Carbon Dioxide/Methane Separation by Adsorption on Sepiolite

In this work,the use of sepiolite for the removal of carbon dioxide from a carbon diox- ide/methane mixture by a pressure swing adsorption(PSA)process has been researched.Adsorption equilibrium and kinetics have been measured in a fixed-bed,and the adsorption equilibrium parameters of carbon dioxide and methane on sepiolite have been obtained.A model based on the LDF approxima- tion has been employed to simulate the fixed-bed kinetics,using the Langmuir equation to describe the adsorption equilibrium isotherm.The functioning of a PSA cycle for separating carbon dioxide/methane mixtures using sepiolite as adsorbent has also been studied.The experimental results were compared with the ones predicted by the model adapted to a PSA system.Methane with purity higher than 97% can be obtained from feeds containing carbon dioxide with concentrations ranging from 34% to 56% with the proposed PSA cycle.These results suggest that sepiolite is an adsorbent with good properties for its employment in a PSA cycle for carbon dioxide removal from landfill gases.     

Synthesis of a New Isoflavone: 7,8,4′-Trihydroxyisoflavone

Isoflavones have been found a wide range of applications as natural antioxidants being suggested in diet as a gents responsible for the prevention of coronary diseases, breast and prostate cancer. [1] Most of the isoflavones have been isolated from natural sources and their simple structural features lead to the development of many synthetic methods. [2] Here we synthesized a new trihydroxyisoflavone.     

CONSTRUCTIONS OF GENE LIBRARIES OF RANA NIGROMACULATA AND MUS MUSCULUS WITH COSMID pHC79

Gene libraries of Rana nigromaculata and Mus musculus (C_(57)J_6) have been constructed bythe cosmid system developed by Collins using BamHl and Pstl as cloning restriction enzymes.A simplified formula, which is a modification of Clarke and Carbon derived from apprixima-tion, was used for calculating the number of colonies or recombinants necessary for theconstruction of a gene library. Pro~ and leu~ complementary to the recipient cells (RB101)with the genetic constitution of pro~- and leu~- have been selected from the BamHl genelibraries of both Rana nigromaculata and the mouse in the present work.     

Synthesis and Properties of An Aminated hypocrellin B

Photodynamic therapy (PDT), using red light and photosensitizers (Sens ), is a promising new treatment for tumor. The naturally occurred hypocrellins,including hypocrellin A (HA) and hypocrellin B (HB,1), have been proposed as the potential photosensitizers for PDT. It has been the subject of many investigations to improve the red absorption and water-solubility of natural hypocrellins by the structural modifications1~3. In this paper, a new derivative 2 was synthesized from 1 and charact…     

Facial Selectivity in the Nucleophilic Additions of endo-Tricyclo[5.2.1.0~(2,6)]deca-2(6),8-dien-3-one

The endo-tricyclo [5.2.1.02,6] decadienone system 1 has been used as a versatile synthon for the synthesis of a great variety of natural products1. The availability of both antipodes of 1 in enantiopure form2, and the ability to undergo [4+2] cycloreversion makes it useful for the enantioselective synthesis of naturally occurring cyclopentanoids with defined stereochemistry and chirality3. Starting from the 1,4 reduced Hertz ester 2, synthesis of the reactive and strained tricyclodecadienone 4…     

A MARKOV-TYPE ANALOG MODEL FOR PREDICTION OF TYPHOON MOTION IN NORTHWESTERN PACIFIC

In this paper, a Markov-type analog model for the prediction of the tropical cyclone motion is developed for the Northwestern Pacific. The probabilities are studied by using the United States National Hurricane Center HURRAN model as a guide. In order to approach and suit to the new circumstance continuously, a Markov process has been used to describe the probability forecast for typhoon movement. The model is different from the traditional analog method both in searching probability solutions and in renewing initial data.A transplantation model (Model 1) has also been developed by using the traditional analog methods. Both Model 1 and Markov-type analog model (Model 2) have been tested for 95 simultaneous cases, which are independent data for the years 1981 and 1982. It has been shown from this examination that the Markov-type model appears to give smaller forecast errors.     

RELATIONSHIP BETWEEN EARTHQUAKE MAGNITUDE AND EPICENTRAL INTENSITY IN CHINA AND ITS APPLICATIONS

This paper gives revised formulas for Chinese earthquakes, describing the relationship between earthquake magnitude, epicentral intensity and hypocentral depth, and these formulas have been derived from calculations of the data of M, I_0 and h of 57 main shocks. Data have been analyzed of foreshocks and aftershocks of several major earthquakes in North China, from which the relationships between magnitude and epicentral intensity for foreshocks and aftershocks are derived. These relationships are also calculated for earthquakes of the Xinfengjiang reservoir. A comparison between these relations indicates that each of the foreshocks, aftershocks and reservoir earthquakes possesses a specific relationship between magnitude and epicentral intensity of itself, which is systematically different from that of the mainshocks.     

Synthesis of cis-(±)-2-Hydroxymethyl-5-(Cytosine-1''''-yl)-1,3-Oxathiolane (BCH-189)

cis-BCH-189 are potent anti-HIV agents and have been synthesized from mannose1 galactose2 or glucose3 etc. Owing to so many synthetic steps, it is difficult and expensive to obtain a few grams. In this paper, we have designed new route and promoted the reaction conditions for the synthesis of this nucleoside cis- (+)- BCH-189 from cheap starting material via a four step route as shown in Scheme 1. By this method, a series of derivatives of title compound can be synthesized conviniently for…     

Two New Oleanene-Type Triterpenoid Saponins from Pueraria peduncularis

Pueraria pedllncltlaris Grab. (Leguminosae) is a plant growing in the southwest of China.The plants of Pueraria DC. are important oriental crude drugs used as a perspiration,antipyretic and antispasmodic agents. Various isoflavonoids and triterpenoidsaponins"' have been discovered from them. Since P pedunculariS is toxic. it hasnever been used as a source for medicines. There are only scarce reports on its chemicalconstituents.In the preceding paper', we reported the isolation of a new …     

Crystallization and Preliminary Crystallographic Analysis of β- Trichosanthin, an Isoform of Trichosanthin from the Root Tuber of Trichosanthe kirilowii

β-Trichosanthin,a type 1 ribosome-inactivating protein (RIP) isolated from the root tuber of Trichosanthe kirilowii Maxim,is an isoform of trichosanthin. Here we report its crystal-lization in two crystal forms using the hanging-drop vapor-diffusion method. The form A and form B crystals belong to the orthorhombic space group P212121 and monoclinic space group P21,respectively. X-ray data have been collected to 1.6 and 1.2 resolution for form A and form B crystals,respectively,using a synchrotron source.     

Purete enantiomerique et configuration absolue de l'acide β-hydroxy β-trifluoromethyl β-phenyl propionique obtenu par synthese asymetrique

The enantiomeric purity of β-hydroxy β-trifluoromethyl β-phenyl propionic acid, prepared by asymmetric synthesis, was determined by NMR with a chiral europium complex. Its absolute configuration was established by correlation with α-hydroxy α-trifluoromethyl α-phenyl acetic acid. At the same time, the absolute configurations of 2-hydroxy 2-trifluoromethyl 2-phenyl ethylamine, 3-hydroxy 3-trifluoromethyl 3-phenyl 1-amino propane, and 2-trifluoromethyl 2-phenyl 1,2 ethanediol were determined.     

Steric control of the excited-state intramolecular proton transfer in 3-hydroxyquinolones: steady-state and time-resolved fluorescence study

3-Hydroxyquinolones (3HQs), similarly to their 3-hydroxychromone analogs, undergo excited state intramolecular proton transfer (ESIPT) resulting in dual emission. In the ground state, 2-phenyl-3HQ derivatives are not flat due to a steric hindrance between the 2-phenyl group and the 3-OH group that participates in the ESIPT reaction. To study the effect of this steric hindrance on the ESIPT reaction, a number of 3HQ derivatives have been synthesized and characterized in different organic solvents by steady-state and time-resolved fluorescence techniques. According to our results, 2-phenyl-3HQ derivatives undergo much faster ESIPT (by nearly 1 order of magnitude) than their 2-methyl-3HQ analogs. Moreover, 1-methyl-2-phenyl-3HQ having a strongly twisted 2-phenyl group undergoes a two- to three-fold slower ESIPT compared to 2-phenyl-3HQ. These results suggest that the flatter conformation of 2-phenyl-3HQ, which allows a close proximity of the 2-phenyl and 3-OH groups, favors a fast ESIPT reaction. The absorption and fluorescence spectra of the 3HQ derivatives additionally confirm that the steric rather than the electronic effect of the 2-phenyl group is responsible for the faster ESIPT reaction. Based on the spectroscopic studies and quantum chemical calculations, we suggest that the 2-phenyl group decreases the rotational freedom of its proximal 3-OH group in the more planar conformation of 2-phenyl-3HQ. As a result, the conformations of 3HQ, where the 3-OH group orients to form an intramolecular H-bond with the 4-carbonyl group, are favored over those with a disrupted intramolecular H-bond. Therefore, the 2-phenyl group sterically favors the intramolecular H-bond and thus accelerates the ESIPT reaction. This conclusion provides a new understanding of the ESIPT process in 3-hydroxyquinolones and related systems and suggests new possibilities for the design of ESIPT based molecular sensors and switchers.     

Reaction of ketenes with N,N-disubstituted α-aminomethyleneketones. XX. Synthesis of 2H-pyrano[2,3-f]quinazoline derivatives

The polar 1,4-cycloaddition of dichloroketene to N,N-disubstituted (E)-6-aminomethylene-7,8-dihydro-(2-methyl)(2-phenyl)quinazolin-5(6H)-ones III , prepared in good yields from 7,8-dihydro-(2-methyl)-(2-phenyl)quinazolin-5(6H)-ones via their 6-hydroxymethylene derivatives I and II , gave in satisfactory to excellent yields N-N-disubstituted 4-amino-3,3-dichloro-3,4,5,6-tetrahydro-(8-methyl)(8-phenyl)-2H-pyrano- [2,3,-f]quinazolin-2-ones IV , which are derivatives of the new heterocyclic system pyrano[2,3-f]quinazoline. This cycloaddition occurred both in the case of aliphatic and aromatic N-substitution only with 2-phenyl-enaminones III , whereas with 2-methyl derivatives III the reaction took place only in the case of aromatic N-monosubstitution. Dehydrochlorination of IV with DBN afforded, generally in excellent yields, N,N-disubstituted 4-amino-3-chloro-5,6-dihydro-(8-methyl)(8-phenyl)-2H-pyrano[2,3-y]quinazolin-2-ones, which were dehydrogenated with DDQ to give N,N-disubstituted 4-amino-3-chloro-(8-methyl)(8-phenyl)-2H-pyrano[2,3-f]quinazolin-2-ones in excellent yields.     

Sulfonated N-heterocyclic carbenes for Suzuki coupling in water

Sulfonated, water-soluble imidazolium and imidazolinium salts were synthesized and the respective Pd-complexes with N,N'-bis(2,6-dialkyl-4-SO(3)(-)-phenyl)imidazol-2-ylidene and N,N'-bis(2,6-dialkyl-4-SO(3)(-)-phenyl)-4,5-dihydroimidazol-2-ylidene ligands were applied in aqueous Suzuki coupling reactions of aryl chlorides.     

Reaction of 2-phenyl(acetyl)-5-methyldiazaphosphole with phenyl azide

Conclusions The reaction of 2-phenyl(acetyl)-5-methyldiazaphospholes with phenyl azide results in the formation of trimers which form 2-phenyl(acetyl)-3-oxo-3-anilino-5-methyl-1,2,3-diazaphospholines during hydrolysis.Translated from Izvestiiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1600–1602, July, 1981.     

Seleno-β-lactams: synthesis of monocyclic and spirocyclic selenoazetidin-2-ones

An efficient protocol for the synthesis of novel seleno-β-lactams using operationally simple strategies is presented. 3-Phenyl/benzylseleno-β-lactams, obtained from 2-phenyl/benzylselenoethanoic acids, are transformed to cis-3-chloro-3-phenyl/benzylseleno-β-lactams, which undergo reaction with various active aliphatic and aromatic substrates catalyzed by Lewis acid to produce cis-3-alkoxy-3-phenyl/benzylseleno-β-lactams and C-3 monosubstituted seleno-β-lactams. Halogen mediated intraselenyl cyclization of cis-3-(prop-2-ynyloxy)-3-benzylseleno-β-lactams affords novel spiro seleno-β-lactams.     

手性双季铵盐诱导下的硝基甲烷与查尔酮的Michael反应

双季铵盐相转移催化剂具有用量少、催化活性高的特点,比单官能团相转移催化剂的催化性能更为显著。手性季铵盐是进行不对称     

Adsorption and elektrokinetic properties of the system: carboxymethylcellulose/manganese oxide/surfactant

The adsorption of carboxymethylcellulose (CMC) in the presence of the surfactants: anionic SDS, nonionic polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (Triton X-100) and their mixtures SDS/polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether with different molar ratios (1:1; 1:3 and 3:1) from the electrolyte solutions (NaCl, CaCl₂) on the manganese dioxide surface (MnO₂) was studied. In every measured system the increase of CMC adsorption in the presence of surfactants was observed. This increase was the smallest in the presence of SDS, a bit larger in the presence of polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether and the largest when the mixtures of SDS/polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether were used. Among the measured mixtures, the mixture of SDS/polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether with the molar ratio 1:3 caused the largest increase of CMC adsorption amount. These results are a consequence of formation of complexes between the carboxymethylcellulose macromolecules and the surfactant molecules. In order to determine the electrokinetic properties of the system the surface charge density of MnO₂ and the zeta potential measurements were conducted in the presence of the CMC macromolecules and the surfactants. The obtained data showed that the adsorption of CMC or CMC/surfactants complexes on the manganese dioxide surface strongly influences the structure of the electric double layer MnO₂/electrolyte solution.     

Reactions with Hydrazonoyl Halides 611: Synthesis of 2,3-Dihydro-1,3,4-Thiadiazoles

2-[1,2-Diaza-3-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))prop-2-enylidene]-3-phenyl-5-substituted 1,3,4-thiadiazolines and 2-{[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]cyanomethylene}-3-phenyl-5-substitu- ted 1,3,4-thiadiazolines were synthesized from hydrazonoyl halides and 4-{-2-aza-2-[(methylthiothioxomethyl)amino]vinyl}-2,3-dimethyl-1-phenyl-3-pyrazoin-5-one and 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-pyrazolin-4-yl)-1,3-thiazol-2-yl]ethane-nitrile, respectively. All synthesize compounds were elucidated by elemental analysis, spectra, and alternative synthesis routes, whenever possible.     

Syntheses Based on Natural α-Amino Acids. Cyanoethylation of 3-Substituted 5-Methyl-2-thiohydantoins

Starting from α-alanine, the C- and S-cyanoethyl derivatives of 5-methyl-3-phenyl(allyl)-2-thiohydantoins have been synthesized. It was shown that the products of hydrolysis of C-cyanoethyl derivatives, 5-methyl-3-phenyl(allyl)-(β-carboxyethyl)-2-thiohydantoins, are formed in addition. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1657–1661, November, 2005.