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61.
An Approach to the Synthesis of Spiro[indene‐pyridoisoquinoline] Derivatives via 1,4‐Dipolar Cycloaddition of Isoquinoline and Acetylene Esters,and (1,3‐Dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile
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Abdolali Alizadeh Vahideh Sadeghi Fahimeh Bayat Long‐Guan Zhu 《Helvetica chimica acta》2014,97(10):1383-1387
A concise and efficient approach to the spiro‐tetrahydroisoquinoline derivatives has been developed by 1,4‐dipolar cycloaddition of zwitterions resulting from isoquinoline and acetylene esters and (1,3‐dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile in MeCN at room temperature. The significance of this method lies in good yields and ease of product purification, and no inert atmosphere is required. The structures of the products were confirmed spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme). 相似文献
62.
The keto-enol equilibria of benzoylacetone (BZA) as a model for 1,3-dicarbonyl compounds are studied in aqueous acid and cationic micellar solution. Evolving factor analysis (EFA), multivariate curve resolution-alternating least-squares (MCR-ALS), and rank annihilation factor analysis (RAFA) are used for complete resolving of measured spectrophotometric data. The acidity constants of the enolic, KaE, and ketonic, KaK, forms of BZA and also the tautomerization constant, Kt, and its related thermodynamic parameters have been determined by using EFA and MCR-ALS methods and spectral variation of BZA solutions in various pHs and temperatures. The concentration and spectral profiles of all species were calculated without any assumption about chemical models. The spectral variation of BZA solutions as a function of cationic micelle concentration sufficiently beyond its critical micelle concentration is analyzed according to the partition model for distribution between water and micellar pseudo-phase and RAFA. The outputs of using RAFA on measured rank deficient data are the spectrum of enolic form in the micellar pseudo-phase, free from contribution of the enolic form in the aqueous phase, the partition coefficient of enolic form, KdE, between the micelle and water phases, and the tautomerization constant in the micellar pseudo-phase, Ktm. 相似文献
63.
Vahideh Mahdavi Fatemeh Ghorbani-Paji Mohammad Kazem Ramezani 《International journal of environmental analytical chemistry》2019,99(10):968-976
Currently, there is growing interest in the degradation pathways of organic contaminants such as pesticides. In the case of pesticides, the determination of metabolites in agricultural products and environment is necessary as some of them could present similar toxicity to or even higher toxicity than the parent compound. The development of analytical methodology for the identification and quantification of carbendazim fungicide and its metabolites in cucumber was studied. Cucumber (cucumis sativus) is a global food in terms of economic importance and nutritional quality. Careful optimisation of the liquid chromatography–mass spectrometry (LC-MS)/MS parameters was achieved in order to attain a fast separation with the best sensitivity. The detection was carried out on an Ion-Trap tandem mass spectrometer (MS/MS) by electrospray ionisation in positive ion mode (ESI+) with multiple reaction monitoring (MRM). 相似文献
64.
Heravi Majid M. Janati Fatemeh Zadsirjan Vahideh 《Monatshefte für Chemie / Chemical Monthly》2020,151(4):439-482
Monatshefte für Chemie - Chemical Monthly - The Knoevenagel condensation reaction is a prominent organic reaction commonly being utilized in the total synthesis of natural and biologically... 相似文献
65.
A computational investigation was carried out to characterize the 17O and 1H chemical shielding (CS) tensors in crystalline aspirin. It was found that O–H⋯O and C–H⋯O hydrogen bonds around the aspirin
molecule in the crystal lattice have a different influence on the calculated 17O and 1H CS eigenvalues and their orientations in the molecular frame of axes. The calculations were performed with the BLYP, B3LYP,
and M06 functionals employing 6-311++G(d,p) standard basis set. Calculated CS tensors were used to evaluate the 17O and 1H chemical shift isotropy (δiso) and anisotropy (Δσ) in crystalline aspirin, which are in reasonable agreement with available experimental data. The difference
between the calculated NMR parameters of the monomer and molecular clusters shows how much hydrogen-bonding interactions affect
the CS tensors of each nucleus. 相似文献
66.
Vahideh KhademHosseini Daryoosh Dideban MohammadTaghi Ahmadi Razali Ismail 《Brazilian Journal of Physics》2018,48(4):406-410
Single-electron transistors (SETs) are nano devices which can be used in low-power electronic systems. They operate based on coulomb blockade effect. This phenomenon controls single-electron tunneling and it switches the current in SET. On the other hand, co-tunneling process increases leakage current, so it reduces main current and reliability of SET. Due to co-tunneling phenomenon, main characteristics of fullerene SET with multiple islands are modelled in this research. Its performance is compared with silicon SET and consequently, research result reports that fullerene SET has lower leakage current and higher reliability than silicon counterpart. Based on the presented model, lower co-tunneling current is achieved by selection of fullerene as SET island material which leads to smaller value of the leakage current. Moreover, island length and the number of islands can affect on co-tunneling and then they tune the current flow in SET. 相似文献