苯乙烯-丁二烯-苯乙烯嵌段共聚物负载Pt催化肉桂醛制备肉桂醇的研究

用紫外光交联的方法制备不同交联度的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)负载Pt的催化膜并探讨其对肉桂醛选择性加氢制备肉桂醇的催化效果.其中催化剂Pt纳米簇用微波法制备,XRD测其平均粒径为3.7 nm.膜载催化剂的负载量、光交联剂三羟甲基丙烷三丙烯酸酯(TMPTA)和光引发剂二苯甲酮(BP)的用量均为3%.用色谱-质谱联用、XRD、紫外分光光度计对膜载催化剂和反应产物进行了表征,结果表明,随着交联度的增加,肉桂醇的催化选择性先增后减,紫外光光照80s时,负载膜交联度23.63%,肉桂醛转化率为91.46,肉桂醇选择性80.98%.质谱分析表明交联度大于30%后,催化产物中开始有膜分解产生的小分子杂质出现,并随交联度的进一步增大而增多;显微镜检测同时说明此时膜结构发生变化,造成肉桂醇选择性的降低.     

改良的QuEChERS结合气相色谱-质谱法测定新鲜水果和肉中肉桂醛残留

建立了改良的QuEChERS技术结合气相色谱-质谱检测水果和肉中肉桂醛残留量的定性定量分析方法。试样用乙酸乙酯溶液均质提取,经N-丙基乙二胺（PSA）、石墨化炭黑（GCB）、C₁₈固相吸附剂净化,在电子轰击电离（EI）源、选择离子监测（SIM）模式下检测,外标法定量。肉桂醛在0.01~0.5 mg/L范围内线性关系良好,相关系数大于0.999。水果和鲜肉中肉桂醛的定量限分别为0.5 mg/kg和1.0 mg/kg。在3个添加水平下,肉桂醛的加标回收率为81.9%~104.5%,相对标准偏差（RSD,n=6）为1.1%~8.6%。该方法操作简单,净化效果好,适用于水果和鲜肉中肉桂醛残留量的快速检测。     

Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over An Ultrafine Co—B Amorphous Catalyst

A novel Co-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of CoCl2 with aqueous NaBH4, which exhibited excellent activity and selectivity during the hydrogenation of cinnamaldehyde to cinnamyl alcohol in liquid phase. The optimum yield of cinnamyl alcohol was 87.6%, much better than the yield of using Raney Ni, Raney Co and other Co-based catalysts.     

Effect of Transition Metals on Selective Hydrogenation of Cinnamaldehyde over Pt／ZrO2 Catalysts

The effect of transition metals (Cr, Mn, Fe, Co and Ni) on the hydrogenation of cinnamaldehyde over Pt/ZrO2 catalysts was studied in ethanol at 343K under 2.0MPa H2 pressure. PtCo/ZrO2 and PtFe/ZrO2 catalysts exhibit high selectivity and activity of hydrogenation for C=O (93.8% at 87.3% conversion and 83.6% at 88.6% conversion, respectively), and PtNi/ZrO2 exhibits high selectivity of hydrogenation for C=C (64.3% at 70.6% conversion). In the presence of trace H2O and NaOH, over the PtNi/ZrO2 (0.4wt%Ni) catalyst the selectivity to hydrocinnamalde hydereaches 90.6% and the conversion of cinnamaldehyde is 90.5%.     

Selective hydrogenation of cinnamaldehyde over carbon nanotube supported pd-ru catalyst

Summary Carbon nanotube supported Pd, Ru and Pd-Ru catalysts have been prepared and tested with the hydrogenation of cinnamaldehyde as a probe reaction. It has been found that the cinnamaldehyde conversion and the selectivity towards the hydrogenation of C=O bond over Pd-Ru/PCNT catalyst could reach 56.6% and 79.1%, respectively, at 120^oC and 5.0 MPa, which is better than Pd/PCNT and Ru/PCNT catalysts under the same reaction conditions. It is assumed that the better performance of Pd-Ru/PCNT catalyst for cinnamaldehyde hydrogenation may be due to the synergic effect of Pd and Ru metals or the promoting effect of Ru metal.     

Studies on high chemical reactivity of nano-NaH

A comparison between the initial reaction rates of nanometric and commercial NaH has been studied in four test reactions: 1) hydrogenolysis of chlorobenzene; 2) selective reduction of cinnamaldehyde to cinnamyl alcohol; 3) metallation of dimethyl sulfoxide; and 4) catalytic hydrogenation of olefins. The experimental results indicate that when NaH is used as a chemical reagent in the first three reactions, the initial reaction rates of nano-NaH is 230, 120 and 110 times higher than those of the commercial ones respectively, and it is in agreement with the difference in specific surface areas between these two forms of NaH. When NaH is used as a catalyst component together with Cp₂TiCl₂ in the fourth reaction, catalyst with nano-NaH gives extremely high activity in the hydrogenation of olefins, while the one with commercial NaH gives no activity at all even if a large amount of the commercial NaH is used to make the total surface area equivalent to that of nano-NaH. Thus, it is evident that although large specific surface area is important for nano-NaH to be used as a catalyst component, high surface energy with surface defects seems to be more important. The large specific surface and the activated surface of nano-NaH with high surface energy should be the main factors for their extremely high chemical reactivity, while whether the former or the latter one plays a leading role depends on the type of reactions involved. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 24(1): 21–24 [译自: 应用化学]     

Polysiloxane microspheres functionalized with imidazole groups as a palladium catalyst support

Polysiloxane microspheres containing a large number of silanol groups were obtained by an emulsion process of modified polyhydromethylsiloxane. N‐substituted imidazole groups were grafted on these microspheres by the silylation of their silanol groups with N‐[γ‐(dimethylchlorosilyl)propyl]imidazole hydrochloride. The progress of the reaction was monitored using ²⁹Si and ¹³C magic angle spinning (MAS) NMR and its impact on microsphere morphology was studied using scanning electron microscopy (SEM). The usefulness of the imidazole‐functionalized microspheres as a support for a metal catalyst was demonstrated by their reaction with PdCl₂(PhCN)₂. In this way a new heterogenized catalyst, Pd(II) complex with imidazole ligands supported on polysiloxane microspheres, was generated. This catalyst, MPd , was characterized using ¹³C and ²⁹Si MAS NMR, X‐ray photoelectron, Fourier transform infrared and far‐infrared spectroscopies, X‐ray diffraction, SEM–energy‐dispersive X‐ray spectroscopy and wide‐angle X‐ray scattering. The catalyst appears in two structures, as Pd(II) complex and Pd(0) nanoclusters. Its catalytic activity was tested using a model reaction, the hydrogenation of cinnamaldehyde, and compared with that of an analogous complex operating in a homogeneous system. MPd showed a high activity in the promotion of hydrogenation of cinnamaldehyde. The activity in the substrate conversion was stable at least in five cycles of this reaction. The main product was hydrocinnamaldehyde which could be obtained with a yield above 70%. A mechanism of the reaction is proposed. Copyright © 2016 John Wiley & Sons, Ltd.     

Quantification of selected aroma compounds in e-cigarette products and toxicity evaluation in HUVEC/Tert2 cells

During recent years, the number of consumers using so-called e-cigarettes, which are electrical devices to aerosolize a liquid consisting of propylene glycol, glycerol, optional nicotine and flavoring chemicals, has been increasing. Aromas vary from common flavors such as mint to more unusual flavors such as buttermilk or pepperoni pizza. Consumers today can buy e-concentrates that consist of propylene glycol and aroma to blend their own desired flavor at home. Little is known about the composition and concentration of various aroma molecules in the different e-liquids and e-concentrates. In addition, the process of EU-wide regulation is still ongoing. The aim of this research study was to identify and quantify possible undesirable aroma compounds in e-liquids and e-concentrates. Flavoring chemicals such as estragole, benzaldehyde and cinnamaldehyde were quantified. The measurements were carried out on a GC–MS system. The results show the presence of highly concentrated flavoring compounds and limonene oxide in lemon-flavored e-concentrates. In the final step, samples and single-aroma standards were tested for their toxicity to HUVEC/Tert2 cells, where some single-flavoring chemicals such as cinnamic aldehyde revealed significant toxic effects.     

Simultaneous Determination of Trans-Cinnamaldehyde and Benzaldehyde in Different Real Samples by Differential Pulse Polarography and Study of Heat Stability of Trans-Cinnamaldehyde

Abstract

A simple, sensitive, and accurate differential pulse polarography method for simultaneous determination of trans-cinnamaldehyde and benzaldehyde in food and drug samples were developed. DC polarography, CV, and coulometric techniques were used for investigation the electrochemical behavior of both compounds. In phosphate buffer (pH = 8.2) and 10% v/v of methanol the differential pulse voltammograms of trans-cinnamaldehyde (?1.05 V) and benzaldehyde (?1.31 V) display reproducible peaks. Under these conditions a strict linearity between both analyte concentrations and their peaks height were observed. The detection limits were calculated to be 2.5 × 10^?8 and 1.2 × 10^?8 M for trans-cinnamaldehyde and benzaldehyde in pH = 8.2, respectively. The relative standard deviations for 1.0 × 10^?6 M of both analytes were 2.04 and 1.18. The heat stability of trans-cinnamaldehyde was studied, and it was found that trans-cinnamaldehyde undergoes a heat-induced decomposition at low temperature (>70°C) to produce benzaldehyde.     

光照下钴镍盐催化肉桂醛的转移加氢反应

以甲醇为氢源,研究了光照下金属镍盐、钴盐催化肉桂醛的转移加氢反应.结果表明,以Co(OAc)2和Ni(OAc)2为催化剂,肉桂醛可以发生催化转移加氢反应,得到肉桂醇;就催化剂的转移加氢活性和产物肉桂醇的选择性而言,Co(OAc)2的催化效果更好.与此同时,在反应体系中添加NaOAc和Na2C2O4等碱性添加剂可提高肉桂...