In this work, we report an efficient and facile preparation of diphenylmethylethers (benzydryl ethers, DPM-ethers) from benzhydrol and alcohols or phenols. Wells-Dawson heteropolyacid (H 6 P 2 W 18 O 62 .24H 2 O), bulk or supported on silica showed catalytic activity for DPM-ethers preparation in toluene, at 60-80°C, in 0.5-1.5h. In these conditions twelve diphenylmethylethers of alcohols and phenol were obtained which excellent yields (78-96%). The heterogeneous reaction conditions provided a

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... ery simple, environmentally friendly, clean, economical and selective protocol, for the preparation of unsymmetrical ethers. The catalyst is easily recycled and reused without loss of the catalytic activity. In view of the obtained results when the bulk catalyst was employed, we used WD 40 /SiO 2 for comparative purposes; very similar yields were obtained in comparable reaction times (entries 15-24). Furthermore, use of the supported catalyst allows an easy separation and recovery for its immediate reutilization. Recycling of the catalyst was studied for the reaction between methanol and benzydrol using WD 40 /SiO 2 . The procedure was repeated twice without any significant loss of activity, as the catalyst remained active even after the third cycle (93% yield, entry 15). Similar results were obtained for DPM-ether of phenol (85% yield, entry 23). Experimental Section General Procedures. Commercially available alcohols and phenols Aldrich or Fluka were distilled or recrystallized before use. Melting points of the compounds were determined in open capillary tubes and are uncorrected. Boiling points were read from a thermometer in the microdistillation head and are reported uncorrected. 1 H-RMN spectra (CDCl 3 ) were recorded on Bruker 200 MHz spectrometer using TMS as internal standard. Low-resolution mass spectra were recorded on a Perkin Elmer GC-MS model (Q-MASS 910). Spectral data agree with the expected values. Elemental microanalyses were performed in F & M instrument. The purity determination of the products was accomplished by GC analysis on a Perkin Elmer instrument and TLC on silica gel 60 F 254 plates, for co-injection with authentic samples prepared by known methods. The purity established by GLC, was better than 97% in all the cases. Catalyst preparations The Dawson acid (H 6 P 2 W 18 O 62 .24H 2 O.) was prepared by the Drechsel method 19, 20 from a α/β K 6 P 2 W 18 O 62 .10H 2 O isomer mixture. This Dawson-type salt was prepared according to the technique reported by Lyon et al. 21 . Concentrated H 3 PO 4 in a 4:1 acid/salt ratio was added to a boiling aqueous solution of Na 2 WO 4 .2H 2 O, and the mixture was kept boiling in a reflux system for 8 h. The salt was precipitated by adding KCl, then purified by recrystallization and cooled overnight to 278 K. The product, which is a mixture of the α and β isomers, was filtered, washed and then vacuum-dried for 8 h. The acid was obtained from an aqueous solution of α/β K 6 P 2 W 18 O 62 .10H 2 O salt, which was treated with ether and concentrated HCl (37%) solution. The Dawson acid so released formed an addition compound with the ether, which allows it to be separated from the solution. After obtaining the ether solution with the acid, the ether was eliminated by flowing dry air and the remaining solution was placed in a vacuum-desiccator until crystallization. Silica-supported Wells-Dawson acids (WD 40 /SiO 2 ) was prepared by wet impregnation Grace Davison silica (Grade 59, specific area= 250 m 2 /g) with an aqueous solution of the synthesized WD acid. A catalyst containing 40 wt% of WD was prepared. After impregnation, samples were dried at room temperature in a vacuum-dessicator for 8 h.