693-95-8Relevant articles and documents
Decarboxylation method for heterocyclic carboxylic acid compounds
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Paragraph 0034; 0035; 0041; 0050; 0051, (2019/05/11)
The invention relates to a decarboxylation method for heterocyclic carboxylic acid compounds. The method comprises the following steps: dissolving the heterocyclic carboxylic acid compounds in an aprotic polar solvent N,N-dimethylformamide, and performing decarboxylation at 85-150 DEG C with an organic acid as a catalyst. The method in the invention allows the yield of decarboxylation products obtained after a reaction to be higher than the yield of the products obtained through decarboxylation methods in the prior art, and does not need an expensive metal catalyst; and the solvent (DMF) in the present invention is more stable than DMSO, is not prone to decompose at a high temperature, and it can be recycled, so the cost is reduced. The method has the advantages of simple operation process, zero pollution, greenness, environmental protection and excellent application prospect.
A TPD-MS study of the interaction of coumarins and their heterocyclic derivatives with a surface of fumed silica and nanosized oxides CeO 2/SiO2, TiO2/SiO2, Al 2O3/SiO2
Kulyk, Kostiantyn,Ishchenko, Valentyna,Palyanytsya, Borys,Khylya, Volodymyr,Borysenko, Mykola,Kulyk, Tetiana
scheme or table, p. 750 - 761 (2011/09/12)
The interactions between coumarins and the surface of fumed SiO 2, CeO2/SiO2, TiO2/SiO2 and Al2O3/SiO2 were assessed by means of temperature-programed desorption mass spectrometry. The different stages of the thermolysis of coumarin were identified and an analysis of the underlying reactions was performed. The kinetic parameters of the involved reactions were thus obtained. The decomposition of thiazolyl-substituted coumarins was found to proceed through a 'thiazole-thiazine' ring expansion in the adsorbed state. A linear correlation between the sigma constants (Σσ) of the coumarin substituents and the activation energy of CO2 formation was obtained. Copyright
Reactivity of neutral nitrogen donors in square-planar d8 metal complexes: The system chloro(2,2′:6′,2″-terpyridine)platinum(II) cation with five-membered N-donor heterocycles in methanol
Pitteri, Bruno,Bortoluzzi, Marco
, p. 2698 - 2704 (2008/10/09)
The kinetics of the forward and reverse steps of the reaction [Pt(terpy)Cl]+ + nu ? [Pt(terpy)(nu)]2+ + Cl- (terpy = 2,2′:6′,2″-terpyridine, nu = one of a number of thiazoles, oxazole, isoxazole, imidazole, pyrazole and 3,5-dimethylpyrazole, covering a wide range of basicities) have been studied in methanol at 25 °C. Both forward and reverse reactions obey the usual two-term rate law observed in square-planar substitution. The second-order rate constants for the forward reactions, k2f, show a slight dependence upon the basicity of the entering nu, while the steric hindrance due to the presence of one methyl group in the α position to the nitrogen markedly decreases the reactivity. The second-order rate constants for the reverse reactions, k2r, are very sensitive to the nature of the leaving group and a plot of log k2r against the pKa of the conjugate acids of the unhindered five-membered N-donors is linear with a slope of -0.51. The results are compared with data from the literature regarding a series of pyridines reacting with the [Pt(terpy)Cl]+ cation under the same experimental conditions. Both in the forward and in the reverse reaction, the reactivity depends not only upon the ligand basicity but also upon the nature of the nucleophile in the order: (thiazoles, oxazole, isoxazole, imidazole, pyrazoles) > pyridines for the entry of N-donors and on the contrary for the displacement by Cl-. Steric retardation, due to the presence of a methyl group in the α position to the nitrogen, is remarkably lower for five-membered N-donors if compared to pyridines both in the forward and in the reverse reaction.