Additions and corrections

Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates and their use as catalysts in the solvent-free tetrahydropyranylation of alcohols and phenols

Vasudevan V. Namboodiri and Rajender S. Varma

Chem. Commun., 2002, 342 (DOI: 10.1039/b110565e). Amendment published 10th April 2002

The chemistry involved in the reported formation of the tetrachloroaluminate salt using AlCl₃.6H₂O is more complex than was reported earlier. The title compound is now redefined as a chloroaluminate melt that catalyzes the solvent-free tetrahydropyranylation of alcohols and predominantly consists of AlCl₄^- with some Al₂Cl₇^- (sharp peak at 102 ppm with linewidth, Δν_1/2, 380 Hz), the remaining aluminium component being in the octahedral environment (broad peak at 6.35 ppm) of unidentified nature. The areas under the downfield and upfield peaks are in the ratio 3:1. On the other hand, the exothermic reaction of the imidazolium chloride with anhydrous AlCl₃ under inert atmosphere does provide the title tetrachloroaluminate salt as a liquid (sharp peak at 103 ppm, neat solution) that also catalyzes the tetrahydropyranylation. However, we find the use of solid product much more convenient in terms of handling in air and moisture. ²⁷Al NMR is recorded for both the solid and liquid product at 104.2 MHz with aluminium chloride in water as the standard at 0 ppm (courtesy of Professor Richard Pagni at University of Tennessee, Knoxville, USA).

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