Novel Product and Its Derivatives from the Reaction of Lappaconitine with HIO_4

Lappaconitine l, a bisnorditerpenoid alkaloid, was isolated from many plants ofAconitum and Delphinium species such as A. barbatum var. puberulum, A.sinomontanuml' 2. It is now used in the clinical practice as an analgesic in China', andantiarrhythmic drugs in Uzbekistan4' 5. In our attempts to prepare the 10-oxygenatedderivatives by treating lappaconitine I with HIO. followed by bromination, unexpectedby-products were obtained in modest yields. This communication described the isolationan…     

Simple and regioselective bromination of 5,6-disubstituted-indan-1-ones with Br2 under acidic and basic conditions

Bromination of 5,6-dimethoxyindan-1-one with Br(2) in acetic acid at room temperature produced exclusively the corresponding 2,4-dibromo compound in 95% yield. Reaction of 5,6-dimethoxyindan-1-one with Br(2) in the presence of KOH, K(2)CO(3) or Cs(2)CO(3 )at ~0 degrees C( )gave the monobrominated product 4-bromo-5,6-dimethoxyindan-3-one in 79%, 81% and 67% yield, respectively. 5,6-Dihydroxyindan-1-one was dibrominated on the aromatic ring affording 4,7-dibromo-5,6-dihydroxyindan-1-one both in acetic acid at room temperature and in the presence of KOH at ~0 degrees C. 5,6-Difluoroindan-1-one and 1-indanone were alpha-monobrominated in acetic acid and alpha,alpha-dibrominated under KOH conditions at room temperature.     

PHOTOPHYSICS and PHOTOCHEMISTRY OF BIS-2-(9-ANTHRYL)ETHYL GLUTARATE

Abstract— The photochemistry and photophysics of bis-(2-(9-anthryl)ethyl glutarate 2 and 2-(9-anthryl) ethyl pivalate 3 have been examined as monomeric models for poly-2-(9-anthryl)ethyl methacrylate 1. The absorption and excitation spectra of 2 show no ground state interaction, but appreciable monomer (51%) and excimer (49%) emission. Delayed monomer and excimer fluorescence are also observed in fluid solution at room temperature. Photolysis of 2 at low temperature produces a photoproduct (44% yield) which is unstable at room temperature and presumably is the head-to-head (H-H) dimer. Steady state irradiation of 2 at room temperature (Λ 350 nm) cleanly produces a head-to-tail (H-T) dimer (6) derived from the singlet state and an additional unidentified adduct (7). The product distribution is concentration dependent, with 6 predominating at high concentrations (> 10⁻³ M ). The fluorescence spectra of the broken dimers derived from 6 and 7 indicate that substantial ir overlap exists in the transition state leading to each product.     

The effect of sterilization methods on the thermo-gelation properties of xyloglucan hydrogels

In this study, the influence of different sterilization methods on the thermo-gelation and structural properties of xyloglucan hydrogels was investigated. Xyloglucan samples were treated by either 70% ethanol, 70% isopropanol, γ-irradiation (10 kGy) at room temperature, γ-irradiation (10 kGy) in dry ice or autoclaving. These samples were tested for sterility by incubation with sterile Lysogeny Broth (LB) at room temperature, 30 °C and 37 °C for 30 days. According to the results obtained, xyloglucan hydrogels were only effectively sterilized by autoclaving or by γ-irradiation either at room temperature or in dry ice. These samples were analyzed by rheology measurements and dynamic and static light scattering analysis. Gamma-irradiation at room temperature markedly changed the polymer structure, preventing thermo-gelation. Only autoclaving and γ-irradiation in dry ice preserved the rheological properties of the polymer. The sol-gel transition as a function of the temperature was similar for these samples and the control sample.     

New isoreticular metal-organic framework materials for high hydrogen storage capacity

We propose new isoreticular metal-organic framework (IRMOF) materials to increase the hydrogen storage capacity at room temperature. Based on the potential-energy surface of hydrogen molecules on IRMOF linkers and the interaction energy between hydrogen molecules, we estimate the saturation value of hydrogen sorption capacity at room temperature. We discuss design criteria and propose new IRMOF materials that have high gravimetric and volumetric hydrogen storage densities. These new IRMOF materials may have gravimetric storage density up to 6.5 wt % and volumetric storage density up to 40 kg H2/m3 at room temperature.     

Benzhydryl as an efficient selective nitrogen protecting group for uracils

Regioselective N-substitution of the less active nitrogen within uracil analogues has been achieved following preliminary N-protection at the more active N-position with a benzhydryl protecting group. This protecting group is stable to concentrated HCl (aqueous) at reflux temperature, TFA at room temperature, and Pd-C-catalyzed normal pressure hydrogenation at room temperature; the benzhydryl group can be removed quantitatively and selectively with a 10% triflic acid solution in TFA at 0 degree C.     

Sydnone Compounds XXX. The Syntheses and Reactions of 3-Aryl-4-Cyanosydnones and 3-Aryl-4-Formylsydnone Oximes

In the presence of pyridine, 3-aryl-4-formylsydnone (II) reacts with hydroxyl-amine hydrochloride to produce 3-aryl-4-formylsydnone oxime (III). This reaction was performed in ethanol solution with reflux or at room temperature; the latter procedure gave an excellent yield (74-98%) and high purity. (III) reacts in acetic anhydride at room temperature to give 3-aryl-4-formylsydnone oxime O-acetate (IV). A convenient method for the synthesis of 3-aryl-4-cyanosydnone (V) is to dehydrate (III) with acetic anhydride at reflux. When (IV) was refluxed with acetic anhydride, (V) was similarly obtained. Another convenient method to prepare (V) from (III), dehydration with thionyl chloride at room temperature, was also investigated.     

The A-site ordered manganese perovskite and its colossal magnetoresistance

The A-site ordered manganites show the charge/orbital order (CO) transition far above room temperature. By using this advantage, we have engaged in the realization of colossal magnetoresistance (CMR) at room temperature by introducing some sophisticated disorders to SmBaMn₂O₆. The inter-site disorder of Sm/Ba results in no significant magnetoresistance (MR) effect. The La-substitution for both Sm- and Ba-sites is effective to realize MR effect. At room temperature and 9 T, we have achieved the record of MR effect about 340% in the sintered Sm_0.90La_0.24Ba_0.86Mn₂O₆. In a single crystal of the compound, the perfect CO insulator to ferromagnetic metal (FM) transition is observed at 9 T, showing the room temperature CMR over 1000%. TEM study reveals that the formation of microdomains with CO and FM or magnetic glassy states is crucial for CMR.     

Bocdene and mocdene derivatives of catechols and catecholamines

[reaction in text] Catechols react chemoselectively, in the presence of either alcohols, 1,2-diols, or simple phenols, with tert-butyl propynoate and with methyl propynoate to give 2-Boc-ethylidene (Bocdene) and 2-Moc-ethylidene (Mocdene) acetals, respectively, in 96-100% yields within 30 min at room temperature, provided that 150 mol % of DMAP is added. Cleavage of these acetals with pyrrolidine readily takes place (at room temperature!) in 95-100% yields. By taking advantage of the features of Bocdene acetals, novel catecholamine-related phosphate mimetics have been prepared.     

Synthesis of 1,2-diols ethers,condensation products of glyoxal with nitrogen-containing nucleophiles: I. Reaction of cyclic sulfites with primary alcohols and glycols

In reactions of 4,5-diacetoxy-2-(dinitromethylene)imidazolidine, 4,5-diacetoxy-2-nitriminoimidazolidine, and 1,2-diacetoxy-1,2-bis(chloroacetylamino)ethane with thionyl chloride at room temperature the corresponding cyclic sulfites were obtained. Treating the sulfites with methanol, ethanol, and 2-chloroethanol at room temperature we prepared acyclic ethers in 80–90% yields. Similarly cyclic ethers were synthesized from ethylene glycol and 1,3-propanediol in 50–60% yields.     

Determination of gastrodin and vanillyl alcohol in Gastrodia elata Blume by pressurized liquid extraction at room temperature

Pressurized liquid extraction (PLE) at room temperature with a laboratory-assembled system was applied for the extraction of gastrodin (GA) and vanillyl alcohol (VA) in Gastrodia elata Blume. The proposed system setup for this current work was simpler as no heating and backpressure regulator was required. Extraction with PLE was carried out dynamically at a flow rate of 1.5 mL/min, at room temperature, under an applied pressure of 10-20 bars with an extraction time of 40-50 min. The extraction efficiencies of the proposed method using 20% aqueous ethanol were compared with heating under reflux using organic solvents such as methanol and ethanol/water (20:80) for different batches of medicinal plant materials. For the determination of GA and VA in G. elata Blume, the extraction efficiencies of PLE at room temperature were observed to be comparable with heating under reflux. The method precision was found to vary from 1.6 to 8.6% (RSD, n = 6) on different days. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC and HPLC/MS/MS. Our work demonstrated the possibility of implementation of PLE at room temperature and the advantages of minimizing the use of organic solvents in the extraction process.     

Identification of organically associated trace elements in wood and coal by inductively coupled plasma mass spectrometry

1-Methyl-2-pyrrolidinone (NMP) was used to extract samples of wood (forest residue) and coal; the extracts were analysed by inductively coupled plasma mass spectrometry (ICP-MS) using two different sample preparation methods, in order to identify trace elements associated with the organic part of the samples. A sample of fly ash was similarly extracted and analysed in order to assess the behaviour of the mineral matter contained within the wood and coal samples. 32% of the biomass was extracted at the higher temperature and 12% at room temperature while only 12% of the coal was extracted at the higher temperature and 3% at room temperature. Less than 2% of the ash dissolved at the higher temperature. Size exclusion chromatograms of the extracts indicated the presence of significant amounts of large molecular mass materials (>1000 mu) in the biomass and coal extracts but not in the ash extract. Trace element analyses were carried out using ICP-MS on the acid digests prepared by 'wet ashing' and microwave extraction. Sixteen elements (As, Ba, Be, Cd, Co, Cr, Cu, Ga, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) were quantified, in the samples before extraction, in the extracts and in the residues. Concentrations of trace elements in the original biomass sample were lower than in the coal sample while the concentrations in the ash sample were the highest. The major trace elements in the NMP extracts were Ba, Cu, Mn and Zn from the forest residue; Ba, Cu, Mn, Pb and Zn from the coal; Cu and Zn from the ash. These elements are believed to be associated with the organic extracts from the forest residue and coal, and also from the ash. Be and Sb were not quantified in the extracts because they were present at too low concentrations; up to 40% of Mn was extracted from the biomass sample at 202 degrees C, while Se was totally extracted from the ash sample. For the forest residue, approximately 7% (at room temperature) and 45% (at 202 degrees C) of the total trace elements studied were in the extract; for the coal, approximately 8% (at room temperature) and 23% (at 202 degrees C) were in the extract. For the ash, only 1.4% of the trace elements were extracted at 202 degrees C, comprising 25% of Cd but less than 1% of Pb.     

Intramolecular Diamination and Alkoxyamination of Alkenes with N-Sulfonyl Ureas With N-Iodosuccinimide

Reaction of N-δ-alkenyl-N'-sulfonyl urea 1 with N-iodosuccinimde (NIS; 2 equiv) and a catalytic amount of AgOTf (20 mol %) at room temperature led to intramolecular alkoxyamination to form bicyclic isourea 2a in 95% isolated yield. In comparison, reaction of 1 with NIS and sodium bicarbonate (1 equiv) at room temperature led to isolation of bicyclic imidazolidin-2-one 2b in 91% yield. These NIS-mediated alkoxyamination and diamination protocols were effective for a range of N-δ-alkenyl-N'-sulfonyl ureas to form the corresponding heterobicyclic compounds in good yield with high chemoselectivity and good to excellent diastereoselectivity.     

Low-temperature reaction of trialkoxysilanes on silica gel: a mild and controlled method for modifying silica surfaces

The room temperature reaction of 4-(triethoxysilyl)butyronitrile, 4-TBN ((C2H5O)3Si(CH2)3CN), on weakly hydrated silica samples pretreated at 393 K has been studied by desorption experiments and by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy at different aging times under various water partial pressures. The reaction is demonstrated by the decrease of desorption of 4-TBN with time and the simultaneous disappearance of the 2980 and 1394 cm(-1) signals in the DRIFT spectra, assigned to the CH3 moiety of the ethoxy functions. Water partial pressure is shown to have a crucial effect on the rate and efficiency of the process as, after 6 days, for samples kept at room temperature under vacuum, ca. 50% of the silane has reacted, while for those kept in a water-saturated atmosphere the silane reaction reaches 96%. Although the silane appears to be irreversibly bonded to the surface, no definite conclusion may be drawn from these preliminary results as to the nature of the bonding (grafting or coating). These samples are compared to modified silicas prepared according to conventional methods. The same extent of silane reaction (50%) is achieved for preadsorbed samples kept under vacuum and either cured at 473 K for 30 h or kept at room temperature for 6 days. A mild and controlled modification of silica by triethoxysilanes can thus be achieved by first physisorbing known amounts of the modifying silanes from an organic solvent on pretreated silica and then letting the samples mature for a few days at room temperature in a water-saturated atmosphere.     

Metal-catalyzed acyl transfer reactions of enol esters: role of Y5(OiPr)13O and (thd)2Y(OiPr) as transesterification catalysts

Primary and secondary alcohols react with vinyl or isopropenyl acetate at room temperature in the presence of catalytic amounts (0.05-1 mol %) of Y5(OiPr)13O to give the corresponding esters. In selected cases, the yttrium catalyst promotes the selective O-acylation of amino alcohols without the formation of the amide. Enol esters also react with alpha-amino acid esters in the absence of a catalyst, at room temperature, to give the corresponding amides.     

Solid polymer electrolytes based on crosslinkable polyoctahedral silsesquioxanes (POSS) for room temperature lithium polymer batteries

Solid polymer electrolytes (SPE), based on polyoctahedral silsesquioxanes (POSS) as a crosslinking agent, were prepared by radical polymerization. The ionic conductivity is greatly enhanced by introduction of crosslinkable POSS with multifunctional groups. The SPE prepared with 5 wt.% crosslinking agent shows an ionic conductivity of 5.3?×?10^?4 S cm^?1 at room temperature. The content of nonvolatile plasticizer, poly(ethylene glycol) dimethyl ether, in the SPE, could be raised to 95 wt.% without any leakage. The SPE is found to be electrochemically stable up to 5.3 V. Lithium polymer cell consisting of Li/SPE/LiCoO₂ exhibits 80% of initial discharge capacity even at the rate of 0.1 C at room temperature after 20 cycles, which is a substantial improvement for practical consideration of lithium polymer batteries at room temperature.     

Nucleophilic addition of TMSCCl3 to N-phosphinoyl benzaldimines: a route to N-phosphinoyl-α-(trichloromethyl)benzylamines

Nucleophilic addition of readily available TMSCCl₃ to N-phosphinoyl benzaldimines allows preparation of N-phosphinoyl-α-(trichloromethyl)benzylamines. Typically, the reaction in THF at room temperature using tetrabutylammonium difluorotriphenylsilicate (TBAT) as a catalytic promoter, afforded very good yields (65–95% range) for most derivatives within 1 h at room temperature.     

The 1.28 μm transparency window of methane (7541-7919 cm⁻¹): empirical line lists and temperature dependence (80 K-300 K)

The high sensitivity absorption spectra of methane at room temperature and 80 K were recorded by CW-Cavity Ring Down Spectroscopy in the 1.28 μm transparency window (7541-7919 cm(-1)). The empirical line parameters of 7690 and 5794 transitions were retrieved at room temperature and at 80 K, respectively. The achieved sensitivity (α(min)≈ 10(-10) cm(-1)) allowed detecting transitions with intensities as small as 5 × 10(-30) cm per molecule. In order to facilitate identification of the CH(3)D transitions present in the CRDS spectrum of methane in "natural" isotopic abundance, the spectrum of a highly enriched CH(3)D sample was recorded by differential absorption spectroscopy at room temperature and at 80 K. The CH(3)D relative contribution in the considered transparency window is found to be significant only at 80 K (up to 15%) but more limited than in the 1.58 μm transparency window.The low energy values of the transitions observed at both room temperature and 80 K were derived from the variation of their line intensities. Empirical lower states and J values have been obtained for 2821 CH(4) transitions representing 94.1 and 98.5% of the absorbance in the region at room temperature and 80 K, respectively. The good quality of these derived energy values is demonstrated by the marked propensity of the corresponding CH(4) lower state J values to be close to integers. The constructed line lists extend to higher energies the WKC (Wang-Kassi-Campargue) line lists of methane in the near infrared (1.71-1.26 μm). They allow one accounting for the temperature dependence of methane absorption between 80 K and 300 K and are of importance for the analysis of the near infrared spectrum of several planetary bodies like Titan, Uranus and Neptune. The centers of the 3ν(2) + ν(3) and 6ν(4) bands responsible of the absorption in the studied region are discussed in relation with recent theoretical calculations.     

Exploratory chemistry of 3-aroylformamido-4-aryl-1,2,5-thiadiazoles

Apart from the previous report, the reaction of 3-(4-nitrobenzoylformamido)-4-(4-nitrophenyl)-1,2,5-thiadiazole ( 2a ) with m-chloroperbenzoic acid in chloroform at room temperature did not proceed, whereas at reflux temperature the same reaction gave 4-nitrobenzoic acid ( 5 ) (86%) and a minute amount of a mixture of 4-nitrobenzoylformamide ( 6 ) and 3-amino-4-(4-nitrophenyl)-1,2,5-thiadiazole ( 7a ). On the other hand the same reaction in a mixture of ethanol and chloroform (1:4) at room temperature gave 3-ethoxycarbamoyl-4-(4-nitrophenyl)-1,2,5-thiadiazole ( 8a ) (24%) as an isolable product. When 3-aroylformamido-4-aryl-1,2,5-thiadiazoles 2 in tetrahydrofuran were treated with various alkoxides in the corresponding alcohols at room temperature, 3-amino-4-aryl- 7 , 3-alkoxycarbamoyl-4-aryl- 8 , and 3-aryl-4-(aryl)(hydroxy)acetamido-1,2,5-thiadiazoles 9 were isolated. The ratios of which were dependent on the kind of bases and the solvent employed. Selected compounds 2 were allowed to react with phosphorus pentasulfide in the presence of pyridine at reflux to give 3-aryl-4-arylacetarnido-1,2,5-thiadiazoles 17 (55–64%), which were also produced by the reaction of 2 with either Lawesson's reagent or hydrogen sulfide gas in the presence of pyridine at reflux.     

溴化钾催化硫化物、硝酸铵和 SiO2-OSO3H 固体酸的氧化反应

A convenient and selective catalytic method for the sulfoxidation of aliphatic and aromatic sulfides by treatment of NH4NO3, silica sulfuric acid, wet SiO2 (50% w/w) and a catalytic amount of KBr in CH2Cl2 at room temperature was developed. Many sulfides can be selectively oxidized at room temperature in good to excellent yields. The reaction proceeds without over-oxidation to sulfones under mild conditions.