预氧化处理后基团对煤氧化反应活性的影响

使用氧化剂对无烟煤进行预氧化处理,利用TPD-MS和TG-DTA等表征方法,研究了煤表面官能基团种类、含量的变化及其对煤氧化活性的影响.结果表明,使用氧化剂处理煤样可以不同程度地改变煤表面官能基团及其分布.双氧水、次氯酸钠处理后的无烟煤,其氧化反应活性的变化不明显;硝酸处理的无烟煤,其低温氧化反应活性有所提高.根据处理前后煤表面基团及其分布的变化推测:无烟煤中的羧基等含氧基团明显提高煤的低温氧化活性,而烷基对煤的低温氧化活性影响不明显,但对煤氧化反应热有一定影响.

Modified graphene‐based materials as effective catalysts for transesterification of rapeseed oil to biodiesel fuel

Production of biodiesel by the transesterification process using different modified graphene‐based materials as catalysts was studied.Solid acid graphene‐based samples were prepared by grafting sulfonic or phosphate groups on the surface of thermally reduced graphene oxide.The obtained materials were thoroughly characterized using scanning electron microscopy,X‐ray diffraction,thermogravimetric analysis,X‐ray photoelectron spectroscopy,N2 adsorption‐desorption measurements,potentiometric titration,elemental analysis,and Fourier transform infrared spectroscopy.The prepared catalysts were tested in the transesterification of rapeseed oil with methanol at 130°C under pressure,and their activities were compared to the performance of a commercially available heterogeneous acidic catalyst,Amberlyst‐15.All modified samples were active in the transesterification process;however,significant differences were observed in the yield of biodiesel,depending on the method of catalyst preparation and strength of the acidic sites.The highest yield of fatty acid methyl esters of 70%was obtained for thermally reduced graphene oxide functionalized with 4‐benzenediazonium sulfonate after 6 h of processing,and this result was much higher than that obtained for the commercial catalyst Amberlyst‐15.The results of the reusability test were also promising.

Iron phthalocyanine-catalyzed radical phosphinoylazidation of alkenes:A facile synthesis of β-azido-phosphine oxide with a fast azido transfer step

Phosphinoylazidation of alkenes is a direct method to build nitrogen-and phosphorus-containing compounds from feed-stock chemicals.Notwithstanding the advances in other phosphinyl radical related difunctionalization of alkenes,catalytic phosphinoylazidation of alkenes has not yet been reported.Here,we describe the first iron-catalyzed intermolecular phosphinoylazidation of styrenes and unactivated alkenes.The method is practically useful and requires a relatively low loading of catalyst.Mechanistic studies confirmed the radical nature of the reaction and disclosed the unusually low activation energy 4.8 kcal/mol of radical azido group transfer from the azidyl iron(III)phthalocyanine species(PcFeulN3)to a benzylic radical.This work may help to clarify the mechanism of iron-catalyzed azidation,inspire other mechanism studies and spur further synthetic applications.

Visible-light photoredox-catalyzed selective carboxylation of C(sp~2)-F bonds in polyfluoroarenes with CO2

Visible light‐driven carboxylation with CO_(2) have emerged as a sustainable and powerful way to transfer waste to treasure.However,it is still challenging for aryl fluorides due to the low reactivities of both C(sp2)−F bonds and CO_(2).Herein,we report the first photocatalytic carboxylation of aryl C−F bonds with CO_(2).The visible‐light photoredox catalysis enables selective carboxylation of strong C(sp2)−F bonds in diverse polyluoroarenes,such as penta‐,tetra‐,and tri‐fluoroarenes under mild conditions,providing a facile access to a series of important polyfluoroaryl carboxylic acids with good yields.In contrast to previous reports of direct capture of polyfluoroaryl radicals,mechanistic studies suggest that the reduction of fleeting polyfluoroaryl radicals into polyfluoroaryl anions might be involved in this transformation,which may open a new avenue for photocatalytic functionalization of aryl C−F bonds.

Microfluidic Immunoprecipitation for Post-Translational Modified Protein Purification

In this paper, we report an antibody functionalized microimmunopreci- pitation （IX IP） method used for enrich lowabundant post-translational modified （PT~ proteins. The device is fabricated by inert, nontoxic and disposable polydimethylsiloxane （PDMS） using a silane-based chemical modification protocol, which yield antibody- terminated PDMS surfaces. In this study, the IX IP device is specifically designed for the purification of carbonylated protein, a representative example here to illustrate the potential applications for any other PTMs, which could be immuno-tagged by specific antibodies. The test model in vitro oxidized bovine serum albumin （BSA） was first derivitized by dinitrophenylhydrazide （DNPH） and then captured by the anti-DNP immobilized on this Ix lP device. The surface functional group mapping was systematically analyzed and validated by fluorescence microscopy. Quantitative study of DNP-derivatized carbonylated protein capture recovery and elution efficiency of the device was also studied. We also envision that this proteome enrichment Ix IP device can be assembled with other lab-on-a-chip components, such as microelectrophoresis or micro-chromatographic devices for follow-up protein analysis. This selective enrichment of modified proteins greatly facilitates the study of low abundant protein biomarkers discovery.

Visible-Light Photoredox-Catalyzed Carbon/Carboxylation of Alkenes with Malonates and CO_(2)

A photoredox-catalyzed cascade carbon/carboxylation of activated alkenes with malonates acetals and CO_(2) has been achieved,leading to a range of functionalized 1,1,3-tricarboxylates in good efficiency under mild reaction conditions.This reaction provides a facile and sustainable method for the synthesis of tricarboxylates by using CO_(2) as the carboxylic source.

一种基于分子结构相似的生物柴油替代燃料模型构建方法

提出了一种通过匹配实际燃料的官能基团来构建生物柴油替代燃料的方法。选取MD5D、正十二烷和1,4-己二烯作为基础燃料,以燃料的重要化学官能基团、H/C比、O/C比和(CH_2)/(CH_3)×[GH_2+CH_3]值等为匹配目标得到各基础燃料的配比,并结合各基础燃料的既有机理构建了生物柴油的替代燃料机理。将获得的替代燃料机理用于理想搅拌反应器燃烧和零维均质着火过程的模拟,模拟结果与实验数据的对比表明,该替代燃料机理能较好地预测生物柴油在不同压力、温度和当量比下的氧化过程和着火特性。本文所提出的生物柴油替代燃料机理构建方法具有一定的通用性,为替代燃料机理的构建提供了新的思路。

采用核磁共振信息的FACE汽油替代燃料机理构建

提出了一种基于核磁共振分析所得的官能基团信息来构建替代燃料模型的新方法。根据核磁共振的光谱信息,定义了五种基本官能基团:烷烃CH_3基团、烷烃CH_2基团、环烷烃CH-CH_2基团、烯烃CH-CH_2基团和芳香烃C-CH基团,并通过匹配实际燃料的这些官能基团来构建FACE汽油替代燃料。选取正丁烷、正庚烷、异辛烷、甲苯、2,5二甲基己烷、甲基环己烷和1-己烯作为备选基础燃料,根据FACE F、FACE G、FACE I和FACE J四种目标燃料的官能基团信息选取合适的替代燃料组分,进而构建相应的替代燃料模型。将所获得的替代燃料机理用于模拟不同初始条件下激波管内的燃料氧化燃烧,模拟结果与实验数据的对比表明,所构建的替代燃料机理能较好地预测FACE汽油在不同温度、压力和当量比条件下的着火特性。

Directing group-assisted transition-metal-catalyzed vinylic C–H bond functionalization

Transition-metal-catalyzed C–H bond activation represents one of the most attractive research areas in organic synthesis.In contrast to the great developments made in directed C–H bond functionalization of arenes,the directing group-assisted activation of non-aromatic vinylic C–H bonds still remains challenging.During the recent years,significant progress has been made in this fascinating field with various functionalized alkenes,heterocycles and carbocycles being obtained.This article will focus on the recent achievements in the field of directing-group-assisted vinylic C–H bond functionalization.

C–H allylation of N-aryl-tetrahydroisoquinolines by merging photoredox catalysis with iodide catalysis

A dual catalytic system, combing visible light photoredox catalysis and iodide catalysis, has been developed for the functionalization of inert C–H bonds. By doing so, radical allylation reactions of N-aryl-tetrahydroisoquinolines(THIQs) were realized under extremely mild conditions, affording a wide variety of allyl-substituted THIQs in up to 78% yields.

Advances and challenges in palladium-catalyzed intermolecular selective allylic C–H functionalization of alkenes

During the past decade, there was increased interest in the functionalization of the allylic C-H bond of alkenes. As opposed to traditional Trost-Tsuji reactions, this strategy avoids the prefunctionalization of the alkene. Many transi- tion metals have been used to promote such processes, and palladium has proved to be one of the best catalysts as it offers great advantages from the point of view of substrate scope and selectivity. Therefore, many groundbreaking re- suits obtained with Pd-catalyzed processes have been re- ported, including allylic C-H oxygenation, amination, al- kylation, and other transformations, which have been well documented in reviews [1].

A facile access for the C–N bond formation by transition metal-free oxidative coupling of benzylic C–H bonds and amides

Using 2,3-dichloro-5,6-dicyano-p-benzoquinone(DDQ)as the oxidant,we communicate an efficient oxidative C–N coupling of benzylic C–H bonds with amides to afford a series of amination products in good yields.A wide range of functional groups as well as various sulfonamides and carboxamides are well tolerated.Moreover,this reaction involves both the challenging C–H functionalization and C–N bond formation.

Palladium-catalyzed R_2(O)P-directed C(sp^2)–H activation

In recent years,transition-metal-catalyzed inert C–H bond activation has developed rapidly and is a powerful protocol for the construction of new C–C or C–X bonds and the introduction of new functional groups.Our group has also developed a series of R2(O)P-directed Pd-catalyzed C–H functionalizations involving olefination,hydroxylation,acetoxylation,arylation,and acylation through an uncommon seven-membered cyclo-palladium pretransition state.Unlike previously used directing groups,the R2(O)P group acts as a directing group and is also involved in the construction of P,-hetero-ligands.

The reductive mechanism of nitrobenzene catalyzed by nine charcoals in sulfides solution

Due to the different sources of charcoals, there are significant differences in their properties. In order to study the catalytic effect of different charcoals to nitrobenzene (NB), we selected nine charcoal-sources to prepare nine charcoals with different properties. The experiments showed that NB could be rapidly reduced by sulfides in the presence of all charcoals. The surface area normalized reduction rate constants of NB increased with H/C and (O+N)/C ratio of charcoals increasing. The difference of catalytic effect for nine charcoals was mainly due to their different species and content of surface functional groups and original organic matter. Based on the theoretical calculation and experimental results, the reaction mechanism of NB catalyzed by charcoal in sulfides solution was analyzed. Some active surface functional groups and original organic matter of charcoals were regarded as the active sites and played an important role in catalyzing the reduction of NB by accelerating the transfer of electrons from sulfides to NB.