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1.
作为稀土显色剂,含不对称胂(膦)酸基的变色酸双偶氮衍生物优于对称的同类化合物。为了进一步提高稀土显色剂的灵敏度和选择性,在不对称变色酸双偶氮衍生物非胂酸基一侧的偶氮基对位上引入推电子基团,邻位引入卤素取代基,得到一系列新的不对称变色酸双偶氮衍生物。其一般结构为: 相似文献
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本文设计、合成了一组新的不对称变色酸双偶氮胂类稀土显色剂。对新试剂进行了提纯鉴定,确定了组成及结构,研究了它们与稀土、钍、锆的显色反应性能。实验证明,试剂分子结构对其反应性能的影响有一定的规律性。其中o-As-DBN试剂是较优良的钍显色剂,毫克级的稀土、铀不干扰测定。 相似文献
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近年来,我国研制成的一系列不对称的变色酸双偶氮衍生物,由于其优异性能而被认为是有发展前途的一类稀土显色剂。含有高电负性多氟取代基的CPAmCF_3就是其中之一。前 相似文献
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在钍的分光光度法中,普遍采用以偶氮胂Ⅲ为代表的一类对称变色酸双偶氮型试剂。这类试剂虽然对钍有较高的灵敏度,然而选择性不很理想。对乙酰基偶氮胂[2-(2-胂酸基偶氮)-7-(4-乙酰基苯偶氮)-1,8-二羟基萘-3,6-二磺酸]是武汉大学化学系研制出的一种不对称双偶氮型试剂,具有比偶氮胂Ⅲ更好的光度特性,目前国内已开始在矿石中应用。本文就对乙酰基偶氮胂测定钍的条件,共存元素的干扰及消除方法进行了详细的试验。通过对比, 相似文献
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选择了6种常用的变色酸双偶氮类试剂作为稀土树脂相显色剂,初步探讨了影响树脂吸附率的因素。实验表明,在硝酸介质中,在大量NO3-存在下,三氯偶氮胂和三溴偶氮胂可应用于稀土树脂相分光光度法。 相似文献
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DBF-偶氮氯膦分光光度法富集测定水中痕量铋 总被引:1,自引:0,他引:1
铋是环境中的稀有分散元素,在地壳中的丰度约为0.2mg/L,海水和天然水中也有铋存在。铋对人体是有毒元素,主要积累在哺乳动物的肾脏,造成病变。白鼠试验表明,1.5mg/d有中毒症状,160mg/d中毒致死,用含铋27mg/L的废水浇灌农作物,会使农作物中毒枯死,因此有必要探索水样中铋含量的测定方法。水样中铋含量测定可采用三波长吸光光度法,但该方法对仪器精度要求较高。近几年,一些新的不对称变色酸双偶氮衍生物试剂成为光度法测定铋的重要显色剂,该类方法具有分析速度快、灵敏度和选择性较高的特点。笔者利用DBF-偶氮氯膦分光光度法测定水样中的铋含量,该法未见文献报道。 相似文献
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合成了8种不对称变色酸双偶氮氟胂型新显色剂,并研究了它们与钍的显色反应,建立了最佳反应体系。试验发现由于引入了吸电子性极强的氟取代基,反应体系的酸度、选择性及灵敏度大为提高,是一组很好的测钍显色剂。 相似文献
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本文以2-氰基-4-硝基-6-溴苯胺为原料,经重氮化后与邻异丙基苯酚偶联,合成2-(2-氰基-4-硝基-6-溴苯偶氮)-6-异丙基苯酚,用乙醇重结晶精制。用元素分析,波谱等鉴定其结构,并测定其离解常数,研究该试剂的一般性质。发现其与Cu2+、Ni2+、Co2+等的显色反应在吐温80表面活性剂存在下有较高的灵敏度。 相似文献
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Synthesis of 4,5-dihydroxybenzofurans and 4,5-dihydroxyindoles by dehalogenation of halo derivatives
A. N. Grinev L. S. Sarkisova V. M. Lyubchanskaya 《Chemistry of Heterocyclic Compounds》1984,20(10):1082-1084
A preparative method for the synthesis of derivatives of 4,5-dihydroxybenzofuran and 4,5-dihydroxyindole by dehalogenation of 4,5-dihydroxy-6-chloro(or bromo) and 4,5-dihydroxy-6,7-dichloro derivatives of benzofuran and indole with heating in aqueous ethanol over Raney nickel has been proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1322–1324. 相似文献
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John E. T. Corrie V. Ranjit N. Munasinghe Wolfgang Rettig 《Journal of heterocyclic chemistry》2000,37(6):1447-1455
4‐Trifluoromethyl‐ or 6‐bromo‐substituted 7‐diethylaminocoumarin‐3‐carboxamide derivatives 2 and 3, each containing a maleimide have been synthesized as potential fluorescent labeling reagents for thiol groups in proteins and their fluorescence properties have been determined. The 4‐trifluoromethyl substituted compound 2 has a significantly greater Stokes shift than the comparable compound lacking this group, but both the new coumarins have low fluorescence quantum yields (?f). When a 4‐trifluoromethyl substituent is present, the 3‐carboxamide is unusually labile to hydrolysis. Bromination of ethyl 7‐diethylaminocoumarin‐3‐carboxylate 17 gave the 6‐ and 8‐bromo derivatives 18 and 19 respectively, and also the 8‐bromo‐7‐monoethylamino compound 20. ?f for the latter compound is 100‐fold greater than for its diethylamino analogue 19. Fluorescence lifetime measurements support an interpretation based on the twisted intramolecular charge transfer (TICT) model to explain these large differences in ?f. 相似文献
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The dissociation constants in the ground state of benzyl 2-pyridyl ketone 2-quinolylhydrazone (BPKQH) have been determined fluorimetrically and spectrophotometrically in aqueous ethanol medium. The pK(a) values of this compound in the excited state have also been established. The analytical properties of the reagent and its chromogenic reactions with some metal ions were studied. 相似文献
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Girwar Singh Neeraj Kumar Ashok K. Yadav A. K. Mishra 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):621-630
( - )- cis -2(4-Methoxyphenyl)-3-hydroxy/methoxy-6,8-dichloro/6-chloro-2,3-dihydro-1,5-benzothiazepin-4[5H/5-chloroacetyl/5-(4'-methylpiperazino-1')acetyl]-ones have been synthesized by the condensation of 2-amino-3,5-dichloro/3-chloro benzenethiol with methyl-( - )- trans -3(4-methoxyphenyl)glycidate in xylene. Ribofuranosides viz ( - )- cis -2(4-methoxyphenyl)-3-methoxy-6,8-dichloro/6-chloro-2,3-dihydro-1,5-benzothiazepine-4-[5-(2',3',5'-tri- O -benzoyl- g -D-ribofuranosyl)-ones have been synthesized by the treatment of 3-methoxy derivatives of 1,5-benzothiazepines with sugar viz g -D-ribofuranose-1-acetate-2,3,5-tribenzoate in toluene at vacuo. Synthesized compounds have been characterized by elemental analysis, IR, 1 H NMR spectral studies and screened for their antimicrobial activity. 相似文献
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Many specific and non-specific chromogenic spray reagents have been used to detect organic pesticides (organophosphorus, organochlorine, carbamates, and pyrethroids) on thin-layer chromatographic (TLC)/high-performance thin-layer chromatographic (HPTLC) plates. To realize high sensitivity and improved selectivity, several chromogenic reagents have been introduced. The physical properties of organic pesticides reported so far are also presented in tabular form. The colors produced on TLC plates due to reactions taking place between pesticides and spray reagents are illustrated in the form of chromatograms, and reaction mechanism is also presented.
相似文献17.
ZHU Chuan-Zheng YANG Bao-Lin ZHAO Hong GU Wen-Xiu AI Shi-YunDepartment of Chemistry East China Normal University Shanghai China 《中国化学》1997,15(1):68-75
The dissociation constant of each step for TB-chlorosulphophenol has been determined by potentiometric method, and the thermodynamic constants, △G°, △H° and △S°, of the dissociation process have been calculated. The protonation constants were measured by the spectrophotometric method. The pH values of various forms of anions of the chromogenic reagent at their concentrations were also calculated. 相似文献
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Levkovskaya G. G. Bozhenkov G. V. Larina L. I. Mirskova A. N. 《Russian Journal of Organic Chemistry》2002,38(10):1501-1506
A new regioselective heterocyclization was revealed in the reaction of 2-chloro- and 2,2-dichloro(bromo)vinyl ketones with N,N-dimethylhydrazine to afford 3-substituted 1-methyl(5-halo)pyrazoles. The reaction is accompanied by elimination of methyl halide and formation of up to 90% of N,N,N-trimethylhydrazinium halide as the second product. 相似文献
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三氮烯试剂的结构与性能关系的研究 总被引:15,自引:0,他引:15
为建立三氮烯试剂结构与性能的关系, 我们研究了在非离子型表面活性剂TritonX-100存在下, 上述试剂亚氨基氢的酸性离解常数及镉(II)与上述试剂的显色反应。研究结果表明: (1)三氮烯试剂亚氨基氢的酸性离解常数遵循Hammett方程式, 其反应常数ρ=2.23; (2)试剂的亚氨基氢的酸性离解常数(pKa)与试剂和镉(II)显色反应的最佳酸度(pH最佳)之间的经验关系式为pH最佳=pKa-(1.70±0.20)。 相似文献
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V. S. Baranovskii V. N. Yatsyuk B. D. Grishchuk 《Russian Journal of General Chemistry》2013,83(11):2040-2043
Bisdiazonium tetrafluoroborates derived from benzidine, 4,4′-diaminodiphenylmethane, and 4,4′-diaminodiphenylsulfone have been used as arylating reagents in the reactions of chloro-, bromo-, and thiocyanatoarylation of acrylamides and methacrylamides. Anionarylation proceeds via two diazo groups to give 3,3′-[4,4′-biphenyl(methane, sulfone)]bis[2-chloro(bromo, thiocyanato)(2-methyl)propionamides]. 相似文献