REACTIONS OF TRIALKYLALUMINUM WITH STERICALLY HINDERED DIOLS

The reactions of trialkylaluminium R3Al (R=Me, Et) with 2,4-pentanedio ls [(CH3)(2)(OH)CCH2C(CH3)(2)OH (A)], [(CH3)(2)(OH)CCH2CH(OH)CH3 (B)] and 2,5-dimethyl-2,5-hexanediol (C) were studied. Sterically hindered 2,4-pentanediols (A, B) react with alkylaluminium compounds to form ma inly cyclic compounds 1-3 of a formula R5Al3[diol(- 2H)](2) possessing one central five-coordinated aluminium atom and two terminal four-coo rdinated aluminium atoms. All the compounds were characterised by mean s of NMR spectra, elemental analysis and molecular weight determinatio n. The molecular structure of the solid Me5Al3[O(CH3)(2)CCH2C(CH3)(2)O ](2) 1 was determined by X-ray diffraction analysis. Substituted at te rminal carbon atoms 2,5-dimethyl-2,5-hexanediol (C) forms organoalumin ium oligomers exclusively. The influence of the diol carbonchain lengt hs and its substituents on the yield of the cyclic complexes and organ oaluminium oligomers are discussed. (C) 1998 Elsevier Science S.A. All rights reserved.