- An All-Organic D-A System for Visible-Light-Driven Overall Water Splitting
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Direct water splitting over photocatalysts is a prospective strategy to convert solar energy into hydrogen energy. Nevertheless, because of the undesirable electron accumulation at the surface, the overall water-splitting efficiency is seriously restricted by the poor charge separation/transfer ability. Here, an all-organic donor–acceptor (D-A) system through crafting carbon rings units-conjugated tubular graphitic carbon nitride (C-TCN) is proposed. Through a range of characterizations and theoretical calculations, the incorporation of carbon rings units via continuous π-conjugated bond builds a D-A system, which can drive intramolecular charge transfer to realize highly efficient charge separation. More importantly, the tubular structure and the incorporated carbon rings units cause a significant downshift of the valence band, of which the potential is beneficial to the activation for O2 evolution. When serving as photocatalyst for overall water splitting, C-TCN displays considerable performance with H2 and O2 production rates of 204.6 and 100.8 μmol g?1 h?1, respectively. The corresponding external quantum efficiency reaches 2.6% at 405 nm, and still remains 1.7% at 420 nm. This work demonstrates that the all-organic D-A system conceptualized from organic solar cell can offer promotional effect for overall water splitting by addressing the charge accumulation problem rooted in the hydrogen evolution reaction.
- Di, Jun,Lei, Yucheng,Li, Huaming,Liu, Chuntai,Liu, Daobin,Lv, Chade,Mo, Zhao,Song, Yanhua,Xu, Hui,Yan, Pengcheng,Yan, Qingyu,Yu, Qing,Zhu, Xingwang
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- A proof of the direct hole transfer in photocatalysis: The case of melamine
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The photoinduced transformation of 2,4,6-triamino-1,3,5-triazine (melamine) was studied by using different advanced oxidation technologies under a variety of experimental conditions. The systems involving homogeneous hydroxyl radicals, as generated by H2O2/hν, Fenton reagent, and sonocatalysis are ineffective. However, melamine is degraded under photocatalytic conditions or by SO4- (S2O82-/hν). The time evolution of long-living intermediates, such as 2,4-diamino-6-hydroxy-1,3,5-triazine (ammeline) and 2-amino-4,6-dihydroxy-1,3,5-triazine (ammelide), has been followed, being 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid) the final stable product. During both photocatalytic and S2O82-/hν experiments, in the early steps, a fairly stable intermediate evolving to ammelide is observed in a large extent. This intermediate was identified as 2,4-diamino-6-nitro-1,3,5-triazine. This indicates that the primary photocatalytic event is the oxidation of the amino-group to nitro-group through several consecutive fast oxidation steps, and that a hydrolytic step leads to the release of nitrite in solution. To elucidate the nature of the oxidant species hole scavengers such as methanol and bromide ions were added to the irradiated TiO2. They completely stop the degradation, whereas chloride and fluoride ions decrease the degradation rate. The study of the photocatalytic degradation rate of melamine at increasing concentrations using two different commercial titanium dioxides, such as P25 and Merck TiO2, showed an intriguing behavior. A drastic abatement of the melamine transformation rate was observed when coagulation of the P25 slurry occurs due both to the pH change and melamine concentration effect that increase melamine adsorption. In the presence of TiO2 (Merck) the melamine initial degradation rates are significantly lower than those observed in the presence of P25 but are not depressed at larger concentrations. The experimental evidences (e.g.; absence of melamine adsorption onto TiO2 surface at low concentrations or at acidic pH or due to the catalyst surface texture, and the lack of reactivity toward OH free and bound) suggest that the effective photocatalytic mechanism is based on an outer sphere direct hole transfer to the melamine. Its formal potential lies in the range 1.9-2.3 V vs NHE. Then, the photodegradation of melamine is an efficient tool to evaluate the direct hole transfer ability of a photocatalyst.
- Maurino, Valter,Minella, Marco,Sordello, Fabrizio,Minero, Claudio
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- An HPLC method with UV detection, pH control, and reductive ascorbic acid for cyanuric acid analysis in water
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Every year over 250 million pounds of cyanuric acid (CA) and chlorinated isocyanurates are produced industrially. These compounds are standard ingredients in formulations for household bleaches, industrial cleansers, dishwasher compounds, general sanitizers, and chlorine stabilizers. The method developed for CA using high-performance liquid chromatography (HPLC) with UV detection simplifies and optimizes certain parameters of previous methodologies by effective pH control of the eluent (95% phosphate buffer: 5% methanol, v/v) to the narrow pH range of 7.2-7.4. UV detection was set at the optimum wavelength of 213 nm where the cyanuric ion absorbs strongly. Analysis at the lower pH range of 6.8-7.1 proved inadequate due to CA keto - enol tautomerism, while at pHs of 7.4 proved more sensitive but their use was rejected because of CA elution at the chromatographic void volume and due to chemical interferences. The complex equilibria of chlorinated isocyanurates and associated species were suppressed by using reductive ascorbic acid to restrict the products to CA. UV, HPLC-UV, and electrospray ionization mass spectrometry techniques were combined to monitor the reactive chlorinated isocyanurates and to support the use of ascorbic acid. The resulting method is reproducible and measures CA in the 0.5-125 mg/L linear concentration range with a method detection limit of 0.05 mg/L in water.
- Cantu,Evans,Kawahara,Shoemaker,Dufour
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- Reactions of hydrated electrons with triazine derivatives in aqueous medium
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A study is made of the kinetics and mechanism of the reaction of radiolytically produced hydrated electron (e-aq) with some triazine derivatives [1,3,5-triazine (T), 2,4,6-trimethoxy-1,3,5-triazine (TMT), 2,4-dioxohexahydro-1,3,5-triazine (DHT), 6-chloro N-ethyl N-(1-methylethyl)-1,3,5-triazine 2,4-diamine (atrazine, AT), and cyanuric acid (CA)] in aqueous medium using pulse and steady-state radiolysis techniques. The second-order rate constants were determined from the pseudo first-order decay of e-aq in the presence of triazines at 720 nm, and the values obtained with T, TMT, AT, and CA are in the order of 109 dm3 mol-1 s-1 and that of DHT was 10 8 dm3 mol-1 s-1 at pH 6. The transient absorption spectra from the reaction of e-aq with T and TMT are characterized by their λmax at 310 nm, and those of DHT and CA are around 280 and 290 nm, respectively. However, a very weak and featureless absorption spectrum is obtained from AT. On the basis of the spectral evidence and on the quantitative electron transfer from the transient intermediates to the oxidant, methyl viologen (MV2+), the intermediate radicals are assigned to N-protonated electron adducts (with the unpaired spin density at carbon) of triazines. The degradation profiles, monitored as the disappearance of parent triazine concentrations as a function of dose, obtained with AT, TMT, CA, and DHT, highlight the potential use of e-aq in the degradation of triazines.
- Varghese, Rani,Mohan, Hari,Manoj,Manoj,Aravind, Usha K.,Vandana,Aravindakumar
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- Photocatalytic degradation of the herbicide terbuthylazine: Preparation, characterization and photoactivity of the immobilized thin layer of TiO2/chitosan
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The aim of this study was to immobilize a photocatalytic TiO2 layer on a suitable support material for potential use in a variety of photoreactor designs. The immobilized TiO2/chitosan thin film was used for the photocatalytic treatment of a triazine herbicide, terbuthylazine as representative agrochemical pollutant in the wastewater. The method of preparation was based on the use of a chitosan as binder and glass fiber woven roving material as a support. The employed method was found to be very simple, low cost and quite effective. Several methods of the photocatalyst characterization, such as FE-SEM/EDX, AAS, ICP-MS, TOC and nitrogen adsorption/desorption at 77 K were employed to correlate structural and morphological properties of immobilized TiO2-chitosan/glass fiber woven roving and its photocatalytic properties under UV irradiation. Reaction was performed in a self-constructed batch mode and annular type of the photoreactor. Comparison of thermal, photolytic and photocatalytical degradation of treated terbuthylazine at different reaction conditions was performed in order to get more insight into the photocatalytic performance and reaction mechanism. It was observed that there is no decay in photocatalytic efficiency over a long period of reaction time using for the photocatalytic degradation of terbuthylazine.
- Le Cunff, Jér?me,Toma?i?, Vesna,Wittine, Ozren
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- Cyanuric and thiocyanuric esters as carriers of boron-containing fragments and their fragmentation in mass spectrometry
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Tripropargylic esters 2 and 10 of cyanuric and thiocyanuric acids were synthesized. Interaction of these compounds with disubstituted amines gives monoaminoderivatives of dipropargyloxy-s-triazine 4 and 11. Diaminosubstituted propargyloxy-s-triazine 6 was
- Azev, Yuri A.,Dülcks, Thomas,Gabel, Detlef
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- Synthesis and cytotoxic activity of trisubstituted-1,3,5-triazines
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1,3,5-Triazine derivatives were screened for phototoxicity as well as the cytotoxic activities against leukemia and adenocarcinoma derived cell lines in comparison to the normal human keratinocytes. A simple and environmentally friendly procedure has been developed for the synthesis of 1,3,5-triazine derivatives under microwave irradiation in the presence of a HY zeolite. The catalyst can be recovered and reused. Thus, the procedure provides a simple and green synthetic methodology under environmentally friendly conditions. Structure-activity relationships between the chemical structures and antimycobacterial and photosynthesis-inhibiting activity of the evaluated compounds are also discussed.
- Arya, Kapil,Dandia, Anshu
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- Synthesis of pyrimidines and triazines in ice: Implications for the prebiotic chemistry of nucleobases
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Herein, we report the efficient synthesis of RNA bases and func-tionalized s-triazines from 0.1 M urea solutions in water after subjection to freeze-thaw cycles for three weeks. The icy solution was under a reductive, methane-based atmosphere, which was s
- Menor-Salvan, Cesar,Ruiz-Bermejo, Dra. Marta,Guzman, Marcelo I.,Osuna-Esteban, Susana,Veintemillas-Verdaguer, Sabino
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- Oxidation of atrazine by photoactivated potassium persulfate in aqueous solutions
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General laws of the photochemical oxidation of atrazine by inorganic peroxo compounds under the impact of solar radiation are studied. It is found that almost complete conversion of atrazine can be achieved via photochemical oxidation with persulfate afte
- Khandarkhaeva,Aseev,Sizykh,Batoeva
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- Using bar infrared spectra and coincidence indexes to study the diversity of solid cyanuric acid structures
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A general method was developed for studying the diversity of individuals in a population based on the diversity of infrared spectra of solid cyanuric acid analytes obtained from various reactions of trichlorocyanuric acid. This method first generates infrared bar spectra for the analytes and then measures the coincidence and continence among pairs of the spectral peaks via confrontation matrices. Class markers are established to characterize analyte classes. Possible correlations among the employed reaction conditions and the nature of the produced solids, which are based on their infrared bar spectra, are discussed. The method of coincidence may be useful for characterizing polymorphs, particularly those of active pharmaceutical ingredients (APIs). The method may also be extended to define the homogeneity of solid analytes. The ANALIN module of the ANALOR software suite running on a dBase platform is used to generate the bar infrared spectra and to handle all calculations.
- Nilo, Marcela C. B. G.,Sim?es, Thais G.,Neto, Claudio Costa
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- Degradation of melamine in aqueous systems by vacuum UV-(VUV-) photolysis. An alternative to photocatalysis
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VUV-irradiation experiments with aqueous solutions of melamine and related triazine derivatives were carried out in the presence or absence of molecular oxygen. Substrate degradation, total organic carbon and evolution profiles of intermediates were monit
- Bianco Prevot, Alessandra,Maurino, Valter,Fabbri, Debora,Braun, André M.,Gonzalez, Mónica C.
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- Liquid-phase synthesis of cyanuric acid from urea
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The focus of this paper was to identify a cheaper solvent from among diesel fuel, kerosene, sulfolane or a mixture of sulfolane and cyclohexanol for the preparation of cyanuric acid heterocyclization of urea. To obtain a higher yield, the effects of catalyst (sodium, ammonium, calcium and zinc salts) and temperature (160 °C to 220 °C) on the trimerization of urea were also carefully studied. We established the optimal reaction conditions and further validated them in our scale-up experiments.
- She, Dong-Mei,Yu, Hai-Lin,Huang, Qi-Liang,Li, Fen-Ming,Li, Chun-Jiu
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- Phosphorus-Doped Carbon Nitride Tubes with a Layered Micro-nanostructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution
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Phosphorus-doped hexagonal tubular carbon nitride (P-TCN) with the layered stacking structure was obtained from a hexagonal rod-like single crystal supramolecular precursor (monoclinic, C2/m). The production process of P-TCN involves two steps: 1) the precursor was prepared by self-assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid-assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P-TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P-TCN exhibited a high hydrogen evolution rate of 67 μmol h-1 (0.1 g catalyst, λ >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 % at 420 nm, which is better than most of bulk g-C3N4 reported. Phosphorus-doped hexagonal carbon nitride tubes were obtained from a rod-like supramolecular precursor through phosphorous acid assisted hydrothermal and subsequent thermal treatment. It exhibits a high visible-light photocatalytic hydrogen evolution performance that is better than most reported bulk carbon nitrides, which is due to the hierarchical micro-nanostructure and P doping.
- Guo, Shien,Deng, Zhaopeng,Li, Mingxia,Jiang, Baojiang,Tian, Chungui,Pan, Qingjiang,Fu, Honggang
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- Novel one-dimensional polymeric Cu(II) complexes via Cu(II)-assisted hydrolysis of the 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine pincer ligand: Synthesis, structure, and antimicrobial activities
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Two unexpected one-dimensional coordination polymers, [Cu(PT)(H2O)Cl]n 1 and [Cu2(BPT)(ClO4)3(H2O)4]n·2nH2O 2, of symmetrical triazine-based ligands were sy
- Soliman, Saied M.,El-Faham, Ayman,El Silk, Sobhy E.
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- A new three-step procedure for the synthesis of cyanuric acid from urea
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A new procedure for preparing high-purity cyanuric acid from urea was suggested and experimentally checked. The procedure is based on urea silylation, followed by pyrolysis of the silyl derivative and fractional distillation of the trimethylsilyl isocyanate formed, for which the temperature limits of mild hydrolysis were determined.
- Lebedev,Sheludyakov,Lebedeva
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- Photocatalytic removal of s-triazines: Evaluation of operational parameters
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The photocatalytic degradation of atrazine (2-chloro-4-ethylamino-6- isopropylamino-1,3,5-triazine) and simazine (2-chloro-4,6-diethylamino-1,3,5- triazine) herbicides widely used in agriculture has been investigated. Experimental design methodology was used to assess the influence of pH and TiO2 concentration and the efficiency of the process. The results indicated that in the experimental domain investigated TiO2 concentration was the most significant factor in contrast to the scarce influence shown by the initial pH. The mechanism of atrazine and simazine photocatalytic degradation was studied under the experimental conditions determined as optimal. No full mineralization of atrazine or simazine was achieved. The main intermediates occurring during the reaction were identified by high performance liquid chromatography (HPLC). Based on the concentration profile of intermediates formed during the treatment a degradation pathway is proposed for each herbicide. The toxicity along the reaction was monitored by means of luminescence bioassays using Vibrio fischeri. The inhibition percentage decreases with the irradiation times what can be associated with the formation of highly hydroxylated intermediates.
- López-Mu?oz,Aguado,Revilla
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- Preparation of diselenides by the oxidation of selenols using trichloroisocyanuric acid
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Selenols are readily oxidized to diselenides by a solution of pyridine, water, benzoic acid, and trichloroisocyanuric acid in acetonitrile and methylene chloride.
- Zhong,Guo
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- Microwave assisted pyrolysis of urea supported on graphite under solvent-free conditions
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The coupling of graphite (support) with microwaves (energy source) is responsible for a high temperature gradient leading to increased reaction rates as compared to conventional procedures. A rapid one-pot preparation of cyanuric acid is described that proceeds from urea by pyrolysis using microwave heating in the absence of water and organic solvents.
- Chemat, Farid,Poux, Martine
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- Machine-Learning-Assisted Selective Synthesis of a Semiconductive Silver Thiolate Coordination Polymer with Segregated Paths for Holes and Electrons
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Coordination polymers (CPs) with infinite metal–sulfur bond networks have unique electrical conductivities and optical properties. However, the development of new (-M-S-)n-structured CPs is hindered by difficulties with their crystallization. Herein, we describe the use of machine learning to optimize the synthesis of trithiocyanuric acid (H3ttc)-based semiconductive CPs with infinite Ag?S bond networks, report three CP crystal structures, and reveal that isomer selectivity is mainly determined by proton concentration in the reaction medium. One of the CPs, [Ag2Httc]n, features a 3D-extended infinite Ag?S bond network with 1D columns of stacked triazine rings, which, according to first-principle calculations, provide separate paths for holes and electrons. Time-resolved microwave conductivity experiments show that [Ag2Httc]n is highly photoconductive (φΣμmax=1.6×10?4 cm2 V?1 s?1). Thus, our method promotes the discovery of novel CPs with selective topologies that are difficult to crystallize.
- Inokuchi, Akihiro,Kamakura, Yoshinobu,Nishikubo, Ryosuke,Ogasawara, Kazuyoshi,Saeki, Akinori,Shibahara, Hiroki,Tanaka, Daisuke,Wakiya, Takuma,Yoshikawa, Hirofumi
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- THE PROCESS FOR OBTAINING OF FLUORALKYLATED CARBON QUANTUM DOTS
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The invention discloses a simple, scalable and convenient solvothermal method of obtaining fluoralkylated carbon quantum dots—Fluocar? Nano materials, by solvothermal pyrolysis of an organic substance in the presence of fluoroorganic substance that contain fluoroalkyl groups. The obtained material is water- and organic solvents soluble, grafted fluorine is hydrolytically stable, and obtained dots having intense luminescence in a wide range of wavelengths, from blue to NIR. Photoluminescent (PL) spectral map of obtained carbon dots solution is highly sensitive to pH changes and rare earth metal ions concentration in this solution. Also PL-map of such material is sensitive to organic complex moiety (e.g. Acidum salicylicum, and penicillinum). Synthesized materials can find use as the classic and fluorescent dye replacement, as the carrier of biologically active substances, for bio-imaging, theranostic, for cytological studies, (photo)catalysis, as electrode component, as well as a sensor or biosensor, or for other uses.
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- Prebiotic Origin of Pre-RNA Building Blocks in a Urea “Warm Little Pond” Scenario
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Urea appears to be a key intermediate of important prebiotic synthetic pathways. Concentrated pools of urea likely existed on the surface of the early Earth, as urea is synthesized in significant quantities from hydrogen cyanide or cyanamide (widely accepted prebiotic molecules), it has extremely high water solubility, and it can concentrate to form eutectics from aqueous solutions. We propose a model for the origin of a variety of canonical and non-canonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs.The dual nucleophilic-electrophilic character of urea makes it an ideal precursor for the formation of nitrogenous heterocycles. We propose a model for the origin of a variety of canonical and noncanonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs. These reactions involve urea condensation with other prebiotic molecules (e. g., malonic acid) that could be driven by environmental cycles (e. g., freezing/thawing, drying/wetting). The resulting heterocycle assemblies are compatible with the formation of nucleosides and, possibly, the chemical evolution of molecular precursors to RNA. We show that urea eutectics at moderate temperature represent a robust prebiotic source of nitrogenous heterocycles. The simplicity of these pathways, and their independence from specific or rare geological events, support the idea of urea being of fundamental importance to the prebiotic chemistry that gave rise to life on Earth.
- Menor Salván,Bouza, Marcos,Fialho, David M.,Burcar, Bradley T.,Fernández, Facundo M.,Hud, Nicholas V.
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p. 3504 - 3510
(2020/10/02)
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- Preparation method of cyanuric acid
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The invention discloses a preparation method of cyanuric acid. The preparation method comprises the following steps: drying and dehydrating urea to obtained treated urea for subsequent usage; then adding an auxiliary agent and the dried and dehydrated urea into a reaction container, and carrying out a direct reaction under the protection of nitrogen so as to obtain a carbamate (R-O-CONH2) derivative after the reaction; and carrying out a thermal cracking reaction on the obtained carbamate derivative or a mixture of the carbamate derivative and urea under the protection of nitrogen, treating the obtained reaction product to obtain a cyanuric acid product, and recycling mother liquor after separation. The cyanuric acid is prepared by adopting a two-step process, and acid pickling refining isnot needed, so the method belongs to a novel environment-friendly process; reaction time is short, continuous production can be achieved, and production efficiency is improved; and finally, auxiliarymaterials are recycled in the production process, energy is saved, emission is reduced, production cost can be reduced, and obvious economic benefits and social benefits are realized.
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Paragraph 0049; 0053-0054; 0058-0059 ;0063-0065; 0069-0071
(2020/11/25)
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- Integrated photocatalytic-biological treatment of triazine-containing pollutants
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The degradation of triazine-containing pollutants including simazine, Irgarol 1051 and Reactive Brilliant Red K-2G (K-2G) by photocatalytic treatment was investigated. The effects of titanium dioxide (TiO2) concentration, initial pH of reaction mixture, irradiation time and ultraviolet (UV) intensity on photocatalytic treatment efficiency were examined. Complete decolorization of K-2G was observed at 60 min photodegradation while only 15 min were required to completely degrade simazine and Irgarol 1051 under respective optimized conditions. High-performance liquid chromatography (HPLC), gas chromatography/mass spectrometry (GC/MS) and ion chromatography (IC) were employed to identify the photocatalytic degradation intermediates and products. Dealkylated intermediates of simazine, deisopropylatrazine and deethyldeisopropylatrazine, and Irgarol 1051 were detected by GC/MS in the initial phase of degradation. Complete mineralization could not be achieved for all triazine-containing pollutants even after prolonged (>72 h) UV irradiation due to the presence of a photocatalysis-resistant end product, cyanuric acid (CA). The toxicities of different compounds before and after photocatalytic treatment were also monitored by three bioassays. To further treat the photocatalysis-resistant end product, a CA-degrading bacterium was isolated from polluted marine sediment and further identified as Klebsiella pneumoniae by comparing the substrate utilization pattern (Biolog microplate), fatty acid composition and 16S rRNA gene sequencing. K. pneumoniae efficiently utilized CA from 1 to 2000 mg/L as a good nitrogen source and complete mineralization of CA was observed within 24 h of incubation. This study demonstrates that the biodegradability of triazine-containing pollutants was significantly improved by the photocatalytic pre-treatment, and this proposed photocatalytic-biological integrated system can effectively treat various classes of triazine-containing pollutants.
- Chan, Cho Yin,Chan, Ho Shing,Wong, Po Keung
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p. 371 - 380
(2019/02/07)
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- Cooperation of the Neutral and the Cationic Leaving Group Pathways in Acid-Catalyzed O-Benzylation of TriBOT
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The reaction profile of acid-catalyzed O-benzylation with 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT) was analyzed to study the reaction kinetics. The first-order kinetic constant for the formation of benzyl cation species from N-protonated TriBOT (neutral leaving group pathway) was estimated and compared with that of the model compound for TriBOT. Since rapid consumption of TriBOT in the late stage could not be explained solely by this pathway, cooperation of another reaction mechanism, the cationic leaving group pathway, was proposed to rationalize the rate acceleration.
- Fujita, Hikaru,Hayakawa, Naoko,Kunishima, Munetaka
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p. 10684 - 10687
(2018/07/25)
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- Method for recovering high purity cyanuric acid compound from blowing agent byproduct
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The present invention relates to a technology for recovering solid cyanuric acid from a blowing agent byproduct comprising cyanuric acid. During a blowing process of a chemical blowing agent, high purity cyanuric acid generated as a byproduct to be removed can be plentifully recovered. An import-substituting effect of cyanuric acid can be obtained, the entire quantity of cyanuric acid being import-dependent from China now. When application and development of materials which can become high value products are performed, the method for recovering cyanuric acid maximizes economical efficiency, minimizes environment pollution caused by existing blowing agent byproduct, and can bring a disposal cost reduction effect of the blowing agent byproduct.COPYRIGHT KIPO 2017
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Paragraph 0049; 0050
(2017/05/18)
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- Expedient and efficient one pot synthesis of trifluoroethyl ethers from metal free 2,4,6-tris-(2,2,2-trifluoro-ethoxy)-[1,3,5] triazene
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An efficient synthesis of fluorinated alkyl and aryl ethers was achieved by the use of s-triazene derived fluorinated reagent 2,4,6-tris-(2,2,2-trifluoro-ethoxy)-[1,3,5] triazene (TriTFET). The procedure offers a very attractive alternative for the synthesis of fluorinated motifs that are found in various bioactive molecules. Moreover, TriTFET is a synthetic non-toxic, non-ozone depleting and stable reagent. All compounds were characterized by 1H, 13C and 19F NMR.
- Mangawa, Shrawan Kumar,Sharma, Chiranjeev,Singh, Ashawani Kumar,Awasthi, Satish K.
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p. 35042 - 35045
(2015/05/04)
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- Synthesis of biologically active pyridoimidazole/imidazobenzothiazole annulated polyheterocycles using cyanuric chloride in water
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An efficient and mild protocol for rapid access to N-fused polyheterocycles via Pictet-Spengler type 6-endo cyclization using cyanuric chloride in an aqueous reaction medium has been developed. The protocol was successfully applied to a wide range of compounds including aryl/heteroaryl aldehydes (8a-o), ketones (10a-e), an electron-rich metallocene aldehyde (8e) and indoline-2,3-diones (12a-c) using cyanuric chloride (15-20 mol%) with tetra-n-butylammonium bromide (TBAB) (2.0 eq.) as an additive at 80-90 °C to give a good to excellent yield (66-92%) of polyheterocycles. Some of the synthesized compounds were found to exhibit antiplasmodial activity against chloroquine-sensitive (CQ-S) 3D7 and chloroquine-resistant (CQ-R) K1 strains of Plasmodium falciparum. This journal is the Partner Organisations 2014.
- Pandey, Anand Kumar,Sharma, Rashmi,Singh, Awantika,Shukla, Sanjeev,Srivastava, Kumkum,Puri, Sunil K.,Kumar, Brijesh,Chauhan, Prem M. S.
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p. 26757 - 26770
(2014/07/21)
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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- Trinitromethylation reactions of chloro-1,3,5-triazines
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Reactions of chloro-1,3,5-triazines with trinitromethane salts were studied. Depending on conditions, trinitromethane salts used and special additives, six types of 2,4,6-trichloro-1,3,5-triazine trinitromethylation reactions were revealed, namely, bis-trinitromethylation-nitro-nyloxylation, bis-trinitromethylation-amination, bis-trinitromethylation-hydroxylation, trinitromethylation-dialkoxylation, trinitromethylation-diaryloxylation, and trinitromethylation-alkoxylation-aryloxylation. The mechanisms of reactions are proposed.
- Gidaspov,Bakharev,Kukushkin
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experimental part
p. 2154 - 2163
(2011/01/07)
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- A Simple Practical Method for the Synthesis of 4,6-Dimethoxy-1,3,5-triazin- 2(1H)-one Using Dimethylamine-Functionalized Solid-Phase Reagents
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A simple practical method for the synthesis of 4,6-dimethoxy-1,3,5-triazin- 2(1H)-one was developed. The desired product was easily obtained from 2-chloro-4,6-dimethoxy-1,3,5-tri-azine and acetic acid by shaking with dimethylamine-functionalized silica ge
- Hioki, Kazuhito,Ohshima, Keiichi,Sota, Yuko,Tanaka, Miki,Kunishima, Munetaka
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experimental part
p. 542 - 544
(2009/07/25)
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- Methods And Devices For Preparing Biuret And Cyanuric Acid
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Provided are methods and devices for preparing biuret and cyanuric acid by thermal decomposition of urea. Specifically, a product of thermal decomposition is cooled to precipitate a crystal and the precipitated crystal is dissolved using an alkali aqueous solution and cooled to obtain biuret having high purity. Furthermore, the cyanuric acid that is one of byproducts by the thermal decomposition of urea is effectively recovered with high purity.
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Page/Page column 5
(2008/06/13)
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- Reactions of aniline in acetic acid solutions containing cyanuric chloride and hydrogen chloride acceptors
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Two reaction pathways in acetic acid solution containing cyanuric chloride, aniline, and some hydrogen chloride acceptors (triethylamine, sodium acetate, pyridine) were studied. Both aryl animation and acylation can be performed with high yields under proper reaction conditions. Contrary to the only known literature report on the reactions between carbonic acids and cyanuric chloride in. the presence of a hydrogen chloride acceptor (triethylamine), it was established that acid chlorides are not formed. A scheme involving the replacement of chlorine atoms by acetate ion in the initial stage was proposed for the acylation of aniline promoted by cyanuric chloride.
- Kolmakov, Kirill A.
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p. 1070 - 1074
(2008/09/17)
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- Methods of preparing highly concentrated aqueous bromine solutions
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The present invention is directed to convenient methods of preparing: (1) highly concentrated liquid bromine-containing biocidal solutions and (2) highly concentrated mixed halogen liquid bromine and chlorine-containing biocidal solutions that have excellent physical and chemical stability. One method involves adding the acidic reaction medium to an alkaline source to effect the final pH adjustment and in another these are co-fed into a common reaction vessel. Both methods minimize the incidence of the acid hydrolysis reaction that undermines chemical yields and generates troublesome sulfate by-products. The methods offer superior reactor cooling efficiencies that reduce batch cycle times and suppress undesirable elevated temperature decomposition reactions.
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Page/Page column 5
(2008/06/13)
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- METHOD FOR THE TREATMENT OF TRIAZINE-CONTAINING WATER OF A MELAMINE PLANT
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The invention relates to a method for treating triazine-containing water of a melamine plant. Said method is characterized in that the water containing ionic and non-ionic triazines in a dissolved form is fed to at least one membrane filtration unit (MF), the water is separated into an ionic triazine-rich fraction and a non-ionic triazine-rich fraction in the membrane filtration unit (MF), whereupon the ionic triazine-rich fraction is discharged and the non-ionic triazine-rich fraction is redirected into the melamine plant. The inventive method allows a great portion of the melamine contained in the triazine-containing water to be redirected into the process while the yield is increased along the entire melamine process. Furthermore, the need for fresh water in the wet part of the melamine plant is decreased. The disclosed method can be carried out continuously and in liquid phase.
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Page/Page column 10-14
(2008/06/13)
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- Synthesis and purification of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
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A method to convert surplus nitroarene explosives (picric acid, ammonium picrate,) into TATB is described. The process comprises three major steps: conversion of picric acid/ammonium picrate into picramide; conversion of picramide to TATB through vicarious nucleophilic substitution (VNS) of hydrogen chemistry; and purification of TATB.
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Page/Page column 2
(2008/06/13)
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- HIGHLY CONCENTRATED BROMINE COMPOSITIONS AND METHODS OF PREPARATION
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Liquid and solid bromine-containing compositions are described. A liquid mixed halogen composition is also described. The highly concentrated liquid compositions and the high-activity solid compositions have excellent physical and chemical stability. The compositions are effective biocides in water treatment. Methods of preparing the compositions are also disclosed. These include combining a bromine compound in the oxidation state of -1 with hydrogen peroxide and a complexing agent followed by the addition of an alkaline source. The methods may further include the use of a solid organic or solid inorganic halogenating agent, conducting a solid-liquid separation, and adding an alkaline source.
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Page/Page column 36-37; 82-83
(2008/06/13)
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- PREPARATION OF CONCENTRATED BROMINE SOLUTIONS AND HIGH ACTIVITY BROMINE SOLIDS
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The invention includes convenient methods of preparing: (1) highly concentrated liquid bromine-containing biocidal solutions, (2) highly concentrated mixed halogen liquid bromine and chlorine-containing biocidal solutions, and (3) high-activity bromine containing biocidal solids, all having excellent physical and chemical stability. One method yields solutions that have concentrations of bromine in excess of 18% as Br2 (8% as C12) in which the mole ratio of hydroxide ion to hydrogen ion source is at least 1.9: 1. Another method employs elemental bromine in conjunction with a solid organic or inorganic halogenating agent to yield halogen solutions at concentrations greater than 22.9% as Br2 (10.2% as C12). This method can be performed under conditions that exceed the solubility of the active ingredient such that it crystallizes and is recovered as a hydrated or anhydrous salt in good yield.
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Page/Page column 31-32
(2008/06/13)
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- Methods for the preparation of concentrated aqueous bromine solutions and high activity bromine-containing solids
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The invention includes convenient methods of preparing: (1) highly concentrated liquid bromine-containing biocidal solutions, (2) highly concentrated mixed halogen liquid bromine and chlorine-containing biocidal solutions, and (3) high-activity bromine-containing biocidal solids, all having excellent physical and chemical stability. One method yields solutions that have concentrations of bromine in excess of 18% as Br2 (8% as Cl2) in which the mole ratio of hydroxide ion to hydrogen ion source is at least 1.9:1. Another method employs elemental bromine in conjunction with a solid organic or inorganic halogenating agent to yield halogen solutions at concentrations greater than 22.9% as Br2 (10.2% as Cl2). This method can be performed under conditions that exceed the solubility of the active ingredient such that it crystallizes and is recovered as a hydrated or anhydrous salt in good yield.
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Page/Page column 8; 11; 14
(2008/06/13)
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- Wet peroxide degradation of atrazine
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The high temperature (150-200 °C), high pressure (3.0-6.0 MPa) degradation of atrazine in aqueous solution has been studied. Under these extreme conditions atrazine steadily hydrolyses in the absence of oxidising agents. Additionally, oxygen partial pressure has been shown not to affect atrazine degradation rates. In no case mineralisation of the parent compound was observed. The addition of the free radical generator hydrogen peroxide to the reaction media significantly enhanced the depletion rate of atrazine. Moreover, partial mineralisation of the organics was observed when hydrogen peroxide was used. Again, oxygen presence did not influence the efficiency of the promoted reaction. Consecutive injections of hydrogen peroxide throughout the reaction period brought the total carbon content conversion to a maximum of 65-70% after 40 min of treatment (suggesting the total conversion of atrazine to cyanuric acid). Toxicity of the effluent measured in a luminometer decreased from 93% up to 23% of inhibition percentage. The process has been simulated by means of a semi-empirical model.
- Rodriguez, Eva M.,Alvarez, Pedro M.,Rivas, F. Javier,Beltran, Fernando J.
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- Method and apparatus for preparing hydrazo-dicarbonamide using urea as starting material
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The present invention relates to a method and apparatus for preparing hydrazodicarbonamide using urea as starting material economically and environmentally desirably. The apparatus includes a pyrolysis furnace to obtain biuret and ammonia by pyrolyzing urea; a recrystallization reactor to purify the biuret obtained from the pyrolysis furnace; a first reactor to obtain an metal monohalobiuret salt by reacting the biuret with metal hypohalogen compound or with halogen and base; a second reactor to synthesize the hydrazodicarbonamide by reacting the monohalobiuret metal salt with ammonia; and an ammonia evaporator to separate the excess ammonia from hydrazodicarbonamide and to supply the separated ammonia to an ammonia concentrator.
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- Nitration of the 6-methyl-1,3,5-triazine derivatives, 6-methyl-1,3,5-triazine-2,4(1H,3H)-dione and 2,4-dimethoxy-6-methyl-1,3,5-triazine
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Nitration of 2-methylpyrimidin-4,6(3H,5H)-dione (II) is known to give, after hydrolysis of the tetranitro intermediate, 1,1-diamino-2,2-dinitroethene (I). However, nitration of analogous 6-methyl-1,3,5-triazine derivatives was found to lead to somewhat different products. Nitration of 6-methyl-1,3,5-triazine-2,4(1H,3H)-dione (III) gave 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid, V) and tetranitromethane (VI). Nitration of 2,4-dimethoxy-6-methyl-1,3,5-triazine (IV) with mixed acid gave 2,4-dimethoxy-6-trinitromethyl-1,3,5-triazine (VII), whilst with nitric acid alone a furazan N-oxide derivative (IX) was obtained.
- Bellamy, Anthony J.,Latypov, Nikolaj V.,Goede, Patrick
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p. 943 - 958
(2007/10/03)
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- Process for the production of malononitrile
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An improved process for the commercial production of malononitrile by the dehydration of cyanoacetamide employs cyanuric chloride in the presence of a catalytic amount of N,N-dimethylformamide and in a polar solvent that is removed by vacuum distillation at a temperature below 100° C. The N,N-dimethylformamide is added in a molar ratio of 0.16 moles for each mole of cyanoacetamide present in the starting solution.
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Page column 3-4
(2008/06/13)
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- PROCESS FOR THE PREPARATION OF RETINOL AND INTERMEDIATES THEREFOR
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The reaction of a halogenated sulfone derivative of general formula (1): wherein Ar is optionally substituted aryl and X is halogen, with a base can attain easy production of retinol useful in the fields of drugs, feed derivatives and food derivatives. The intermediate in this production can easily be obtained by reaction of a diol compound of general formula (2): wherein Ar is as defined above, which can be derived from relatively inexpensive starting materials, with a Group IV transition metal halide without protecting the primary hydroxyl group.
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- Process for producing retinal and intermediate for producing the same
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There are disclosed sulfone aldehyde derivatives of the Formula (1): wherein Ar is an optionally substituted aryl group, a process for producing retinal by using the same, and an intermediate for producing the sulfone aldehyde derivative.
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- Preparation of disulfides by the oxidation of thiols using trichloroisocyanuric acid
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Thiols are readily oxidized to disulfides by a solution of pyridine, water, benzoic acid and trichloroisocyanuric acid in acetonitrile and methylene chloride.
- Zhong,Guo
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p. 1825 - 1828
(2007/10/03)
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- Tetraene derivative and process for producing the same
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A tetraene derivative of the formula (1): wherein Ar represents an aryl group which may be optionally substituted with at least one substituent, and R1 and R2 are identical or different and represent a hydrogen atom, a lower alkyl group or a protective group of a hydroxyl group; synthesis methods therefor and synthesis methods using the same.
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- Stability of cyanuric acid to photocatalytic degradation
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TiO2, O2, H2O → photocatalytic degradation conditions X = OH, no degradation X= OMe, kH/kD = 3.3 for degradation X= 18OH, no isotope exchange Cyanuric acid is unique among organic molecules in being resistant to photocatalytic degradative conditions by TiO2 in oxygenated water. Trimethyl cyanurate shows an isotope effect of 3.1-3.3 on degradation selectivity when the methyl groups are deuterated, and cyanuric acid enriched in 18O does not exchange hydroxyl groups with bulk water under these conditions. Thus, the tolerance of cyanuric acid to photocatalysis is not due to rapid and reversible addition to the aromatic nucleus.
- Tetzlaff, Troy A.,Jenks, William S.
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p. 463 - 465
(2008/02/11)
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- Method for halogenating an aromatic compound
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A method for halogenating an aromatic compound, which comprises reacting the aromatic compound of the formula (I): STR1 wherein X is a hydroxyl group, an amino group or an acylamino group, each of Z1 and Z2 is a hydrogen atom or a halogen atom, one of R and Y is a hydrogen atom and the other is a nitro group, a cyano group or a trifluoromethyl group, and Q is a nitrogen atom or --C(T)= (wherein T is a hydrogen atom, a halogen atom, a nitro group, a cyano group or a trifluoromethyl group), with a halogenating agent to obtain a 3-halogenoaromatic compound of the formula (II): STR2 wherein one of R' and Y' is a halogen atom and the other is a nitro group, a cyano group or a trifluoromethyl group, and X, Z1, Z2 and Q are as defined above.
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- Liquid-crystalline compounds
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Liquid-crystalline compounds of the formulae I and II, where Z1 is the radical of an m-valent alcohol an m-valent acid or certain trivalent triazine derivatives; Z2 is an n-valent radical of a monocyclic or polycyclic aromatic compound; X1 is a chemical bond or --CO--; X2 is --O--, --S--, --CO--O--, --O--CO--, --SO2 --, --SO2 --O--, --O--SO2 --O--, --NR4 --, --CO--NR4 --NR4 --O-- or --CO--N4 is H or C1 -C8 -alkyl; m and n are 3 to 6; R1 is a C2 -C20 -bridge having 2 to 12 bridging members, which may be interrupted by --O--, --S-- or --NR4 --, each of these hetero units being separated by at least 2 carbon atoms; Y is a chemical bond, --O--, --S--, --CO--O--, --O--CO--, --NR4 --, --CO--NR4 -- or --NR 4 --CO--; M is a mesogenic group. These compounds are suitable for the production of optical and electro-optical data carriers and display elements.
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