A mild and efficient synthetic protocol for Ferrier azaglycosylation promoted by ZnCl2/Al2O3

An improved method for the Ferrier sulfonamidoglycosylation of tri-O-acetyl-d-glucal with different N-nucleophiles has been developed. ZnCl₂ impregnated on activated alumina acts as an excellent reagent system for the conversion of 3,4,6-tri-O-acetyl-d-glucal into 2,3-unsaturated-N-pseudoglycals with good yields and preferential α-anomeric selectivity.     

Direct alkylation of aromatics using alcohols in the presence of NaHSO4/SiO2

Simple and efficient procedure for alkylation of aromatics from alcohols in the presence of NaHSO₄/SiO₂ was developed. Various triaryl methanes were obtained in good yields in short reaction time. For instance the reaction of mesitylene with benzhydrol in the presence of NaHSO₄/SiO₂ gave the corresponding triaryl methane in a quantitative yield. NaHSO₄/SiO₂ was regenerated by simple treatment and could be recycled eight times without activity loss.     

An efficient and mild carboxylation of multiwall carbon nanotubes using H2O2 in the presence of heteropolyacid

A clean,fast,and facile oxidation of multiwalled carbon nanotubes（MWCNTs） by H₂O₂/heteropolyacid(H₃PW₁₂O₄₀) gave highly carboxylated MWCNTs under mild conditions,at a conveniently accessible temperature.After an easy workup,the product was characterized by SEM,XRD,and FT-IR.     

Synthesis of 2-oxazolines and related N-containing heterocycles using [Et2NSF2]BF4 as a cyclodehydration agent

The preparation of 2-oxazolines and related N-containing heterocycles from the corresponding hydroxyamides using XtalFluor-E ([Et₂NSF₂]BF₄) as a cyclodehydration agent is described. A wide range of heterocycles are obtained under mild conditions in good to excellent yields.     

An efficient synthesis of β-hydroxyethylpyrazoles from propylene and styrene oxide using Cs2CO3

Bases such as caesium carbonate efficiently catalyze the regioselective ring opening of propylene and styrene oxide with various substituted pyrazoles.     

Synthesis of 1,2-disubstitued benzimidazoles using SiO2/ZnCl2

A general and easy method for the synthesis of several 1,2-disubstituted benzimidazoles using SiO₂/ZnCl₂ and solvent-free conditions is described. This efficient and improved method furnishes selectively and in good yields the corresponding 1,2-bis(organyl)-benzimidazoles starting from o-phenylenediamine and aromatic or aliphatic aldehydes. The catalytic system was re-used up three times and the use of focused microwaves accelerates the reaction.     

Synthesis of arylaminotetrazoles by ZnCl2/AlCl3/silica as an efficient heterogeneous catalyst

Abstract  

Arylaminotetrazoles were efficiently synthesized from secondary arylcyanamides by application of ZnCl₂/AlCl₃/silica as a reusable heterogeneous Lewis acid catalyst. 5-Arylamino-1H-tetrazoles can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while with electron-releasing groups 1-aryl-5-amino-1H-tetrazoles will be produced. The former isomer is also produced within longer reaction times (~20 h) even with electron-releasing groups.     

The cathodic reduction of HCl dissolved in LiCl+KCl+ZnCl2 melts

The cathodic reduction of HCl dissolved in molten LiCl+KCl eutectic with the presence of up to 19 mol %ZnCl₂ was investigated chronopotentiometrically and voltammetrically. On glassy carbon electrodes the reduction is a reversible, one-electron charge transfer forming soluble product and without kinetic complications. While the ZnCl₂ causes an increase in solubility of the HCl, it also causes a decrease in the diffusion coefficient of the reduced species. Results obtained when using a platinum working electrode contrasted with those for the same solvent when using a glassy carbon electrode. The difference is probably due to adsorption occurring on the working electrode, the degree of adsorption approximating to monolayer coverage. The adsorption can be explained by either an AR, SR model or an SAR model and while the accuracy is insufficient to enable differentiation betwen the two, the latter mechanism is favoured.     

An unusual oxidation-dealkylation of 3,4-dihydropyrimidin-2(1H)-ones mediated by Co(NO3)2·6H2O/K2S2O8 in aqueous acetonitrile

4-Aryl-6-methyl-3,4-dihydropyrimidin-2(1H)-one (DHPM) scaffolds of Biginelli type were oxidized using Co(II)/S₂O₈²⁻ and the reaction afforded 6-unsubstituted pyrimidin-2(1H)-ones through an unprecedented dealkylation process. 4-Alkyl DHPMs under similar conditions afforded yet another unusual product, ethyl tetrahydropyrimidin-2,4(1H,3H)-dione-5-carboxylate.     

ZnCl2 catalyzed efficient synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole

New methods for the synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole have been described. No cyclizations took place in the absence of ZnCl₂. 1,3,4-Thiadiazoles are formed in the presence of ZnCl₂ alone, whereas oxadiazoles are produced when a base such as Et₃N or KOH was used along with ZnCl₂. % Yields are optimized.     

Chemical fixation of CO2 with highly efficient ZnCl2/[BMIm]Br catalyst system

The chemical fixation of CO₂ with mono-substituted terminal epoxides or cyclohexene oxide to form cyclic carbonates under the ZnCl₂/[BMIm]Br catalyst system without using additional organic solvents was achieved in excellent selectivity (>98%) and TOF (5410 h⁻¹) and the catalyst could be used six times almost without losing its catalytic activity and selectivity. Besides, the pure cis-cyclic carbonate of cyclohexene oxide was obtained in this catalyst system.     

ZnCl2 promoted efficient,one-pot synthesis of 3-arylmethyl and diarylmethyl indoles

Anhydrous ZnCl₂ mediated convenient, one-pot synthesis of 3-arylmethyl and diarylmethyl indoles was accomplished in good yields. Under reaction condition, in situ formation of kinetically stable bis(indolyl)methane product was identified. Its subsequent conversion to the thermodynamically stable 3-diarylmethyl indole at elevated temperature and pressure was confirmed by carrying out pressure tube reaction with bis(indolyl)methane.     

氯化锌催化下C60与枞酸的反应

拟利用枞酸分子中的非同环共轭二烯在氯化锌作用下异构化成具有同环共轭二烯的海松酸结构, 再与C₆₀进行Diels-Alder加成反应, 预测可以得到Diels-Alder加成产物. C₆₀、枞酸及氯化锌在邻二氯苯溶剂中, 在氮气保护下于175～180 ℃反应8 h, 将反应物洗涤后进行硅胶柱层析分离, 采用FT-IR, ¹³C NMR, ¹H NMR和MALDI-TOF-MS等分析方法对反应主要产物进行结构测定, 却意外发现得到C₆₀与枞酸的加成过程中发生了脱羧脱氢反应且产物含有芳环的化学结构.     

Ionic liquid: An efficient and recyclable medium for the synthesis of fused six-membered oxygen heterocycles

The investigation for replacement of organic solvents in chemical synthesis is a growing area of interest due to increasing environmental issues. The use of ionic liquid salts as solvents and catalysts in organic reactions has gained extensive interest. Ionic liquids provided a new environmentally benign and improved alternative to traditional methods in modern synthetic chemistry. The aim of present review is to focus on the applications of ionic liquids for the synthesis of fused six-membered oxygen heterocycles.     

AlCl3(ZnCl2,MgCl2)对Sm2O3的氯化效果及电化学行为

研究了AlCl_3(ZnCl_2、MgCl_2)对Sm_2O_3的氯化效果以及Sm_2O_3在Li Cl-KCl-AlCl_3(ZnCl_2、MgCl_2)熔盐体系中的电化学行为。在Li Cl-KCl-Sm_2O_3熔盐中加入AlCl_3(ZnCl_2、MgCl_2)后,ICP测量结果表明,AlCl_3体系中Sm(Ⅲ)离子的浓度最高,并且在923 K时达到最大值;固相反应表明,AlCl_3氯化Sm_2O_3生成SmCl_3,而Sm_2O_3和ZnCl_2(MgCl_2)反应生成Sm OCl。电化学行为表明,AlCl_3体系中观察到了两种Al-Sm的合金峰,而ZnCl_2体系中只观察到Zn-Sm金属间化合物的形成峰,MgCl_2体系中没有形成合金。在-6.25 A·cm~(-2)下,W电极上恒电流电解2 h获得了Al-Li-Sm合金,经XRD分析,合金为Al_2Sm相。     

AlCl3(ZnCl2,MgCl2)对Sm2O3的氯化效果及电化学行为

研究了AlCl₃(ZnCl₂、MgCl₂)对Sm₂O₃的氯化效果以及Sm₂O₃在LiCl-KCl-AlCl₃(ZnCl₂、MgCl₂)熔盐体系中的电化学行为。在LiCl-KCl-Sm₂O₃熔盐中加入AlCl₃(ZnCl₂、MgCl₂)后,ICP测量结果表明,AlCl₃体系中Sm(Ⅲ)离子的浓度最高,并且在923 K时达到最大值;固相反应表明,AlCl₃氯化Sm₂O₃生成SmCl₃,而Sm₂O₃和ZnCl₂(MgCl₂)反应生成SmOCl。电化学行为表明,AlCl₃体系中观察到了两种Al-Sm的合金峰,而ZnCl₂体系中只观察到Zn-Sm金属间化合物的形成峰,MgCl₂体系中没有形成合金。在-6.25 A·cm^-2下,W电极上恒电流电解2 h获得了Al-Li-Sm合金,经XRD分析,合金为Al₂Sm相。     

An efficient method for chlorination of alcohols using PPh3/Cl3CCONH2

A new and convenient method for the chlorination of alcohols utilizing PPh₃/Cl₃CCONH₂ is addressed. Various alcohols could smoothly be converted into their corresponding alkyl chlorides in high yield under mild conditions with short reaction times. A mechanism is disclosed with the evidence of inversion of configuration of the analogous alkyl chloride derived from R-(−)-2-octanol.     

ZnCl2、KOH和HNO3改性MWCNT对苯酚的吸附行为研究

通过扫描电子显微镜、X射线衍射仪、N₂吸附分析仪及Boehm滴定法获得ZnCl₂、KOH和HNO₃化学处理对高纯多壁碳纳米管的结构和表面含氧官能团的影响,通过批处理实验考察吸附条件（吸附时间、初始浓度、温度）对处理前后的碳纳米管吸附苯酚行为的影响,并采用准一级、准二级、Evolich动力学模型和热力学方程拟合其吸附数据,分析其动力学行为、热力学行为和吸附机理。结果表明,虽然ZnCl₂、KOH和HNO₃化学处理法均未对碳纳米管BET比表面积产生显著影响,但会影响其表面化学性质（即,对于ZnCl₂和KOH化学处理降低表面羧基、内酯基含量和增大碱性官能团量,而对于HNO₃化学处理可以增大表面羧基、内酯基含量,而碱性官能团略有增加）;改性处理影响碳纳米管去除苯酚效率：由于ZnCl₂和KOH改性处理降低碳纳米管表面羧基量,故其提高了苯酚去除率,而HNO₃处理则略减小碳纳米管的苯酚去除率,可能是由于碳纳米管结构和表面化学性质共同影响所致;碳纳米管的苯酚去除率均随苯酚溶液初始浓度的增大而减小;高温不利于吸附;热力学研究发现碳纳米管吸附苯酚过程是自发的和放热的,属于物理吸附;动力学研究表明,吸附过程符合准二级动力学方程。通过ZnCl₂和KOH化学处理,可以显著提高碳纳米管对苯酚的吸附性能。     

Electrophilic cyclization of N-alkenylamides using a chloramine-T/I2 system

A new protocol for the cyclization of N-alkenylamides using chloramine-T and iodine is described. When N-alkenylsulfonamides are treated with chloramine-T and iodine, three- to six-membered N-heterocycles are obtained with complete stereoselectivity. The method is compatible with the cyclization of the allylbenzamide or allylbenzthioamide to afford an oxazoline or thiazoline derivative, respectively. Mechanistic studies indicate that the chloramine-T/I₂ system functions as an effective iodonium species.     

PEG3400-Cu2O-Cs2CO3: an efficient and recyclable microwave-enhanced catalytic system for ligand-free Ullmann arylation of indole and benzimidazole

A mild, simple and efficient microwave-enhanced copper-catalyzed protocol for N-arylation using high molecular weight poly(ethylene glycol) (PEG₃₄₀₀) as a solvent is reported. Indole and benzimidazole have been N-arylated in the presence of cuprous oxide, cesium carbonate, and PEG₃₄₀₀, under microwave activation, with no supplementary ligands. Simple treatment by precipitation in Et₂O and filtration provided the expected product after evaporation and recovery of the catalytic system as a precipitate. The recovery and one successful re-use of the catalytic system is also described. The formation of copper-based nanoparticles was demonstrated by TEM analysis.