Aluminium Oxyfluoride and the Polymerized Species in AlOCl Solutions

Abstract

ALTHOUGH the crystalline aluminium oxyhalides AlOCl, AlOBr and AlOI are known^1–3, the corresponding AlOF is not. We have tried to prepare AlOF by the procedure which is commonly used to prepare the other AlOX compounds, namely, the reaction of 3 AlF₃ with As₂O₃ in sealed evacuated glass ampoules at elevated temperatures. However, AlOF was not formed at temperatures up to 480° C, although reaction between AlF₃ and As₂O₃ did occur. Details of these experiments will be published elsewhere. Whereas AlOCl can be prepared by the reaction of steam and AlCl₃ (ref. 4), it does not appear that AlOF can be prepared by a comparable reaction with AlF₃. Schober and Thilo⁵ found that AlF₃ reacts with steam at temperatures up to 600° C to form a product with a 5.2 per cent fluorine content, and lower fluorine contents at higher temperatures. They formulated their product as Al₇O₁₀F. Locsei⁶ obtained similar results but preferred to formulate the product as a mixture of Al₂O₃ and AlOF. No reason was given for the latter choice, but even if it were correct the product would be predominantly Al₂O₃.