سال انتشار: ۱۳۸۷

محل انتشار: دومین کنگره بین المللی علوم و فناوری نانو

تعداد صفحات: ۲

نویسنده(ها):

Abdolhamid Bamoniri – Department of Chemistry, College of Science, University of Kashan, Kashan,I.R.Iran
Azadeh Azimi –

چکیده:

Solid acid catalysts have served as important functional materials for the petroleum refinery e.g. cracking processes, and for the production of chemicals. However, processes involving conventional acids are typically associated with problems of high toxicity, corrosion, catalyst waste, use of large amounts of catalyst, and difficulty of separation and recovery. Because solid acids are environmentally friendly with respect to corrosiveness, safety, reduced waste, and ease of separation and recovery, replacement of liquid acids with solid acids is desirable in the chemical industry [1].Nanoparticles such as silica have been widely used to reinforce polymer systems and fabricate nanocomposite[2,3]. It can be prepared by sol-gel method, which is being actively studied in leadinglaboratories all over the world [4]. The sol–gel reaction has already been widely used in the preparation of organic/inorganic hybrid materials in recent years. The sol–gel process consistsof hydrolysis and condensation reactions. One of the major advantages of the sol-gel process is the possibility to prepare multi-component systems [5]. Acylals have interest as an alternative to acetals for the protection of aldehydes because of their stability to basic and neutral media. 1,1-diacetates are synthetically important precursors for the preparation of 1-acetoxy dienes for Diels-Alder reaction[1]and so are useful intermediate in various transformations such as nucleophilic substitution reactions [6]. In continuation of our investigation about application of solid acids in organic synthesis, here we wish to report a new application of nano silica phosphoric acid, for the conversion of carbonyl compounds to acylals under mild and heterogeneous condition. The products were achieved in good to excellent yields