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961.
1,4-Dioxane is a flammable liquid and tends to form explosive peroxides. Its formation in glycols (low parts-per-million levels), which are used as dehumidifying agents in refineries, may take place by condensation. 1,4-Dioxane thus formed gets distilled over with benzene in the refinery process. Therefore, it is necessary to identify and determine the levels of 1,4-dioxane in glycols as well as benzene. Gas chromatography (GC) is probably the best technique for this purpose. GC analysis may be carried out using a flame ionization detector. Results show that 1,4-dioxane can be comfortably determined down to 2 ppm in glycols and benzene. 相似文献
962.
Kumar S Hundal MS Kaur N Singh R Singh H Hundal Nee Sood G Ripoll MM Aparicio JS 《The Journal of organic chemistry》1996,61(22):7819-7825
The N(Py).HN(amide) hydrogen bonding within the macrocyclic cavities in 9, 10, and 13 invokes their symmetrical electron-deficient structures ((1)H NMR) and consequently bind with water. This results in their poor ionophore characters. The steric requirement of methyl/benzyl substituents on amide N in 11 and 12 takes the substituents out of the cavity and thus positions the amide O toward the cavity ((1)H, (13)C NMR and X-ray analysis). This arrangement of two pyridine N and two amide O ((13)C NMR, IR) binding sites provides an appropriate environment for selective binding toward Ag(+) over Pb(2+), Tl(+), alkali, and alkaline earth cations. The increased spacer length in 14 leads to a lop-sided twist of pyridine rings (X-ray) and disturbs the above arrangement and leads to its poor binding character. 相似文献
963.
8-hydroxyquinoline (oxine) and uranyl acetate react in the solid state in 13 stoichiometry to give UO2(C9H6NO)2·C9H6NOH. This reaction is diffusion controlled with an activation energy of 44.4 kJ mol–1. The reaction occurs by the surface migration of 8-hydroxyquinoline, which penetrates the product lattice to react with uranyl acetate. The isothermal decomposition of the solution phase product UO2Q2·HQ (Q=C9H6NO) obeys the Prout-Tompkins equation with an energy of activation of 53.3 kJ mol–1.
Zusammenfassung Die Festkörperreaktion von 8-Hydroxychinolin und Uranylazetat im Verhältnis 13 liefert UO2(G9H6NO)2·C9H6NOH. Die Reaktion ist diffusionsbestimmt und besitzt eine Aktivierungsenergie von 44.4 kJmol–1. Die Reaktion verläuft durch die Oberflächenmigration von 8-Hydroxychinolin, welches zur Reaktion mit Uranylazetat in das Gitter des Produktes eindringt. Die thermische Zersetzung der Mischphase UO2Q2·HQ mitQ=C9H6NO unterliegt der Prout-Tompkins-Gleichung mit einer Aktivierungsenergie von 53,3 kJ·mol–1.
8- 13, UO2(C9H6NO)2·C9H6NOH. 44,4 ·–1. 8-, . UO2 Q 2 · HQ (Q=C9H6NO) - 53,3 ·–1.相似文献
964.
Navjeet Kaur Neha Ahlawat Yamini Verma Pooja Grewal Pranshu Bhardwaj Nirmala Kumari Jangid 《合成通讯》2020,50(8):1075-1132
AbstractOne of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review. 相似文献
965.
B. S. Randhawa P. S. Bassi Sukhraj K. Randhawa Sandeep Kaur 《Journal of Radioanalytical and Nuclear Chemistry》1990,145(4):249-257
Solid state photolysis of alkaline earth tris/malonato/ferrates/III/, i.e., M3[Fe(CH2C2O4)3]2.xH2O /M=Mg, Ca, Sr, Ba/ has been investigated employing Mössbauer, infrared and reflectance spectroscopic techniques. The complexes were irradiated for 400 h using a medium pressure mercury vapour lamp of 250 Watts. Photoreduction led to the formation of M[FeII(CH2C2O4)2(H2O)2]. The extent of photoreduction showed the following order: Ca>Sr>Mg>Ba. The results have been compared with those of analogous alkaline earth tris/oxalato/ferrates/III/. 相似文献
966.
B. S. Randhawa P. S. Bassi Sandeep Kaur 《Journal of Radioanalytical and Nuclear Chemistry》1994,188(4):279-286
Thermal decomposition of lithium tris (malonato) ferrate (III) tetrahydrate i.e. Li3[Fe(CH2C2O4)3].4H2O has been studied in the temperature range of 353–873 K in static air atmosphere using Mössbauer, infrared spectroscopy and nonisothermal techniques (TG-DTG-DTA). The anhydrous complex decomposed into ferric oxide of varying particle sizes and alkali metal malonates/carbonates in succesive stages. Fimally a solid state reaction between -Fe2O3 and alkali metal carbonate gives fine particles of lithium ferrite (LiFeO2) at a temperature lower than for oxalate precursor and for ceramic method. 相似文献
967.
Navneet Kaur 《Tetrahedron letters》2004,45(37):6883-6885
N-α-Boc-l-Histidine upon direct τ(N-1) ring alkylation with various alkyl halides in the presence of sodium hydride in DMF or CH3CN easily afforded N-α-Boc-1-alkyl-l-histidines 2a-f. The reaction works equally well in either DMF or CH3CN as solvent, however, CH3CN is preferred due to ease of reaction work-up. 相似文献
968.
A computational study on dichalcogenide molecules (R2X2; X = O, S, Se; R = H, CH3, NH2) has been carried out employing B3LYP and MP2 levels using 6-31+G*, 6-311+G*, 6-311++G**, and PVDZ basis sets. The relative energies have been evaluated at G2MP2 also. The rotational barriers and bond dissociation energies indicate that S–S bond is stronger than Se–Se and O–O bond. NBO analysis at MP2/6-31+G* suggest the presence of partial π character between X–X bond that decreases in the order S–S > Se–Se > O–O. Fuki functions for nucleophilic and electrophilic attack fail to distinguish the reactivity of S and Se. The proton affinities of the O2H2, S2H2, Se2H2 decrease in the order Se > S > O. 相似文献
969.
S.K. Vasisht Tripat P. Kaur Jyotsna Kaushal Seema Dixit 《Journal of organometallic chemistry》1997,540(1-2):51-54
Sodium bis(trimethylstannyl)amide NaN(SnMe3)2, isolated by the reaction of trimethylstannyldiethylamine with sodium amide, reacts with tris(trimethylsilyl)hydrazino—dichloro-phosphine to form bis(trimethylsilyl)bis(trimethylstannyl)-2-phospha-2-tetrazene, (Me3Si)2N-N=P-N(SnMe3)2. Both the molecules have been isolated and characterized. 相似文献
970.
Mandeep?S.?BakshiEmail author Rajinderpal?Kaur Ishpinder?Kaur Rakesh?Kumar Mahajan Pankaj?Sehgal Hidekazu?Doe 《Colloid and polymer science》2003,281(8):716-726
Single and mixed micelle formation by sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) and their mixtures in pure water and in the presence of water-soluble polymers such as Synperonic 85 (triblock polymer, TBP), hydroxypropylcellulose (HPC), and carboxymethylcellulose sodium salt (CMC) were studied with the help of conductivity, pyrene fluorescence, cyclic voltammetry, and viscosity measurements. Conductivity measurements showed a single aggregation process for pure surfactants and their mixtures both in pure water as well as in the presence of water-soluble polymers. Triple breaks corresponding to two aggregation processes for SDS, SDBS, and their mixture in the presence of TBP were observed from fluorescence measurements. The first one demonstrated the critical aggregation process due to the adsorption of surfactant monomers on TBP macromolecule. The second one was attributed to the participation of surfactant–polymer aggregates formed at the first one, in the micelle formation process. The aggregation number ( N agg) of single and mixed micelles and diffusion coefficient ( D) of electroactive probe were computed from the fluorescence and cyclic voltammetry measurements, respectively. Both parameters, along with the viscosity results, indicated stronger SDS–polymer interactions in comparison to SDBS–polymer interactions. Mixed surfactant–polymer interactions showed compensating effects of both pure surfactants. The nature of mixed micelles was found to be ideal in all cases, as evaluated by applying the regular solution and Motomura's approximations. 相似文献