偶氮苯的同步辐射光电离及光解离

芳香族偶氮化合物(通式为Ar-N=N-Ar)是品种最多、应用最广的一类合成染料。由于偶氮苯类化合物容易发生感光异构[1],近年来已引起材料学家对它们的光子模式信息存储性能方面的广泛关注[2,3]。本文报道同步辐射光电离质谱法研究偶氮苯获得了该类物质的IP、AP、D0等重要参数。1　实验采用光束线编号为U10A同步辐射光源[4],工作波段35-300nm,分辨λ/△λ>500,波长精度±0 1nm,样品处光通量在1011光子/秒,样品处光斑大小3(水平)×1(垂直)mm。实验样品为固体,所以在光电离室电离区的正下方安装了一个加热炉,将固态样品放在炉内,通过调节…     

小分子团簇的同步辐射光电离

同步辐射光电离质谱技术是研究小分子团簇的重要手段。通过测量团簇离子的产生阈值,可获得团簇的电离势、离解能、质子亲和能、溶剂化作用能、生成热等热化学数据;通过电离离解产物的测量,可以了解团簇内的质子转移、电子转移、离子-分子反应等弛豫过程。本文对同步辐射光电离质谱实验装置、小分子团簇的热化学及弛豫过程作了较详细的介绍。     

243～263nm CH3COCH3 的多光子电离研究

在243～263 nm紫外光波段通过质量选择光电离激发谱研究了丙酮（CH3COCH3）的光化学反应通道。分析母体离子CH3COCH3+和碎片离子CH3CO+ 、 CH3+的光电离激发谱和质谱峰宽可以知道: 此光波段丙酮分子的光化学反应主要包括了丙酮分子经由(S1,T1)中间态产生母体离子的（1+1）双光子电离通道,母体离子进一步解离产生碎片离子CH3+的“光电离-光解离”通道和丙酮分子经由(S1,T1)中间态解离成中性自由基碎片CH3CO后再进一步被双光子电离的“光解离-光电离”通道。由母体离子光电离激发谱双光子阈值波长（255.67 nm）给出的丙酮电离势（IP）为（9.696±0.004）eV。     

2,4,6-三硝基-1,3,5-三羟基苯的一种新制备方法

为降低2,4,6-三硝基-1,3,5-三羟基苯（TNPG）在生产过程中对环境造成的危害并探究其高效且低污染的规模化生产工艺,本文以3,5-二甲氧基氟苯为原料,通过硝酸钾-浓硫酸组成的硝化体系进行硝化。在冰水淬灭硝化反应时氟原子被水解,得到中间体3,5-二甲氧基-2,4,6-三硝基苯酚（2）,用冰乙酸溶解中间体2,再用氢溴酸脱甲基得到目标化合物TNPG,总收率96.13%。对该反应进行公斤级规模放大,发现重现性较好。采用核磁共振（NMR）、X-射线单晶衍射分析（XRD）和元素分析（EA）等方法对TNPG进行结构表征;利用差示扫描量热（DSC）和热重（TG）方法研究TNPG的热分解过程,结果发现：TNPG在157.11 ℃出现吸热峰,在171.60 ℃和191.63 ℃处出现放热峰。该合成方法简洁且收率较高。在温度为-173.15 ℃时,6TNPG·4H2O单晶密度为1.939 g/cm³,属trigonal晶系,P-3c1空间群。     

二溴甲烷的同步辐射光电离研究

采用５０～２００ｎｍ同步辐射光，对ＣＨ２Ｂｒ２的光电离过程进行了研究，根据测定的母体离子及其碎片离子出现势，得到二溴甲烷的绝热电离势为１０．２３±０．０１ｅＶ，并获得了离子的生成焓，解离能及键能等热力学数据，分析了碎片离子的光解离电离通道。     

新型树状化合物1,3,5-三{3-[2,4,8,10-四氧杂\|9(3,5-二(2,6-二氧杂-4,4-二羟甲基环己基)苯基]螺[5.5]十一烷基}苯的制备

本实验采用季戊四醇与苯三甲醛缩合, 制成树状化合物1,3,5-三{3-|[2,4,8,10-四氧杂-9(3,5-二(2,6-二氧杂-4,4-二羟甲基环己基)苯基)螺[5.5]十一烷基}苯. 该类树状分子具有手性螺环结构, 手性密度很高, 可开发成理想的高效手性催化剂[3~8], 具有诱人的应用前景.     

反相气相色谱法研究1,3,5-三氨基-2,4,6-三硝基苯的表面特性

采用反相气相色谱技术(IGC)研究了4种不同粒度的1,3,5-三氨基-2,4,6-三硝基苯(TATB)的表面性质。4种不同粒度的TATB表面自由能的色散分量（γds）随着温度的升高而增加;粒度越大的粒子,其色散自由能上升越快;在较高温度下,粗颗粒TATB显示了更强的色散作用(γds=193.2 mJ/m2,353 K),粒度最小的亚微米TATB显示了最弱的色散作用(γds=64.0 mJ/m2,353 K)。由于制备方法不同和粒子大小的差异,4种TATB的表面酸碱性质显示了明显的差别,细颗粒TATB表面有较强的亲电子特性;而其他3种TATB在极性探针分子的作用下的吸附均表现为吸热吸附,表现出在分子内和分子间具有强烈的相互作用,其Ka和Kb值均为负。     

1,3,5-三苯基苯的简便合成方法

采用氯化亚砜-无水乙醇为催化剂，以苯乙酮为原料一步合成了1，3，5-三苯基苯。研究了最佳反应配比和反应条件：反应时间为45～60min时，n(苯乙酮)／n(氯化亚砜)／n(乙醇)=3／15／5时反应产率达到最高，产率80％～85％，并对反应机理进行了讨论。     

2,4,6-三萘基-1,3,5-三嗪的合成与光谱行为

本文通过Suzuki偶联反应高效合成了两种三萘基三嗪化合物,即2,4,6-三(1-萘基)-1,3,5-三嗪(T1NT)和2,4,6-三(2-萘基)-1,3,5-三嗪(T2NT). 考察了介质的极性、温度以及THF-H₂O二元溶剂体系中的溶解性等因素对它们吸收和发射光谱行为的影响.研究发现, 由于T1NT比T2NT具有更好的分子平面性,其激发态下分子内电荷转移的程度较大,导致其在溶液中吸收光谱、发射光谱比T2NT呈现显著红移.冻结态下,分子平面性较差的T2NT显示出较短波长的发光.     

1,3,5-三芳基吡唑类化合物合成的新方法

发现了一种以查耳酮(1a～1g)等不饱和酮(1h)和苯肼为主要原料,二氢铬酸四吡啶合钴(TPCD)为脱氢芳构化试剂,经“一锅法”合成1,3,5-三芳基吡唑(3a～3g)等吡唑类化合物的新方法.合成过程中首先生成的1,3,5-三取代吡唑啉不需要分离,直接在二氢铬酸四吡啶合钴氧化下脱氢芳构化成相应的吡唑类化合物,反应物分子中的碳-碳双键不受加入的二氢铬酸四吡啶合钴影响.该合成方法原料易得,反应条件温和,产率较高(65%～93%).     

均三甲苯的合成

介绍了由丙酮、偏三甲苯及连三甲苯合成均三甲苯的反应。参考文献15篇。     

乙苯光电离的实验研究

利用真空紫外同步辐射和反射式飞行时间质谱研究了乙苯分子的光电离, 通过测量母体分子的光电离质谱(PIMS)以及母体离子和主要碎片离子的光电离效率曲线(PIEs), 确定了乙苯分子的电离能IE(C8H+10)=(8.66±0.02) eV, 主要碎片离子C7H+7和C6H+6的出现能分别为(10.81±0.02)和(10.99±0.02) eV; 利用经验公式计算出产生碎片离子C7H+7和C6H+6需要的解离能(Ed)分别为(2.15±0.04)和(2.33±0.04) eV. 结合相关的热化学参数, 推算出C8H+10, C7H+7和C6H+6的标准生成焓分别为865.5, 927.2和1037.9 kJ/mol. 为进一步研究乙苯的大气光氧化反应机理提供了参考.     

溴乙烷光电离解离的理论计算和实验

分子的电离电势、键能和离子的标准生成焓等都是非常重要的物理化学数据,它们对化学反应机理等研究有很大帮助,精确测定离子的出现势,就可以获得这些热力学常数.迄今为止,有关溴乙烷(Ｃ2Ｈ5Ｂｒ)电离解离过程的研究已有若干报导[1-3],但这些结果均是在常温条件下,用电子轰击电离、彭宁电离或真空紫外灯辐照等方法获得的,由于常伴有热带效应、离子分子反应、离子对形成等过程[4],其结果的准确性往往较差.本文首次报导使用同步辐射光源对Ｃ2Ｈ5Ｂｒ进行光电离解离研究.通过准确测量母体离子以及几种主要碎片离子的出现势,结合已有的公认的热力…     

Molecular and Crystal Structure of 1,3,5- Tris(benzimidazol- 1-ylmethyl)-2,4,6-Trimethylbenzene

INTRODUCTIONCrystal engineering and supramolecular chemistry aimed at developing systems to perform optical, magnetic and electronic functions as well as intercalation systems for ion- or molecule-exchange and catalytic properties are some of the most attractive research areas in present years, and much progress has been achieved in both theoretical studies and their applications as new materials[1]. One of the most remarkable development in crystal engineering may be that it is possible t…     

Photoionization and Dissociative Photoionization Study of Cholesterol by I R Laser Desorption/Tunable Synchrotron VUV Photoionization Mass Spectrometry

Elementary cholesterol was analyzed with IR laser desorption/tunable synchrotron vacuum ultraviolet photoionization mass spectrometry. An exclusive molecular ion of cholesterol is observed by near threshold single-photon ionization with high efficiency. Fragments are yielded with the increase of photon energy. The structures of various fragments are determined with commercial electron ionization time-of-flight mass spectrometry. Dominant fragmentation pathways are discussed in detail with the aid of ab initio calculations.     

Acidity,Crystallite Size and Pore Structure as Key Factors Influencing 1,3,5-Trimethylbenzene Hydrodealkylation Performance of NiMoS/ZSM-5

NiMoS supported on ZSM-5 with different Si/Al ratio, crystallite size and pore structure was prepared by incipient impregnation method and applied in 1, 3, 5-trimethylbenzene (1, 3, 5-TMB) hydrodealkylation (HDAK). The physicochemical properties of samples were characterized by XRD, FTIR, SEM, N₂ adsorption–desorption, NH₃-TPD, Py-FTIR, H₂-TPR, HRTEM and TGA. It is demonstrated that for microporous NiMoS/ZSM-5, acid amount and crystallite size of HZSM-5 are key factors affecting HDAK performance. The larger acid amount and smaller crystallite size can promote the conversion of 1, 3, 5-TMB, especially the dealkylation reaction, resulting in higher BTX yield. Compared to NiMoZ-3, mesopores in micro-mesoporous NiMoAKZ-3 are beneficial to accessibility of 1, 3, 5-TMB to NiMoS and acid sites in close proximity, and the diffusion of reactant and product molecules inside pores, thus resulting in superior HDAK performance of NiMoAKZ-3. Moreover, the reaction network of 1, 3, 5-TMB HDAK was revealed according to product distribution.

Graphic Abstract

NiMoS supported on ZSM-5 was developed for heavy aromatic hydrodealkylation (HDAK). Acid amount and crystallite size of microporous ZSM-5 are key factors affecting 1,3,5-trimethylbenzene (1,3,5-TMB) HDAK. Mesopores inside ZSM-5 facilitate accessibility of 1,3,5-TMB to NiMoS and acid sites in close proximity and improve HDAK performance.

     

UV Photoionization Study of the Ethyl Radical

Introduction Ashighlyreactivebuildingblocksandfundamen talreactionintermediatesinorganicsynthesis,thealkyl radicalfamilyplaysacentralroleinadiversearrayof importantprocessesrangingfromcombustion[1]toat mosphericchemistry[2].Amongalkylradicals,theeth ylrad…     

Study on the 1,3,5-triazine gamma-radiolysis

Triazines are a class of molecules which have been found in meteorites such as Orgueil meteorite. Despite their poor resistance to UV radiation, these molecules survived millions of years inside a meteorite. The present work is dedicated to the examination of the radiation resistance of the simplest sym-triazine: 1,3,5-triazine. The crystals of this molecule have been irradiated with γ-radiation at 50 and 350 kGy and were studied by electronic absorption spectroscopy, liquid chromatography, FT-IR spectroscopy and differential scanning calorimetry (DSC). All the data suggest the relatively low stability of this molecule to high energy radiation. The resulting products from radiolysis are formamidine together with triazine dimers and oligomers. Other radiolysis products are H₂, CH₄, HCN and other gases.     

1,4-二氧六环的光电离解离

采用同步辐射光源、飞行时间质谱和分子束方法研究了1．4-二氧六环的光电离解离过程．由光电离效率曲线得出离子产物的出现势，计算了产物的生成焓．若重分析了m／e=28,29.41等离子碎片的解离通道以及离子碎片的可能结构，提出1、4-二氧六环在光电离解离过程中发生了重排反应     

Experiments and Calculations on Photoionization and Dissociative Photoionization of CH2CO

The dissociative photoionization of molecular‐beam cooled CH₂CO in a region of ?10–20 eV was investigated with photoionization mass spectrometry using a synchrotron radiation as the light source. Photoionization efficiency curves of CH₂CO⁺ and of observed fragment ions CH₂⁺, CHCO⁺, HCO⁺, C₂O⁺, CO⁺, and C₂H₂⁺ were measured to determine their appearance energies. Relative branching ratios as a function of photon energy were determined. Energies for formation of these observed fragment ions and their neutral counterparts upon ionization of CH₂CO are computed with the Gaussian‐3 method. Dissociative photoionization channels associated with six observed fragment ions are proposed based on comparison of determined appearance energies and predicted energies. The principal dissociative processes are direct breaking of C=C and C‐H bonds to form CH₂⁺ + CO and CHCO⁺ + H, respectively; at greater energies, dissociation involving H migration takes place.