The Photochemistry of Diazomethane the Reaction of Methylene with Ammonia and Methylamine

In the photolysis of diazomethane in the presence of ammonia, the ratio of the products, [CH₃NH₂/[C₂H₄], has been studied as a function of pressure, temperature and composition of diazomethane-ammonia mixture, respectively. This ratio increases with increase in total pressure at low pressures and approaches a constant at high pressures. In the diazomethane-methylamine system, the ratio of products, [CH₃CH₂NH₂]/[(CH₃)₂NH], is independent of the pressure in the range from 23 to 500 torr. The rates of insertion of singlet methylene into C–H bond and N–H bond of CH₃NH₂ are found to be about the same.     

The Photochemistry of Diazomethane the Reactions of Methylene with Toluene and P-Xylene in Liquid Phase (I)

The photochemistry of diazomethane in toluene and p-xylene solutions was investigated. The reactions of methylene with toluene gave eight products. In the diazomethane p-xylene solution, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5 and three unidentified compounds were found as products of the reaction of methylene with p-xylene. The relative rates of addition and insertion reaction of methylene with toluene and p-xylene have been calculated.     

The Photochemistry of Ketene the Reactions of Methylene with Toluene and P-Xylene in Vapor Phase (II)

In the photolysis of ketene with toluene in the vapor phase, ethylbenzene, xylenes, 2-methylcycloheptatriene-1, 3, 5, and three unidentified compounds are found as the products of the reactions of methylene with toluene. In the ketene-p-xylene system, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5, and three unidentified compounds are obtained as the products of the reactions of methylene with p-xylene. The reaction mechanism is discussed.     

The Photochemistry of Diazomethane-Acetonitrile Mixtures. The Reaction of Methylene with Acetonitrile

The photochemistry of diazomethane-acetonitrile gaseous mixtures has been studied. Propionitrile was produced by the reaction of methylene radicals with acetonitrile. At lower pressures the product propionitrile decomposes and the measured decomposition rates are 1.14×10⁹ sec^?1 and 2.70×10⁸ sec^?1 at 3660 and 4358 Å, respectively.     

Decomposition Reactions of Methanol and Ethanol Catalyzed by Tungsten Oxide Supported on Activated Carbon

Activity of the catalysts to obtain the dehydration products linearly increases with their total surface acidity. Results obtained seem to point out that the surface basicity of the support influences the acid strength of the tungsten oxide particles, especially at low tungsten loading.     

氨基酸-银反应的光化学特点

氨基酸与银的反应是一个不借外加能量热力学上即可进行的过程,但当引入光之后,可改变反应速率.研究发现:Soret带出现吸收所需光照度的大小顺序为Asp Ag(I)>Thr Ag(I)>Tyr Ag(I)>Lys Ag(I),对于Cys Ag(I)体系,Cys的α羧基氧、α氨基的氮与银(I)结合时光照有利于反应的进行,而S原子与银(I)结合与光照度几无关系.此反应是光助化学反应.     

Solvent-free Reactions of Formylferrocene with Active Methylene Containing Compounds

Since ferrocene was synthesized, derivatives of ferrocene have attracted the attention of chemists, and recently solvent-free organic reaction has been an important new dimension in preparative organic chemistry. [1] Solventless synthesis without the use of supporting reagents which can avoid the risk of high pressure development and volatile toxic solvent employment is very amaizing and eco-friendly.     

Reactions of Laser Ablation-magnesium Plasma with Methanol Clusters

IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st…     

The Influence of Carbon Surface Oxidation on the Adsorption of Methanol and Ethanol

The influence of microporous carbon oxidation on thermodynamic properties of methanol and ethanol adsorbed at 308, 328, and 348 K was investigated. Adsorption mechanisms are suggested and the obtained results are compared with the presented previously for adsorption of methane and carbon tetrachloride on nonoxidised and oxidised microporous carbons. This revised version was published online in August 2006 with corrections to the Cover Date.     

Photochemistry in Interstellar Space and Reactions Generating Interstellar Molecules

Over 20 different molecules and radicals have so far been detected in interstellar space. The number of such molecules and radicals and their frequently complicated structure raise the question of the processes leading to their formation. Diatomic molecules and radicals could arise in gas-phase reactions. Formation of polyatomic molecules can be explained in terms of reactions proceeding on the surface dust particles and possibly involving interstellar radiation. The author demonstrates, with the aid of a model, that the molecular abundances and distributions within dust clouds in certain regions can be explained by photocatalytic reactions.     

Reactions of Aliphatic Diazo Compounds: VI. Reactions of Diazomethane and Ethyl Diazoacetate with (E)-2-Arylmethylene-1,2,3,4-tetrahydronaphthalen-1-ones

Diazomethane and ethyl diazoacetate add to (E)-2-arylmethylene-1,2,3,4-tetrahydronaphthalen-1-ones in a regio- and stereoselective fashion, yielding the corresponding 4'-aryl-1,2,3,4,4',5'-hexahydro-3'H-naphthalene-2-spiro-3'-pyrazol-1-ones. The products formed by addition of ethyl diazoacetate undergo isomerization into 4,5-dihydro-1H-pyrazole derivatives.     

鉴别甲醇和乙醇的新方法

据文献记载,鉴别甲醇和乙醇的方法通常有三种。(1>使甲醇和乙醇分别与碘和氢氧化钠反应,有黄色晶体生成者为乙醇,无此现象者为甲醇,亦即碘仿反应方法。(2)将甲醇和乙醇分别用热铜丝或氧化铜氧化,随后加入品红试剂,当滴加稀硫酸溶液紫色不消失者为甲醇,紫色消失者为乙醇o (3)分别向甲醇和乙醇中加入铬酸及几滴浓硫酸,温热后溶液呈紫色者为甲醇,无此现象者为乙醇。本文介绍一种适合中学化学教学的鉴别甲醇和乙醇的新方法。该方法操作简便,反应时间短,现象明显。操作步骤如下。     

Facet Dependence of Photochemistry of Methanol on Single Crystalline Rutile Titania

The crystal phase, morphology and facet significantly influence the catalytic and photocatalytic activity of TiO₂. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing new sophisticate TiO₂ structures with desired facet exposure, necessitating the understanding of chemical properties of individual surface. In this work, we have examined the photooxidation of methanol on TiO₂(011)-(2×1) and TiO₂(110)-(1×1) by two-photon photoemission spectroscopy (2PPE). An excited state at 2.5 eV above the Fermi level (E_F) on methanol covered (011) and (110) interface has been detected. The excited state is an indicator of reduction of TiO₂ interface. Irradiation dependence of the excited resonance signal during the photochemistry of methanol on TiO₂(011)-(2×1) and TiO₂(110)-(1×1) is ascribed to the interface reduction by producing surface hydroxyls. The reaction rate of photooxidation of methanol on TiO₂(110)-(1×1) is about 11.4 times faster than that on TiO₂(011)-(2×1), which is tentatively explained by the difference in the surface atomic configuration. This work not only provides a detailed characterization of the electronic structure of methanol/TiO₂ interface by 2PPE, but also shows the importance of the surface structure in the photoreactivity on TiO₂.     

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.     

Photodissociation Dynamics of Methanol and Ethanol at 157 nm

157 nm photodissociation of jet-cooled CH3OH and C2H5OH was studied using the high-n Rydberg atom time-of-flight (TOF) technique. TOF spectra of nascent H atom products were measured. Simulation of these spectra reveals three different atomic H loss processes: one from hydroxyl H elimination, one from methyl (ethyl) H elimination, and one from secondary dissociation of the methoxy (ethoxy) radical. The relative branching ratio indicates secondary dissociation of ethoxy is less important than that of methoxy. The average angular anisotropy parameter of methanol is negative (withβ≈-0.3), indicating the transition dipole moment is perpendicular to the C-O-H plane. The slightly more negative β value of ethanol (with β≈-0.4) implies that ethanol has a longer rotational period. These experimental results indicate that both systems undergo fast internal conversion to the 3s surface after it is excited to the 3px surface, and then dissociate on the 3s surface. The translational energy distribution of the CH3O+H products reveals extensive CH3 rocking or CH3 umbrella excitation in the CH3O radical. However the vibrational structures are not resolved in the C2H5O radical     

Photochemistry of Transition-Metal Atoms: Reactions with Molecular Hydrogen and Methane in Low-Temperature Matrices

Reactions of metal atoms with molecular hydrogen and alkanes are prototypical of more complex systems involving metal-mediated reactions in solution, on supports, and on surfaces. The simplicity of metal-atom reactions makes them particularly attractive for fundamental experimental and theoretical studies. Following the first reports of H₂ and CH₄ activation by photoexcited metal atoms in cryogenic matrices, the behavior of a number of transition-metal atoms in their ground and selected electronically excited states has been examined with molecular hydrogen, methane, and ethane. A wealth of structural, electronic, reactivity, and selectivity information is emerging from these studies and it is now becoming possible to recognize the controlling factors at work in these fundamental chemical reactions. In this article, some experimental results for a number of metal-atom systems, in particular, those involving silver, copper, manganese, and iron atoms, are presented along with a discussion of the factors that are believed to be important in the understanding of the observed physical and chemical behavior.     

Voltammetric Behavior of Trolox in Methanol and Ethanol Solutions

Electrochemical oxidation of trolox on carbon electrodes was investigated by means of some voltammetric techniques in methanol and ethanol solutions in the presence of an excess of acid or base. The oxidation occurs according to EEC mechanism, i.e. in two quasireversible one‐electron steps yielding the corresponding phenoxyl radical and, subsequently, phenoxonium cation. Phenoxonium ion decays because of a pseudo‐first order follow‐up chemical reaction with nucleophiles. The electrochemical behavior of trolox is strongly influenced by the surrounding environmental conditions. In acidic solutions, a single two‐electron anodic wave was observed. The presence of a strong base drastically improves the stability of the intermediate, phenoxyl radical. Under these conditions, the two‐electron wave was found to split into its one‐electron components over a range of scan rates. The resolution is much distinct in ethanol. Simulations with DigiSim software were used to fit the cyclic voltammograms in order to estimate thermodynamic and kinetic data for the reaction mechanism studied.