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291.
Limin Zhou Jinbo Ouyang Hamza Shehzad Zhanggao Le Zhao Li Adesoji A. Adesina 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1377-1385
The carboxymethylated chitosan (CMC)/Na-bentonite (Na-Bt) composite membranes were prepared and throughly characterized. The Na-Bt/CMC mass ratio was optimized, and CB10 (membrane with Na-Bt/CMC mass ratio of 10%) was selected as the best membrane for U(VI) sorption. XPS analysis indicates that the main mechanism for UO22+ sorption onto CB10 is through inner-surface complexation. The sorption kinetics followed pseudo-second order model, indicating the chemisorption as the rate-controlling step. The U(VI) sorption on CB10 is endothermic and spontaneous, with the maximum mono-layer adsorption capacity of 115.6 mg/g at pH 5.0 and 298 K. Finally, the U(VI)-loaded CB10 can consecutively desorbed and reused for several cycles. 相似文献
292.
In situ generated 2,4-diaryl substituted münchnones from 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids react with acetic anhydride in the presence of 2-nitromethylene thiazolidine, which is most likely acting as a base, and unexpectedly undergo a Dakin–West type reaction and a concurrent autoxidation reaction leading to the formation of (E)-1-(N,4-dimethylbenzamido)-1-(4-fluorophenyl)prop-1-en-2-yl acetate, 4-substitutedphenyl-N-methyl-N-(4-substitutedbenzoyl) benzamides and p-substituted benzoic acids. In addition, a novel and efficient access to N-acyl urea derivatives is described by the reaction between 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids and cyclohexyl, isopropyl carbodiimides in the presence of a base. The structures of all new products were identified on the basis of NMR and IR spectra, along with X-ray diffraction data and HRMS measurements. 相似文献
293.
Polyurethane foams immobilizing dithizone and lead diethyldithiocarbamate were prepared and examined, respectively, for the detection of cadmium and copper in aqueous solution. In batch tests, amounts as low as 0.1 and 0.05 μg ml?1 of cadmium and copper are easily detected. Lower concentrations of these metal ions were detected in flow experiments using columns packed with 0.5 g of the reagent foam. Semiquantitative determination of these metals is also possible using a suitable standard color scale. 相似文献
294.
M M Badawi A Guggisberg P van den Broek M Hesse H Schmid 《Helvetica chimica acta》1968,51(8):1813-1817
Two new macrocyclic alkaloids oncinotine ( 1 ) and isooncinotine ( 2 ) have been isolated from Oncinotis nitida BENTH . 1 can be converted into 2 by an amide exchange reaction. The spermidine residue was present in both bases. The structural elucidation was based mainly on (I) the determination of the functional groups, (II) degradation to compounds 12 and 13 and (III) mass spectrometric investigation of 1 and of the above mentioned degradation products. 相似文献
295.
296.
Yasser M. Loksha Erik B. Pedersen Ahmed A. El‐Barbary Mahmoud A. El‐Badawi Claus Nielsen 《Journal of heterocyclic chemistry》2003,40(4):593-599
4‐tert‐Butyl‐1,3‐dihydroimidazol‐2‐ones and 1,3‐dihydroimidazol‐2‐thiones were synthesized from 1‐amino‐3,3‐dimethylbutanone and subjected to alkylation reactions. The latter compounds were S‐alkyl‐ated with iodoacetamide under alkaline conditions. The N1 N3‐unsubstituted derivative was iodinated and subsequently alkylated with alkylation reagents which previously have been used for the synthesis of anti‐HTV active imidazoles. Unfortunately, the present products were devoid of activity against HTV. 相似文献
297.
The voltammetric behaviour of 19 ions in 1M ammonium fluoride solution has been investigated, using a rotating platinum electrode. In this base electrolyte, manganese(II) is oxidised reversibly to manganese(IV) at + 0.52 V vs. S.C.E. and this reaction has formed the basis for a simple voltammetric method for the determination of steels and cast iron of low cobalt content. 相似文献
298.
Coupling of dimedone with the diazonium salt of 4-aminoantipyrine afforded 2,3-dimethyl-4-[2-(5,5-dimethyl- 2,6-dioxocyclohex-2-ylidend)-hydrazino]-5-oxo-1-phenylpyrazoline (3). Reaction of 3 with excess phenylhydrazine gave the mixed trishydrazone derivative 4. Treatment of 3 with hydroxylamine produced the bisoxime 5 which upon dehydrative cyclization with acetic anhydride gave the corrsponding tetrahydrobenzo[d][1,2,3]triazole derivative 7. A one-pot synthesis of 7 was done by reacting 3 with hydroxylamine hydrochloride in pyridine, followed by heatment with acetic anhydride. 相似文献
299.
The Systemic Approach in Teaching and Learning Chemistry (SATLC)was established in 1997^[1-3].Our interest in developing the SATL strategy arose from the recognition of the increasing globalization of a wide specturm of human activities such as economics,media,politics,and entertainment,Systemics is our attempt to provide the student with a global view of his/her studies of chemistry. 相似文献
300.
Mohamed Rifaat Hamza Elmoghayar Sanaa Osman Abdalla Mohamed Yousry Abdel-Samad Nasr 《Journal of heterocyclic chemistry》1984,21(3):781-784
Benzoyl and ethoxycarbonyl isothiocyanates reacted with 2-cyanoethanoic acid hydrazide 2 to afford 1-cyanoacetyl-4-substituted thiosemicarbazide ( 5a,b ). Compound 5a afforded the pyrazolo[1,5-a]-s-triazine derivative 6 on treatment with 5% potassium hydroxide, and cyclised to 2-benzoylamino-5-cyanomethyl-1,3,4-thiadiazole ( 8 ) when boiled under reflux in glacial acetic acid. Compound 8 condensed with aromatic aldehydes to yield the corresponding arylidene derivatives 9a-c . It undergoes coupling with aromatic diazonium salts to afford the hydrazones 11a-c . Similarly, it coupled with diazotised aminopyrazole to afford the cyclic product 12 . 相似文献