排序方式: 共有48条查询结果,搜索用时 234 毫秒
1.
Different novel phthalazino[2,3‐b]phthalazine‐5,7,12,14‐tetraones were synthesized in a simple and environmentally benign method from the reaction of phthalic anhydrides with semicarbazide or thiosemicarbazide using montmorillonite K‐10 clay as solid heterogeneous acidic catalyst and microwaves under solvent‐free conditions in good yields and short reaction times. Products were characterized by the elemental analysis, IR, NMR, and mass spectrometry. 相似文献
2.
Jian Ping LI* Qian Fu LUO Yi Yang SHEN Yu Lu WANG Hong WANG College of Chemistry Environmental Science Henan Normal University Xinxiang Department of Chemistry Luoyang Teacher''''s College Luoyang 《中国化学快报》2001,(2)
The subject of organic solid-state synthesis is a fascinating one. It has many advantages such as high efficiency and selectivity, easy separation and purification, mild reaction conditions, and environmental acceptability1. In recent years, this method has been widely used in a variety of organic reactions including substitution2, condensation3, oxidation-reduction4, rearrangement5 and elimination6. However, the solid state reaction using K3Fe(CN)6/KOH to oxidize substituted semicarbazides… 相似文献
3.
K. I. Pashkevich D. V. Sevenard O. G. Khomutov O. V. Shishkin E. V. Solomovich 《Russian Chemical Bulletin》1999,48(2):359-363
2-Polyfluoroacylcyclohexanones react with semicarbazide and thiosemicarbazide to give 2-(thio)carbamoyl-3-hydroxy-3-polyfluoroalkyl-3,3a,4,5,6,7-hexahydro-2H-indazoles, one of which was studied by X-ray diffraction.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 361–365, February, 1999. 相似文献
4.
5.
Twenty-one new organogermanium compounds with the formulae Ph3GeCHR1CH2CONHNHC(X)NHR2 (1) (R1=H, Ph; = Ph, p-CH3Ph, O -CH3Ph, p-ClPh, COPh, X = S, O) and (R1 = H, Ph; R2 = Ph, p-CH3Ph, o-CH3Ph, p-ClPh; X=S, O) were synthesized and characterized by elemental analysis, 1H NMR, IR, MS and X-ray diffraction techniques. Compounds l were prepared by the reactions of Ph3GeCHR1CH2CONHNH2 with R2NCX in chloroform in 77-94% yields, and 2 were obtained by refluxing l with sodium hydroxide (8%) with yields of 55-94%. 相似文献
6.
A new and highly sensitive spectrophotometric method is developed for the determination of sub ppm levels of the widely used organophosphorus insecticide dichlorvos. The method is based on alkaline hydrolysis of dichlorvos to dichloroacetaldehyde followed by coupling with diphenyl semicarbazide (DPC) in alkaline medium. The absorption maxima of the wine red dye compound formed is measured at 490 nm. Beer's law is obeyed over the concentration range of 4.3 to 34 μg in a final solution volume of 25 mL (0.18–1.36 ppm). The molar absorptivity, Sandell's sensitivity and correlation coefficient were found to be 2.9 × 105 l mole?1 cm?1, 0.013 μg cm?2 and 0.9999, respectively. The standard deviation and relative standard deviation were found to be ± 0.007 and 1.90%, respectively. The lower limit of detection is 0.04 μg. The method is simple, sensitive and free from interferences of other pesticides and diverse ions. Other organophosphorous pesticides do not interfere with the proposed method. The method has been satisfactorily applied to the determination of dichlorvos in environmental and agricultural samples. 相似文献
7.
Biju Mathew B. Narayana B. Muralidhara Rao C. H. Raghavan Nambiar B. Ramachandra 《Mikrochimica acta》1996,122(3-4):295-299
A simple and accurate complexometric method is proposed for the determination of Tl(III) using semicarbazide hydrochloride as a releasing agent. In the presence of diverse metal ions, thallium is complexed first with a known excess of EDTA, and the surplus EDTA is then titrated with standard zinc sulfate at pH 5.0–6.0 (hexamine) using xylenol orange indicator. An excess of 5% aqueous neutral solution of semicarbazide hydrochloride is then added and the released EDTA is titrated against standard zinc sulfate solution. The method works well in the range 2–50 mg of Tl(III) with relative errors < 0.5%, standard deviations 0.05mg and coefficient of variation 0.4%. The method is applied for the determination of thallium content in complexes and alloy compositions 相似文献
8.
9.
10.
Using ferric chloride to oxidize aryl substituted semicarbazide for preparing azo compounds has been described for the first time in this paper. Nine azo compounds have been synthesized in a good to excellent yield (≥88%). This method only needs cheap reagents, simple instruments and a short reaction time. 相似文献