光替代谷氨酸氧化酶及荧光法测定谷氨酸

在弱碱性介质中,紫外光的照射引起谷氨酸的光化学反应,产生Ｈ２Ｏ２和ＮＨ３,与谷氨酸氧化酶存在下的酶促反应等效。利用氯化血红素（ｈｅｍｉｎ）作为过氧化酶的替代物,催化Ｈ２Ｏ２与对羟基苯乙酸（ＨＰＡ）的偶合荧光反应,建立了间接荧光法测定谷氨酸的方法。     

A preliminary study of a colorimetric method for anisole determination

The colour reaction between anisole, concentrated sulphuric acid and formaldehyde has been studied in glacial acetic acid as solvent The reaction can be used for the quantitative colorimetric analysis of anisole in mixtures with acetic acid and with benzene.     

A multistage,one-pot procedure mediated by a single catalyst: a new approach to the catalytic asymmetric synthesis of beta-amino acids

A catalytic asymmetric procedure for the preparation of beta-amino acids (specifically beta-substituted aspartic acid derivatives) is reported. The cinchona alkaloid catalyst benzoylquinine (BQ) mediates up to five distinct steps of a reaction pathway, all in one reaction vessel. The products of this reaction, highly optically enriched beta-substituted aspartic acid derivatives, were prepared from N-acyl-alpha-chloroglycine esters and acid chlorides in the presence of the catalyst. This approach was also amenable to the synthesis of small polypeptides containing beta-substituted aspartic acid units, including a non-natural fragment of the antibiotic lysobactin. The addition of Lewis acids to this system was found to accelerate the rate of specific steps in the reaction pathway. Mechanistic aspects of this reaction, such as imine formation and Lewis acid chelation to the beta-lactam intermediate, were investigated through comparison of IR, NMR, and other physical data.     

Synthesis of a New Phosphonate Methacrylate Monomer

In this work, a new methacrylate phosphonate monomer synthesis was described according to a two-step reaction. First the monoaddition of thioglycolic acid onto dimethylvinyl phosphonate monomer led to dimethyl–5-carboxymethyl-2-thiaethylphosphonate, a new phosphonate acid compound. This reaction also led to the thioester homologue of dimethyl–5-carboxymethyl-2-thiaethylphosphonate with a 15% yield by reaction of a thioglycolic acid thioester with dimethylvinyl phosphonate. Second, dimethyl carboxy-4-thia-butyl phosphonate reacted with glycidyl methacrylate. This epoxy-acid addition reaction was catalyzed by chromium salt at 70°C and led to the new methacrylate phosphonate monomer. We showed that only the secondary alcohol was obtained via a β addition. The two-step reaction final yield was calculated to be about 85%.     

Formation and stability of a nitric oxide donor: S-nitroso-N-acetylpenicillamine

The formation, reaction dynamics, and detailed kinetics and mechanism of the reaction between nitrous acid and N-acetylpenicillamine (NAP) to produce S-nitroso-N-acetylpenicillamine (SNAP) was studied in acidic medium. The nitrous acid was prepared in situ by the rapid reaction between sodium nitrite and hydrochloric acid. The reaction is first order in nitrite and NAP. It is also first order in acid in pH conditions at or slightly higher than the pK(a) of nitrous acid. In lower pH conditions, the catalytic effect of acid quickly saturates. Higher acid concentrations also induce a faster decomposition rate of the SNAP, thus precluding the quantitative formation of SNAP from HNO2 and NAP. Both HPLC and quadrupole time-of-flight mass spectrometry techniques proved that SNAP was the sole product produced. No nitrosation occurred on the secondary amine center in NAP, and only the thiol group reacted to form the nitrosothiol. Cu(I) ions were found to be effective SNAP-decomposition catalysts. Cu(II) ions had no effect on the stability of SNAP. Ambient oxygen in reaction solutions was found to have no effect on initial rates of formation of SNAP, products obtained, and stability of SNAP. The formation of SNAP occurs through two distinct pathways. One involves the direct reaction of NAP and HNO2 to form SNAP and eliminate water, and the second pathway involved the initial formation of the nitrosyl cation, NO+, which then nitrosates the thiol. The bimolecular rate constant for the reaction of NAP and HNO2 was derived as 2.69 M(-1) s(-1), while that of direct nitrosation by the nitrosyl cation was 3.00 x 10(4) M(-1) s(-1). A simple reaction network made up of four reactions was found to be sufficient in simulating the formation kinetics and acid-induced decomposition of SNAP.     

Eutectic Media Open a Synthetic Route to Oligocitrazinic Acid Fluorophores of Purple Hue

Under isochoric and solvent-free conditions, the reaction between ammonium formate and citric acid results in a deeply purple reaction product with fluorescent properties. This brings this reaction in the realm of bio-based fluorophores and bottom-up carbon nanodots from citric acid. The reaction conditions are optimized in terms of UV–vis spectroscopic properties and, subsequently, the main reaction product is separated. While the structural analysis does not give any indication for carbon nanodots in a general sense, it points towards the formation of molecular fluorophores that consist of oligomerized citrazinic acid derivatives. Furthermore, EPR spectroscopy reveals the presence of stable free radicals in the product. We hypothesize that such open-shell structures may play a general role in molecular fluorophores from citric acid and are not yet sufficiently explored. Therefore, we believe that analysis of these newly discovered fluorophores may contribute to a better understanding of the properties of fluorophores and CND from citric acid in general.     

Total synthesis of the alkaloids martinelline and martinellic acid via a hetero Diels-Alder multicomponent coupling reaction

[reaction: see text] A concise synthesis of the guanidine alkaloids, (+/-)-martinelline and (+/-)-martinellic acid, using a protic acid catalyzed 2:1 hetero Diels-Alder coupling reaction between N-Cbz 2-pyrroline and methyl 4-aminobenzoate, is described. Protic acid catalysis, rather than Lewis acid catalysis, was necessary to achieve the desired sense of diastereocontrol in the coupling reaction.     

Syntheses of salvilenone and related compounds: II. A novel rearrangement of a tetrahydrophenalenone to a naphthopyranone

The reaction of isopropenyl carbinol ( 2 ) with aqueous hydrobromic acid and hydroiodie acid gave salvilenone ( 1 ) and naphthopyranone ( 3 ) respectively. The reaction mechanism has been investigated. The formation of ( 3 ) was undergone a novel rearrangement of a tetrahydrophenalenone to a naphthopyranone.     

硫酸高铈催化合成丙酸苄酯

以结晶硫酸高铈为催化剂对丙酸苄酯的合成进行了研究，考察了反应时间、催化剂用量、醇酸摩尔比和带水剂等因素对反应的影响，结果表明，在最佳反应条件下，酯化率在85％以上。     

Rapid synthesis of cyclodepsipeptides containing a sugar amino acid or a sugar amino alcohol by a sequence of a multicomponent reaction and acid-mediated macrocyclization

Cyclodepsipeptides incorporating a sugar amino acid (alcohol) have been synthesized. A three-component reaction of a sugar amino acid (SAA) derivative, an aldehyde, and a dipeptide isonitrile in refluxing methanol afforded the corresponding 5-aminooxazole which, after saponification, underwent a trifluoroacetic acid promoted macrocyclization to furnish the cyclic sugar amino acids.     

Optical resolution and racemization mechanism of a tellurinic acid

[reaction: see text] Optically active tellurinic acid was obtained for the first time by chromatographic resolution of racemic 2,4,6-triisopropylbenzenetellurinic acid (1) using a chiral column. Optically active tellurinic acid (+)-1 was stable toward racemization in hexane, although racemization occurred in hexane/2-propanol. The kinetic studies for the racemization, oxygen exchange reaction using H(2)(18)O, and theoretical studies clarified that the racemization of the optically active tellurinic acid in solution proceeds via a hypervalent tellurane formed by addition of water remaining in solvent.     

Oxalic acid catalyzed reaction between dithioacetals and acetals. A simple and eco-friendly method for a conversion of a dithioacetal to a carbonyl compound

Oxalic acid catalyzes a reaction between dithioacetals and acetals. This reaction is useful in a new and eco-friendly method to convert dithioacetals to carbonyl compounds.     

Electrolysis of Nitric Acid by Using a Glassy Carbon Fiber Column Electrode System

The electrochemical redox behavior of nitric acid was studied using a glassy carbon fiber column electrode system, and its reaction mechanism was suggested and confirmed in several ways. Electrochemical reactions in less than 2.0M nitric acid was not observed. However, in more than 2.0M nitric acid, the reduction of nitric acid to nitrous acid occurred and the reduction rate was slow so that the nitric acid solution had to be in contact with an electrode for a period of time long enough for an apparent reduction current of nitric acid to nitrous acid to be observed. The nitrous acid generated in more than 2.0M nitric acid was rapidly and easily reduced to nitric oxide by an autocatalytic reaction. Sulfamic acid was confirmed to be effective to destroy the nitrous acid. At least 0.05M sulfamic acid was necessary to scavenge the nitrous acid generated in 3.5M nitric acid.     

A mild and efficient synthesis of a chiral pyridazinone derivative

We found a mild and efficient reaction condition for construction of a chiral 5-methyl-4,5-dihydropyridazin-3(2H)-one from a chiral β-methyl γ-ketocarboxylic acid via the corresponding acid hydrazide without racemization. Furthermore, we demonstrated that this two-step reaction can be attained by one-pot reaction. This method could be applied to various kinds of substrates because of the mild reaction conditions.     

Development of a continuous homogeneous process for denitration by treatment with formaldehyde

Removal of nitric acid from high level liquid wastes (HLLW) of nuclear fuel reprocessing plants is warranted for simplifying the procedure for waste fixing. Chemical denitration aims to reduce the waste volume by destroying the acidity and subsequent concentration by adding suitable reductants. Reduction of nitric acid to gaseous products is an attractive way to accomplish denitration. Nitric acid reduction with formaldehyde proceeds with the formation of CO₂, NO₂, NO or N₂O depending on the reaction conditions and all the reaction products except water can be eliminated from the system in gaseous form. The HNO₃–HCHO reaction is governed by a complex mechanism of exhibiting relatively long induction period, depending upon the temperature, concentration of reactants and nitrous acid reaction intermediate. In the present work, a homogeneous denitration process with formaldehyde which offers safety and is governed by controlled kinetics was demonstrated on a laboratory scale. The induction period before commencement of the reaction was eliminated by maintaining the reaction mixture at a pre determined temperature of 98 °C. Based on the results accrued from lab scale experiments, the equipment for pilot plant scale operation was designed, the reaction efficiency for continuous denitration was determined and the investigation of nitric acid destruction was extended to full-scale plant capacity. The role of organics in the waste in foaming up of the reaction mixture was also studied using a synthetic waste solution.     

Effect of acid strength distribution on conversion of FCC gasoline over a ZSM-5 zeolite catalyst

Summary Acid strength distribution and the distribution of aromatics formed in the FCC gasoline conversion reaction on a ZSM-5 zeolite with different Na contents have been studied. With increasing Na content in the ZSM-5 zeolite, the acid sites determined by NH₃-TPD technique, especially the strong acid sites, clearly decrease. When used as catalyst for the aromatization reaction, the transformation of olefins in the FCC gasoline into aromatics is governed directly by the strong acid sites on the ZSM-5 catalyst. Only under the conditions that a ZSM-5 catalyst possesses suitable strong acid sites is reaction temperature favorable for the aromatics formed.     

一种含氧供电基团的染料合成及其光伏性能

以对溴苯酚为原料,经碘丁烷的烷基化后,与硼酸三甲酯反应生成对丁氧基苯硼酸.环戊二噻吩经N-溴代丁二酰亚胺(NBS)的溴化和Vilsmeier-Haack反应,再与对丁氧基苯硼酸偶联、氰基乙酸缩合,生成目标化合物环戊二噻吩基光敏染料(L1).该化合物是一种以含氧基团为给体,环戊二噻吩作为共轭桥的有机染料,将其制备成有机染料敏化太阳能电池,在AM 1.5,100 mW/cm2的光强下,电池的单色光的光电转换效率(IPCE)值达到62%,开路电压(Voc)为535mV,短路电流密度(Jsc)为6.4mA·cm-2,填充因子(FF)为0.60,总光电转换效率为2.1%.     

新型磷钨酸基固体酸催化油酸酯化合成生物柴油

利用磷钨酸（PTA）与1,2,3-三氮唑-4,5-二羧酸（TDA）在水溶液中的反应,合成了一种新的固体酸TDA-PTA,采用X射线粉末衍射（XRD）、扫描电镜（SEM）、红外光谱（FT-IR）、热重（TG）以及电位滴定等方法对其进行了表征,并以油酸与甲醇的酯化反应为探针反应,考察了其催化性能,探讨了催化剂用量、醇酸物质的量比、反应时间、反应温度以及催化剂重复利用次数等对产物收率的影响。结果表明,TDA-PTA不仅保留有磷钨酸典型的Keggin结构,而且具有较强的酸强度;经修饰后,催化剂具有规整的球形形貌,比表面积明显大于磷钨酸;TDA-PTA在油酸与甲醇的酯化反应中表现出了优良的催化活性,尤其显示出好的重复利用性,六次使用后,仍得到86.8%的油酸甲酯产率,催化剂的物相以及Keggin结构没有明显变化。     

Potentiometric studies of dithiooxamide with a sulphide-selective membrane electrode

The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide.     

Brazilin类似物的合成

以3-(3,4-二甲氧苯基)丙酸为原料, 经分子内傅-克反应、双羟基化、Lombardo 反应, 高价碘的氧化及类Pinacol重排等共10步反应, 完成了brazilin类似物的合成.