The Enol of Acetone during Photochemical Reactions of 3-Hydroxy-3-methyl-2-butanone and of Acetone

The enol of acetone, formed by disproportionation reactions of 1-hydroxy-1-methylethyl radicals, is detected by NMR, spectroscopy during photoreactions of 3-hydroxy-3-methyl-2-butanone in acetonitrile and of acetone in 2-propanol and slowly tautomerizes to acetone. The photolysis of 3-hydroxy-3-methyl-2-butanone is shown to proceed via Type I cleavage, predominantly from an excited triplet state.     

Temperature Dependence of the Emission Spectrum of Silicon Nanoparticles in Acetone and Isopropanol Solvents

This study investigated the emission spectra of select silicon nanoparticles when subjected to various temperature changes. Two sizes of silicon nanoparticles, dispersed in both isopropanol and acetone solvents, were studied. Photoluminescence responses of the samples were measured in an environmental chamber that allowed exposure to temperatures in the range of ?73 to 65 °C (?100 to 150 °F). These silicon nanoparticles exhibited emission dependence on the temperature of their environment. The emission become brighter as the temperature decreased and less intense as the temperature increased. Thus, the response of these silicon nanoparticles in a harsh environment has been qualified.     

The Photochemistry of Acetone: The Primary Decomposition of Acetone and Biacetyl Yields

In the photolysis of acetone at 265nm at 27°C the quantum yield of biacetyl has been determined to be 0.34 and the primary decomposition yield is evaluated to be about 0.68. The fraction of triplet acetone decomposed into methyl and acetyl radicals is estimated to be 0.14 at 313nm. The acetyl radicals undergo reaction to form biacetyl 50 times faster than decomposition to methyl radicals and carbon monoxide.     

Low Temperature Photochemistry of the Acetone/2-Propanol System

During UV.-irradiation of acetone/2-propanol mixtures at ?70° products of photo-addition of acetone to intermediate enols are formed. The yields of these products exceed the yield of pinacol, the major room temperature product. At ?70° the photoadditions are favoured by the long lifetime of acetone enol (≥ 5000 s).     

光化学反应在流动注射分析中的应用研究V.硝酸根-鲁米诺光化学反应体系化学发光法测定痕量硝酸根

基于紫外光照射下硝酸根能够转化生成过氧化亚硝酸酯及过氧化亚硝酸酯氧化鲁米诺而产生化学发光,建立了流动注射光化学反应测定痕量硝酸根的新方法。测定硝酸根的线性范围是5×10(-8)～1×10(-4)mol/L,进样频率为60～80次/h.     

A Photochemical Ligation System Enabling Solid-Phase Chemiluminescence Read-Out

The peroxyoxalate chemiluminescence (PO-CL) reaction is among the most powerful and versatile techniques for the detection of hydrogen peroxide (H₂O₂) and has been employed in various biological and chemical applications over the past 50 years. However, its two-component nature (peroxyoxalate and fluorophore) limits its use. This contribution introduces an innovative and versatile photochemical platform technology for the synthesis of inherently fluorescent PO probes by exploiting the nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) reaction. In the presence of hydrogen peroxide, the pioneered “2-in-1” molecule emits either yellow or blue light, depending on tetrazole (Tz) structure. Even in the absence of base, the emitted light remains visible and H₂O₂ could be detected in the nanomolar range. Critically, the PO-Tz can be readily incorporated into polymeric materials. As a first application of this promising material, a tailor-made PO-Tz is grafted on poly(divinylbenzene) (PDVB) particles to enable solid-phase chemiluminescence on microspheres.     

Radiolytic Processes in Boiling Acetone

High Energy Chemistry - The composition and yields of the radiolysis products of boiling acetone change significantly compared to those at room temperature. Boiling in combination with a high dose...     

丙酮在固体碱催化剂上的缩合反应

随着石油化学工业的发展,丙酮产量不断增加,开展丙酮化学的研究及以丙酮为原料开发精细化工产品具有重要意义。丙酮经缩合反应可得到如异丙叉丙酮、异佛尔酮、甲基异丁基酮等一系列重要化工产品。由于异佛尔酮具有共轭不饱和酮结构,故其双键可进一步反     

氧化铝催化双子丙酮缩合反应的机理

为了研究2,15－十六烷二酮在氧化铝表面的环合机理,选择小分子丙酮为模型化合物,用量子化学半经验AM1方法研究双分子丙酮在氧化铝表面的醛醇缩合机理,给出了反应过程中的5个过渡态和4个中间体的结构和几何参数,该催化反应可以认为是氧化铝分子与两分子丙酮分子发生静电络合作用,然后借助氧原子的负电荷导致脱氢并实现缩合,根据中间体的能量变化,推测有较稳定的铝复合物生成。     

The Photochemical Reactions of Ketene-Benzene Mixture

In the photolysis of ketene with benzene in the gas phase, Cycloheptatriene (CHT) and totuene (Tol) have been observed as the products. The ratio, (CHT)/(CHT)+(Tol) are studied at various conditions. The difference of activation energy of formation between toluene and cycloheptariene is evaluated to be 4.76 kcal/mole.     

The Photochemical Behavior of Nalidixic Acid

The influence of intermolecular proton transfer on the spectral properties of nalidixic acid (nlqH) in the ground and excited electronic states was studied. A scheme of possible protolytic reactions that occurred in this compound under the action of pH and UV radiation in aqueous medium was constructed. The total energies of model nlqH molecules in the monomeric and dimeric states were calculated quantum-chemically. Proton transfer was found to substantially influence the radiation capacity of nlqH related to the protonation and dimerization of molecules. Original Russian Text ? A.V. Polishchuk, M.V. Kazachek, E.T. Karaseva, V.E. Karasev, 2008, published in Zhurnal Fizicheskoi Khimii, 2008, Vol. 82, No. 4, pp. 754–758.     

Acetone and perdeuterated acetone in UV-IMS

Measuring a mixture of acetone and perdeuterated acetone (acetone-d6) with an ultra-high resolution drift time ion mobility spectrometer (resolving power of R_p?=?235) and ultraviolet ionization (10.6 eV) at ambient pressure reveals three separated peaks. Two of the peaks can easily be associated with acetone and perdeuterated acetone. In a former publication several findings indicated an exchange of a methyl group and the formation of a H₃COCD₃ related peak. In this work the formed ion species were analyzed with a high resolution drift time ion mobility time of flight mass spectrometer. The mass spectra clearly show the formation of three proton-bound dimer peaks whereas the peak between acetone and acetone-d6 is a proton-bound mixed dimer consisting of one acetone and one acetone-d6 molecule.     

The Crystal Structure of the Pentaphenylethane/Acetone Solvate by X-Ray Analysis

The crystal structure of the acetone solvate of pentaphenylethane (C₃₂H₂₆ · 1/2 C₃H₆O; monoclinic, a = 8.625, b = 16.587, c = 16.961 Å, β = 95.75°, space group P2₁/c, Z = 4) has been determined by X-ray analysis. The structure was solved by direct methods and refined to a final R of 0.056. The central ethane bond has a length of 1.612 (3) Å. The cavity enclosing the solvent retains the inversion centre in the crystal: as a consequence, a two-fold disordered orientation was observed for the acetone molecule. The rotational orientation of the methyl groups was found to be staggered with respect to the C, O-bond.     

电感耦合等离子体原子发射光谱分析信息系统的开发 Ⅰ.系统分析

根据电感耦合等离子体原子发射光谱（ＩＣＰ－ＡＥＳ）分析的实际需要，开发了一种 ＩＣＰ－ＡＥＳ分析信息系统。该系统包括谱线管理系统、识别干扰程度系统、校准及干扰校正系 统、帮助系统等子系统。本文将讨论系统分析。系统设计和系统评价将在另文中讨论。     

Photochemical Fluorescence Enhancement of Terbuium-Fleroxacin System and Determination of Fleroxacin

ABSTRACT

The sensitized fluorescence of the terbium ion (Tb³⁺) can be observed when excited in the presence of fleroxacin (FLRX) in the aqueous solution because a Tb³⁺ -FLRX complex was formed. The sensitised fluorescence was greatly enhanced after the complex system was irradiated by 365nm ultraviolet light. The irradiation makes the complex system undergo photochemical reactions and a new terbium complex which is more favourable to the intramolecular energy transfer is formed. On this basis a new sensitive and selective photochemical fluorimetric method for the determination of FLRX was developed. Under the optimum experimental conditions, the linear range of the determination is 1.0—200×10^?7 mol 1^?1 for FLRX, and the detection limit is 1.2×10^?8mol 1^?1. Without any pre-treatment the recoveries of FLRX in human urine samples were determined with satisfaction.     

The Photochemical Methylenecyclopropane Rearrangement of Feist's Ester

In contrast to the thermal rearrangement, the photochemically induced methylenecyclopropane rearrangement of diethyl trans-methylenecyclopropane-2,3-dicarboxylate (I) and of ethyl ethoxycarbonylcyclopropylideneacetate (syn or anti) produced diethyl cis-methylenecyclopropane-2,3-dicarboxylate. A true photoequilibrium was not observed.     

光化学反应在流动注射分析中的应用研究 Ⅳ.亚甲基蓝光化学反应体系测定抗坏血酸

基于抗坏血酸光化学还原亚甲基蓝光化学反应,建立了流动注射光化学反应测定抗坏血酸的新方法。方法线性范围为0.12～5.60μg/ml,进样频率为55～60次/h。应用于医用维生素C片剂中抗坏血酸的测定,结果满意。