Aluminium chloride complexes of 2-isocyanatobenzoyl chloride and phenyl isocyanate—an infrared spectroscopic study

Abstract

The i.r. spectrum of the 1 : 1 complex of aluminium chloride and 2-isocyanatobenzoyl chloride (1), in ethylene dichloride solution has been compared with the spectra of (1)–HCl and PhNCO–AlCl₃ adducts. The (1)–AlCl₃ adduct has been shown to be an equilibrium mixture of at least four structures, namely (1), N-dichloroalanylphenylcarbamoyl chloride (11), the insertion compound (12), and the 1 : 2 adduct (14). The formation of N-dichloroalanylphenylcarbamoyl chloride in the reaction of aluminium chloride with phenyl isocyanate has been demonstrated. The 1 : 2 adduct of (1)–AlCl₃ has been postulated to exist as an equilibrium mixture of the acyclic compound (14) and the cyclic 1-dichloroalanyl-2-oxo-3,1-benzoxazinium ion (15).