Silicotungstic Acid Modified Bentonite: An Efficient Catalyst for Synthesis of Acetal Derivatives of Aldehydes and Ketones

Acetals and ketals are among the important materials of organic synthesis and as protecting agent of carbonyl functionality. A milder, efficient and green synthesis of acetals and ketals has been developed using Silicotungstic acid modified Bentonite (STA-Ben) as a catalyst. STA-Ben has been synthesized and characterized by various analytical techniques. It has been found to be an efficient and reusable catalyst for the synthesis of acetyl derivatives in excellent yields. In order to elucidate the efficiency of the STA-Ben as catalyst, reaction has also been performed using various catalysts. The reaction conditions (time and amount of catalyst) have been optimized using various catalysts. The products of the various reactions have been characterized by FT-IR, NMR.

Ambient Ionic Liquids Used in the Reduction of Aldehydes and Ketones

The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.

A simple and efficient method for solvent-free iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid by grinding method

Green,mild and efficient iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid in the solidstate by grinding under solvent-free conditions at room temperature.This method provides several advantages such as environmentally friendly,short reaction times,high yields,non-hazardous and simple work-up procedure.

Oxidation of benzyl alcohols to ketones and aldehydes by O3 process enhanced using high-gravity technology

In this study,a practical process for ozonization of benzyl alcohols to ketones and aldehydes in a rotating packed bed(RPB-O3)reactor has been developed.Using 1-phenylethanol as a model reactant,the performance of RPB-O3 process in different solvents has been compared with the commonly used stirred tank reactor(STR-O3).Ethyl acetate was the optimum solvent for the conversion of 1-phenylenthanol to acetophenone in RPB-O3 process,with 78%yield after 30 min.In a parallel STR-O3 experiment,the yield of acetophenone was50%.Other experimental variables,i.e.O3 concentration,reaction time,high-gravity factor and liquid flow rate were also optimized.The highest yield of acetophenone was obtained using O3 concentration of 80 mg·L-1,reaction time of 30 min,high gravity factor of 40 and liquid flow rate of 120 L·h-1.Under the optimized reaction conditions,a series of structurally diverse primary and secondary alcohols was oxidized with(19%–92%)yield.The ozonization mechanism was studied by Electron Paramagnetic Resonance(EPR)spectroscopy,monitoring the radical species formed upon self-decomposition of O3.The characteristic quadruple peak with the 1:2:2:1 intensity ratio that corresponds to hydroxyl radicals(·OH)was observed in the electron paramagnetic resonance(EPR)spectrum,indicating an indirect oxidation mechanism of alcohols via·OH radical.

Efficient Synthesis of Dicycloalkenopyridines:One-pot Multicomponent Condensation of Aldehydes with Cyclic Ketones

Under microwave irradiation, the one-pot multicomponent condensation reaction of three moles of aromatic aldehydes with two moles of cyclic ketones having free a,a＇-methylene positions such as cyclopentanone or cyclohexanone in the presence of ammonium acetate and acetic acid afforded dicycloalkenopyridines with two a-arylidene groups in high yields. Under the similar reaction condition, the reaction of aromatic aldehydes with 1-tetralone having only one a-methylene position alternatively resulted in 10-aryl-2,3：5,6-dibenzoacridines.

Mechanochemical Reaction of Aromatic Ketones and Aldehydes in the Presence of Zn-ZnCl_2

The solvent-free reactions of aromatic ketones and aldehydes in the presence of Zn-ZnCl2 were performed with the aid of high-speed vibration mill, Retsch MM200 mixer mill and Retsch RM100 mortar grinder to give pinacol coupling and reduction products in varying yields.

Cu-catalyzed deoxygenative gem-hydroborylation of aromatic aldehydes and ketones to access benzylboronic esters

Organoboron compounds are widely used in synthetic chemistry,pharmaceutical chemistry and material chemistry.Among various organoboron compounds,benzylboronic esters are unique and highly reactive,making them suitable benzylation reagents.At present,the synthetic methods for the syntheses of benzylboronic esters are still insufficient to meet their demands.It is necessary to develop novel and practical methods for their preparation.In this work,a novel copper‐catalyzed deoxygenative gem‐hydroborylation of aromatic aldehydes and ketones has been developed.This direct and operationally simple protocol provides an effective approach for the synthesis of a variety of primary and secondary benzylboronates,in which broad functional group tolerance was presented.Widely available B2pin2(pin=pinacol)was used as the boron source and alcoholic proton was applied as the hydride source.

Acetic acid assisted cobalt methanesulfonate catalysed chemoselective diacetylation of aldehydes

Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions. After reaction, cobalt methanesulfonate can be easily recovered and reused many times. The reaction was mild and efficient with good to high yields.

Cobalt Sulfate as a Recyclable Catalyst for Chemoselective Synthesis of Diacetates from Aldehydes

A mild and efficient method for diacetylation reaction was developed,by which diacetate could be achieved through the reaction of aldehyde with acetic anhydride,in the presence of cobalt sulfate,with an admirable yield,at room temperature,without solvent.The catalyst could be recycled six times without a distinct loss of activity.

PHOTOPOLYMERIZATION OF PROPARGYL ACETATE WITH MICHLER’S KETONE AS PHOTOINITIATOR

Photopolymerization of propargyl acetate (PAT) with Michler's ketone (MK) asphotoinitiator in benzene has been investigated for the first time. Some features of the PATphotopolymerization with MK as photoinitiator is described.

Expression of Acetaldehyde Dehydrogenase Gene Increases Hydrogen Production and Acetate Consumption by <i>Rhodobacter sphaeroides</i>

Rhodobacter sphaeroides RV (RV) produces high yields of hydrogen from organic acids in the presence of light. The hydrogen production from acetate is lower than that from lactate, probably because of its low ability to metabolize acetate. In this study, gene of acetaldehyde dehydrogenase (ACDH, EC 1.2.1.10) that catalyzes the reversible conversion of acetaldehyde and CoA to acetyl-CoA with the concurrent reduction of NAD to NADH, is overexpressed in the RV strain. The produced acetyl-CoA can be oxidized to carbon dioxide in the tricarboxylic acid (TCA) cycle, wherein electrons are generated and used for hydrogen production. The byproduct NADH can be used as reducing agent for acetate to produce acetaldehyde by acetate dehydrogenase. The recombinant RV strain (RVAC) expressing the ACDH gene showed ACDH activity with a specific activity of 3.2 mU/ mg, and the RV and the recombinant RV strain that harbored the intact (empty) plasmid pLP-1.2 (RVI) showed no detectable ACDH activity. The hydrogen yields of the RVAC strain from 21-mM acetate were 1.5-fold higher than that of the wild type RV strain and also that of the RVI strain. In contrast, hydrogen yield from 21-mM lactate was 30% lower than that in the control strains.

Polyoxometalates based compounds for green synthesis of aldehydes and ketones

Molecular oxygen within Polyoxometalates(POMs)based compounds are ideal oxidants with high atom economy and its use results in the production of water as the only byproduct.Significant progress has been made in the development of catalytic methods for aerobic alcohol oxidation to have aldehydes and ketones with POMs based compounds.They are alternative to the use of traditional hypervalent iodine catalyst systems which are with molecular oxygen as a terminal oxidant.Further,POMs based catalysts can be applied to catalytic reactions with different modes of energization such as thermocatalysis,photocatalysis and electrocatalysis.This review summarizes the frontier advances in polyoxometalates for catalytic alcohol selective oxidation in thermocatalytic,electrocatalytic,and photocatalytic applications.The three advantages of POM catalysts in terms of performance,economy,and environmental protection are highlighted.These include the use of sol-gel and electrostatic assembly methods to increase the reaction surface area,reduce the use of precious metals,and improve the stability of POMs catalysts.The field of selective alcohol oxidation is advanced.Finally,the challenges of preparing more efficient and“green”catalysts are presented.

抑制AKR1B1表达通过调控巨噬细胞极化改善大鼠脓毒症所致急性肺损伤

目的 探究抑制醛酮还原酶1成员B1(AKR1B1)对脓毒症所致急性肺损伤(ALI)模型大鼠的影响及作用机制。方法 将60只SD大鼠按随机数字法分为对照组、模型组、低剂量组、高剂量组,每组15只,除对照组的其余3组大鼠以盲肠结扎穿刺法制备脓毒症ALI模型,低、高剂量组大鼠分别按照50 mg/kg、100 mg/kg灌胃依帕司他,1次/d,连续6周。6周后,免疫组织化学染色检测对照组和模型组大鼠肺组织内AKR1B1表达;ELISA法测定4组大鼠支气管肺泡灌洗液(BALF)和血清中炎性细胞因子肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)及IL-6水平;天平称量4组大鼠左侧肺组织湿质量(WW)与干质量(DW),计算WW/DW比值;苏木精-伊红(HE)染色法观察4组大鼠肺组织病理形态变化,TUNEL染色检测4组大鼠肺组织细胞凋亡情况;流式细胞分析术检测4组大鼠BALF中M1型(F4/80^(+)CD86^(+))与M2型(F4/80^(+)CD206+)巨噬细胞表达情况;实时荧光定量PCR测定4组大鼠肺组织内M1型巨噬细胞标志基因与M2型巨噬细胞标志基因的表达水平。结果 模型组大鼠肺组织内AKR1B1表达较对照组增加(P<0.05);与模型组比较,低、高剂量组大鼠血清与BALF中TNF-α、IL-1β及IL-6含量均降低(P<0.05),右侧肺组织WW/DW值下降(P<0.05),肺组织病理损伤得到明显改善,炎症细胞浸润减少,TUNEL阳性细胞率减少(P<0.05),BALF中F4/80^(+)CD86^(+)阳性表达率降低、(F4/80^(+)CD206+)阳性表达率升高(P<0.05),肺组织内M1型巨噬细胞标志基因TNF-α、iNOS、IL-6的mRNA相对表达量均下调(P<0.05),而M2型巨噬细胞标志基因TGF-β、Arg-1、IL-10的mRNA相对表达量均上调(P<0.05)。结论 AKR1B1在脓毒症所致ALI大鼠肺组织中表达升高,而抑制AKR1B1通过抑制巨噬细胞向M1型转化并促进向M2型转化来减轻大鼠肺损伤。

广西环境空气中醛酮类化合物污染特征研究

为探究广西醛酮类化合物的污染状况,选择2022年9—10月和2023年5—6月臭氧质量浓度较高时段,分别对广西臭氧质量浓度较高的典型城市如南宁、桂林、北海、贵港、百色、贺州和来宾等城市的环境空气中醛酮类化合物进行监测,分析不同城市醛酮类化合物的季节特征、浓度水平、组分特征以及臭氧生成潜势(OFP),并利用比值法对醛酮类化合物的来源进行初判。研究结果表明,南宁、桂林和来宾等典型城市醛酮类化合物质量浓度季节特征与臭氧一致,均表现为秋季(2022年9—10月)高于春夏季(2023年5—6月);监测期间,广西醛酮类物质平均质量浓度为23.64μg/m~3,其中贺州最高,为31.30μg/m~3,北海最低,为13.58μg/m~3,与其他城市相比,广西各市醛酮类化合物质量浓度处于中等偏下水平;各城市的醛酮类化合物化学组分中甲醛占比最高,占比为43.8%(贺州)~58.2%(贵港);各城市OFP值为77.32μg/m~3(北海)~159.35μg/m~3(贵港),其中甲醛对OFP贡献最大,贡献占比为52.1%(北海)~70.1%(贵港)。各城市甲醛和乙醛的质量浓度比值(C1/C2)为2.55~3.22,醛酮类化合物主要以机动车尾气排放以及人为源碳氢化合物氧化为主,其中北海和百色的C1/C2均在2.6左右,受机动车尾气等人为源影响更明显,在臭氧污染期间须加强机动车尾气等人为源管控。

中山市大气中醛酮类化合物的污染特征研究

为探究中山市大气中醛酮类化合物污染特征,于2022年6月份、12月份,利用苏玛罐采样、大气预浓缩-气相色谱质谱联用技术对中山市大气中的醛酮类化合物进行采样分析,并对大气中醛酮类化合物的主要组成、浓度特征进行了分析研究。研究表明:中山市大气中检测出15种醛酮化合物,总质量浓度为54.16μg/m^(3),浓度占比较大的为甲醛、乙醛、丙酮和2-丁酮,它们的质量浓度关系为2-丁酮>丙酮>乙醛>甲醛,该4种化合物共占醛酮类化合物总质量浓度的82.47%。同时分析了甲醛、乙醛、丙酮和2-丁酮四种醛酮类化合物的臭氧生成潜势(OFP),甲醛和乙醛臭氧生成潜势的贡献较大,二者总占比为74.72%。

渭南市大气中醛酮类化合物的污染特征分析

2022年6月—2023年5月在渭南市师范学院挥发性有机物组分站获得醛酮类项目的监测数据,围绕渭南市醛酮类化合物的浓度水平、组成特征、变化趋势进行探究,用PMF模型识别和量化出醛酮类化合物在臭氧前体物中的贡献。对识别出的组份进行排序并逐一分析高组分物质的主要来源,找到污染源头,为VOCs污染减排提供相关科学技术支持。

甲醇制烯烃工业装置水系统运行问题研究及改进措施

水系统作为甲醇制烯烃工业装置重要组成部分,解决其堵塞换热设备清洗频繁、塔盘压差高、浓缩水醛酮高难以有效利用等难点问题,对装置长周期运行具有重要意义。基于1.8×10^(6) t/a甲醇制烯烃工业装置自开车以来数年间的水系统运行情况,分析水系统问题的成因,通过前端预防、过程控制和末端治理三重手段解决了水系统存在的一系列行业共性问题。

溶液吸收-高效液相色谱法测定环境空气中16种醛酮类化合物

本研究建立溶液吸收-高效液相色谱法测定环境空气中16种醛酮类化合物的方法。色谱柱为SymetryShield RP18(4.6 mm×250 mm×5.0μm),流动相为乙腈-水二元梯度洗脱,采用紫外检测器。实验结果表明,16种醛酮类化合物在0~4.0 mg/L浓度范围内具有较好的线性关系,相关系数均≥0.999,方法检出限为0.001~0.002 mg/m^(3),相对标准偏差RSD为1.8%~6.4%,加标回收率范围为83%-102%,并用该方法测定实际环境空气样品,均满足方法要求。结果确认本实验室具备开展测定环境空气中16种醛酮类化合物的能力。

袋式法检测车内非金属部件醛酮类物质的测量不确定度评定

根据GB/T 39897-2021中袋式法检测车内非金属部件醛酮类物质含量,对检测结果进行不确定度评定和影响不确定度的各个因素进行分析,结果表明:不确定度主要来源于标准工作曲线拟合、测量重复性和仪器定量测量重复性。