Rapid determination of products of phenol hydrogenation in a supercritical water system using headspace gas chromatography

This paper reports a headspace analysis technique for the determination of products, i.e., cyclohexanone (CE) and cyclohexanol (CL), of phenol hydrogenation in a supercritical water reaction system (SWRS) with water removal by hydrate formation. An addition of anhydrous calcium chloride leads to water absorption resulting in crystal water; thus, the samples can be quantitatively measured without the influence of water. After achieving equilibrium at 150°C and maintaining it for 5 min, the obtained results showed a relative standard deviation of less than 5.3% and the recovery ranged from 93% to 104%. The presented method is simple and accurate for the analysis of CL, CE and phenol in samples from phenol conversion in SWRS.     

自然光照下PEG/PAA凝胶在Fe~(3+)/CA溶液中的凝胶-溶胶转化行为

将PEG/PAA凝胶浸入铁/柠檬酸(Fe3+/CA)溶液中,自然光照一定时间可实现凝胶-溶胶的相互转化,而且转化行为受溶液的组成及其p H影响。只有当溶液中[Fe3+]0∶[CA]0≤1∶2,且溶液的p H在1~6之间,该转化才会发生,通过改变溶液中[Fe3+]0∶[CA]0的值或溶液的p H可以有效地控制其转化速率。此外,结果还表明,当凝胶转化为溶胶后,向其中加入高价金属阳离子,例如Fe3+、Al3+、Ce4+、Cu2+等,溶胶又会再次转化为凝胶。由于这种新颖的特性,该凝胶有望应用于药物释放、细胞培养等领域。     

1,2,4‐Triazole Links and N‐Azo Bridges Yield Energetic Compounds

Triazole links and polynitropyrazole rings give rise to compounds with energetic properties. These materials were fully characterized by NMR and infrared spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). In addition, the structures of compounds 5 and 8 were confirmed by single‐crystal X‐ray diffraction analysis. Detonation properties, calculated from heats of formation and experimental densities, thermal stabilities, and impact and friction sensitivities support the potential use of these materials for explosive applications.     

Cobalt‐Catalyzed Cross‐Coupling of 3‐ and 4‐Iodopiperidines with Grignard Reagents

A cobalt‐catalyzed cross‐coupling between 3‐ and 4‐iodopiperidines and Grignard reagents is disclosed. The reaction is an efficient, cheap, chemoselective, and flexible way to functionalize piperidines. This coupling was used as the key step to realize a short synthesis of (±)‐preclamol. Some mechanistic investigations were conducted that highlight the formation of radical intermediates.     

Nickel N‐Heterocyclic Carbene Catalyzed CC Bond Formation: A New Route to Aryl Ketones

A novel nickel N‐heterocyclic carbene catalyzed cross‐coupling reaction of aryl aldehydes with boronic esters for the synthesis of aryl ketones was developed. This reaction provides a mild, practical method toward aryl ketones, which are versatile intermediates and building blocks in organic synthesis.     

Formation of the Main Cores Present in Natural Products by Tandem Additions

A rapid route to 5,5‐ and 5,6‐ bicyclic systems is provided by an 1,3‐alkyl‐shift process mediated by a hypervalent iodine reagent on aromatics. The structures obtained contain several unsaturations with different behaviors and reactivities. Such diversity allows further elaborations for the rapid formation of compact systems present in a variety of natural products. The potential for further transformations has been demonstrated by performing a double Michael addition. This cyclization process is regio‐ and stereoselective due to the presence of a former benzylic substituent. Furthermore, an extension of this approach has been accomplished on indole derivatives.     

Fluorescent Coumarin–Artemisinin Conjugates as Mitochondria‐Targeting Theranostic Probes for Enhanced Anticancer Activities

Mitochondria‐targeting theranostic probes that enable the simultaneously reporting of and triggering of mitochondrial dysfunctions in cancer cells are highly attractive for cancer diagnosis and therapy. Three fluorescent mitochondria‐targeting theranostic probes have been developed by linking a mitochondrial dye, coumarin‐3‐carboximide, with a widely used traditional Chinese medicine, artemisinin, to kill cancer cells. Fluorescence images showed that the designed coumarin–artemisinin conjugates localized mainly in mitochondria, leading to enhanced anticancer activities over artemisinin. High cytotoxicity against cancer cells correlated with the strong ability to accumulate in mitochondria, which could efficiently increase the intracellular reactive oxygen species level and induce cell apoptosis. This study highlights the potential of using mitochondria‐targeting fluorophores to selectively trigger and directly visualize subcellular drug delivery in living cells.     

Remote Construction of Chiral Vicinal Tertiary and Quaternary Centers by Catalytic Asymmetric 1,6‐Conjugate Addition of Prochiral Carbon Nucleophiles to Cyclic Dienones

An unprecedented remote construction of chiral vicinal tertiary and quaternary centers by a catalytic asymmetric 1,6‐conjugate addition of prochiral carbon nucleophiles to cyclic dienones has been developed. Both 5H‐oxazol‐4‐ones and 2‐oxindoles were found to be very efficient carbon nucleophiles in this reaction at a remote position, giving products with excellent enantio‐ and diastereoselectivities (up to 99 % ee and >19:1 d.r. for 5H‐oxazol‐4‐ones and up to 97 % ee and >19:1 d.r. for 2‐oxindoles).     

Simultaneous determination of naphazoline and pyridoxine in eye drops using excitation–emission matrix fluorescence coupled with second-order calibration method based on alternating trilinear decomposition algorithm

A novel method is developed for the direct determination of naphazoline hydrochloride(NAP) and pyridoxine hydrochloride(VB6) in commercial eye drops. By using excitation–emission matrix(EEM)fluorescence coupled with second-order calibration method based on the alternating trilinear decomposition(ATLD) algorithm, the proposed approach can achieve quantitative analysis successfully even in the presence of unknown and uncalibrated interferences. The method shows good linearity for NAP and VB6 with correlation coefficients greater than 0.99. The results were in good agreement with the labeled contents. To further confirm the feasibility and reliability of the proposed method, the same batch samples were analyzed by multiple reaction monitoring(MRM) based on LC–MS/MS method.T-test demonstrated that there are no significant differences between the prediction results of the two methods. The satisfactory results obtained in this work indicate that the use of the second-order calibration method coupled with the EEM is a promising tool for industrial quality control and pharmaceutical analysis due to its advantages of high sensitivity, low-cost and simple implementation.     

液相色谱串联质谱法测定水果中复硝酚钠残留量

以甲醇提取样品,采用超高效液相色谱串联质谱法(UPLC–MS/MS)测定水果中复硝酚钠的残留量。以甲醇–10 mmol/L乙酸铵水溶液(体积比为60∶40)为流动相,质谱采用电喷雾负离子MRM检测模式。对硝基苯酚钠和5-硝基愈创木酚钠的线性范围为0.05~2.00 mg/L,检出限为0.01 mg/kg,邻硝基苯酚钠的线性范围为2.5~100.0 mg/L,检出限为0.5 mg/kg,线性相关系数均大于0.995。实际样品中对硝基苯酚钠、邻硝基苯酚钠和5-硝基愈创木酚钠的加标回收率分别为83.0%~93.4%,81.0%~87.4%,83.0%~91.8%,测定结果的相对标准偏差小于7%(n=6)。该法操作简单、快捷,精密度、准确度高,适用于水果中复硝酚钠的残留分析。