From Catalysis in Application

S. Koujout and D.R. Brown
Centre for Applied Catalysis, Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield HD1 3DH, UK

1 INTRODUCTION

In the recent drive to prepare mesoporous solid acid catalysts for liquid phase processes, a popular approach has been to tether sulfonic acid groups to mesoporous silica supports.1 &2 The preferred method for functionalising has been to incorporate 3-mercaptopropylsilane in the synthesis gel for the mesoporous silica, and then, after precipitation and isolation, to oxidise the thiol group to sulfonic acid.2 These materials have exhibited relatively high catalytic activity and the approach is emerging as one of the most successful for preparing acid forms of porous silica.

It is instructive to compare these new supported sulfonic acids with the well established polystyrene-supported sulfonic acids which have been used as acid catalysts in reactions such as MTBE synthesis for many years. 3 5 These sulfonated polymers are generally thought to be limited in application because of their relatively low acid strength and poor stability at reaction temperatures above 150 C.4 &5 However, we and others have shown how sulfonated polystyrene resins with high levels of sulfonation (above the stoichiometric level of one sulfonic acid group per styrene unit) exhibit significantly higher acid strengths and catalytic activities than resins with the more usual, roughly stoichiometric, level of sulfonation. 5 11 An important aspect of this is that these higher acidities and activities are observed not only in dry resins, but also in the presence of water,...

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Catalysts and Initiators
Catalysts and initiators start or promote chemical reactions used to produce organic chemicals, polymers and adhesives.
Inorganic Chemicals and Compounds
Inorganic chemicals, inorganic salts and inorganic compounds are substances of mineral origin that do not contain carbon in their molecular structure.
Monomers, Intermediates, and Base Polymers
Monomers, intermediates, and base polymers are starting raw materials or binders for the production of compounded resins, plastics and elastomers, paints or organic coatings, adhesives and sealants;
Ion Exchange Resins
Ion exchange resins are typically porous, cross-linked polystyrene beads that trap ions (iron, manganese, etc.) in a solution, usually water, while releasing (or exchanging) other ions (sodium, etc.). They are used to reduce water hardness.

Topics of Interest

A.K. Aboul-Gheit, S.M. Abdel-Hamid and A.E. Awadallah Process Development Division, Egyptian Petroleum Research Institute, Nasr City, P.O. Box 9540, Cairo 11787, Egypt; E-mail: 1 INTRODUCTION The...

The early work on the sulfonation of aliphatic compounds is described in Suter's book;1 there are also several general references 2 6 which include the use of chlorosulfonic acid in the sulfonation of...

5 Phenols Phenols readily undergo sulfonation due to the electron-donating (+M, -I) property of the hydroxyl group and to the possible formation of intermediate sulfate esters which rapidly rearrange...

1 Introduction Sulfonation is a bimolecular electrophilic substitution reaction (S E2) which may be depicted in general terms as shown (Equation 1): (1) The general S E2 mechanism involves addition...

9 Aromatic Amines and Related Compounds 9.1 Anilines Aromatic amines are often protected before treatment with chlorosulfonic acid to avoid decomposition; the protection may be achieved by...