六钨酸四丁基铵盐和异丙醇体系的催化氧化反应的ESR研究Ⅰ.

本文研究了六钨酸四丁基铵盐在紫外光辐照的条件下催化氧化异丙醇为丙酮的反应。采用自旋捕捉技术与电子自旋共振相结合的方法,在位检测到氧化反应过程中有活泼自由基中间体产生,并观察到光电流产生。文中对六钨酸四丁基铵盐的催化反应机理进行了讨论。     

十聚钨酸季铵盐催化H2O2氧化环己醇为环己酮

研究了十聚钨酸十六烷基三甲基季铵盐H₂O₂体系催化氧化环己醇直接合成环己酮的反应,环己醇的转化率为89.6%～96.4%,环己酮产率为82.4%～89.1%.实验结果表明,该催化剂能促使H₂O₂的活性氧转移,有效地把环己醇氧化为环己酮.     

钨酸铋担载钯纳米粒子光催化甲苯及其衍生物到醛的氧化反应（英文）

甲苯及其衍生物的选择性氧化是化学工业中重要的一环.氧化产物醛、酮和酸类化合物是各种农药、染料、防腐剂、阻燃剂、香料、塑料的合成中间体.在传统的化工过程中,通常在苛刻的条件下,如高温、高压以及酸性溶剂中进行甲苯的选择性氧化.光催化有机合成作为一种"绿色"的合成方法受到越来越多的关注.我们发现钨酸铋作为可见光响应的光催化剂,可以利用氧气作为氧化剂,对甲苯及其衍生物进行催化氧化反应.通过调节水热法合成钨酸铋的酸碱条件,控制其成核生长过程,改变其形貌,发现在pH值为0.49时,得到花状钨酸铋粉末活性最高.X射线衍射、扫描电镜、紫外可见吸收光谱和比表面测定结果发现,花状钨酸铋粉末表现出最佳的甲苯氧化活性很可能是与它最大的比表面积有关系.为了进一步提高催化的活性,我们将助催化剂担载在钨酸铋粉末上,发现Pd的担载量为0.1wt%时甲苯氧化反应活性最高.将邻、间、对位甲基取代以及对位甲氧基和氯取代的甲苯衍生物进行反应,发现均可高选择性地得到目标产物.在加入电子牺牲剂硝酸银和空穴牺牲剂草酸铵到反应体系后,发现反应被完全禁阻,说明在甲苯氧化反应过程中电子和空穴都起到了相应的作用.通过电化学测试发现,钯作为助催化剂担载在钨酸铋表面后,产生更强的氧化和还原信号,说明其在电子和空穴发生反应的过程中都起到了相应的促进作用.由此推测,在甲苯的氧化反应中,钨酸铋材料表面吸收可见光,产生光生电子和空穴,而钯的担载则促进了电子和空穴进行氧气还原和甲苯氧化的过程.     

钨酸铋担载钯纳米粒子光催化甲苯及其衍生物到醛的氧化反应

甲苯及其衍生物的选择性氧化是化学工业中重要的一环.氧化产物醛、酮和酸类化合物是各种农药、染料、防腐剂、阻燃剂、香料、塑料的合成中间体.在传统的化工过程中,通常在苛刻的条件下,如高温、高压以及酸性溶剂中进行甲苯的选择性氧化.光催化有机合成作为一种"绿色"的合成方法受到越来越多的关注.我们发现钨酸铋作为可见光响应的光催化剂,可以利用氧气作为氧化剂,对甲苯及其衍生物进行催化氧化反应.通过调节水热法合成钨酸铋的酸碱条件,控制其成核生长过程,改变其形貌,发现在pH值为0.49时,得到花状钨酸铋粉末活性最高.X射线衍射、扫描电镜、紫外可见吸收光谱和比表面测定结果发现,花状钨酸铋粉末表现出最佳的甲苯氧化活性很可能是与它最大的比表面积有关系.为了进一步提高催化的活性,我们将助催化剂担载在钨酸铋粉末上,发现Pd的担载量为0.1 wt%时甲苯氧化反应活性最高.将邻、间、对位甲基取代以及对位甲氧基和氯取代的甲苯衍生物进行反应,发现均可高选择性地得到目标产物.在加入电子牺牲剂硝酸银和空穴牺牲剂草酸铵到反应体系后,发现反应被完全禁阻,说明在甲苯氧化反应过程中电子和空穴都起到了相应的作用.通过电化学测试发现,钯作为助催化剂担载在钨酸铋表面后,产生更强的氧化和还原信号,说明其在电子和空穴发生反应的过程中都起到了相应的促进作用.由此推测,在甲苯的氧化反应中,钨酸铋材料表面吸收可见光,产生光生电子和空穴,而钯的担载则促进了电子和空穴进行氧气还原和甲苯氧化的过程.     

溶剂和杂多酸盐中季铵阳离子对环已烯环氧化反应上转移催化的影响

考察了溶剂和催化剂Q3[PO4（WO3）4]中季铵盐阳离子对环已烯环氧化反应的影响，在环已烯环氧化反应中，以氯仿和叔丁醇为溶剂时，环氧化反应的结果最好，当催化剂中季铵盐阳离子的碳数适合时，才能形成反应控制相转移催化过程，催化剂本身不溶于反应体系，但在过氧化氢的作用下形成可溶于反应体系的活性物种，均相地催化环氧化反应，当过氧化氢消耗尽时，催化剂又恢复到起始结构并从反应体系中析出。     

活性粉状白钨酸与十聚、六聚及其他多聚钨酸盐的联系和应用

本文扼要总结了作者近年来关于活性粉状白钨酸与十聚、六聚钨酸的工作,包括它们的制备、分离及相互转化。聚钨酸有机铵盐的光敏性,活性粉状白钨酸用于合成众多新化合物,对三价钨的簇合物以及从WO_4~(2-)转变到黄钨酸系列过程的推测等也给予了相应的评述。     

钨酸催化氧化环己烯合成己二酸

以钨酸/有机酸性添加剂为催化体系, 在无有机溶剂、相转移剂的情况下, 催化30%过氧化氢氧化环己烯合成己二酸. 当钨酸∶有机酸性添加剂∶环己烯∶过氧化氢＝1∶1∶40∶176(摩尔比, 钨酸用量为2.5 mmol)时, 使用有机酸性添加剂考察钨酸的催化性能, 结果表明以钨酸/间苯二酚催化氧化环己烯的催化效果最优, 反应8 h时己二酸分离产率达90.9%、纯度为～100%; 而不使用有机酸性添加剂时, 己二酸分离产率只有72.1%, 产品纯度为96.2%. 当使用磺酸水杨酸、草酸、水杨酸为有机酸性添加剂时, 随反应时间的增加, 己二酸分离产率均升高, 但反应6 h以后, 己二酸分离产率随时间的变化不明显. 当磺酸水杨酸用量为2.5 mmol时, 己二酸分离产率和纯度均较高. 钨酸-磺酸水杨酸催化体系重复使用五次后, 己二酸分离产率仍可达到80.5%.     

溶剂和杂多酸盐中季铵阳离子对环己烯环氧化反应控制相转移催化的影响

 考察了溶剂和催化剂Q3［PO4（WO3）4］中季铵盐阳离子对环己\r\n烯环氧化反应的影响．在环己烯环氧化反应中，以氯仿和叔丁醇为溶剂\r\n时，环氧化反应的结果最好．当催化剂中季铵盐阳离子的碳数合适时，\r\n才能形成反应控制相转移催化过程．催化剂本身不溶于反应体系，但在\r\n过氧化氢的作用下形成可溶于反应体系的活性物种，均相地催化环氧化\r\n反应．当过氧化氢消耗尽时，催化剂又恢复到起始结构并从反应体系中\r\n析出．     

N-羟基邻苯二甲酰亚胺及其类似物催化下的分子氧氧化反应

本文综述了近年来N-羟基邻苯二甲酰亚胺（NHPI）及其类似物催化下分子氧氧化的各种反应,并对它们的催化机理作了简要介绍。NHPI与过渡金属离子组成的催化体系能高效的催化乙烷氧化为乙酸、环烷烃氧化为二元羧酸、甲苯氧化为苯甲酸、烯烃氧化为环氧化物、炔烃氧化为炔酮、酰胺氧化为酰亚胺;NHPI单独使用能催化金刚烷发生氧化羰基化反应、催化氧化醇制取过氧化氢;NHPI与有机助催化剂如：偶氮二异丁腈、溴化季铵盐、蒽醌、醇等也能催化分子氧氧化反应。     

铂电极上二茂铁甲基季铵盐电催化氧化异烟肼的电化学及其动力学性质研究

在0.1 mol·L-1Na2SO4水溶液中,二茂铁甲基季铵盐对异烟肼的电化学氧化具有很好的催化作用。运用循环伏安法研究了二茂铁甲基季铵盐和异烟肼的浓度、扫描速率分别对该电催化氧化体系的影响,同时运用循环伏安法和计时电流法探讨了该电催化氧化反应体系的电化学动力学规律,由电化学动力学测定并计算出了该催化体系的电子转移系数α、反应级数、催化反应速率常数k值。     

Improvement of 2,4-dinitrophenylhydrazine derivatization method for carbon isotope analysis of atmospheric acetone

Through simulation experiments of atmospheric sampling, a method via 2,4-dinitrophenylhydrazine (DNPH) derivatization was developed to measure the carbon isotopic composition of atmospheric acetone. Using acetone and a DNPH reagent of known carbon isotopic compositions, the simulation experiments were performed to show that no carbon isotope fractionation occurred during the processes: the differences between the predicted and measured data of acetone-DNPH derivatives were all less than 0.5 per thousand. The results permitted the calculation of the carbon isotopic compositions of atmospheric acetone using a mass balance equation. In this method, the atmospheric acetone was collected by a DNPH-coated silica cartridge, washed out as acetone-DNPH derivatives, and then analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using this method, the first available delta13C data of atmospheric acetone are presented.     

气相色谱法测定工业废气中的丙酮

用活性炭吸附管采集吸附工业废气中的丙酮,经二硫化碳解吸后由自动进样器送入气相色谱仪中分离并由FID检测器检测。2 mL二硫化碳解吸溶剂中丙酮的绝对量在1.58~6.32 mg时,测定结果的相对标准偏差为2.4%~3.7%(n=5)。当样品采集量为10 L时,方法检出限为0.4 mg/m3。所用活性炭采样管对丙酮的吸附效果良好,100 g活性炭对丙酮的穿透容量大于15 mg。二硫化碳溶剂对吸附在活性炭中的丙酮解吸效果较好,丙酮加标量为3.95~15.80 mg时,解吸效率为93.8%~100.9%。     

菠菜叶绿素的浸提和协同萃取反应

有机溶剂;菠菜叶绿素的浸提和协同萃取反应     

Photooxidation of acetone on TiO2(110): conversion to acetate via methyl radical ejection

It is generally held that radicals form and participate in heterogeneous photocatalytic processes on oxide surfaces, although understanding the mechanistic origins and fates of such species is difficult. In this study, photodesorption and thermal desorption techniques show that acetone is converted into acetate on the surface of TiO2(110) in a two-step process that involves, first, a thermal reaction between acetone and coadsorbed oxygen to make a surface acetone-oxygen complex, followed second by a photocatalytic reaction that ejects a methyl radical from the surface and converts the acetone-oxygen complex into acetate. Designation of the photodesorption species to methyl radicals was confirmed using isotopically labeled acetone. The yield of photodesorbed methyl radicals correlates well with the amount of acetone depleted and with the yield of acetate left on the surface, both gauged using postirradiation temperature programmed desorption (TPD). The thermal reaction between adsorbed acetone and oxygen to form the acetone-oxygen complex exhibits an approximate activation barrier of about 10 kJ/mol. A prerequisite to this reaction is the presence of surface Ti3+ sites that enable O2 adsorption. Creation of these sites by vacuum reduction of the surface prior to acetone and oxygen coadsorption results in an initial spike in the acetone photooxidation rate, but replenishment of these sites by photolytic means (i.e., by trapping excited electrons at the surface) appears to be a slow step in a sustained reaction. Evidence in this study for the ejection of organic radicals from the surface during photooxidation catalysis on TiO2 provides support for mechanistic pathways that involve both adsorbed and nonadsorbed species.     

TWO WATER-SOLUBLE FLUORESCENCE PROBES FOR CHEMIEXCITATION STUDIES: SODIUM 9,10-DIBROMO- AND 9, 10-DIPHENYLANTHRACENE-2-SULFONATE. SYNTHESIS, PROPERTIES AND APPLICATION TO TRIPLET ACETONE AND TETRAMETHYLDIOXETANE

The syntheses of sodium 9,10-dibromo- and 9,10-diphenylanthracene-2-sulfonate (DBAS and DPAS, respectively) are described and their photophysical properties determined. These two probes were used in aqueous solution studies of the kinetic parameters of tetramethyldioxetane thermolysis, which were found to be the same as in organic solvents. The yields of triplet and singlet acetone generated by the decomposition of this dioxetane in water are also comparable to the literature values in organic medium. The lifetime of triplet acetone in water was determined to be 13 ± 2 u.s by a method based on the measurement of the fluorescence decay of DBAS excited via energy transfer from triplet acetone, by the time-correlated single-photon counting technique. Sorbate ion quenches triplet acetone from tetramethyldioxetane with a rate constant smaller but close to the diffusion-controlled limit.     

在阴离子交换树脂催化剂上合成二丙酮醇的动力学研究

动力学研究表明,在碱性树脂催化剂上丙酮缩合制二丙酮醇是一个1-1级可逆反应,本文对此多相催化的反应机理进行了探讨。     

The role of dipole—dipole interactions in the formation of the structure of amorphous Teflon AF2400 and complexation of acetone with perfluorodioxolane rings

FTIR spectroscopy investigation have shown that the contact of acetone with the film of Teflon AF2400 led to changes in the intensities of some absoption bands of the polymer and to the splitting of the stretching vibration band ν_C=O of acetone. The theoretical vibration spectrum of a model of AF2400 repeat unit was obtained. It is in good agreement with the experimental spectrum of the film of this polymer. The bands, whose intensities change during the contact of the AF2400 film with acetone, belong to the stretching and deformation vibrations of the C-F bond of the dioxolane ring as a whole. Structural, energy, and electron characteristics of a complex of acetone with the perfluorodioxolane ring were calculated by the B3LYP/6-31G(d) method. The dipole-dipole character of interaction of acetone with the repeat unit of AF2400 with the involvement of the whole dioxolane ring was demonstrated. The polarizabilies of the C=O bonds in acetone and the C-F bonds in the dioxolane ring of the polymer are substantially changed, which is in good agreement with the experimental IR spectrum of the AF2400 film that had been in the contact with acetone. The results of quantum chemical and molecular dynamics calculations testify the orthogonal-block structure of the chains in AF2400, which explains great stiffness and a large free volume of this polymer.     

顶空气相色谱法测定粉状大豆磷脂中的丙酮残留量

 采用顶空气相色谱法测定大豆磷脂中的丙酮残留量。色谱柱为 2m× 3mmi d 内填GDX 10 3的不锈钢柱 ,柱温为 16 0℃。试验结果的相对标准偏差为 1 2 % ,在 2 5 0 μg/g～ 10 0 μg/g范围内 ,回收率为 98 4%～10 4%。     

Interaction of acetone with ammonia and alcohols over a HZSM-5 zeolite: Part 1. Methanol

Temperature-programmed desorption accompanied by conversion (TPDC) of preadsorbed acetone was studied on a HZSM-5 zeolite with Si/Al=13.5. The reactivity of surface species created from acetone with methanol, ammonia and mixtures of these was investigated by analysing the composition of the products released (using a mass spectrometer) and the composition of the surface species (using a ¹³C MAS NMR spectrometer). It was found that ammonia reacts with the carbonyl group of acetone surface species to imino carbocations in both the absence and presence of methanol, and methanol alkylates the acetone surface species whether ammonia is present or absent. The decomposition of the species created from acetone, methanol and ammonia leads to different products than the decomposition of the species formed on the zeolite either from acetone (or methanol) alone or from acetone (or methanol) and ammonia. The strong dehydrogenation function of HZSM-5 resulted in the release of acetonitrile and HCN from acetone and methanol, respectively (in the presence of ammonia), while pyridinium bases (in the presence of all 3 reactants) appeared only in trace amounts.