Dehydration Reactions in Water. Surfactant-type Brønsted Acid-catalyzed Dehydrative Etherification, Thioetherification, and Dithioacetalization in Water
作者:Shu Kobayashi、Shinya Iimura、Kei Manabe
DOI:10.1246/cl.2002.10
日期:2002.1
Dehydration reactions such as etherification, thioetherification, and dithioacetalization are efficiently catalyzed by a surfactant-type Bronsted acid in water.
Dehydration reactions in water have been realized by a surfactant-type catalyst, dodecylbenzenesulfonic acid (DBSA). These reactions include dehydrative esterification, etherification, thioetherification, and dithioacetalization. In these reactions, DBSA and substrates form emulsion droplets whose interior is hydrophobic enough to exclude water molecules generated during the reactions. Detailed studies on the esterification revealed that the yields of esters were affected by temperature, amounts of DBSA used, and the substrates. Esters were obtained in high yields for highly hydrophobic substrates. On the basis of the difference in hydrophobicity of the substrates, unique selective esterification and etherification in water were attained. Furthermore, chemospecific, three-component reactions under DBSA-catalyzed conditions were also found to proceed smoothly. This work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.
Hydrophobic Polymer-Supported Catalyst for Organic Reactions in Water: Acid-Catalyzed Hydrolysis of Thioesters and Transprotection of Thiols
作者:Shinya Iimura、Kei Manabe、Shū Kobayashi
DOI:10.1021/ol026906m
日期:2003.1.1
A hydrophobic polystyrene-supported sulfonic acid was found to be effective for hydrolysis of thioesters in pure water. It was revealed that the catalyst was much superior to other Bronsted acid catalysts. Transprotection of thiols from thioesters to thioethers has been successfully performed in water using this catalytic system.
Synthesis of symmetrical and unsymmetrical alkyl disulfides with attached flavin analog for formation of self-assembled monolayers on gold
作者:Suk-Wah Tam-Chang、James C Mason
DOI:10.1016/s0040-4020(99)00836-4
日期:1999.11
We describe a general procedure for the synthesis of symmetrical and unsymmetrical disulfides with an attached flavin analog. Self-assembled monolayers of these disulfides on gold have potential applications as pH sensors and electrocatalysts, The use of a self-assembled monolayer prepared from one of these disulfides in probing the pH Of solutions is reported. (C) 1999 Elsevier Science Ltd. All rights reserved.