 97.35 and 96.60% at 520 and 685 °C, respectively.     

Preparation and luminescent properties of Tb3+ doped Y2O2SO4 microflakes

Abstract

Tb³⁺ doped Y₂O₂SO₄ (Y₂O₂SO₄:Tb³⁺) microflakes were prepared by a combination method of electrospinning and calcination. The two-dimensional microflakes had smooth surface and high radial/axial ratio. Crystal structures of the Y₂O₂SO₄:Tb³⁺ microflakes resulted in layer by layer growth in axial direction. A possible formation mechanism was proposed on the basis of experimental results, which indicated that poly(vinyl pyrrolidone) played the role of the nanostructure directing template and revealed the growth priority in radial direction. The microflakes showed a favourable fluorescent property symbolised by the characteristic green emission (541 nm) resulting from the ⁵D₄→⁷F₅ transition of Tb³⁺ ions under 229 nm ultraviolet excitation. The maximum intensity of Tb³⁺ emission of the Y₂O₂SO₄:Tb³⁺ microflakes was 2·3 times stronger than that of the Y₂O₂SO₄:Tb³⁺ bulk powders with the same doping concentration.     

Synthesis of HFC-134a over CrF3/AlF3 catalysts

The effect of the structure of AlF₃ supports in CrF₃/AlF₃ catalysts and their activity were studied, and a selection of suitable reaction conditions for fluorination of trichloroethylene and HCFC-133a was made. We found that neither AlF₃ (- and -modifications) nor CrF₃/-AlF₃ exhibits significant activity for the reaction of HF with CCl₂=CHC1 or CF₃CH₂Cl. However, CrF₃/-AlF₃ exhibits high activity, which increases with increasing surface area and decreasing crystallite size of the -AlF₃ support, and that dramatically affects the fiuorination of CF₃CH₂Cl. Investigation of a series of CrF₃/-AlF₃ catalysts shows that the turnover rates per unit of the total surface area and of the free CrF₃ surface area significantly increase with increasing content of Cr³⁺ loading. Optimum temperature for the reaction of HF with CCl₂=CHCl is 260°C, while with CF₃CH₂Cl it is 350°C, with flow ratios HFTCE = 61 andHFHCFC-133a = 101.     

Efficiency and Mechanism of Ciprofloxacin Hydrochloride Degradation in Wastewater by Fe3o4/Na2S2O8

ABSTRACT

The nanosized Fe₃O₄ catalyst was synthesized via a modified reverse coprecipitation method and characterized by means of a scanning electron microscope (SEM) and an X-ray diffraction (XRD) analysis instrument. The degradation efficiency and reaction rate of Fe₃O₄ in activating sodium persulfate used to degrade ciprofloxacin were determined from the catalyst dosage, oxidant concentration, and initial pH. The results showed that under the optimum conditions of a catalyst dosage of 2.0 g·L^?1, a sodium persulfate concentration of 1.0 g·L^?1, and an initial pH of 7, the degradation rate of ciprofloxacin was 93.73%, the removal rate of total organic carbon was 78%, and the first-order reaction constant was 0.06907 min^?1 within 40 min. It was also demonstrated that the reactive oxygen species in the Fe₃O₄/sodium persulfate catalytic system were mainly composed of SO₄^– and supplemented by OH· and HO₂· using probe compounds such as ethanol, tertiary butanol, and benzoquinone.     

NO reduction over La2O3 using methanol

Nitric oxide (NO) reduction by methanol was studied over La₂O₃ in the presence and absence of oxygen. In the absence of O₂, CH₃OH reduced NO to both N₂O and N₂, with selectivity to dinitrogen formation decreasing from around 85% at 623 K to 50–70% at 723 K. With 1% O₂ in the feed, rates were 4–8 times higher, but the selectivity to N₂ dropped from 50% at 623 K to 10% at 723 K. The specific activities with La₂O₃ for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of 35 _μmol NO/s m² was obtained whereas that for methanol was 600 μmol NO/s m². The Arrhenius plots were linear under differential reaction conditions, and the apparent activation energy was consistently near 14 kcal/mol with CH₃OH. Linear partial pressure dependencies based on a power rate law were obtained and showed a near‐zero order in CH₃OH and a near‐first order in H₂. In the absence of O₂, a Langmuir–Hinshelwood type model assuming a surface reaction between adsorbed CH₃OH and adsorbed NO as the slow step satisfactorily fitted the data, and the model invoking two types of sites provided the best fit and gave thermodynamically consistent rate constants. In the presence of O₂ a homogeneous gas‐phase reaction between O₂, NO, and CH₃OH occurred to yield methyl nitrite. This reaction converted more than 30% of the methanol at 300 K and continued to occur up to temperatures where methanol was fully oxidized. Quantitative kinetic studies of the heterogeneous reaction with O₂ present were significantly complicated by this homogeneous reaction. This revised version was published online in July 2006 with corrections to the Cover Date.