%0 Journal Article
%T ZSM-5-SO3H: An Efficient Catalyst for Acylation of Sulfonamides Amines, Alcohols, and Phenols under Solvent-Free Conditions
%A Ahmad Reza Massah
%A Roozbeh Javad Kalbasi
%A Mahdiehsadat Khalifesoltani
%A Fariba Moshtagh Kordesofla
%J ISRN Organic Chemistry
%D 2013
%R 10.1155/2013/951749
%X Sulfonamides amines, alcohols, and phenols were efficiently acylated with carboxylic acid anhydrides and chlorides using ZSM-5-SO3H as catalyst under mild and solvent-free conditions. Also, direct esterification of alcohols with carboxylic acids occurred readily in the presence of this catalyst. Different types of amides and esters were obtained in moderate to high yields and purity after a simple workup. No chromatographic separation is needed for isolation of the acylated product. The catalyst was recovered and reused for up to four times without a noticeable decrease in catalytic activity. 1. Introduction The acylation of alcohols, phenols, and amines is one of the most frequently used processes in organic chemistry. It provides an economical and efficient method for protecting hydroxyl groups during oxidation, peptide coupling, and glycosidation reactions [1]. Acylation is usually carried out by treatment of an alcohol or amine with carboxylic acid chlorides or anhydrides in the presence of an acid or a base catalyst in a suitable organic solvent. Basic catalysts such as 4-(dimethylamino) pyridine (DMAP) [2], tributylphosphines [3], 4-pyrrolidinopyridine [4], and acidic catalysts like Sc(OTf)3 [5], Gd(OTf)3 [6], lanthanide(III) tosylates [7], RuCl3 [8], Al(HSO4)3 [9], Bi(OTf)3 [10], and LiClO4 [11] catalyze acylation reactions with acid chloride or anhydride as the acylating agent under homogenous conditions. Use of homogenous catalysts poses serious problems, such as difficulty in the separation and recovery of the catalyst, disposal of the spent catalyst, and corrosion problems. Solid acid catalysts such as commercial zeolites [12] and montmorillonite K-10 or KSF clay [13] and ZnO [14] have been reported for the acylation of alcohols with acetic anhydride. Though acylation of alcohols can also be brought about by the action of Lewis acid reagents in conjunction with carboxylic acids, the Lewis acid is destroyed in the workup procedure resulting in substantial waste production [15]. Some heterogenized homogenous catalysts have also been reported for the acylation of alcohols and amines [16]. Most of the methods have some disadvantages, such as exothermic reaction, formation of by-products, complicated conditions, and excess acylating agents, and require longer reaction times, use of halogenated solvents, and expensive moisture-sensitive toxic reagents. Apart from these difficulties, some of the above methods do not satisfy the requirements of green synthesis due to the inability to recover and reuse the catalyst. Thus, due to high importance of the
%U http://www.hindawi.com/journals/isrn.organic.chemistry/2013/951749/