Synthesis of potassium salts ofO-substitutedN-nitrohydroxylamines

Potassium salts of O-substitutedN-nitrohydroxylamines were synthesized by nitration of O-substituted.N-acetylhydroxylamines followed by treatment of the reaction products with potassium methoxide.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 178–179, January, 1994.     

甲苯定向硝化的理论研究

运用密度泛函理论(DFT)B3LYP方法，在6-31G~(* *)基组水平上，全优化计算 了硝酰阳离子NO_2~+对苯和从0-，m-,p-位进攻甲苯亲电取代硝化后应，求得4条反 应途径上包括反应物、过渡态和Wheland中间体共(4×3)12个反应驻点σ络合物的 分子几何、电子结构、能量和IR光谱等性质，阐明了反应中无同位素效应的实验事 实，求得各反应途径的活化能排序：p-＞o-＞PhH＞m-和σ络合物(R,TSak或INT)的 相对稳定化能排序：p-ArCH_3-NO_2~+＞o-ArCH_3-NO_2~+＞m-ArCH_3-NO_2~+＞ PhH-NO_2~+，从而阐明了甲基对苯环致活(或致钝)以及增加甲苯硝化络合物稳定性 的双重功能，对甲苯定向硝化的理论预示与实验结果相吻合。     

蒙脱石修饰碳糊电极测定氨基酸的研究：Ⅱ.酪氨酸的测定

本文报道蒙脱石修饰碳糊电极测定酪氨酸，在０．００１ｍｏｌ／Ｌ ＫＣｌ－ＨＣｌ（ｐＨ＝２．０）溶液中开路富集，介质交换后微分脉冲阳极溶出伏安法测定，在０．５－２．５μｇ／ｍｌ范围内有线性，检测限为６３ｎｇ／ｍｌ。可避免其他氨基酸，微量元素和常量金属元素的干扰，直接用于氨基酸药物样品的分析，获得了满意的结果，还对酪氨酸在电极上的反应机理进行了探讨。     

Short range photoinduced electron transfer in proteins: QM-MM simulations of tryptophan and flavin fluorescence quenching in proteins

Hybrid quantum mechanical-molecular mechanics (dynamics) were performed on flavin reductase (Fre) and flavodoxin reductase (Fdr), both from Escherichia coli. Each was complexed with riboflavin (Rbf) or flavin mononucleotide (FMN). During 50 ps trajectories, the relative energies of the fluorescing state (S₁) of the isoalloxazine ring and the lowest charge transfer state (CT) were assessed to aid prediction of fluorescence lifetimes that are shortened due to quenching by electron transfer from tyrosine. The simulations for the four cases display a wide range in CT–S₁ energy gap caused by the presence of phosphate, other charged and polar residues, water, and by intermolecular separation between donor and acceptor. This suggests that the Gibbs energy change (ΔG₀) and reorganization energy (λ) for the electron transfer may differ in different flavoproteins.     

Synthesis and Photophysical and Electrochemical Study of Tyrosine Covalently Linked to High‐Valent Copper(III) and Manganese(IV) Complexes

As bio‐inspired chemical model of the oxygen‐evolving complex (OEC) in photosystem II, a new tyrosine‐modified corrole ligand 3 and its high‐valent copper and manganese complexes 3a and 3b were synthesized and characterized. The copper complexes 1a and 2a of corrole 1 and 2 were also prepared for comparison. The emission property indicates that the emission of ligands 2 and 3 is located at 670 nm, but no emission is observed for their metal complexes due to its suppression by the metal center. The electrochemical study shows that 3a might dimerize at the first two reversible oxidations, a behavior which was not observed in the case of 1a and 2a . The corrolato manganese(IV) complex 3b shows one reversible reduction and one quasireversible oxidation at ?0.17 and 0.77 V vs. Ag/Ag⁺, respectively.     

Nitropyrazoles

A method for the synthesis of bi-, ter-, and quaterpyrazoles by cyclization ofC-(diformylmethyl)nitropyrazoles with hydrazine has been elaborated. Some of theirC- andN-derivatives have been obtained. The compounds prepared have been characterized by¹H,¹³C,¹⁴N, and¹⁵N NMR spectra.For communication 6, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1941–1945, November, 1993.     

Nitration Reaction Catalyzed by Horseradish Peroxidase in the Presence of H2O2 and NaNO2

The enzymatic nitration of phenol and m-cresol catalyzed by horseradish peroxidase was studied in the presence of H2O2 and NaNO2. The results showed that the nitration products of phenol were 2-nitro and 4-nitrophenols. There was also a small amount of by-products of hydroquinone and catechol. The influences of various reaction parameters, including pH, organic solvent type, and concentrations of NaNO2 and H2O2, on the nitration products were investigated. The yields of 4-nitrophenol and 2-nitrophenol were 14% and 12%, respectively. The nitration products of m-cresol were 4-nitro-m-cresol and 6-nitro-m-cresol, and the yields of 4-nitro-m-cresol and 6-nitro-m-cresol were 19% and 30%, respectively.     

Microwave assisted synthesis of an unusual dinitro phytochemical

A novel dinitro secondary metabolite, 2-nitro-4-(2^′-nitroethenyl)phenol from a marine source, has been prepared via highly accelerated, microwave assisted, nitration reactions using mild reagents. ipso-Substitution of a carboxy group by a nitro group is discussed.     

Synthesis and some properties ofN-polynitromethyl derivatives of fused benzotriazoles

The procedures for the synthesis ofN-polynitromethyl derivatives of benzo[1,2-d;4,5d]ditriazole-4,8-dione are described. Some chemical properties of the compounds obtained are investigated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1623–1625, September, 1993.     

改性ZSM—5分子筛在甲苯一段硝化中的应用

对ＮａＺＳＭ－５分子筛进行改性，在其表面引入铁，镁离子，用作硝硫混酸对甲苯一段硝化反应的催化剂，明显提高产物中对硝基甲苯的生成比例，研究了影响反应结果的因素。