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71.
Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds with iodine and bromine or their sodium salts proceed well in the presence of Fe(NO3)3·1.5N2O4/charcoal in CH2Cl2 at room temperature. 相似文献
72.
The model of weight loss taking place in each step of a scheme of consecutive reactions was applied to nonisothermal thermogravimetric records of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide). The release of HBr was found to be faster in air than in nitrogen. A significant reduction in the apparent activation energy of dehydrobromination as compared with decomposition of the nonbrominated polymer was ascribed not only to a reduction in the activation energy of the initiation reaction, but also to an increase in the order of the termination reaction (from 1 for the nonbrominated polymer to 2 for the highly brominated polymer). 相似文献
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76.
I. Grosu S. Mager G. Plé R. Martinez M. Horn R. R. Gaviño 《Monatshefte für Chemie / Chemical Monthly》1995,126(8-9):1021-1030
Summary New compounds containing the 2,4,8,10-tetraoxaspiro[5.5]undecanic skeleton, substituted with brominated groups, have been synthesized by a regioselective radicalic bromination reaction. The stereochemistry of the compounds was studied by high resolution NMR methods. The anancomericity or the flipping of the rings was inferred from the conformational analysis. The chirality of the spiranic skeleton was investigated by means of the diastereotopicity of hydrogen and carbon atoms.On leave from Organic Chemistry Department, Babes-Bolyai University, RO-3400 Cluj-Napoca, Romania 相似文献
77.
V. D. Dyachenko A. A. Nikishin A. N. Chernega 《Chemistry of Heterocyclic Compounds》2003,39(9):1153-1160
4,4-Dialkyl-substituted N-methylmorpholinium 3,5-dicyano-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates were synthesized by the condensation of 2-alkyl-2-cyanoethyl crotonates with cyanothioacetamide and N-methylmorpholine. They were used for the production of substituted 2-alkylthio-1,4,5,6-tetrahydropyridines, 2-acetylthio-1,4,5,6,-tetrahydropyridine, 6-hydrazino-1,4,5,6-tetrahydropyridine, and 2,3,4,5,6,7-hexahydrothiazolo[3,2-a]pyridine. The structure of 6-bromo-3-bromomethyl-6,8-dicyano-7,7-dimethyl-2,3,4,5,6,7-hexahydrothiazolo[3,2-a]pyridine was proved by X-ray crystallographic analysis. 相似文献
78.
Conversion of alcohols to alkyl bromides is one of the most frequently used functional group transformation reactions. Phosphorus tribromide is one of the most popular classical reagents. Triphenylphosphine has been used in combination with bromine,carbon tetrabromide,N-halo imides and other bromide compounds as a mild reagents for the preparation of alkyl bromides. More reacently, halotrimethylsilanes were found to be useful for halogenation of alcohols. Geo- rge A.Olah successfully convert… 相似文献
79.
A series of bromo-, nitro-, and bromonitrofluorenones were synthesized chemo- and regioselectively in 90–98% yield via electrophilic aromatic bromination and nitration under mild conditions using water as the sole solvent. These synthetic methods involve simple workup procedures and use only minimal amounts of organic solvents during the purification of products. The newly developed methods have the advantages of being cost-effective and environmentally friendly and could potentially be used for the large-scale synthesis of fluorenone derivatives. 相似文献
80.
《中国化学会会志》2017,64(12):1408-1416
An improved and greener protocol has been developed for the synthesis of 2,4‐disubstituted thiazoles via C–Br, C–S, and, C–N bond formations in a single step from readily available ketones, N‐bromosuccinimide (NBS), and thiourea catalyzed by citric acid in a mixture of ethanol and water (3:1) under reflux conditions. This method has the advantages of freedom from the isolation of lachrymatory α‐bromoketones, ease of carrying out, cleaner reaction profile, broad substrate scope, freedom from chromatographic purification, and suitability for large‐scale synthesis. 相似文献