Catalytic Reactions of n-Propanol and n-Butanol with Hydrogen Sulfide

The transformations of n-propanol and n-butanol in an H₂S atmosphere at T = 300–350°C and P = 0.1 MPa in the presence of acid–base catalysts were studied. Only alcohol dehydration with the release of alkenes occurred at a high rate on catalysts with strong proton sites (tungstosilicic and tungstophosphoric acids on SiO₂ or a decationized high-silica zeolite), whereas alcohol thiolation with the formation of alkanethiols also occurred on catalysts with Lewis acid sites (Al₂O₃; NaX; MgO; Cr/SiO₂; and Al₂O₃ modified with W, K, Na, K₂WO₄, or Na₂WO₄). The rate of reaction decreased with decreasing strength of Lewis acid sites and with increasing strength of basic sites; however, the selectivity of thiol formation increased. Alumina modified with alkaline additives was the most selective catalyst. In the presence of this catalyst, an alcohol selectively reacted with H₂S to form an alkanethiol, and the alkanethiol underwent partial decomposition with the release of an alkene and H₂S at a long contact time.     

Thermal Reactions of Sulfur and Hydrogen Sulfide and Its Derivatives with Organic Compounds

The review summarizes the results of the authors' studies on thermal reactions of sulfur, hydrogen sulfide, and their derivatives with organic compounds, performed since 1944 till 2000.     

Thermal Reactions of Chloroarenes with Hydrogen Sulfide in the Presence of Methanol

Gas-phase reactions of chloroarenes (ClC₆H₄X, X = H, 4-CH₃, 4-OH, 4-Cl, 4-CF₃) with hydrogen sulfide or its precursors were investigated in the presence of methanol, which was a stronger H-donor than hydrogen sulfide. Introducing methanol increased the selectivity of arenethiols formation at X = H and 4-CH₃ and did not affect the reaction selectivity at acceptor X. The efficiency of methanol influence was considered from the viewpoint of free-radical reaction mechanism and the stability of the arenethiyl radicals.     

Experimental and Theoretical Study of Reactions between Manganese Oxide Cluster Cations and Hydrogen Sulfide

Manganese oxide cluster cations Mnm180n＋ were prepared by laser ablation and reacted with hydrogen sulfide （H2S） in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments suggest that oxygen-for-sulfur （O/S） ex- change reaction to release water took place in the reactor for most of the manganese oxide cluster cations： MnmlSOn＋＋H2S→Mnm18On-1S＋＋H218O. Density functional theory cal- culations were performed for reaction mechanisms of Mn202＋＋H2S, Mn203＋＋H2S, and Mn204＋＋H2S. The computational results indicate these O/S exchange reactions are both thermodynamically and kinetically favorable, thus in good agreement with the experimental observations. The O/S exchange reactions identified in this gas-phase cluster study parallel similar behavior of related condensed phase reaction systems.     

Reactions of Group V Metal Atoms with Hydrogen Sulfide:Argon Matrix Infrared Spectra and Theoretical Calculations

The reaction of laser-ablated vanadium, niobium and tantalum atoms with hydrogen sulfide has been investigated using matrix isolation FTIR and theoretical calculations. The metal atoms inserted into the H-S bond of H₂S to form the HMSH molecules (M=V, Nb, Ta), which rearranged to H₂MS molecules on annealing for Nb and Ta. The HMSH molecule can also further react with another H₂S to form the H₂M(SH)₂ molecules. These new molecules were identified on the basis of the D₂S and H₂³⁴S isotopic substitutions. DFT (B3LYP and BPW91) theoretical calculations are used to predict energies, geometries, and vibrational frequencies for these novel metal dihydrido complexes and molecules. Reaction mechanism for formation of group V dihydrido complex was investigated by DFT internal reaction coordinate calculations. The dissociation of HVSH gave VS+H₂ on broad band irradiation and reverse reaction happened on annealing. Based on B3LYP calculation releasing hydrogen from HVSH is endothermic only by 13.5 kcal/mol with lower energy barrier of 16.9 kcal/mol.     

用于光催化分解硫化氢制氢的金属硫化物

硫化氢(H₂S)作为一种剧毒、恶臭的强腐蚀性气体,广泛来源于人类活动和自然界,对动植物生存和环境都具有较大的危害。光催化分解H₂S制氢是一种理想的H₂S处理技术,可以同时实现H₂S的转移和清洁能源氢气的产生。近年来,金属硫化物由于其优异的可见光响应、恰当的能带结构和对H₂S有高的稳定性,因此被广泛地应用于光催化分解H₂S制氢。本文对近年来国内外金属硫化物驱动H₂S资源化利用制氢领域取得的重要进展进行了概述和总结,探讨了不同反应媒介下光催化分解H₂S制氢机制;特别关注了一些为实现高效稳定光催化H₂S资源化利用制氢的优异调控策略;最后,对H₂S资源化利用的挑战和前景进行了展望。     

氢氧化钠吸收硫化氢的工业技术讨论

硫化氢作为目前酸雨形成的原因之一,其排放量正越来越多的受到国家的重视,为此工业生产中各种处理硫化氢的工艺应运而生。本文首先对鼓泡式与塔吸收式的吸收方法进行对比讨论,同时在鼓泡式吸收的基础上,通过实验测定出氢氧化钠吸收硫化氢以及硫化钠吸收硫化氢的反应速率。     

Reactions of Cyclic Anhydrides XIV. Facile Syntheses of Fused Heterocycles via Anilic Acids Pyridobenzoxazinones,Isoquinolinobenzoxazinones and Isocoumarinoquinolines

o-Carboxyhomomaleanilic acids (5) and o-carboxyhomophthalanilic acids (6) on treatment with sodium acetate-acetic anhydride furnished pyridobenzoxazinones (8) and isoquinolinobenzoxazinones (9) respectively in quantitative yields. Conversion of o-formylhomophthalanilic acid (7) to isocoumarinoquinoline (11) via 2-axo-3(o-carboxyphenyl)quinoline (10) is also described.     

实验与教具

为了配合高中化学迎考总复习,本刊特邀请了北京市海淀区教师进修学校卞学诚同志、北京四中的胡晓萍同志、北京123中学的夏枚同志,撰写了这组有助于培养思维能力的实验稿。     

Reactions of tert-Butyl Tetraethylphosphorodiamidite with Acetic and Trifluoroacetic Acids

Reactions of tert-butyl tetraethylphosphorodiamidite with acetic and trifluoroacetic acids involve substitution of the amido group. This process was described by a scheme beginning with protonation of phosphorus and proved by modeling separate reaction stages. A probable scheme of the proposed reactions is described.     

Coupling Reactions of Anhydro-Aldose Tosylhydrazones with Boronic Acids

A catalyst-free coupling reaction between O-peracetylated, O-perbenzoylated, O-permethylated, and O-permethoxymethylated 2,6-anhydro-aldose tosylhydrazones (C-(β-d-glycopyranosyl)formaldehyde tosylhydrazones) and aromatic boronic acids is reported. The base-promoted reaction is operationally simple and exhibits a broad substrate scope. The main products in most of the transformations were open-chain 1-C-aryl-hept-1-enitol type compounds while the expected β-d-glycopyranosylmethyl arenes (benzyl C-glycosides) were formed in subordinate yields only. A mechanistic rationale is provided to explain how a complex substrate may change the well-established course of the reaction.     

Reactions of Acetylenic Hydrocarbons with Various CH Acids

Russian Journal of Organic Chemistry -     

Reactions of 1-Germatranol Hydrate with Dicarboxylic Acids

Russian Journal of General Chemistry - The reactions of 1-germatranol hydrate with malonic, succinic, maleic, cork, sebacic acids, and bistrimethylsilyl ester of succinic acid, and also of...     

Reactions of Unsaturated Phosphonic Acids with 2-Aminopyridine

Abstract

Different unsaturated phosphonic acids of the general formula (R=C1, OCH₃, OH, NMe₂, C₆H₅; R′=C1, OCH₃, H, NMe₂) have been prepared starting from propargyl alcohol. Reaction of chlorophosphonic acids with 2-amino-pyridine yields phosphoramidates, which in the next step undergo a base-catalyzed cyclization by addition of the ring nitrogen across the unsaturated bond, leading to the unstable derivative 1. In the case of the allenic phosphonic acid in which R=R′=NMe₂, the NH₂ group of 2-aminopyridine adds first to the allenic system yielding an enamine, which on heating cyclizes to give a new phosphorus-nitrogen heterocyclic system 2.     

Kinetic Model of the Reaction of Methanol with Hydrogen Sulfide

The kinetics of the reaction of methanol with hydrogen sulfide in the presence of an IKT-31 catalyst was experimentally studied. The experiments were performed in a fixed-bed flow reactor under the following conditions: T = 598-653 K, P = 0.1-1.0 MPa, and P⁰ _{H 2 S}/P⁰ _Me =0.4-15.0. Rate equations were derived which describe the rates of formation of methanethiol as the main product and dimethyl sulfide and dimethyl ether as by-products. The rate constants and activation energies were found by the mathematical treatment of experimental data. The model proposed can be used for reactor design.     

A Single Fluorescent Probe to Visualize Hydrogen Sulfide and Hydrogen Polysulfides with Different Fluorescence Signals

Hydrogen sulfide (H₂S) and hydrogen polysulfides (H₂S_n, n>1) are endogenous regulators of many physiological processes. In order to better understand the symbiotic relationship and cellular cross‐talk between H₂S and H₂S_n, it is highly desirable to develop single fluorescent probes which enable dual‐channel discrimination between H₂S and H₂S_n. Herein, we report the rational design, synthesis, and evaluation of the first dual‐detection fluorescent probe DDP‐1 that can visualize H₂S and H₂S_n with different fluorescence signals. The probe showed high selectivity and sensitivity to H₂S and H₂S_n in aqueous media and in cells.     

紫外光分解硫化氢制氢的研究

以10W低压汞灯(特征谱线波长,λ=253.7nm,简称UVC)作为光源,硫化钠的水溶液作为反应介质,进行了UVC直接分解硫化氢制氢反应(简称UVC-H₂S-H₂)的研究.考察了反应介质中硫的存在形式、硫化钠的浓度、反应介质pH值以及连续通入硫化氢的流量等反应条件对UVC-H₂S-H₂的影响.实验结果表明,UVC可以在无催化剂条件下直接分解硫化氢制氢.当以0.6mol/L硫化钠水溶液为反应介质,以25mL/h流量连续向反应介质中通入硫化氢时,UVC-H₂S-H₂产氢速率可达3.0mL/W·h.     

检测硫化氢分子的荧光探针

硫化氢（H₂S）是继一氧化碳和一氧化氮之后,第三种可在生命体内发挥生理作用的内源性气体信号分子。该气体分子在心血管和神经系统中担负着重要的生理病理调节作用。因此,选择性识别和高灵敏检测生物体内的H₂S具有十分重要的生物医学意义。在生物检测技术手段中,荧光探针法具有选择性好、灵敏度高、对生物样品损伤小以及可实现实时原位检测等独特的优势,故应用荧光探针法检测细胞内H₂S浓度的变化是近年来研究热点之一。本文依据荧光探针与H₂S之间的化学反应类型,将近三年来所研发的H₂S荧光探针按照其母体荧光团进行分类和总结,综述了H₂S荧光探针的研究进展,概述了相关荧光探针的设计理念、检测机理及生物应用,探讨了探针的结构和性能之间的关系,最后展望了H₂S荧光探针的发展趋势和应用前景。