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Michael K. Manthey Stephen G. Pyne Roger J. W. Truscott 《Journal of heterocyclic chemistry》1992,29(1):263-264
The hydrogen peroxide-induced decomposition of cinnabarinic acid 2 has been examined. Two major compounds were found to arise from the decomposition; 3-hydroxyanthranilic acid 1 , and an isomeric mixture of two novel hemiketals. 相似文献
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Determination of carbon-bonded sulfur in soils by hydriodic acid reduction and hydrogen peroxide oxidation 总被引:2,自引:0,他引:2
A sequential extraction method has been developed for the determination of carbon-bonded sulfur in soils. The soil sample has been sequentially reduced with HI and oxidized with hydrogen peroxide, and finally the residue has been digested with a mixture of nitric acid and perchloric acid. All inorganic sulfur components and ester sulfur has been reduced to H2S by HI except the unreducible sulfur including pyritic sulfur, carbon-bonded sulfur and a previously unidentified sulfur fraction. Whereas a part of the carbon-bonded sulfur has been dissolved in the HI reducing solution another part of carbon-bonded sulfur was removed by hydrogen peroxide oxidation. The total carbon-bonded sulfur compose for oxic soils of the HI-dissolved sulfur and the H2O2-oxidized sulfur. However, because the pyritic sulfur can be completely decomposed by H2O2, this form of sulfur should be subtracted from the sum of the two sulfur fractions in case of anoxic soils. Unidentified sulfur components were also detected in the residue after the sequential extraction. 相似文献
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Mild treatment of sepiomelanin and biosynthetic eumelanins with NaBH4 in 0.1 N NaOH leads to the isolation of 5,6-dihydroxyindole-2-carboxylic acid (), a component of structural interest which may account for most of the degradation products of melanins so far obtained. 相似文献
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4-Hydroxyproline, 8-hydroxyquinoline, 4-hydroxyquinoline-2-carboxylic acid and 4-hydroxyphenylacetic acid (HPA) react with H2O2 when irradiated with UV light to yield fluorescent products. Sub-micromolar detection limits of H2O2 are possible with HPA. The fluorescent product is the same as that formed in the peroxidase enzyme-mediated H2O2 oxidation of HPA. Several compounds that participate in the photomediated reaction do not react in the enzyme-mediated system. A mechanism for the photomediated reaction involving an aryloxy radical derived from the substrate is suggested. Although the limits of detection for H2O2 do not equal the best achievable with the enzyme-mediated systems, the simplicity of a single-step reaction and an ability to “photodevelop” the product offer a range of novel analytical possibilities. 相似文献
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Aqueous xenon trioxide solution has been used as the oxidizing agent in three precise methods of analysis for hydrogen peroxide. A catalytic method, which utilizes hydrogen peroxide to initiate the reaction between t-butanol and xenon trioxide, is described for determining amounts of hydrogen peroxide as low as 0.9 microg or 36 parts per milliard (ppM). A direct spectrophotometric titration was found to have a lower limit of about 50 microg, or 20 ppM. An indirect titrimetric method was also used to determine hydrogen peroxide in amounts as low as 50 microg with a relative standard deviation of 4% which decreased to 1 % for amounts over 200 microg. 相似文献
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Since graphene-based materials have shown great potential in many fields,it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide(rGO) using inexpensive reducing agents under mild conditions.Here,we reported a novel method for the ultrafast chemical reduction of graphene oxide(GO) at room temperature using sodium borohydride(NaBH4),sodium molybdate(Na2MoO4) and hydrochloric acid(HCl).The reduction was carried out within 2 min.A series of characterization results revealed that the obtained reduced graphene oxide has higher reduction degree than that synthesized by NaBH4 alone at high temperature.Moreover,rGO electrode based on the present reducing method exhibited a superior specific capacitance of 139.8 F/g at a current density of1 A/g,indicating that it can be used as electrode materials for supercapacitors. 相似文献
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D. N. Sokolov O. A. Luzina M. P. Polovinka N. F. Salakhutdinov 《Chemistry of Natural Compounds》2011,47(2):203-205
The reaction of (+)-usninic acid and its pyrazole derivative with sodium borohydride was studied. The reduction occurred stereoselectively
at the endocyclic carbonyl group. Novel (+)-usninic acid derivatives that were reduction products of the carbonyls were obtained. 相似文献
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A method for asymmetric reduction of α-and β-ketophosphonates using a chiral complex prepared from sodium borohydride and D-or L-tartaric acid is developed. Reduction of α-or β-ketophosphonates by these reagents led to formation of corresponding (S)-or (R)-hydroxyphosphonates. Reduction of chiral di(1R,2S,5R)-menthylketophosphonates by the chiral complex NaBH4/(R,R)-tartaric acid due to the dual compliant asymmetric induction resulted in increased stereoselectivity of the reaction and led to formation of the hydroxyphosphonates with ee 90% or higher. On the other hand, reduction of di(1R,2S,5R)-methylketophosphonates by the chiral complex NaBH4/(S,S)-tartaric acid proceeded as non-compliant dual asymmetric induction and resulted in decreased reaction stereoselectivity leading to formation of hydroxyphosphonates with ~45–60% ee. The developed methodology was applied to the synthesis of (R)-phosphocarnitine in multigram amounts. 相似文献
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The analytical utility of the hydrogen peroxide—hypochlorite singlet oxygen chemiluminescence reaction for the determination of hypochlorite in water is investigated. Effects of pH and hydrogen peroxide concentration are discussed and interference data for over 35 species in the absence and presence of hypochlorite are provided. The limit of detection is 4 μg l-1 with a usable non-linear calibration curve up to about 200 μg l-1. The new method is shown to be relatively free from interferences and to give results for tap water comparable to a standard colorimetric method based on a reaction with N, N-diethyl-p-phenylenediamine. 相似文献
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活性炭及甲酸催化过氧化氢氧化噻吩脱硫研究 总被引:19,自引:2,他引:17
以噻吩代表汽油中的有机硫化合物,将其溶解于正辛烷配制成反应原料,考察了活性炭对噻吩的吸附脱硫情况,研究了质量分数为30%的过氧化氢水溶液为氧化剂,在活性炭和甲酸的催化作用下,反应原料中噻吩氧化脱硫。考察了活性炭的催化性能及反应条件对其催化性能的影响。实验结果表明,30%H2O2-HCOOH-AC(活性炭)三元体系产生的过氧甲酸和羟基自由基能将模型有机硫化合物氧化,噻吩的氧化脱硫率可达到85%以上;活性炭和甲酸的催化氧化性能明显优于单纯使用甲酸催化性能。甲酸浓度、活性炭加入量、过氧化氢初始浓度及温度对噻吩硫的氧化脱除均有影响。 相似文献
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Chloroquinones are prepared conveniently from phenol, naphthols and aromatic amines. 相似文献
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In the presence of a catalytic amount of BH3·Me2S, TiCl4 or Me3SiCl, LiBH4 or NaBH4 are capable of hydroborating alkenes by following the unusual order of decreasing reactivity: tetramethylethylene > 1-methylcyclohexene > cyclohexene; the key step of the catalytic cycle is the exchange reaction between LiBH4 and the mono- or dialkylboranes resulting from hydroboration of the more substituted alkenes with BH3. 相似文献
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本文采用原位合成法制备了钌/氮掺杂石墨烯(Ru/NGR)催化剂,并采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)等手段对催化剂的结构形貌进行了表征。将Ru/NGR催化剂应用于硼氢化钠水解制氢体系,考察了钌的负载量、硼氢化钠的浓度、反应温度等对硼氢化钠产氢的催化性能的影响。研究结果表明:当温度为25℃,硼氢化钠浓度为2 wt%,钌负载量为3.9%时,产氢速率可达32.95 L·(gRu·min)^-1。通过对Ru/NGR催化剂催化硼氢化钠水解反应动力学数据研究研究得出该催化剂的活化能为46 kJ·mol^-1。 相似文献
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硼氢化钠水解制氢的研究 总被引:8,自引:0,他引:8
采用置换镀的方法在泡沫镍基体上获得不同载钌量的NaBH4水解制氢催化剂。实验结果表明,NaBH4水解制氢反应为零级反应,氢气生成速率随载钌量的增加而变快;当泡沫镍表面完全被钌覆盖时,载钌量为6%,相应的催化能力最强。与离子交换树脂载钌催化剂相比,泡沫镍载钌催化剂更稳定、耐用。实验还证实,30%比35%的NaBH4水溶液在相同的催化剂作用下更易发生水解反应;NaBH4水溶液中加入少量的NaOH有助于提高钌催化剂的催化性能。通过对NaBH4储氢体系的能量计算,说明采用该氢源体系的微型燃料电池的能量密度有望达到甚至超过锂离子电池的比能量水平。 相似文献