Hydrolysis of isobutylaluminum aryloxides studied by 1H NMR and quantum chemical methods

The results of ¹H NMR and quantum chemical studies of hydrolysis of isobutylaluminum aryloxides are presented. According to the data of ¹H NMR spectroscopy, the hydrolysis of monomeric diisobutylaluminum aryloxides (2,6-Bu₂ ^t—C₆H₃O)AlBu₂ ⁱ and (2,6-Bu₂ ^t,4-Me—C₆H₂O)AlBu₂ ⁱ occurs selectively at the Al—OAr bond to form the corresponding sterically bulky phenol and polyisobutylaluminoxane. At the molar ratios Al: H₂O = 2, the formed sterically bulky phenol reacts slowly with diisobutylaluminum monoaryloxide to form isobutylaluminum diaryloxide. Dimeric aryloxide [(2-Bu^t—C₆H₄O)AlBu₂ ⁱ]₂ is not hydrolyzed under similar conditions. The quantum chemical calculations confirmed the experimental results: the hydrolysis at the Al—OAr bond has a lower energy barrier than that at the Al—C bond because of the formation of ({H_{{H_2}O}} ldots {O_{O - Ar}}) hydrogen bonds.