Photo-electro catalytic oxidation of aromatic alcohols on visible light-absorbing nitrogen-doped TiO2

Visible light illumination of nitrogen-doped TiO₂ brings about the selective oxidation of benzyl and cinnamyl alcohol to the corresponding aldehydes. The photocatalyst was prepared by a sol-gel method and characterised mainly by XRD, UV-vis diffuse reflectance and Raman spectroscopy. The conditions limiting the observation of visible light photoactivity are the use of dry nitriles as nonaqueous solvents and aromatic alcohols as the substrates. No visible light oxidation takes place in an aqueous medium. The efficiency of benzyl and cinnamyl alcohol photo-oxidation in nitrile solvents follows the order: CH₃CN > CH₃CH₂CN > CH₃(CH₂)₂CN. Conversely, since alcohol photo-oxidation occurs with 100% selectivity on electrodes in O₂ saturated solutions at potentials close to E_fb or under open-circuit conditions, suspensions of the photocatalyst can be advantageously employed. The process involves a relatively weak adsorption of the alcohol substrates which, however, do not readily capture the photogenerated holes. On the basis of the electrochemical and photoluminescence data, it appears that the solvent (e.g. acetonitrile), in addition to O₂ has an active role in the reaction mechanism.     

^99mTc—MIBI SPECT与^18F—FDG PET诊断胶质瘤复发及恶变对比分析

对２８例经过治疗的胶质瘤患者进行Ｇｄ－ＤＴＰＡＭＲＩ和＾１８Ｆ－ＦＤＧＰＥＴ显像，其中１４例同时进行＾９９ｍＴｃ－ＭＩＢＩＳＰＥＣＴ显像，并与治疗前解剖影像对比，ＰＥＴ结果发现１４例高代谢，１０例低代谢，４例瘤灶中心坏死，周边ＦＤＧ环状摄取，８例首次手术病理Ｉ－Ⅱ级星形细胞瘤患者中５例为高代谢，＾１８Ｆ－ＦＤＧＰＥＴ和＾９９ｍＴＣ－ＭＩＢＩＳＰＥＣＴ诊断胶质瘤复发及恶变的灵敏度依次为９３．３％，９     

聚芳醚腈连续纤维增强复合材料制备与性能研究

以双酚A型聚芳醚腈(PEN)为基体树脂,采用预浸渍工艺(溶液预渍工艺)和后浸渍工艺(薄膜叠层法)相结合的方法制备了PEN连续纤维增强复合材料;并研究了以ZnCl2为催化剂在热处理前后PEN复合材料性能的变化。研究结果表明:PEN连续纤维增强复合材料具有很高的力学强度和热稳定性,复合材料经热处理后由于PEN树脂侧链腈基产生交联反应,力学强度和热稳定性得到大幅提高。     

脂肪一步催化氨化和脱水制备脂肪腈的研究——(二)工艺部分

详细介绍了脂肪一步催化氨化和脱水制备脂肪腈的工艺流程。并考察了催化剂用量、氨流量、反应温度及分馏柱温度或填充物对反应活性的影响。结果表明,最佳反应条件是:催化剂用量为3％～5％,氨流量800(L/h·kg油脂),末段反应温度270℃以上,分馏柱温度80～86℃,分馏柱填充物用脱水性物质。实验最好的反应结果为腈得率约92％。     

Defined vanadium phosphorus oxides and their use as highly effective catalysts in ammoxidation of methyl aromatics

The heterogeneous catalytic ammoxidation of methyl aromatics and methyl hetero aromatics is a preferred method for the synthesis of aromatic and hetero aromatic nitriles. The resulting nitriles are valuable intermediates for the production of dyestuffs, pesticides, pharmaceuticals and other chemical products. Usually, the ammoxidation is carried out using V-containing oxides (e.g. V/Ti, V/Sn, V/Mo) promoted by further transition metals as catalysts. However, we have shown recently that defined vanadium phosphates (VPO) revealed an excellent ammoxidation performance. The ammoxidation of toluene was used as model reaction. An intense characterisation of some VPO catalysts under pre-treatment and working conditions by the use of various in situ-methods has thrown more light in formation and stability of the used VPO solids as well as the effect of different reactants (ammonia, toluene) on VPO surface and bulk properties.     

Highly selective aerobic oxidation of primary amines to nitriles by ruthenium hydroxide

A highly selective ruthenium catalyzed aerobic oxidation of primary amines to corresponding nitriles was developed in water and organic solvents. The catalyst system was highly efficient and widely applicable, and several functional groups were tolerated under the reaction conditions employed.     

Occurrence of nitriles in Taraxacum labelled honeys

Nitrile compounds, whose presence is not common in honey, have been found in the volatile fraction of a few honey types, their relative amounts being particularly high in honeys commercialized under the Taraxacum label. Among them, 2-methylpropanenitrile, 2-methylbutanenitrile, 3-methylbutanenitrile, 2-butenenitrile (cis- or trans-isomer), 3-butenenitrile and 3-methylpentanenitrile, have been identified for the first time in honeys. Melissopalynological analysis of Taraxacum labelled honeys showed a relatively high pollen contribution of other species flowering in spring, such as Diplotaxis sp. Nitrogen-containing compounds, such as nitriles, thiocyanates and isothiocyanates have been previously described as products of hydrolysis of glucosinolates present in Diplotaxis sp. and other Brassicaceae. The nectar contribution of species belonging to the Brassicaceae family is proposed as the origin of the high relative amount of nitriles in Taraxacum honeys.     

Ammoxidation of methylaromatics over vanadium phosphate catalysts. I. Effect of the size, position and electronic properties of substituents on the catalytic conversion of methylaromatics to the corresponding nitriles

The heterogeneous-catalytic ammoxidation of several mono- and disubstituted methylaromatics and heteroaromatics to their corresponding nitriles was studied. The reaction was carried out on an ammonium oxovanadium pyrophosphate ((NH₄)₂[(VO)₃(P₂O₇)₂]) generated during the catalytic process. The study shows that the catalytic activity and the nitrile selectivity depend mainly on the position and the electronic nature of the particular substituent due to a changed accessibility of the methyl group as well as a possible different electronic stabilization.