Phase Transfer Catalysts

An effective procedure for the synthesis of α-hydroxyphenylacetic acid with cyclodextrin (CD) catalysts was developed. The phase-transfer catalyst types, catalyst loadings, reaction times, reaction temperatures, and substrate molar ratios were investigated to optimize the reaction conditions. In addition, the factors that affect the reaction were studied, and the relationship between benzaldehyde and β -cyclodextrin (β -CD) was analyzed through 2D-ROESY. The equilibrium constant when β -CD was used as the catalyst was calculated.

10p tudichquannguyet 29-11-2021 8 1   Download

Aripiprazole is a widely used antipsychotic approved by the FDA (Food and Drug Administration) in 2002. Methods for preparation of aripiprazole mainly involve the use of expensive and toxic solvents, and the reaction time can be even several hours long.

6p tocectocec 25-05-2020 9 0   Download

New optically active bis-quaternary ammonium salts were synthesized and applied to catalytic asymmtric alkylation of tert-butyl glycinate benzophenone Schiff base to provide a chiral α-amino acid derivative with 54% ee.

3p giesumanh 13-11-2018 22 1   Download

Six 5-arylidene-3-methylrhodanine derivatives were synthesized by the crossed aldolization of aromatic aldehydes with 3- methylrhodanine using 1-butyl-3-methylimidazolium chloride ([BMI]Cl) as phase transfer catalyst in water.

6p baoanhlib 24-01-2017 53 3   Download

Three-phase fixed-bed reactors are very often encountered in industrial applica- tions for carrying out different chemical reactions between gaseous and liquid reactants on porous catalysts, in processes such as, hydrogenation, hydrotreating, purification, the Fischer–Tropsch synthesis, and in many others. These processes form the basis for production of a large variety of intermediate and ultimate products in refinery, bulk and fine chemistry, in manufacture of monomers, sol- vents, pharmaceuticals, fragrances, fuels, food additives, etc....

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Much faster alkylation of enolate anions can often be achieved in dimethylformamide (DMF), dimethylsulfoxide (DMSO) or 1,2-dimethoxyethane (DME) than in the usual protic solvents. The presence of hexamethylphosphoramide (HMPA) or a triamine or tetramine can also enhance the rate of alkylation. This is thought to be because of the fact that these solvents or additives solvate the cation, but not the enolate, thereby separating the cation–enolate ion pair. This leaves a relatively free enolate ion, which would be expected to be a more reactive nucleophile than the ion pair.

0p taisaocothedung 12-01-2013 49 3   Download