Thermal decomposition of primary and secondary amine adducts of triethylaluminium and diethylaluminium halides

Abstract

The stabilities of the adducts Et₂XAl–NHMe₂ and Et₂XAl–NH₂Bu^t toward thermal elimination of ethane follow the order X = Et < Cl < Br < I. This order is correlated with i.r. and n.m.r. spectral data to show that adduct stability is principally a function of the negative charge density on the α-carbon atoms of the ethyl groups bonded to aluminium, and not a function of the nitrogen proton acidity. A discussion of the factors influencing the distribution of electron density in the Al–C bond is presented. A study of the thermal decomposition of Et₂ClAl–NHMe₂ shows that the reaction follows zero-order kinetics, indicating that it is predominantly surface catalysed.