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51.
Narisawa Masaki Okabe Yoshio Iguchi Masahiro Okamura Kiyohito Kurachi Yasuo 《Journal of Sol-Gel Science and Technology》1998,12(3):143-152
Inorganic-organic hybrid gels were prepared by simultaneous condensation of the liquid mixture of ethyl silicate, ethyl borate and water soluble phenol resin with low molecular weight. The liquid mixtures were changed into lightly colored transparent gels after a catalyst addition and stirring. The obtained gels were crushed, dried and fired in controlled conditions to yield the inorganic precursors. Since the tailored inorganic precursors mainly consisted of SiO2 and carbon, silicon carbide was formed with the heat treatments in an Ar atmosphere beyond 1773 K with carbothermic reduction. The properties and morphology of the formed silicon carbide powders in terms of the starting precursor compositions and the conditions of the carbothermic reduction were investigated with SEM, XRD and TG-DTA analysis. 相似文献
52.
N. E. Golantsov A. V. Karchava M. A. Yurovskaya 《Chemistry of Heterocyclic Compounds》2006,42(8):1021-1024
Methods of obtaining ketones and enamino esters have been developed on the basis of reactions of 1-(1-phenylethyl)indole-2-carbonitrile
with organomagnesium and organozinc compounds. Removal of a benzyl group from the indole nitrogen atom by the Grignard reagent
has been discovered.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1179–1183, August, 2006. 相似文献
53.
54.
V. Slavinska Dz. Sile G. I. Chipens Yu. Balodis G. Rozenthal K. Venteris E. Lukevics 《Chemistry of Heterocyclic Compounds》2003,39(12):1579-1583
A method was developed for the synthesis of N-[1-(S)-(ethoxycarbonyl)-3-phenylpropyl]alanylproline (enalapril) by reductive alkylation of alanylproline with ethyl 2-oxo-4-phenylbutenoate under the conditions of hydrogenation in the presence of palladium black and 1.6% Pd/C. The yield of enalapril amounted to 65%. With the ethyl ester of the -oxo acid the diastereoselectivity of formation of the S,S,S-diastereomer was higher than with the saturated synthon. It is assumed that with ethyl 2-oxo-4-phenylbutenoate as synthon a conformationally restricted surface complex is formed between the unsaturated synthon and the active centers of the catalyst. During reductive alkylation of alanylproline by ethyl 2-oxo-4-(2-thienyl)butenoate poisoning of the catalyst occurs. 相似文献
55.
标题化合物C19H23O4Cl(4)是由邻氯苯甲醛(1)与5,5-二甲基-1,3-环己二酮(2)、2,2-二甲基-1,3-二氧六环-4,6-二酮(3)在乙醇中反应而得。结构通过单晶X-射线衍射分析确定,其晶体属于单斜晶系,空间群晶体结构用直接法解出,使用全矩阵最小二乘法对原子参数进行修正,最后的偏离因子R=0.034,Rw=0.042。在晶体结构中存在一个共轭的烯醇结构。单晶X-射线分析表明;平面1(C(1)~C(6)、Cl)和平面2(C(8)~C(10)、C(12)、C(13))之间的两面角为97.11°,原子C(7)呈变形的四面体构型。 相似文献
56.
A. A. Vasil'ev A. L. Vlasyuk G. V. Kryshtal E. P. Serebryakov 《Russian Chemical Bulletin》1995,44(10):1946-1951
Stereospecific syntheses of (±)-3-methyl-6-isopropenyl-3(Z),9-decadien-1-yl acetate and (±)-3,9-dimethyl-6-isopropenyl-3(Z),9-decadien-1-yl propionate (the Racemoc forms of the pheromones of the scalesAonidiella aurantii andPseudaulascaspis pentagona) with a geometrical purity of the (Z)-trisubstituted double bond not lower than 99 % were performed. The key step in both syntheses was the 1,4-cis-hydrogenation of the corresponding ethyl 3-methyl-6-(1, 1-ethylenedioxyethyl)-2,4,9-decatrienoates catalyzed with chromium carbonyl complexes. These 2,4-dienes were obtained in five conventional steps including the alkylation of ethyl acetoacetate by the appropriate 1-bromo-3-butenes and the Horner-Emmons olefination of the corresponding -branched aldehydes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2026–2031, October, 1995. 相似文献
57.
本文对Ln(phen)(C6H5COO)3、Ln(phen)2P-(OC6H4CHO)3·3H2O.Ln(phen)2P-(OC6H4COOC2H5)3(Ln=Tb、Eu)固体配合物的制备和光谱性质进行了研究。根据元素分析、红外光谱、摩尔电导测定,X射线粉末衍射、热重差热分析以及紫外可见光谱确定了其组成及配位形式,并对其发光性能进行了研究。 相似文献
58.
The addition of secondary and primary amines to ethyl (1-amino-9,10-anthraquinon-2-yl)propynoate affords an easily separable
mixture of the corresponding ethyl 3-dialkylaminoor 3-alkylamino-3-(1-amino-9,10-anthraquinon-2-yl)acrylate and 3-dialkylamino-
or 3-alkylaminonaphthol[2,3-h]quinoline-2(1H), 7,12-trione (in ∼4: 1 ratio). Intramolecular cyclization of the resulting substituted ethyl acrylates results in the formation
of 4-dialkylaminoor 4-alkylamino-2-chlorinated pyridine rings. Subsequent nucleophilic substitution of the chlorine atom gives
2-functionalized 4-dialkylamino- or 4-alkylaminonaphtho[2,3-h]quinoline-7,12-diones.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2327–2332, November, 1998. 相似文献
59.
60.
《Electroanalysis》2006,18(12):1193-1201
A chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10?5 cm2 s?1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10?5 M–2.0×10?3 M and 3.1×10?5 M–3.3×10?3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10?5 M and 9.0×10?6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations. 相似文献