可控微波促进对称1,n-亚甲基二酯的环境友好合成

采用可控微波加热技术,在水作溶剂或无溶剂条件下芳甲酸与1,n-二溴代烷发生双酯化反应,“一锅”法高效地合成了系列亚甲基二羧酸酯类化合物.考察了反应温度、时间、碱、溶剂对双酯化产率的影响,在优化实验条件下合成了31种亚甲基二羧酸酯,底物适用范围广,并提出了合理的反应机理.该方法操作简单、时间短,产率较高,同时符合绿色化学的原则.

无溶剂快速合成S-1和TS-1分子筛

Silicalite-1(S-1)和Titanium Silicalite-1(TS-1)沸石分子筛因其良好的疏水性、热稳定性和择形性等特点,作为环境友好的绿色催化剂在工业应用上极具优势和价值.采用无溶剂法成功合成了TS-1分子筛,并利用X-射线衍射仪、全自动比表面和孔隙分析仪、紫外可见光谱仪和扫描电镜等表征仪器研究了晶化时间和硅钛摩尔比对所制备TS-1分子筛的物化性质的影响.结果表明,合成的TS-1沸石分子筛具有较高的结晶度和纯度、均一的晶粒大小、高的比表面积和在分子筛骨架中四配位和六配位的钛物种.无溶剂合成TS-1沸石具有低成本、环境友好和高效的优点,研究将为工业上沸石的规模合成提供一定的理论借鉴.

Wet carbon-based solid acid/NaNO_3 as a mild and efficient reagent for nitration of aromatic compound under solvent free conditions

Nitro aromatic compound can be obtained in high yields via nitration of aromatic compound with wet carbon-based solid acid and NaNO_3 under solvent free oxidation at room temperature.

Highly efficient synthesis of β-amino esters via Mannich-type reaction under solvent-free conditions using ZnCl_2 catalyst

β-Amino esters were synthesized via ZnCl2-catalyzed Mannich-type reaction of imines and malonate esters under solvent-free conditions in 6 min. The β-amino ester was converted into the corresponding aspartic acid derivatives.

Microwave-assisted synthesis of asymmetric thiocarbonohydrazones under solvent-free conditions

Six new asymmetric thiocarbonohydrazones 3a-3f were synthesized from following steps： firstly hydrazine hydrate reacted with carbon disulfide to form thiocarbonohydrazide （1） under microwave irradiation. Then compound （1） reacted with ketone and different aldehydes step by step to give 3a-3f with excellent yields under solvent-free conditions using microwave irradiation. Their structures have been determined by elemental analysis, IR, MS and ^1H NMR data. 2009 Qing Han Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Efficient synthesis of bis(indolyl) methanes catalyzed by(PhCH_2PPh_3)^+Br_3^- under solvent-free conditions

Benzyltriphenylphosphonium tribromide（BTPTB） has been applied as an efficient catalyst for the preparation of bis（indolyl）-methanes （BIMs） via electrophilic substitution of indoles with aldehydes in the absence of solvent.

A convenient synthesis of pyrroles catalyzed by acidic resin under solvent-free condition

A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition.Macroporous strongly acidic styrol resin(D001) as a novel,efficient,cost-effective,and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions.The pyrroles were obtained in high yields in short reaction times.

Oxalic acid catalyzed solvent-free one pot synthesis of coumarins

Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.

Microwave-assisted synthesis of new N^4-[bi-(4-fluorophenyl)-methyl]-piperazine thiosemicarbazones under solvent-free conditions

Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.

An efficient and solvent-free one-pot synthesis of dihydropyrimidinones under microwave irradiation

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives using formic acid as catalyst, from aldehydes, β-ketoester and urea(thiourea) without solvent under the irradiation of microwave is described. Compared with the classical Biginelli reaction, this new method has the advantage of good yields (77–94% for aromatic aldehydes) and short reaction time (3–8 min).

Microwave-assisted chemoselective copper-catalyzed amination of o-chloro and o-bromobenzoic acids using aromatic amines under solvent free conditions

Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported. Some of the advantages of this method are high chemoselectivity, short reaction times, ease of work up procedure and elimination of the need for acid protection. 2009 Published by Elsevier B.V. on behalf of Chinese Chemical Society.

Silica supported sodium hydrogen sulfate(NaHSO_4/SiO_2):A mild and efficient reusable catalyst for the synthesis of aryl-14-H-dibenzo[a,j]xanthenes under solvent-free conditions

A simple and efficient procedure for the preparation of aryl- 14-H-dibenzo [aj]xanthenes by a one-pot condensation reaction of 2-naphthol and aryl aldehydes, in the presence of silica supported sodium hydrogen sulfate （NaHSO4/SiO2） as a catalyst and in the absence of solvent has been developed. The present method offers several advantages such as excellent yields, short reaction time （10-30min）, mild condition, simple work-up, and the use of a cheap and environmentally friendly catalyst with remarkable reusability.

BF_3·OEt_2 Promoted Solvent-free Synthesis of Benzimidazole Derivatives

Differently substituted benzimidazoles have been synthesized in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of BF3·OEt2 as a catalyst. The method is applicable to aromatic, unsaturated and aliphatic aldehydes and to substituted o-phenylenediamines without significant differences.

V(HSO_4)_3 catalyzed chemoselectivity acetylation of alcohols and phenols in solution and under solvent-free conditions

A variety of alcohols and phenols are efficiently acetylated with acetic anhydride in the presence of a catalytic amount of V（HSO4）3 in solution and under solvent free conditions. Mild reaction conditions, high yields of the products, easy procedure and selective acetylation of alcohols and phenols in the presence of amines and thiols are the main advantages of this procedure.

One-pot synthesis of tri- and tetra-substituted imidazoles using sodium dihydrogen phosphate under solvent-free conditions

Sodium dihydrogen phosphate （NaH2PO4） efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.

Regioselective ring opening of epoxides using NH_4SCN/silica sulfuric acid:An efficient approach for the synthesis of β-hydroxy thiocyanate under solvent-free conditions

Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.

Solvent-free Synthesis of Dihydrofuran-fused [60]Fullerene Derivatives by High-speed Vibration Milling

Solvent-free reactions of 1, 3-cyclohexanedione, 5, 5-dimethyl-1, 3-cyclohexanedione, 2, 4-pentanedione and ethyl acetoacetate with C60 in the presence of Mn（OAc）3·2H2O and ceric ammonium nitrate （CAN） under the high-speed vibration milling conditions afforded dihydrofuran-fused C60 derivatives. CAN is the better oxidant than Mn（OAc）3·2H2O in these mechanochemical reactions.

Solvent- and catalyst-free synthesis of dihydropyrimidinthiones in one-pot under focused microwave irradiation conditions

Fifteen dihydropyrimidinthiones have been synthesized by microwave-assisted Biginelli reactions without any solvent or catalyst. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and catalysts.

Solvent Free One-Pot Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles Catalyzed by Secondary Amine Based Ionic Liquid and Defective Keggin Heteropoly Acid

Secondary amine based ionic liquid and defective Keggin type heteropoly acid (HPA) are separately used for efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles assisted by microwave (MW). Eco-friendly solvent free procedure, short reaction time, high yield of products and reusability of catalysts are important features of the synthesis. A comparative study on the efficiency of the two catalysts is reported. This work further demonstrates the alternate use of urea, instead of often used ammonium acetate, as source of nitrogen.

An expeditious and one-pot synthesis of unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles under microwave irradiation and solvent-free conditions

A one-pot synthesis of some unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles via cyclocondensation of benzoylhydrazines with orthoesters under solvent-free and microwave conditions are described here. The reaction is efficiently catalyzed by silica- supported sulfuric acid as it provided the title compounds in high yields and relatively short times. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reactions.