Journal of Molecular Catalysis A: Chemical 366 (2013) 171–178 Contents lists available at SciVerse ScienceDirect Journal of Molecular Catalysis A: Chemical j our na l ho me p age: www.elsevier.com/locate/molcata Friedel–Crafts alkylation of sodium salicylate with 4-tert butylbenzyl chloride performed in aqueous dispersions of mesoporous oxides Zebastian Bohström a,∗ , Hanna Härelind b , Krister Holmberg a a Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, SE-412 96 Göteborg, Sweden b Department of Chemical and Biological Engineering, Applied Surface Chemistry and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden a r t i c l e i n f o Article history: Received 4 January 2012 Accepted 18 September 2012 Available online 26 September 2012 Keywords: Reactant incompatibility Friedel–Crafts alkylation Sodium salicylate 4-tert-Butylbenzyl chloride Mesoporous oxides a b s t r a c t Reactant incompatibility is a common problem in organic chemistry. In this study we investigate the use of concentrated aqueous dispersions of mesoporous oxides to overcome incompatibility in the Friedel–Crafts reaction between sodium salicylate and 4-tert-butylbenzyl chloride. The mesoporous material was first impregnated with the water-soluble nucleophile, sodium salicylate, and the “loaded” particles were then dispersed in the apolar electrophile, 4-tert-butylbenzyl chloride. A range of different mesoporous oxides and one clay mineral, montmorillonite, were investigated as catalyst for the reaction. These were all characterised with small angle X-ray scattering (SAXS) and with nitrogen adsorption (BET and BJH methods). Their Lewis and Brønstedt acidities were determined by ammonia adsorption exper- iments using diffuse reflection infrared Fourier transform (DRIFT) spectroscopy as detection method. The reaction proceeded well and gave high yields provided proper stirring was maintained. Alumina, an aluminosilicate and montmorillonate were the most efficient catalysts. These were also the materials that showed the strongest Lewis acidity. In general, there was good correlation between Lewis acidity and efficiency of the material as catalyst for the Friedel–Crafts alkylation. Attempts to reuse the catalyst were not entirely successful. Deactivation occurred after the first run. ESCA indicated that the reduction in performance was due to adsorption of carbonaceous residues on the catalyst. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Friedel–Crafts alkylation is one of the most useful types of reac- tions in synthetic organic chemistry and a common method for C C bond formation to aromatic rings [1]. Typically, an alkyl halide is reacted with an arene using a strong Lewis acid, such as AlCl 3 , ZnCl 2 or BF 3 [1]. The alkyl halide may be replaced by an alkene or some other species capable of generating a carbocation when exposed to strong acid [1]. The carbocation formed acts as the electrophile in an electrophilic aromatic substitution. Also strong Brønstedt acids, such as H 2 SO 4 and HF, can be used as catalyst [2]. Liquid phase Friedel–Crafts alkylations performed in large indus- trial scale, employing Lewis or Brønstedt mineral acids, give rise to large volumes of corrosive waste streams [3,4]. Increased public awareness and more rigid environmental leg- islation have elevated the drive towards sustainable development and cleaner, less hazardous synthetic routes [5]. Environmen- tally benign synthesis routes sometimes suffer from increased cost and/or reduced process effectiveness and the use of ∗ Corresponding author. Tel.: +46 031 772 2812. E-mail address: zebastian.bostrom@chalmers.se (Z. Bohström). water-soluble reactants may lead to problems with poor compat- ibility between reagents. Performing a Friedel–Crafts alkylation reaction with incompatible reactants in a two-phase system would require the use of a phase transfer catalyst (PTC). The PTC, usually a quaternary ammonium compound or a crown ether, is a rela- tively toxic species and needs to be completely removed from the product after completed reaction [6]. As an alternative to the PTC approach, a solvent capable of dissolving both hydrophobic and hydrophilic reactants may be used. Examples of such solvents are the polar aprotic liquids, such as dimethylsulfoxide, acetonitrile and tetrahydrofuran. These solvents are relatively expensive and have non-negligible toxicity [7–9]. It has previously been reported that a suspension of mesoporous oxide particles in an apolar medium is an environmentally attractive approach to the problem of reactant incompatibility [10–12]. The hydrophilic mesoporous particles are filled with an aqueous solution of the polar reactant and the surrounding apolar phase contains the apolar reactant. If the apolar reactant is a liquid, it may constitute the apolar phase, i.e., the reaction is then performed without any organic solvent. The environmental and safety advantages of such reaction systems are obvious. Solid catalysts are attractive for industrial processes because they are normally relatively easy to separate from the product and 1381-1169/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molcata.2012.09.020